Troubleshooting is getting to be a lost art. Parts replacers and tech that just give up are taking over. Nice to see a person like you in action. Certainly hope some young kid see this and learn a valuable lesson. Thanks for the vid and your effort.
I have one of these that I built in about 1988. Prior to that, I was using a Sony TAE-5450. The difference in detail and soundstage was amazing! I still use the TAN-5550 V-FET amp that came with it, to drive my tweeters. Alas, all my gear is in need of re-capping. I'll certainly pay attention to circuit voltages and increase headroom when I do it. Thanks for the heads-up!
Fantastic repair I love how you take us through the troubleshooting process that is really helpful. I'm going to lock that tip about using heat by a transistor to help find a noisy component in the ole bag of tricks. You got to love vinyl.
Its people like you who make me appreciate electronics technicians. You have so much patience and knowledge. I could learn a few things from you. Time to binge watch your videos for the next few days. You've earned yourself a subscriber!
This is helpful. The left channel of my dh-200 sounded just like that just before the right channel destroyed a resistor (or diode, we'll have to match dental records). I know they are quite different units, but as a n00b I very much appreciate your explaining why you check what.
LOL. As I watch you fix this pre amp, your voice is going through that exact same model here I'm using for my computer sound! I don't remember what the problem mine had years ago, but it's been great after I fixed it. I like the nice linearity of all the pots. The remaining problem with my Hafler is just a POP out of the speakers when I power it up. I just have to remember to turn the amp on after the pre amp goes on. Ya, those boards are a bear to work on. At least the whole board is exposed when the bottom cover is removed. Good job. Mine has the rack mount ears too.
I have a fisher ca39 that does the same pops even at no volume on power on. If your pops are bad or if you dont want them to happen, easy thing to do is stick a full sized headphone jack to 3.5mm jack adapter inside the headphone line it and pull it out after power up. Kind of a pain, in my case the pop isnt that bad though. Cheers
Congratulations for such a good repair!!! You are a genius searching for failures with such a few tools like a single multimeter and sometimes the scope. I think this preamp should be a very expensive one when it was new, because you have spent so much time fixing it up. Don’t want to imagine how much this repair cost to the owner.
i worked for a small manufacturer of custom military power supplies for 25 years, we did almost everything in house - made our own PWB's, all of our metalwork including heatsinks. Sometimes you would have a short on the heatsink and sure enough it was a burr that was punching through a mica insulator. These were TO3 transistors so you had to desolder the leads to get to the heatsink surface - what a pita.
Carl Franz I always thought they were all in kit form like the dynamo amps, but others have told me they were available factory assembled. I was building heathkit around the time these were out. Yes they do sound nice.
12voltvids I think your correct except that the factory assembled were from kits and were simply cost plus for assembly. I was a little teary seeing a 110 like that. Had it been a 120 I'd have probably in tears. I have really fond memories of my first major kit builds. Anyway, good on you for fixing the wee beknighted thing.
Haffler 110 Preamp produced from 1979 thru 1983... this unit is anywhere from 37 to 41 years old! FIRST rule of thumb: replace ALL electrolytic capacitors regardless of ESR testing. If they show still good, they will fail soon. Crazy how the leaking electrolyte caused conduction on that voltage regulator heat sink. A capacitor leakage tester is always a wise investment. Looks like Haffler used a proprietary numbering system for their transistors. Some manufacturers do that so that unknowing techs would feel obligated to order from them instead of using a standard cross-reference chart. I am not trying to be a troll here just my observations is all. I respect the patience and time it takes to troubleshoot electronic circuits, not a job for the meek that's for sure. Chasing electrons can be very interesting sometimes. Good job!
Can only replace what the customer is willing to do. Most of these units I do are for flippers. They just want them operational at the lowest cost so they can sell. They don't care if the new owner has to spend money down the road. And you are incorrect, as I have lots of old equipment that is 40 years old and the caps are still fine. Not all will fail, usually only certain caps in certain circuits will go bad, and those have been done.
Hafler - A division of Radial Engineering Ltd. Could not resist, had to google Hafler and they appear to be in your backyard there in BC. I was surprised at the number of components that gave up the ghost and it made me think the unit, since it might be a kit, must had been made with junk parts. But it looks like the design was doing it in, ie the working volts of the electrolytics etc. Good repair job. Watched the whole thing.
Hafler amps are now made in Canada. They are about as high end as you are going to find. Absolutely stunning. This one is one of the legacy products and they were USA designed and assembled for the prebuilt pieces. Dynaco is also Hafler, same company for the old tech.
I remember back in Europe,(in1980's),reading article about Haffler amplifiers.Local DIY magazine was claiming that Haffler was high-end product. For some reason I clearly remember after all this years article was describing how Haffler is using quality parts and only the best,polypropylene capacitors!I didn't know much about polypropylene capacitors and I don't know much about them right now,but those ones in these video look like regular electrolytic caps. If I was owner of these preamp,I would pay you to replace all capacitors. I just like old products.
Just to add to what others have surely said. The lettering system on European transistors 'Pro Electron' system by Philips and Mullard: 1st letter A=germanium B=silicon 2nd letter A =low power diode B=varicap C=small signal D=power etc. The valve system was similar ie. ECC81 was E=6.3V C=triode(x2) then the number of type. For us Europeans who are familiar with US numbering and Japanese numbering too, it's like someone doesn't know where milk comes from. Edit; It's cows.
Nitpick: 2N3904 or NTE/ECG123A *do not* make a very good Q12 replacement. BC550B is a garden variety high beta Euro transistor, B traditionally being the medium grade - it's the input of a Darlington and probably running at only around 15 µA going by R33, you need something that doesn't tank at Ic that low. I would have thought most everyone involved in audio would have a bunch of BC550s/560s floating around, as they really are super common, but I guess not. If you have 2SC945 or 2SC1845, those would do with some pin twisting. BC416C specs match those of ON Semi's BC560C very closely, so I'd recommend one of those. I have literally no idea why they would have used BC414/416 in one circuit and BC550 in another unless they knew something not obvious from the datasheet - maybe two circuit different designers, or the former were slightly cheaper than the latter. Otherwise, great job as usual. Never would have figured innocent little Euro transistors would trip you up!
Of course a 2N3904 will go well below 15uA and do it quite nicely. The BC550 would be a European number, and we don't see much of that here, plus I am not about to order a transistor in, or drive 50 miles round trip to buy one at the not so local electronics shop. I use what I have kicking around the shop if I have an equivalent substitute.
I have a cheap vacuum solder sucking station. No Hacko or anything like that but it's gold. Not sure if you use a sucker and wick but the vacuum solder sucking station is amazing!
@@12voltvids I just heard your comment about solder guns in the mini pioneer amp repair video :D To be honest, when they are working well they are amazing, but they do mess up and require quite a bit of fiddling. If i were a pro repair man i would probably buy a hacko but i settled with a half decent solder desolder station o fund on ebay. What a crazy design on that pioneer mini! I was thinking why! Why didn't they just make a nice simple amp, all the time they must have put into that thing. It was pretty novel and a bit strange but not really something i would pay any money for. Would be nice to see more professional power amp and high end 80's 90's audiophile repairs. Amazing work!
@@izzzzzz6 In the tube days they were good for soldering point to point, and making chassis ground connections because you needed lots of heat, but overkill for circuit board work.
Thanks for the great video Dave of this repair. I know this is way off what you work on but it's basically the same. I'm working on a Sears Road Talker 40 AM/SSB vintage CB Radio and it has the same fault in it's audio output. So using your technique of heating transistors may just find the fault and fix this very rare vintage two way radio. "It has crackling noise at the mono speaker output that uses a UBC1182H 5 watt audio IC." Because these radio's are 30+ years old leaking electrolytic cap's cause most of the problems with these old radio's. So thank you as you have given me something else to try to get it working great again. Dallas
You can up the voltage and it won't hurt anything but it will change the sound. Not by much but higher voltage capacitor will also have higher esr which is the resistance to passing an ac signal. With coupling capacitors changing the pass resistance will change the sound. In the case of equalization it will change the band pass. I made that mistake once back in the 80s on one of the first amps I ever recapped. All the originals were 63v and all the caps the shop bought was 160 and 250, so I changed them all out. Fire it up sounded fine. Sent it out and it became a boomarang. Customer said it sounded like crap. Ended up changing them all a second time. Boss wasn't happy and told me I was wrong that the caps I put is were fine and it was always ok to up the voltage. I ordered in lower voltage 63 volt and changed them all back. Amp went out again and didn't come back. That was my first and last lecture from an audiophool because after that 1 experience my boss started refusing to work on any of those high end amps and told the owners to take them somewhere else.
the curve tracer is the best piece of test equipment I own you can run through that amp in no time and locate the defective components 👍 been using it for several years
I have hardly any test gear and have no intention of buying any more because i do this only as a hobby and have no real interest investing too much into something that i could just decide one day i don't want to do it anymore.
my Magnavox Astro-Sonic had transistors in TO-1 cases and i had a hell of a time putting new transistors in because the holes on the board didn't correspond to order the transistor leads were on the To-1 case so i got to-5
Smashing repair dave. "Put that in your pipe and smoke it!" I havnt heard that saying in years lol :-D. That preamp never stopped giving did it lol :-D, but i bet you enjoyed doing some of it. I have to give the Lm317 full marks for not failing, i know regulators do have protection but i've seen so many that have popped on overloads. i find the Lm317T very handy, 1.25v ref between two resistors programming. Also the TL431 is a handy little shunt regulator, 2.5v ref between resistors, used in the feedback of switchmodes.
zx8401ztv These units are generally pretty good to work on as they are pretty simple. I much rather work on vintage stuff than new crap. I give up pretty quick on the modern junk but the old units I have much more patience with.
There are a few other old quotes I could use like "I haven't seen one of those in a ----'s age" but I don't need that attention. I one said said 'I haven't see one of those since god was a child" and I caught hell for that one.
do you think maybe the non shorted leaking cap has spilled its guts on the circuit boad and the electrolite is causing a short or at least a paristic drain load?
what about using BC182L for NPN and BC181L for PNP both seem to be 50v, for a 10w amp I would use BD131 for the the NPN and BD132 for the PNP might have it flipped.
I'm very impressed with your diagnostic skills! But what causes solid state components like those transistors to short and go bad?? Was that enabled by the wonky voltage by that shorted regulator? Electrolytic caps going bad, I can definitely understand.
Transistors definitely do go bad. When the regulator failed due to the carbonation of the plastic screw it pulled the + rail down from 23v to 3v. The transistor that failed was on the - supply rail. It may have been stressed because the + side was low. I don't know. I do know that initially it did work, as I had both channels playing and then there was a pop when I wiggled one of those flat connectors that connect the input / output panel to the board and the left channel went dead. I had been starting to investigate the noisy preamp initially. So it may have been a connection on the plug that was bad and when disturbed it surged and popped that transistor. There was MUCH footage cut on the troubleshooting on this unit. I may go back and cut a long version for patreon users showing the complete process which would be well over 2 hours in length, as I did cut much stuff out while I was disconnecting circuits and checking for shorts ect that were dead ends so they were removed. Only the hard core troubleshooters would be interested in this. I don't have many patreon users though, so releasing special versions are not high priority right now, but this one may be interesting enough to do a second version.
great video repair tutorial I have one of those units with similary problems on phone channels hum noise i would appreciate any recommendation thanks regards
Hi Dave, Just like the earlier voltage regulator repair you did, did these bad transistors just decide to fail all on their own? Or, did that short caused by the leaking electrolytic capacitor have something to do with it? I used to think that a solid state component would fail mostly because some other component failed. Thanks for all the troubleshooting details, Tom
you get in there with tools to start troubleshooting where the distortion is or you take it to someone who's competent in repairing it and be prepared to pay whatever they charge you to fix it. Option two is just buy a new one.
My transistor guitar amp is hissing at every note played, but silence when im not playing anything, can anyone help suggest a solution? This is way too technical for me to understand, thank you
Ha ha. My *Hafler P3000* puts out a few DC volts at start up, and then drops to 0.004 volts after about 20 seconds. How do I track that down? Other than put new transistors in. New caps maybe? Not too healthy for a speaker coil. ha ha .
Transistors won't cause that. It is unbalanced start up, and there is little you can do except have a speaker switch and keep them disconnected until everything has stabilized. Start changing caps and you may make it worse. Haffler were bad designs because they had no protection for speakers. Any amp worth being called an amp will have a DC protection circuit that will kill the speakers at the first sign of DC and keep them delayed until everything is stable at power up.
@@12voltvids YOU are the MAN! Thanks. I also have an AB International Precedent 900a power amp that sounds really really good. I'll just stick with that. Thanks
Hello I have an old dh-110 myself that has problems with the tone circuit. Horrible poping and cracking as the tone bypass button is touched. Anyway I can get intouch with you for repair work? Thx Tim
Never seen that before but it made me think of when a board gets burned out and leaves carbon behind making it conductive. If repairing a burned out board always remove all of the carbon to avoid conductivity where you don't want it.
Another interesting and educational video from 12voltvids (I learn something new by watching each one) - is there anything you can't fix? cheers for this one. "2 thumbs up"
Apparently not. Just restored my old Rogers Majestic that I started on a few weeks ago. Had it barely working last time, but now it works like a champ.
SinsBird. The Motorola 416 is common as much. What the C designater means I don't know. That said, a good replacement with a better noise floor are 2N4401 and 2N4403 especially in RIAA circuts.
2N3906 and 2N3904 where the ones I subbed in. They cross to a 159 and 123A respectively. I just use what I have on hand. The basing will likely be different, and this might cause some confusion should anyone else work on it in the future, but anyone with a background will quickly figure out that they were subbed. Been doing this long enough to know what parts can and can not be subbed. 37 years in the electronics service business. I do think I know what I am doing, but so far 2 have given me the middle finger.
hi is possible you let me know where I can download the parts list like the one u have on the video include nobs and potentiometers for this unit and where I can buy parts for/ please if u can thanks so much
Sorry for my noob question, when 22v is grounded to the chassis, would that not zap you when you touched the chassis? If not, what are the reasons? To little current at that point? any help understanding it appreciated! Thanks! Amazing video, some GREAT information to learn from here! Thank you much 12voltvids!
Well you have to have a path from the source to ground. Devices with transformers are electrically isolated from the supply by the nature of how a transformer works. That is why my work bench test power is running on an isolation transformer. So for example if I was standing in a bucket of water and I touched the hot or return wire to my transformer I would feel nothing. Try that with the hot wire from the mains and you are going to feel pain. Why, well the mains transformer is earthed at the pole as all the neutral wired are bonded together and grounded. The current would flow from hot, to ground and then back to the grounded neutral at the transformer. Now with your isolation transformer you would be grounded but it wouldn't matter which of the secondaty wires you touched you would not receive a shock because the other side is open. To get a shock from isolation transformer would require touching both wires at the same time. The ground would not matter as it is not in the circuit. It is isolated by the transformer.
@@12voltvids That brings up another question. I saw a video where STS Telecom channel got zapped by lightning, that video and the comments lead me to an isolated transformer explanation (by Carlson's Lab) saying that the newer ones (like last ~50 years) are likely not really isolated because the "chassis" of the isolated transformer as well as the ground pins on the outlet side are all connected to ground. Then it's mentioned that your ground outlets are actually tied into your neutral in your power box outside - giving a low ohms pathway? If this is true, does it not defeat the purpose of a isolated transformer? Also giving you an illusion of safety when this is the case? Thanks for your help and feedback! Your videos have helped answer a lot of questions over the time I have been learning.
@@whoisntwhoisit2126 well if the transformer is grounded and the ground is passed through to the secondary side then it's not an isolation transformer. There are transformers that have 3 prong grounded outlets on both the input and output outlets. These are not insolation transformers. They are transiet supressor transformers. They use the iron core to saturate and absorb transiets and noise and prevent noise generates on the secondary from making it back into the mains line. A true isolation transformer has a 2 prong plug and a 2 prong outlet. There is no ground at all. You can convert the other type by cutting the ground wires and the neutral to case bond on the secondary side.
@@12voltvids Interesting and here I thought Paul at Carlson's Lab was extremely bright -now I have come across a few things that have made me wonder what is up... thank you for taking the time to explain! :)
@@whoisntwhoisit2126 I know Paul. He does know a few things. He is more into test equipment and old radios where I deal with mostly solid state and video gear. Thats what I did for a living for many years. I collect old radios and restore them to make them operational safely, but I don't bother with the super tuning and alignment because I really don't use them. Nice to have functional for local radio but as far as dx goes I don't rely use them. Don't want to run excessive hours on antique tubes. For me they are more a display piece that I plug in every so often and run for an hour or so to demonstrate but far too valuable to use as a daily driver and therefore if it is slightly out of alignment it isn't important. Besides, align it today and let it sit and it will need doing all over again.
Why was the amp distorted? You made it spill it's guts!! :) Great detective work!! That bad transistor in the phono pre-amp makes a noise like a bad connection.
Hi, where can i download electonic service manual / circuit diagram ? there's one clips you show how and sites, not remember which one . great video always. thank you.
I think it is perfectly akin to nitrogen CPU overclocking when they use caps without voltage headroom. Both scenarios attempt to gain perfomance at the cost of reliability. In the initial case, what is someone going to do - stay there and pour for the rest of the machine's life (rhetorical?) In the latter case, I think the design engineers are chasing some effeciency or whatnot, but as evidence shows, that is an extremely poor decision overall. As someone that loves best sound possible for any given gear, reliability is still far more of an important consideration. As you said, holy crap no headroom. Not intelligent design but it is probable that the chance to learn better from data available from the units in the field (aka: failure rate) inspired better thinking! We can hope! Even to the best of the best in large companies, as a consumer and a simple 2 cents, this is what I hope you can provide.
hey i got a denon 2802 would you like to work on it? hey but i also see that you don't answer your comments. if want support you also have to answer you the comments.
Can't believe the owner didn't want all the electrolytics to be replaced. Even using "audio grade" Nichicon, Elnas or Rubycons at those values would be cheap to replace and there'd be no worries about further failures down the line for many years. My guess is that the owner intends to put this unit on Ebay as a working unit and take as much profit as he can, even though it will most likely fail relatively soon due to the remaining old electrolytics; pretty shitty that.
Not every electrolytic is going to fail. There are common ones that fail, and they fail over and over. Others will never fail. I just do what people ask. If someone comes in and asks for all the caps to be replaced, I do that and charge by the hour. Rarely do I get those gravy jobs because usually if someone wants all the caps replaced, they just do it themselves. As to it being sold on Ebay, who knows. Generally when I fix something myself that I intend to sell I just do what is necessary to get the unit going, because once it is gone it isn't my problem, and I would bet that 99.9% of people selling are going to do the same thing. It doesn't take troubleshooting skill to shotgun it and change all the caps. It does take skills to find the bad part and change just the bad part. In this one changing all the caps wouldn't have fixed it anyway, because there was more than just a bad cap.
"As to it being sold on Ebay, who knows. Generally when I fix something myself that I intend to sell I just do what is necessary to get the unit going, because once it is gone it isn't my problem, and I would bet that 99.9% of people selling are going to do the same thing". Well I've never done that. I've thrown what I knew was shit away rather than Ebay it. I would never screw somebody over like that.
How is that screwing someone over. If it works it works. There is no point is spending 100.00 fixing something that you can get 100 for when you can fix it for 10 and still get 100. Putting 100 worth of parts in it doesn't mean you will get 1000 for it. Hell when I fix something for myself I won't put more into it than necessary to get it fixed, because replacing parts that are good, just because they are old does NOT GUARANTEE that it is going to last longer. Many times just changing all the caps will create more problems, because all that work unsoldering and soldering in new parts can disturb or stress other parts. Yes putting in new caps can and does stress other parts. Newer caps have different specs, and can respond totally different from the different electrolytic formulation which can cause different charge up characteristics. This can affect the long term stability of other parts. The only people that I know of that will replace every part are those that really don't understand what the problem is, blame it on capacitors and just replace em all. That is what is referred to as the "Canadian Tire" way. Take your car in, and they just start replacing parts until they get it fixed as opposed to the technician actually diagnosing the part that is faulty and changing that 1 part. This is actually much more difficult to do. If 1 capacitor is causing the fault and you change them all you are going to fix it. There are times when you do want to change all the capacitors. Those time being in vintage vacuum tube gear because they didn't know how to make capacitors back in the early days. Caps made in the 70's and early 80's were fantastic and rarely went bad. Then the quality took a dive that lasted from about 86 though to about 2006 it seems where they were just crap. Again if someone brings me a piece and says change all the caps, that is exactly what I do, but I have yet to have anyone do this in the 35 years I have been repairing electronics, and for 23 of those years I did it full time, made my living doing it. Nobody wants to spend more than they have to to fix something. When you say I can fix it for 100.00, but for 200 I can change out all the capacitors regardless if they are good or not just because they are old nobody is going for it. Hell if it was 100 to replace just the bad one, and 125 to do them all nobody I know of is going for that. I did work on some really high end stuff too, and even the audiophools whom paid a small fortune for their expensive equipment didn't want to spend 1 dollar more than they had to to get it fixed.
Which is a fair point. My point is that there are people who will sell a product as in good working order but which still has faults, that the seller is fully aware of, but which would dig too far into the profit margin to be worth repairing; they will then take the "their purchase now their problem" attitude.
Mark Anderson I put tape around the hole only then punched a hole in the tape so the screw won't contact the insulator. Just to give it more clearance. I don't have any new insulators. There is heat sink compound under the tab and it doesn't get warm.
andi1274 Did I ever say it was? My variac is plugged into an isolation transformer under the bench. I have done at least 2 videos showing it and how it works.
Just age. Electrolytics need to be replaced after 20-30 years. As far as running them close to the limit, Hafler isn't the only one, as a lot of manufacturers run parts too close to the limit, but they should have been 35V parts to begin with.
umajunkcollector Hamburger concerto. 23 minutes straight. I saw a live on tape performance of that. They played it live and it sounded just like the record and there were no computers and prerecordings back then in concert. Real musicians played it live.
Andy Palm I have seen plastic insulators break down before but it is usually the plastic insert that goes through the tab with a metal screw. Someone tightens it too much. Cracks the insulator and then it is just a matter of time.
With all this time you spend on fixing boards and doing component level repair; why don't you save yourself some aggravation and get a professional desoldering tool like a Hakko FR-300? Solder Wick will always be a last resort since having one of these..
I had a professional desoldering station years ago. Trouble was every time I needed it the bloody tip was clogged up, and in frustration I tossed it in the garbage. For the little bit of work I do I get by just fine with solder wick, or just heat the pins up and pull. Remember I don't do this full time. I retired from the business 15 years ago. If I was doing repair work every day, all day then yes I probably would invest in another vacuum pump, and perhaps if I come across one at a good price I might consider it, but really it is no effort to use wick except on some of those big IPM modules on a double sided plated board. Fortunately I don't see many of those. Last one I saw I changed the board as I had a salvage board in stock.
shaun lomas You to me. I had no idea. I plug em in and see if they work. If they don't I go looking to see why. The left channel did initially work, as I switched to phono and heard that fault. I wiggled the interconnect cable and it popped and that was it for the left channel. So either that transistor was ready to go, or a loose connection on the connector caused a spike that popped it.
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Troubleshooting is getting to be a lost art. Parts replacers and tech that just give up are taking over. Nice to see a person like you in action. Certainly hope some young kid see this and learn a valuable lesson. Thanks for the vid and your effort.
I fixed my adcom 555 while watching this video. Thanks for the repair energy to pull me through!
I have one of these that I built in about 1988. Prior to that, I was using a Sony TAE-5450. The difference in detail and soundstage was amazing! I still use the TAN-5550 V-FET amp that came with it, to drive my tweeters. Alas, all my gear is in need of re-capping. I'll certainly pay attention to circuit voltages and increase headroom when I do it. Thanks for the heads-up!
Fantastic repair I love how you take us through the troubleshooting process that is really helpful. I'm going to lock that tip about using heat by a transistor to help find a noisy component in the ole bag of tricks. You got to love vinyl.
Fascinating stuff. Using heat to find faulty transistor - amazing
Seriously that was a boss move right there.
Its people like you who make me appreciate electronics technicians. You have so much patience and knowledge. I could learn a few things from you. Time to binge watch your videos for the next few days. You've earned yourself a subscriber!
Thanks. Yes it is fun to work on the old serviceable vintage stuff.
This is not a "hocus pocus", but with a lot of patience searching for the malfunctions. Thumbs up for Dave's repair and music choice!
Thank you for sharing your shop adventures. I'm at the hobbyist level, so it's nice to learn from a veteran.
This is helpful. The left channel of my dh-200 sounded just like that just before the right channel destroyed a resistor (or diode, we'll have to match dental records).
I know they are quite different units, but as a n00b I very much appreciate your explaining why you check what.
LOL. As I watch you fix this pre amp, your voice is going through that exact same model here I'm using for my computer sound! I don't remember what the problem mine had years ago, but it's been great after I fixed it. I like the nice linearity of all the pots. The remaining problem with my Hafler is just a POP out of the speakers when I power it up. I just have to remember to turn the amp on after the pre amp goes on. Ya, those boards are a bear to work on. At least the whole board is exposed when the bottom cover is removed. Good job. Mine has the rack mount ears too.
I have a fisher ca39 that does the same pops even at no volume on power on. If your pops are bad or if you dont want them to happen, easy thing to do is stick a full sized headphone jack to 3.5mm jack adapter inside the headphone line it and pull it out after power up. Kind of a pain, in my case the pop isnt that bad though. Cheers
Congratulations for such a good repair!!! You are a genius searching for failures with such a few tools like a single multimeter and sometimes the scope. I think this preamp should be a very expensive one when it was new, because you have spent so much time fixing it up. Don’t want to imagine how much this repair cost to the owner.
Massive respect for your fault-finding abilities. The results speak for themselves.
i worked for a small manufacturer of custom military power supplies for 25 years, we did almost everything in house - made our own PWB's, all of our metalwork including heatsinks. Sometimes you would have a short on the heatsink and sure enough it was a burr that was punching through a mica insulator. These were TO3 transistors so you had to desolder the leads to get to the heatsink surface - what a pita.
Very cool to see you fixing those units and we learn alot too !
These were REAL nice sounding units when working! GREAT JOB!
Once again fantastic tutorial and a proud owner of David hafler equipment
Marvelous tutorial because there were numerous issues.
Very informative video for all kind of difficult faults, witch can cause a major head ache for hobbyist like me. Thanks
watched it twice, learned a bunch. thank you for posting this!
I dont know of any non kit dh110 or dh120. They were made to pair with something like the dh220 amp which were also kits. Also really nice sounding.
Carl Franz
I always thought they were all in kit form like the dynamo amps, but others have told me they were available factory assembled. I was building heathkit around the time these were out. Yes they do sound nice.
12voltvids I think your correct except that the factory assembled were from kits and were simply cost plus for assembly.
I was a little teary seeing a 110 like that. Had it been a 120 I'd have probably in tears. I have really fond memories of my first major kit builds.
Anyway, good on you for fixing the wee beknighted thing.
Carl Franz
That unit needs some cosmetic work and I bet it will get that from the owner. He will likely repaint the cover and make it look like new.
Haffler 110 Preamp produced from 1979 thru 1983... this unit is anywhere from 37 to 41 years old! FIRST rule of thumb: replace ALL electrolytic capacitors regardless of ESR testing. If they show still good, they will fail soon. Crazy how the leaking electrolyte caused conduction on that voltage regulator heat sink. A capacitor leakage tester is always a wise investment. Looks like Haffler used a proprietary numbering system for their transistors. Some manufacturers do that so that unknowing techs would feel obligated to order from them instead of using a standard cross-reference chart. I am not trying to be a troll here just my observations is all. I respect the patience and time it takes to troubleshoot electronic circuits, not a job for the meek that's for sure.
Chasing electrons can be very interesting sometimes. Good job!
Can only replace what the customer is willing to do. Most of these units I do are for flippers. They just want them operational at the lowest cost so they can sell. They don't care if the new owner has to spend money down the road. And you are incorrect, as I have lots of old equipment that is 40 years old and the caps are still fine. Not all will fail, usually only certain caps in certain circuits will go bad, and those have been done.
@@12voltvids Oh okay... now I understand. Thanks for the feedback!
Hafler - A division of Radial Engineering Ltd.
Could not resist, had to google Hafler and they appear to be in your backyard there in BC. I was surprised at the number of components that gave up the ghost and it made me think the unit, since it might be a kit, must had been made with junk parts. But it looks like the design was doing it in, ie the working volts of the electrolytics etc.
Good repair job. Watched the whole thing.
Hafler amps are now made in Canada. They are about as high end as you are going to find. Absolutely stunning. This one is one of the legacy products and they were USA designed and assembled for the prebuilt pieces.
Dynaco is also Hafler, same company for the old tech.
I remember back in Europe,(in1980's),reading article about Haffler amplifiers.Local DIY magazine was claiming that Haffler was high-end product.
For some reason I clearly remember after all this years article was describing how Haffler is using quality parts and only the best,polypropylene capacitors!I didn't know much about polypropylene capacitors and I don't know much about them right now,but those ones in these video look like regular electrolytic caps.
If I was owner of these preamp,I would pay you to replace all capacitors.
I just like old products.
You fixed the half of the Haffler that wasn't working. Now , it's a whole Haffler again. Excellent work as always and that's not the Haffler of it!
super job on fixing that unit
nice... Ive cut a few traces to find the short. Thank you for sharing, big time saver for any tech!
Focus! Great group. Great musicians.
Just to add to what others have surely said. The lettering system on European transistors 'Pro Electron' system by Philips and Mullard: 1st letter A=germanium B=silicon 2nd letter A =low power diode B=varicap C=small signal D=power etc.
The valve system was similar ie. ECC81 was E=6.3V C=triode(x2) then the number of type.
For us Europeans who are familiar with US numbering and Japanese numbering too, it's like someone doesn't know where milk comes from.
Edit; It's cows.
😅
Nitpick: 2N3904 or NTE/ECG123A *do not* make a very good Q12 replacement. BC550B is a garden variety high beta Euro transistor, B traditionally being the medium grade - it's the input of a Darlington and probably running at only around 15 µA going by R33, you need something that doesn't tank at Ic that low. I would have thought most everyone involved in audio would have a bunch of BC550s/560s floating around, as they really are super common, but I guess not. If you have 2SC945 or 2SC1845, those would do with some pin twisting.
BC416C specs match those of ON Semi's BC560C very closely, so I'd recommend one of those. I have literally no idea why they would have used BC414/416 in one circuit and BC550 in another unless they knew something not obvious from the datasheet - maybe two circuit different designers, or the former were slightly cheaper than the latter.
Otherwise, great job as usual. Never would have figured innocent little Euro transistors would trip you up!
I just did a full test down to 3 nano amps - .003 micro amps on 2N3904 perfect operation
emitter resistor 68 k bass resistor 2.7 meg power 24 micro watts 3 nano amps bass 9 volt rail station 500 cart on the turn table
Of course a 2N3904 will go well below 15uA and do it quite nicely.
The BC550 would be a European number, and we don't see much of that here, plus I am not about to order a transistor in, or drive 50 miles round trip to buy one at the not so local electronics shop. I use what I have kicking around the shop if I have an equivalent substitute.
good tip on heating up the faulty Transistor
I have a cheap vacuum solder sucking station. No Hacko or anything like that but it's gold. Not sure if you use a sucker and wick but the vacuum solder sucking station is amazing!
I have a manual solder sucker. Rarely use it because it sucks.
@@12voltvids I just heard your comment about solder guns in the mini pioneer amp repair video :D To be honest, when they are working well they are amazing, but they do mess up and require quite a bit of fiddling. If i were a pro repair man i would probably buy a hacko but i settled with a half decent solder desolder station o fund on ebay.
What a crazy design on that pioneer mini!
I was thinking why! Why didn't they just make a nice simple amp, all the time they must have put into that thing. It was pretty novel and a bit strange but not really something i would pay any money for.
Would be nice to see more professional power amp and high end 80's 90's audiophile repairs.
Amazing work!
@@izzzzzz6 In the tube days they were good for soldering point to point, and making chassis ground connections because you needed lots of heat, but overkill for circuit board work.
Thanks for the great video Dave of this repair. I know this is way off what you work on but it's basically the same. I'm working on a Sears Road Talker 40 AM/SSB vintage CB Radio and it has the same fault in it's audio output. So using your technique of heating transistors may just find the fault and fix this very rare vintage two way radio.
"It has crackling noise at the mono speaker output that uses a UBC1182H 5 watt audio IC."
Because these radio's are 30+ years old leaking electrolytic cap's cause most of the problems with these old radio's.
So thank you as you have given me something else to try to get it working great again.
Dallas
holly crap, that poor thing was pretty messed up, good job man.
If I have room on the board, I always up the voltage ratings for caps... it's just good sense.
You can up the voltage and it won't hurt anything but it will change the sound. Not by much but higher voltage capacitor will also have higher esr which is the resistance to passing an ac signal. With coupling capacitors changing the pass resistance will change the sound. In the case of equalization it will change the band pass. I made that mistake once back in the 80s on one of the first amps I ever recapped. All the originals were 63v and all the caps the shop bought was 160 and 250, so I changed them all out. Fire it up sounded fine. Sent it out and it became a boomarang. Customer said it sounded like crap. Ended up changing them all a second time. Boss wasn't happy and told me I was wrong that the caps I put is were fine and it was always ok to up the voltage. I ordered in lower voltage 63 volt and changed them all back. Amp went out again and didn't come back. That was my first and last lecture from an audiophool because after that 1 experience my boss started refusing to work on any of those high end amps and told the owners to take them somewhere else.
@@12voltvids That's good to know. I was referring to power supplies.
the curve tracer is the best piece of test equipment I own you can run through that amp in no time and locate the defective components 👍 been using it for several years
I have hardly any test gear and have no intention of buying any more because i do this only as a hobby and have no real interest investing too much into something that i could just decide one day i don't want to do it anymore.
my Magnavox Astro-Sonic had transistors in TO-1 cases and i had a hell of a time putting new transistors in because the holes on the board didn't correspond to order the transistor leads were on the To-1 case so i got to-5
ECG-123A, used to buy them by the dozens in the 70's and 80's. I forget the SK#.
TSM
Used a 123a for the npn and a 159 for the pnp on this repair.
great sounding repair job
Smashing repair dave.
"Put that in your pipe and smoke it!" I havnt heard that saying in years lol :-D.
That preamp never stopped giving did it lol :-D, but i bet you enjoyed doing some of it.
I have to give the Lm317 full marks for not failing, i know regulators do have protection but i've seen so many that have popped on overloads.
i find the Lm317T very handy, 1.25v ref between two resistors programming.
Also the TL431 is a handy little shunt regulator, 2.5v ref between resistors, used in the feedback of switchmodes.
zx8401ztv
These units are generally pretty good to work on as they are pretty simple. I much rather work on vintage stuff than new crap. I give up pretty quick on the modern junk but the old units I have much more patience with.
There are a few other old quotes I could use like "I haven't seen one of those in a ----'s age" but I don't need that attention. I one said said 'I haven't see one of those since god was a child" and I caught hell for that one.
Some people have no sense of humor, never trust anyone that does not have it.
So dont trust bank managers, tax man, the govenment, or dentists lol.
zx8401ztv
What's wrong with dentists? Besides them making your wallet very light.
Some just dont have any humor at all, its like being worked on by a slightly annoyed robot lol.
Yes they can be expensive.
I will be spending a lot of time with you ;) Thank you again
Beautiful video quality
do you think maybe the non shorted leaking cap has spilled its guts on the circuit boad and the electrolite is causing a short or at least a paristic drain load?
what about using BC182L for NPN and BC181L for PNP both seem to be 50v, for a 10w amp I would use BD131 for the the NPN and BD132 for the PNP might have it flipped.
Awesome video as always, thumbs up!!! :D
I wish I could learn more of this stuff. But where to start? I got "Electronics for Dummies." But that's a bit too slow. I guess I'm not a dummy.
I'm very impressed with your diagnostic skills! But what causes solid state components like those transistors to short and go bad?? Was that enabled by the wonky voltage by that shorted regulator? Electrolytic caps going bad, I can definitely understand.
Transistors definitely do go bad. When the regulator failed due to the carbonation of the plastic screw it pulled the + rail down from 23v to 3v. The transistor that failed was on the - supply rail. It may have been stressed because the + side was low. I don't know. I do know that initially it did work, as I had both channels playing and then there was a pop when I wiggled one of those flat connectors that connect the input / output panel to the board and the left channel went dead. I had been starting to investigate the noisy preamp initially. So it may have been a connection on the plug that was bad and when disturbed it surged and popped that transistor.
There was MUCH footage cut on the troubleshooting on this unit. I may go back and cut a long version for patreon users showing the complete process which would be well over 2 hours in length, as I did cut much stuff out while I was disconnecting circuits and checking for shorts ect that were dead ends so they were removed. Only the hard core troubleshooters would be interested in this. I don't have many patreon users though, so releasing special versions are not high priority right now, but this one may be interesting enough to do a second version.
Congratulations ! great job. I learn so much. the vinyl velocity is accelerated ?-
could it be your typical failing electrolytic crapacitor shorting things out? Have you run an ESR check on them?
great video repair tutorial I have one of those units with similary problems on phone channels hum noise i would appreciate any recommendation thanks regards
What a kool haffe 110 predmp
What kool mucik
Hi Dave,
Just like the earlier voltage regulator repair you did, did these bad transistors just decide to fail all on their own? Or, did that short caused by the leaking electrolytic capacitor have something to do with it? I used to think that a solid state component would fail mostly because some other component failed.
Thanks for all the troubleshooting details, Tom
What is the model of the turntable? I love turntables and cassette decks! Oh reel to reels are my favorite!
It's an Akai AP D33 direct drive.
Hi I have a technical pro H2502UrBT, 2500 Watts hybrid amplifier and I am getting distortion in the right channel. How do I fix it?.
you get in there with tools to start troubleshooting where the distortion is or you take it to someone who's competent in repairing it and be prepared to pay whatever they charge you to fix it. Option two is just buy a new one.
Thanks 12voltvids.
The traces on the board look wrinklely, are they separating from the board?
My transistor guitar amp is hissing at every note played, but silence when im not playing anything, can anyone help suggest a solution? This is way too technical for me to understand, thank you
Ha ha. My *Hafler P3000* puts out a few DC volts at start up, and then drops to 0.004 volts after about 20 seconds. How do I track that down? Other than put new transistors in. New caps maybe? Not too healthy for a speaker coil. ha ha .
Transistors won't cause that. It is unbalanced start up, and there is little you can do except have a speaker switch and keep them disconnected until everything has stabilized. Start changing caps and you may make it worse. Haffler were bad designs because they had no protection for speakers.
Any amp worth being called an amp will have a DC protection circuit that will kill the speakers at the first sign of DC and keep them delayed until everything is stable at power up.
@@12voltvids YOU are the MAN! Thanks.
I also have an AB International Precedent 900a power amp that sounds really really good. I'll just stick with that.
Thanks
Hello I have an old dh-110 myself that has problems with the tone circuit. Horrible poping and cracking as the tone bypass button is touched. Anyway I can get intouch with you for repair work? Thx Tim
My Email address is available on the main RUclips page.
Never seen that before but it made me think of when a board gets burned out and leaves carbon behind making it conductive. If repairing a burned out board always remove all of the carbon to avoid conductivity where you don't want it.
And how do I get the schematic diagram for it?.
I go to Hi-Fi engine and look there and if they don't have it then I start googling. Sometimes I can find schematics other times I can't.
Another interesting and educational video from 12voltvids (I learn something new by watching each one) - is there anything you can't fix?
cheers for this one. "2 thumbs up"
Apparently not. Just restored my old Rogers Majestic that I started on a few weeks ago. Had it barely working last time, but now it works like a champ.
Hi There, this is an awesome video. Quick question, do you keep the amp plug into the wall and on while testing all the connections? Thanks
What do you mean they're not normal numbers? BC416C seems normal to me.
SinsBird
Not in the nte master cross reference. They are just normal bipolar transistors. Equivalent to ecg / nte 123a and 159.
Oh, I see.
SinsBird. The Motorola 416 is common as much. What the C designater means I don't know. That said, a good replacement with a better noise floor are 2N4401 and 2N4403 especially in RIAA circuts.
2N3906 and 2N3904 where the ones I subbed in. They cross to a 159 and 123A respectively. I just use what I have on hand. The basing will likely be different, and this might cause some confusion should anyone else work on it in the future, but anyone with a background will quickly figure out that they were subbed. Been doing this long enough to know what parts can and can not be subbed. 37 years in the electronics service business. I do think I know what I am doing, but so far 2 have given me the middle finger.
Very nice video thanks
Thank You! You are the best
my Electrophonic had a roaring channel in nearly all the positions . I wish the internet was around MUCH sooner
hi is possible you let me know where I can download the parts list like the one u have on the video include nobs and potentiometers for this unit and where I can buy parts for/ please if u can thanks so much
What kool mucik
Sorry for my noob question, when 22v is grounded to the chassis, would that not zap you when you touched the chassis? If not, what are the reasons? To little current at that point? any help understanding it appreciated! Thanks!
Amazing video, some GREAT information to learn from here! Thank you much 12voltvids!
Well you have to have a path from the source to ground. Devices with transformers are electrically isolated from the supply by the nature of how a transformer works. That is why my work bench test power is running on an isolation transformer. So for example if I was standing in a bucket of water and I touched the hot or return wire to my transformer I would feel nothing. Try that with the hot wire from the mains and you are going to feel pain. Why, well the mains transformer is earthed at the pole as all the neutral wired are bonded together and grounded. The current would flow from hot, to ground and then back to the grounded neutral at the transformer. Now with your isolation transformer you would be grounded but it wouldn't matter which of the secondaty wires you touched you would not receive a shock because the other side is open. To get a shock from isolation transformer would require touching both wires at the same time. The ground would not matter as it is not in the circuit. It is isolated by the transformer.
@@12voltvids That brings up another question. I saw a video where STS Telecom channel got zapped by lightning, that video and the comments lead me to an isolated transformer explanation (by Carlson's Lab) saying that the newer ones (like last ~50 years) are likely not really isolated because the "chassis" of the isolated transformer as well as the ground pins on the outlet side are all connected to ground. Then it's mentioned that your ground outlets are actually tied into your neutral in your power box outside - giving a low ohms pathway? If this is true, does it not defeat the purpose of a isolated transformer? Also giving you an illusion of safety when this is the case?
Thanks for your help and feedback! Your videos have helped answer a lot of questions over the time I have been learning.
@@whoisntwhoisit2126 well if the transformer is grounded and the ground is passed through to the secondary side then it's not an isolation transformer. There are transformers that have 3 prong grounded outlets on both the input and output outlets. These are not insolation transformers. They are transiet supressor transformers. They use the iron core to saturate and absorb transiets and noise and prevent noise generates on the secondary from making it back into the mains line. A true isolation transformer has a 2 prong plug and a 2 prong outlet. There is no ground at all. You can convert the other type by cutting the ground wires and the neutral to case bond on the secondary side.
@@12voltvids Interesting and here I thought Paul at Carlson's Lab was extremely bright -now I have come across a few things that have made me wonder what is up... thank you for taking the time to explain! :)
@@whoisntwhoisit2126
I know Paul. He does know a few things. He is more into test equipment and old radios where I deal with mostly solid state and video gear. Thats what I did for a living for many years. I collect old radios and restore them to make them operational safely, but I don't bother with the super tuning and alignment because I really don't use them. Nice to have functional for local radio but as far as dx goes I don't rely use them. Don't want to run excessive hours on antique tubes. For me they are more a display piece that I plug in every so often and run for an hour or so to demonstrate but far too valuable to use as a daily driver and therefore if it is slightly out of alignment it isn't important. Besides, align it today and let it sit and it will need doing all over again.
Why was the amp distorted? You made it spill it's guts!! :)
Great detective work!!
That bad transistor in the phono pre-amp makes a noise like a bad connection.
Hi, where can i download electonic service manual / circuit diagram ?
there's one clips you show how and sites, not remember which one .
great video always. thank you.
G O O G L E. Thats where I begin my search.
Great job , how to get usefull schematics ?
Beats me
What do you think of the school National Radio Institute?
Frank
I think it is perfectly akin to nitrogen CPU overclocking when they use caps without voltage headroom. Both scenarios attempt to gain perfomance at the cost of reliability. In the initial case, what is someone going to do - stay there and pour for the rest of the machine's life (rhetorical?) In the latter case, I think the design engineers are chasing some effeciency or whatnot, but as evidence shows, that is an extremely poor decision overall. As someone that loves best sound possible for any given gear, reliability is still far more of an important consideration. As you said, holy crap no headroom. Not intelligent design but it is probable that the chance to learn better from data available from the units in the field (aka: failure rate) inspired better thinking! We can hope! Even to the best of the best in large companies, as a consumer and a simple 2 cents, this is what I hope you can provide.
Wow , I can't believe that short !
hey i got a denon 2802 would you like to work on it? hey but i also see that you don't answer your comments. if want support you also have to answer you the comments.
Can't believe the owner didn't want all the electrolytics to be replaced. Even using "audio grade" Nichicon, Elnas or Rubycons at those values would be cheap to replace and there'd be no worries about further failures down the line for many years. My guess is that the owner intends to put this unit on Ebay as a working unit and take as much profit as he can, even though it will most likely fail relatively soon due to the remaining old electrolytics; pretty shitty that.
Not every electrolytic is going to fail. There are common ones that fail, and they fail over and over. Others will never fail. I just do what people ask. If someone comes in and asks for all the caps to be replaced, I do that and charge by the hour. Rarely do I get those gravy jobs because usually if someone wants all the caps replaced, they just do it themselves.
As to it being sold on Ebay, who knows. Generally when I fix something myself that I intend to sell I just do what is necessary to get the unit going, because once it is gone it isn't my problem, and I would bet that 99.9% of people selling are going to do the same thing. It doesn't take troubleshooting skill to shotgun it and change all the caps. It does take skills to find the bad part and change just the bad part. In this one changing all the caps wouldn't have fixed it anyway, because there was more than just a bad cap.
"As to it being sold on Ebay, who knows. Generally when I fix something myself that I intend to sell I just do what is necessary to get the unit going, because once it is gone it isn't my problem, and I would bet that 99.9% of people selling are going to do the same thing". Well I've never done that. I've thrown what I knew was shit away rather than Ebay it. I would never screw somebody over like that.
How is that screwing someone over. If it works it works.
There is no point is spending 100.00 fixing something that you can get 100 for when you can fix it for 10 and still get 100.
Putting 100 worth of parts in it doesn't mean you will get 1000 for it. Hell when I fix something for myself I won't put more into it than necessary to get it fixed, because replacing parts that are good, just because they are old does NOT GUARANTEE that it is going to last longer. Many times just changing all the caps will create more problems, because all that work unsoldering and soldering in new parts can disturb or stress other parts. Yes putting in new caps can and does stress other parts. Newer caps have different specs, and can respond totally different from the different electrolytic formulation which can cause different charge up characteristics. This can affect the long term stability of other parts.
The only people that I know of that will replace every part are those that really don't understand what the problem is, blame it on capacitors and just replace em all. That is what is referred to as the "Canadian Tire" way. Take your car in, and they just start replacing parts until they get it fixed as opposed to the technician actually diagnosing the part that is faulty and changing that 1 part.
This is actually much more difficult to do. If 1 capacitor is causing the fault and you change them all you are going to fix it.
There are times when you do want to change all the capacitors. Those time being in vintage vacuum tube gear because they didn't know how to make capacitors back in the early days. Caps made in the 70's and early 80's were fantastic and rarely went bad. Then the quality took a dive that lasted from about 86 though to about 2006 it seems where they were just crap.
Again if someone brings me a piece and says change all the caps, that is exactly what I do, but I have yet to have anyone do this in the 35 years I have been repairing electronics, and for 23 of those years I did it full time, made my living doing it. Nobody wants to spend more than they have to to fix something. When you say I can fix it for 100.00, but for 200 I can change out all the capacitors regardless if they are good or not just because they are old nobody is going for it. Hell if it was 100 to replace just the bad one, and 125 to do them all nobody I know of is going for that. I did work on some really high end stuff too, and even the audiophools whom paid a small fortune for their expensive equipment didn't want to spend 1 dollar more than they had to to get it fixed.
Which is a fair point. My point is that there are people who will sell a product as in good working order but which still has faults, that the seller is fully aware of, but which would dig too far into the profit margin to be worth repairing; they will then take the "their purchase now their problem" attitude.
Yes I know. I have bought "working" devices on Ebay only to have to fix them myself.
Did you find that record at the dollar store or the thrift store?
Got it for a buck at the thrift store.
@@12voltvids That's why I like thrift stores. Got 6 items of furniture for less than 200$.
Can I send you my preamp for repair?
Focus, lol, Hocus Pocus. Jan Akermann.
Did you replace that insulator or put tape on it?
Mark Anderson
I put tape around the hole only then punched a hole in the tape so the screw won't contact the insulator. Just to give it more clearance. I don't have any new insulators. There is heat sink compound under the tab and it doesn't get warm.
i wish i could find another Fluke 12. The best meter ever!!!!!
Where do you get your schematics from?
Hi fi engine
@@12voltvids thanks. Ive been hunting high and low for one for LG LV210 VHS player any ideas?
hello, your variac is not a isolation transformer
andi1274
Did I ever say it was? My variac is plugged into an isolation transformer under the bench. I have done at least 2 videos showing it and how it works.
sorry my English is not good, ok.
Nice!! Great job!!
focus hocus pocus
Haffler used to be top notch, what happened?
umajunkcollector. Age. These things are from 1980 or so.. Also Dave died (a day of mourning in my shop).
Just age. Electrolytics need to be replaced after 20-30 years. As far as running them close to the limit, Hafler isn't the only one, as a lot of manufacturers run parts too close to the limit, but they should have been 35V parts to begin with.
umajunkcollector
They are top notch. At least with all discrete parts they are very serviceable.
umajunkcollector
Hamburger concerto. 23 minutes straight. I saw a live on tape performance of that. They played it live and it sounded just like the record and there were no computers and prerecordings back then in concert. Real musicians played it live.
when he yodals, he sure hits those high notes!
Holy shit,a plastic screw was "infected"! That's so odd. Never would believe that one,...until now! Interesting for sure.
Andy Palm
I have seen plastic insulators break down before but it is usually the plastic insert that goes through the tab with a metal screw. Someone tightens it too much. Cracks the insulator and then it is just a matter of time.
hell of a lot of work there at any rate. a simple amp but damn,I could tell that was more than 2 hours of digging. Nice job.
Andy Palm
It was well over 2 hours over 2 days. Probably 2 hours each day. Lots of time went into this one.
I think that's the problem with my preamp because it makes the very same noise. Now all I have to do is try and fix it without blowing it up.
With all this time you spend on fixing boards and doing component level repair; why don't you save yourself some aggravation and get a professional desoldering tool like a Hakko FR-300? Solder Wick will always be a last resort since having one of these..
I had a professional desoldering station years ago. Trouble was every time I needed it the bloody tip was clogged up, and in frustration I tossed it in the garbage. For the little bit of work I do I get by just fine with solder wick, or just heat the pins up and pull. Remember I don't do this full time. I retired from the business 15 years ago. If I was doing repair work every day, all day then yes I probably would invest in another vacuum pump, and perhaps if I come across one at a good price I might consider it, but really it is no effort to use wick except on some of those big IPM modules on a double sided plated board. Fortunately I don't see many of those. Last one I saw I changed the board as I had a salvage board in stock.
Nice to see you didn't do a "Haffler" ass job...LOL
Some would say I did. 2 at least anyway so far. Got my 2 thumbs down.
LOL...people are just negative Nancy's...LOL
Why so many faults
shaun lomas
You to me.
I had no idea. I plug em in and see if they work. If they don't I go looking to see why. The left channel did initially work, as I switched to phono and heard that fault. I wiggled the interconnect cable and it popped and that was it for the left channel. So either that transistor was ready to go, or a loose connection on the connector caused a spike that popped it.
I save old power supplies and tvs and strip insulators from them.
🇵🇪👋🇵🇪
Poor thing.