The Guitologist Schools a Pupil for the Day! - Fender Pro Junior III Diagnosis and Repair
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- Опубликовано: 4 дек 2017
- I promised a friend recently that in exchange for helping me move house I'd let him sit in on an amp repair of his 2005 Fender Pro Junior 3 combo. So in this video, we'll let Scott sit in the Captain's Chair most of the way while we attempt to diagnose and repair his guitar amplifier. The symptoms are the amp is completely dead. We track that down to a blown fuse, but why is it blowing fuses? Eventually, we track the problem to the bias voltage supply on the output, which was causing red plating output tubes intermittently. It was too late in the evening by the time we fixed it to do a demo, so just take my word for it...amp sounded and operated like it should.
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I enjoyed this. I appreciate the troubleshooting, safety and other tips.
Love all the new technical terms I learn from your videos (21:49)!
Nice work Scott!
That was a great show! Looks like the diagnosis and repair was a success!
Scott was a fast learner. First time he ever soldered and he's using my monstrous 100W thing.
The way you look into the camera, and then say, "Hey fellers.... Brad the Guitologist here.... and there's another dude, back there..." I about fell off my chair. Epic! As always another great video, Brad. Thanks for posting!
Dude, you are quickly becoming one of my favorite youtube channels. Keep up the good work.
Thanks, Randall.
Teacher knows best-good role for you Brad
That's cool Brad teaching a young one the ropes,noticed he kept trying to dig in there with both hands and you, letting him no that's a big no no.One hand not two,unless it's safe to do so,That's what my teacher said! Thanks again for the straight forward info,always entertaining.Peace.
bob bitchen My dad taught me many, many years ago that when going into a live circuit to place one hand behind my back or in my pocket and keep it there. Fuse boxes...
Another awesome video! Love the holiday decor.. riiiiiight.. NOW. .
Good exchange!
Caps that think they are resistors. Troublesome little critters indeed. Good fix Brad.
It's like women who think they're smarter than me. :P
Love your channel... Cheers from Sweden!
Great Video Brad
The pro jr & the blues jr are famous for loose tube socket pins which is where you get quite a bit of interference/noise ,I also noticed in many of these amps. that the green filament wires from the PT to the tube socket board are hardly ever twisted ,I have dissoldered them to add a few twist that possibly could help with noise.
There's been a lot of debate on amp builder forums about the benefits of twisting. Some had stopped doing it altogether. If you think about it, the 6.3V board traces aren't twisted.
Hey Brad, Good on you for teaching someone else some skills. BTW, loved your voice at the end on the cover of "Come as you are". Good stuff mate..
+Dan79istheman thanks Dan. Good to hear from you. Hope all is well on the bottom of the world today.
Love watching soldering techniques. I have three resistors that burned on a Fender board and will need to replace them, IF the trace isnt melted. I've been putting this off for along time. I also have filters to replace on a '86 JCM 800.
lots of good tips in here... put in parts with the values facing up so people can read them seems like such common sense, but as a lot of us know, often something overlooked! also, when I was learning how to solder... i would simply heat solder and glob it on. it was difficult, resulted in so many bad/cold joints. learning to heat what you are soldering TO, was such a big A-HA moment for me! kinda like when I was learning how to roll joints and someone told me to roll the papers, not the weed. life changing lol
More of this would be great!
"Don't put your hand anywhere near it, it's energised", directly followed by you getting your hand all up in it 😂. Great vid though, kinda like you're forced to vocalise your thoughts more than usual to avoid student electrocution! Imagine the paperwork!
So...is there a Pt. 2? What a guy you are! Maybe for the newbies, you could explain why incorrect bias voltages can make an output tube red plate. If not, it was really great to see a newbie get first hand, pro experience from the Master! You may be getting more offers than just moving! Great Brad! As soon as found out you had posted this installment of Who came for dinner, I dropped what I was doing and got a cold water( needed a break and drink any way) and watched this video. Never can tell what you will come up with! Thankz
There will eventually be a Part 2. He brought another amp over as well - a SS Vox amp - that we got into but had to order a part. Part will take a while.
He's a natural.
Blowing fuses is a perfect time to use a current-limiting light bulb. It limits the current to keep things from burning up, but keeps power applied so you can chase the problem down. It's bailed me out of tough problems.
A variac helps, but a lightbulb is like an automatic variac - it limits the current to a safe value with no effort on your part. Especially good if you're dealing with something that may short with no warning.
If you short the output of a variac, you can be outputting many amps even at low voltage. A variac is more of a voltage limiter rather than a current limiter.
Omg!😂 I don't know why but the fast forward always cracks me up!
+Roger Philabaum what fast forward? :)
The Guitologist when you speed the video up. Makes me laugh out loud everytime!
The Guitologist I'm easily amused. Lol
A hammer to the bottom of the workbench , when he stuck his hand into the powered amp , is a more effective way to teach him not to stick his hands where they don't belong . Vo-tech school in the 70's , when teachers had fun with us students . I'm sure there is some ' Don't scare the crap out of students ' law these days .
The county here still allows corporal punishment, but won't allow peanut butter sandwiches.
cool tips on the capacitor without soldering on the board
Liked the video bro and helper.
Thanks man. Scott will be thrilled to hear, I'm sure.
Cool, thank.
Hoegaarden beer sighted - Grunt approves
Cool idea. Maybe one day you can have me on to fix my crappy amp.
I remember working on my first tube amp. Touched the tube plate with it on by mistake. Nerve from my finger to my elbow was numb for 3 days. Was alot like putting your tongue on a 9v battery.
Don't ever change the power fuse while the amp is on. I got bit once but never again.
yeah im in for the next move as well, im gonna need one of those sweet hammond a0 35s though. dont worry ill take one as is and convert it myself!!!!!! put me on the list!!!
Once you break a ribbon cable, you're hosed! I prefer to just rebuild these things with a hand wired circuit if the repair goes much further than this amp. Great platform for a 5E3, 6G3 or 6G2 circuit. Or even the stock Pro Jr. circuit on a turret board. Sometimes it's cheaper and always WAY more reliable
Looking forward to those Reel to Reel amps!
Break a ribbon cable and it rapidly becomes no fun. Because you'll have to replace those with wires, and by the time you do that you might as well put some real sockets in and hard wire those, and by the time you do that, you might as well rip the whole motherboard out and start over.
The Guitologist Exactly, I asked about a replacement board for a 2X12 Deville from Fender, it was more than the amp was worth at the time. Hand wired turret boards with all of the required components cost under $20 if you diy.
MATT FIELDS what is the pro junior iii circuit called?
I'm paused at 14:04, I need to give myself a tap on the shoulder cause I spotted that solder joint right before you put your finger on it, so basically at the same time as you. We shall find out soon enough. :-)
I just paused again at 14:59, the other joint next to it, towards the left seems bad too.
Yeah I alway replace Bias Caps usually to a higher voltage as big as you can fit. The Bias caps are usually running hot and the amp companies tend to cheese out on those.
Very cool idea, fix a guy's amp he will rock for a day
Teach a guy to fix his OWN amp ...
+poot111111 he got a good trade.
Cleaning the pots sounded like my granny walking down the hall in middle of the night to bathroom. yep, walking farts.
Great Video! what is your opinion about changing the volume potentiometer in a Fender Hot rod Deluxe from the stock linear taper to Audio taper?
Good man. ;)
I traded away my used Fender Deluxe III and Deville (USA) for a Traynor YGL2 and a MIM Telecaster. Glad I did.
Are these solder joints completed by an individual at a factory. when i see solder that has a poor wetting angle it is a COLD Joint as I call it. thanks for this post very helpful.
bless y'all. y'all funny. ZAP! ow. this ain't prom night......
Hey Brad. Now let me get this straight. Scott helped you move house and as a reward you're letting him fix his own amp. Sounds fair to me.
+Tim Edwards heheh..,well, he helped one day. And I gave him a washer, dryer, and Hammond L-100 organ as well.
The Guitologist - Oh well. Why didn't you say ?! That's fine then. A washer-dryer and a Hammond constitute standard union rates for a day of house-moving.
The Hammond was a tip. You should see the shit I leave on the table at Denny's.
"Marge? What the heck does nee-chee-con mean?"
The Guitologist only the best for Denny's!
Wow, pause at 14:22 and look at the 8 Misfits Fiend-Club Skulls toward the upper right corner!
Its pissing down with rain here! Do your job man! ;) Its a fucking monsoon! Lol. Cheers.
Uh, huh. Couldn't find the charger. Right, you're just messing with Scott for making that deal. ;)
That soldering iron again! Did you steal that from Ben Franklin! Love the videos. You really need a Sencore PR570 for several reasons. If I come across smother one at a good price I am shipping it to you. Robert
When you clean the pots, are you using DeOx-It? I used to use Blue Shower but I was overseas (working on large antenna high power amplifiers for the AFSCN) for a few years, and when I returned I could not find Blue Shower anywhere. When I asked about it, all I got was dumb looks. I guess they don't pay the people, selling electronic parts and supplies, enough to keep anyone for longer than a year at best.
Thanks! Great channel, by the way! Sub'ed.
such a shame this channel is so underrated , open patrion
RUclips is actively trying to kill my channel right now for some reason. They've had it out for me about the last month.
Can anyone tell me how to get that LED light socket mounted back in the panel top?? It's not a 'push-though' and thread, but 4 prong tabs. Thanks
So i'm looking at the schematic for this amp and can't for the life of me figure out where the phase inversion for the output tubes is. I'm guessing it'll be somewhere in or around the second 12AX7? Any help with this much appreciated.
Looks like this amp was given a second lease on life. In had a 'diamond' ('06) Blues Jr that always seemed too loud for home use. The Pro Jr maybe would have been better. This one sounded good.
I noticed at 4:57, when you just barely touched the power tubes with your chop stick, that the voltage on capacitor one dropped from a steady 23.8 volts to 16, then steadied off at 19.8. It seemed like the right power tube. Was that indicative of anything?
That was just an edit. Thanks though.
Question: Did you first test the suspect caps ON the board, powered, or did you take them off then test them?
Thanks for the vid man, who did the cover of come as you are at the end credits?
I believe it's actually himself
Hell, if you're taking on students, I'm 90 minutes away! ;-)
In fact, I was thinking...on a whim...of coming to Louisville tonight (Tuesday, Dec.5th) to see Cannibal Corpse. Not my thing at all, but I'm trying to understand metal genres beyond thrash. Turns out the show was sold out days, if not weeks ago.
They were playing at the Diamond Pub concert hall.
+jaybone23 had I known that, I might have gone myself. The Bleeding is a masterpiece of the genre. A guy I know did all the photos for their new album.
That's cool about your photographer acquaintance. Yeah, the various metal genres will make your head spin, but I'm starting to find things I like. I pretty much stopped at Slayer back in the 90s, as I couldn't get past the vocals in death metal. But I figured I'd try again since there's a lot of interesting things going on within metal as a whole. I just wish I'd known about the Cannibal Corpse show earlier!
It always seems like when one repairs an amplifier, there is always one last gasp in the bias resistor or bias setup that’s just enough to super-heat one or the other power output tubes. Do you find that odd? I know I do...
ESR meter HT Caps. When board’s out, change the caps. It’s $20!
I hope you told him to never to repair an amp without a wooden chop stick!
And what solder do you use Brad? Size and what materials with %, if you don't mind.
brad what is this chassis/circuit called i picked one up yest at a yardsale and it is missing. i would like to replace it. got it for $20 with a upgraded fender special design speaker.
Come on, the guy doesn't have that southern accent, how can you expect him to... oh he got it working? Give him a solid state amp next time! ;)
Hey Brad, you're pretty good at building guitar components- have you ever considered building your own rotary speaker cab?
I actually have an interesting method - IF you are only looking to RECORD the rotating speaker sound - of using a swinging mic to get the phasing sound like a Leslie.
I might make a video about it, a couple people have asked about it, and it's somewhat difficult to explain in text.
One of the first projects I ever did was disassembling an old organ and turning the parts into a guitar amp and separate leslie from the internal leslie.
Have I told you (Brad) about my "rotating speaker" trick for recording?
+Adam Rainstopper don't recall. I get the feeling I'm gonna hear about it now. :)
Yeah if its a high end amp you would want everything to look Factory . But for amps like this just get the caps secure and soldered and its fine.
Yeah, I just don't see the need to risk breaking other things doing it the long, hard way when this way is just as secure if done properly.
Where do I get a Celine Dion shirt like that!?
Your charger will show up in a weird place so maybe have a look around the house in any of the weird places you can think of and it might be one of those places, is there one of the electrolytic caps in the power supply may have caused the rectifier diodes to overheat and possibly blow the main fuse you had this problem before and you fixed this one particular version before was it last week? I think the old electrolytic caps should be replaced with Technics electrolytics capacitors.
I just looked in my personal "nude room" and it's not there. Any other ideas?
I don't think power caps were at fault in this case. Replacing those was just a preemptive measure.
The Guitologist did you stash the charger in the glove box of your car as you were moving home a few days ago
+DAVID GREGORY KERR no. I'll find it eventually. It's probably somewhere with my helping hand magnifying glass drinking pina coladas.
I need to replace the 47uF 450V capacitor, can I use a 47uF 400V?
Always try going for the same voltage or higher never lower
Yep first thing I saw.
Probably a stupid question but what were you using to clean the pots with?
It's just CRC contact cleaner.
There is a common issue on these models where the metal bracket holding the power tubes is too close to the speaker magnet - which causes output tubes to go crazy and red plate.
That would be an odd problem, indeed. One tube socket was kinda loose so we retensioned that. If the problem returns, we'll look into the retainer theory.
So the next episode would be titled "The retainer conspiracy" I presume? :)
Keep up the good work, I'm really enjoying watching your videos lately!
+Delatsch thanks for watching. I appreciate the support.
Retainer conspiracy? The international orthodontic cartel rears its ugly head again!
Is this like the drummer I've had chained to my kit for the last couple months? Do you at least feed him? You have to make sure there's fresh food and water, they don't last long without it...
DO NOT FEED THE DRUMMER!!!
- Parks Dept.
I don't feed him after midnight, what's the big deal? I need him to be capable of playing to a god damn click....
+Adam Rainstopper even well-fed drummers can't do that. We don't want them going too close to the road!
It depends what you're feeding them. Mine gets very good balance of Drummer Chow, table-scraps and meth. It works for me. As for keeping him off the road, well it IS usually the drummer that owns the vehicle that has room for equipment, like a late 80's Astro van with all but the front seats ripped out. We never flew anywhere, it was more expensive than just doing a gas & go (you didn't have to prepay back then) and I had a fear of flying, and so that van served as transportation AND a hotel. This is the high-life when you play in a punk band, unless you count Green Day as a punk band . . . . .
If you feed drummers, you'll make them tame. Tame drummers don't last too long in the wild, which means you'll have to keep it.
1:22 2:24 22:00 24:40
Héhéhéhé
You should take that amp and see what you can make it into.
My experience with these is more of the same .I don't even consider them to be real fender tube amps. When you consider the build quality and the fact that you are actually hearing opamp and transistor preamp distortion you might as well be playing pedals into a SS amp.it's designed to be a throw away amp with many problems.
Hey out there and In my You Tube, Got An Old Gibson “ Paul “ as A gift , The
Thing is It Has To Much Relief . Truss Rod Doesn’t Work , groans , and Creeks!
Lubed it a bit, Doesn’t want to work at all , I Live 275 miles from a real city , Ideas
Suggestions and help very much Appreciated, ‘Tis a pitiful thing , Cream DiMarzios , Sharp faded tea burst
What brand caps did you put back in? They look like those cheap China caps from ebay? Surly not...
2:10 You didn't plug this in, did you?
1:22
Hey I have a question concerning my amp and can you contact me
You should take the time to explain why the capacitors were shit during this era. It is important to know because any item with caps in it from this era will have the same issue as this Fender amp. Capacitor Plague.
en.wikipedia.org/wiki/Capacitor_plague
first :-P cheers brad :-p
Ken Hanock second
"trainwreck"....lol.....but did you even think of having a lovely bikini wearing assistant instead of Scott?.....
The only time I think about that is every minute of the day. Know any volunteers?
Hope you don't break a nail working.
YT has demonetized this video also. My last one was reviewed and restored about the same time they demonetized this one. This is beyond ridiculous at this point. Fuck RUclips. If the goal is to foment extreme animosity, that's been achieved.
They seem to be demonetizing anything that they deem unprofitable to advertise for at this point, electronics is usually niche of an audience to say toy unboxing videos. Its nothing about swearing or politically correctness as much of what they demonetize doesn't even fall under any of the "adpocalypse" categories that they claim is the reasoning behind this. It's all about their bottom line under the guise that they're cracking down on "extremism".
looks bad for the guitar world when 2 major players have serious debt problems, if GC folds, will Gibson be next?
In the logic of things, I know top mounting the caps is OK... I couldn't bring myself to do that though... pain or not, I'd be pulling the board out... and swearing.
I hear what you're saying, but it's not just that it's a pain, its a safer repair on PCBs to do it this way. Much less risk of breaking traces, overheating the board, or breaking something else like a ribbon cable. If an amp is a collectible or something, then ok, but a working amp like this...there's no extra points for style really.
Maybe I'm just a huge fan of my solder sucking iron. Trust me, I'm not being disrespectful... Every tech has their own style. Then again, you get a flood of guitar amps to work on, and I get tons of miscellaneous crap that nobody in my area even wants to try fixing.... TV's, stereo stuff, weird devices I don't even know what they are... lots of computers... Guitar amps are a treat around here. Rumor says I'm getting an Echoplex in the shop... that will be fun.
I don't much care for working on any PCB. Point to point all the way. But you do what you gotta sometimes.
PCB when done right, is fine. Just take a look at 1975-1985 Peavey gear... That's PCB done properly... big strong traces, and easy to work on....very modular. Point to point is great too.
Just curious, how much money did u bank by fixing intermittent volume issues by spraying contact cleaner into headphone inputs? Lol.
After watching so many shows featuring the insides and workings of many different amazing amps, these modern Fender looks cheap and nasty. It looks like it was knocked up in China, or should i say Mexico, using cheap parts. I bought a new Fender deluxe reverb silver face. Even thou it sounded ok, i took the back off. I was presented with a board a lot like that. It was sent back. That was 1100 UK pounds. Not cheap for something made in Mexico! If people keep buying crap, they will keep making it for them! Always would rather wait, buy the best i can afford.
I thought procguitaroligists wear rubber gloves and tell guys to cough ?
Those power tubes are clearly used up.
Also this is a 2015 model. Mk. III Hot Rod and Junior series with the black chassis face wasn't around in 2005.
I was going by the date on the PCB.
The Guitologist fair. I don’t think the Pro Junior had any circuit changes with the Mk. III line. It was just cosmetic. Probably a circa 2005 revision board. Good catch on the bias caps! I’m not quite sure the generic unbranded caps in the filter section are an upgrade on longevity...but those IC brand caps are the worst!!
After watching this video it really pisses me off that the store he bought the amp from just did whatever necessary to sell the amp.
Meanwhile he could have burnt his house down with the output tubes red-plating.
Whatever to make a buck right?
+poot111111 it could have been ignorance on their part as well. And maybe they had a "repair guy" they trusted do the "fix". Either way, I would not shop there again if it were me.
Hey Bren how you doing wassail 45 seconds of summer of your opening video this one you had a like you had but it was on a Bernie Sanders Commercial I guess you advertisement pro Bernie Sanders how does that make you feel? Inquiring means needs to know and of course Bob the Jew boy flying Dutchman guitarist is interested in knowing of course it might be very personal to you cuz it's politics but I think you've made your leanings on let me issues will known LOL sincerely yours, Bob jewboy blind bedroom guitarists boy that's getting hard to say I don't like it speech to text and all that stuff