I want to try something new. Something more live. So I’m running a 3-part live workshop that takes us on… A Time Travel Through Vintage Electronics. We’ll rewind the clock, dive into the tech of the times… (and study the very history of how things were broken and repaired has evolved) From the 1950s all the way to 2020s. It's still just an idea. The dates and times are to be confirmed. But if you're reading this, then the workshop hasn't yet taken place. So if you're interested and don't want to miss out, you can sign up here: menditmarkk.ck.page/6e8fbd9521
Excellent video, I love the ‘Hal 9000’ quote at the end. I’ve been repairing vintage and modern electronics for a long time now and I find your videos extremely informative.
While I enjoy a successful repair as much as anyone else, what I most enjoy is the process of trying to find the fault in the first place. In that regard, this video did not disappoint.
You need repaired 2000 gear, you can have it all ! Radio's, HD HDD recorders, DVD, come and take some trash if you need it, i did repair it all, not needed by anyone, so come and take them please !
Before I went back to school and then medical school and became a surgeon, I was an engineer who did some service work on the side. It didn't take me long to figure out that I wouldn't work on Denon equipment. They have a terrible service history. They are the electronic version of Range Rover. I once repaired a 400-watt RMS mono block amp whose only problem was a cold solder point on a component. The owner sent it into the maker and they said that they couldn't find the problem. The whole repair took me about 10 minutes. Stunning.
And he doesn't start talking about something that is barely related to the unit being looked at or spends 30 seconds trying to get the camera to focus on something we can just take his word for. Other repair channels really bug me with 20 minutes of actual related repair and 10 minutes of faff. As Monty Python used to say "Get on with it!"
I have this excat denon amp from over 20 years ago it's my baby I actually cleaned it out recently and it's still alive after all this time I'm sad to see this one has died this was my first ever Amp it has a special place in my heart ♥ After watching this video I pray it's got many more yrs to live
Reminds me of my 1974 Sansui Radio / Amp. Bought 2nd hand from my boss . He bought a newer one. Mine had a green radio valve on one side. The full valve lit up when you were on the radio channel. It also got brighter with the volume. A solid steel chassis. Part transistors part valve. Stunning sound. The handbook gave you the full circuit diagram and possible faults and how to repair them.
You are one of the best electronic repair channel on RUclips. I definitely learned more about electronics with you than in school. Thank you for sharing your passion with us.
That receiver may be repairable. The RESET MCU line is two-way. It can be a watch-dog timer output if the MCU is stuck in a loop. According to the MCU TMP87CM71 datasheet section 1.11 "Reset circuit", in watch-dog activation mode the RESET line can be a pulsed output with a period of 2^20 / Fc [s] = 131ms at Fc = 8Mhz. In this unit the crystal gives Fc = 4MHz. Thus the watch-dog output period here is 262ms which gives 3.8146 Hz, which is virtually exactly what you are seeing at 9:32. Therefore the MCU may be stuck, glitched. This can be a classic case of supercap holding up the stuck MCU. I recommend you gently fully discharge the memory supercap which seems to be C401. Don't bother with reset procedures, the supercap is THE reset procedure. Simply pressing power a few times is NOT the official reset procedure. And check for shorted outputs. That (protection mode) and other reasons may also be why the MCU does not come up. Please keep trying. It is highly probable that the unit can be fixed. It is highly unlikely that the MCU is bad. Good luck. Let me know if I can be of further assistance. [ Edit ] One more thing: Please be aware that for complete grounding often the complete back panel must be attached or jumper wires connected to fully connect all grounds. Failure to do so can often lead one down the wrong path. Perhaps not in this unit, but still good practice.
@@marcseclecticstuff9497 Me neither. But something was odd. There was nothing else connected to that reset line. I don't know why I took the time, but I was just very suspicious. I have never seen that or at least bothered to look it up before. I should look closely when examining datasheets. Likely more of them do that. Hope it helps. Happy listening ... yet ... ?
Thanks Tim. I dig a little bit deeper and as far as I understood according to the TMP87CM71F datasheet (1.10) the watchdog behavior must be initialized after reset. So my guess is a "Adress Trap Reset" caused by degraded rom (for example cant find qualified reset vector) and matches the timing diagram. There is also a OTP replacement part (TMP87PP71F) but without firmware and special programmer (example: Xeltek ~1k$) I think is hopeless.
Back in the 80s, when these computer controlled audio receivers became popular, we had a lot of success "discharging" the MOSFET inputs by power off, connecting a jumper to ground and swiping it across all the legs of the MCU. Not exactly sure, really didn't care since it worked, this worked, and I hadn't thought of it in 30 years. It might be worth a try, if you haven't trashed the Denon yet. I enjoy watching you work. I've been away from component level repair for more than 20 years, having gotten into IT when I saw the repair business disappearing, with "swap while in warrantee, and trash when out" manufacturer philosophy. Thanks for sharing.
Amazing, I got a Denon AVR receiver just last week with the exact same issue -- only the standby light on, no other display and no reaction from the power switch or any other switches no matter what -- AND all of the output voltages were there so it acted like it was on. I came to the same conclusion -- dead CPU. I learned a lot in the troubleshooting though, and also learned never to bother with a Denon showing only a standby light again. Thanks for the video, now at least I have some confirmation I wasn't way off base!
I have a Denon amplifier PMA 1500 R where the microprocessor of the interface PCB appeared defect. Cost of the ampiifier € 1600 .... Contacted Denon in Japan. Interface PCB is not available as spare part. Shame to Denon !!!!!!
Ho letto i messaggi di alcuni utenti su queste discussioni per il raggiungimento della riparazione finale, per far tornare in vita l'apparecchio. E sono sempre più convinto che 40anni fà ho fatto la scelta giusta, per aver deciso di studiare l'elettronica. Il mio indirizzo di studio era radio e tv. Grazie a Mark e a TUTTI QUANTI VOI, per aver conosciuto anche soltanto leggendo, le vostre assolute grandi capacità di arrivare fino in fondo alla riparazione. Mark è assolutamente eccezionale nel riparare di tutto, ma leggo con mia grande gioia che ci sono altrettanti Mark a cui poter tranquillamente affidare in riparazione i propri gioelli elettronici. GRAZIE A TUTTI VOI ❤
best repair channel ever i may just take classes as i like this stuff not to new not to old like tube only channel . i love Mr Carlson a lot to but not much newer stuff presented to learn about
I don’t know how I got here. I have no idea what pins and transistors are advocating signal and voltage drop is. But I find it very relaxing and helping fall asleep. Typing is making me sleepy too
Iam so glad your Channel came up on my RUclips. It was great to see you go through diagnosing the fault .I Have Subscribed and will be checking some other videos of yours, Great work Mark.
Absolutely fascinating. I detest the way we have to throw away stuff now. I recently repaired my 1994 akai integrated amp. Cost 17p for a couple of capacitors and resistors . Sadly went again 6 months later so beyond my skill to fix. I then wnet for a marantz costing over a grand. Sadly I know some day maybe ten years from now something will go and it will be another bin job. It is crazy. Thanks for the video, I am subscribing.
I have a Denon 35 watt am fm receiver I bought in the eighties. It's class A and can be cranked up to maximum volume with little distortion. Great video on this one Mark............
well tried I forgotten a lot I learned since my stroke so admire you and being a radio ham i need to repair things but often i just leave them , thanks for the video
Excellent!. Had I seen your vids when I was 15 or 16 I would have surely chosen a different career ... still find it a bit of a 'Magicians apprentice' job. Went into Mainframe software development and OS instead but now (over 70) the old hardware still calls to me. Well done!
I have a similar era Denon receiver, an AVR 2500 that I bought new in 1996 or so. I've used it heavily and it's my favorite receiver ever. It has the ability to make any set of speakers you hook up to it sound fantastic. It ran a pair of Klipsch Chorus IIs for about a decade, it lived through 8 years on a modified sine wave power inverter in my cabin, now it runs a sub/satellite Bose speaker system in my office. It was my 2nd "big" audio purchase ever and I hope it lives another 27 years. Only quirk it has is sometimes the buttons on the unit will act like you pressed a totally different button.
Have repaired thousand of thousands of Denon Hi-Fi between late 80's to early 2000. Do even have a DRA-275 for my pc.. :P It's was a very very reliable receiver. Most common thing was blown inputs (due to user connecting/disconnecting stuff with all stuff turned on) or a cooked mains transformer because of stacking things on top and drive it hard. The transformer has a temp fuse you can locate and wiggle out and replace with some handywork. Your thing is rare and seems more of just get the remote and turn it on or manual reset by first discharge all caps completely then use a solderwick and ground all legs on the mc by drag the grounded wick over the legs of the mc. Feel free to holler if you need Denon tips.
Yes when AV Receivers and the like are controlled by a Microprocessor it's a ticking bomb. Onkyo AV receivers are also notorious with similar problem in their Syscon boards. With this Denon you may succeed in fidling for the On/Off control to power up but other function like source selection, etc. may not work either so yeah it's parts out unit then. I love watching videos on this channel which give good information. Mark is really patient at work and always smile.
Great video - I worked in a Hifi shop at weekends 30 years ago when I became interested in electronics and building amps and active crossovers. I was horrified at the amount of nasty cheap components in the signal path - stuff I would never put in my own builds - carbon film resistors in the signal path - even in the NFB in amps costing a months wages! Marketing, Gimmickry, proprietary protectionism and planned obsolescence, not much has changed.
@@mikw1809 You can't possibly have a clue about the application or topology I'm talking about and you've gone out of your way to prove it. John Linsley Hood described it as "as any component that directly affects the amplitude, phase, or frequency of the signal, then this resistor qualifies, as it influences the gain and linearity of the amplifier's output signal". I've done the experiments with measurable and audible differences. Rod Elliot has a website where he shows the differences. At RF as Siegfried Linkwitz describes it, it becomes so critical it's the difference between a design that works or doesn't at all.
Excellent work. The comment, "That's weird?" .........is something I have muttered a hundred times when trying to debug a circuit. I know the unit is old, but to be unable to fix a receiver because of software in a discontinued chip is very disappointing. That software/chip is just an unnecessary (control) wart in the circuitry: I am old school....all you need is: input jacks, selector switches, preamp, amp, speaker jacks. Leave the software to iPads.
Great to see, hopefully further advice from comments will see this working. I used to work at Marshall Amplification in test & service (88-93), then Alpine Car Audio (93-97), before the days of in-circuit firmware upgrades so regularly replaced similar controllers.
Every identifiable date code in that is from 1996. That’s way before the transition to lead-free. But cracked joints (not “dry joints” - dry joints are a specific type of soldering error, which does not include thermal cycling induced fracture) happen to thermally cycled joints with leaded solder.
This is why I steer clear of all Denon receivers. I've seen way too many broken ones and I'm not a skilled enough technician to keep them alive. Thanks for sharing this video Mark!
I have a Denon receiver that I bought about 10 years ago as a 'demo' unit. Was the last one on the shelf at the store, it had been a powered display unit for awhile. It's been a great unit, sound quality is fantastic, the 5 channels inside are separate. Only thing I've had to do once in awhile is take the remote apart and clean the button pads, especially for the volume up/down etc. But since it's going to be over 10 years old soon, if it ever dies, I'll chuck it. Was on sale at a pretty good discount since it was 'open box'.
I quit buying Denon products many years ago when they were known as a somewhat "high end" brand and all I seemed to have was bad luck with them. Too many better options out there to take the risk in my opinion.
If I still may suggest, provided it is not yet scrapped, I would suggest you to check main Vcc pins on MCU on an (fast DSO) scope during power on. If some capacitor on power rail is dead, which I can imagine there may well be some, the inrush current to MCU will cause a voltage drop, simply causing MCU to reset. All I am saying this could be as simple as power supply issue.
I'm surprised he didn't notice or mention the multiple, easily visible puddles in the dust at the beginning of the video, where things have obviously gotten wet at some point. I'm betting a lot of the caps have leaked onto the board and are now effectively nothing more than resistors to the circuit
I’ve fixed more older inoperative electronics with recapping then anything. They loose their value with age and they short other components when they leak.
Maybe not the inrush current, however you can get shorts, oscillating power regulators, etc. Electrolytic caps tend to die with age, as Fireship1 posted earlier.
Hey Mark, I have one of the same model that is also dead. I hope you can solve this. I look forward to seeing your second episode. I get motivation from your smile. Go ahead.
Excellent channel on the topic of repairing electronics, on par with NorthridgeFix, which is based exclusively on microsoldering. Mark seems to be much more versatile and modest than NorthridgeFix guy. At the same time Mark shows his work very entertaininly...
What a shame !! I love your channel-and your good and cheery humour,I’ve watched you successfully fix quite a number of products-but sadly ‘you can’t win ‘em all’ !!
Age-wise, according to HiFi Wiki, the manufacturing years for that Denon receiver was from 1996 - '98. I have a 'DRA 425-R' receiver that's older, but still runs fine. Maybe one aspect that has kept it in shape was using a power-strip as a power-on/power-off switch; as I am suspect of push-button on/off switch's lifespan.
I had this exact amplifier, I'm fairly sure from memory that you need it's remote control to bring it out of standby and that was the only way you could do it. I assume the processor is generating it's own reset cycle. Thanks for the excellent continue, reminds me of my TV and audio repair days.
i picked up the same reciever about 9 years ago for 30$cad at a yard sale. It's been my bedroom radio for quite some time. I always thought there was more on the inside. So far i been lucky no issues yet
My compliments for your endurance anf skills. A pitty to waste a Denon. I still have an AVR 1000 pro logic recoevet with excellent audio quality. Build around 1992 and still going strong. Greetz from 🇳🇱
I can not stop watching your videos! I have no words! Just brilliant! Perfect! I am not sure about your background. Priest? School teacher? Bilioner hobbiest? All together?
I happen to have a DRA335R unit. very similar to this model. My problem with it is the pull out knob for the variable loudness has a nasty crackle to it and it will cut out randomly. I have tried to rotate the knob in every position pushing and pulling etc to try and clear the static (carbon build up?) tried a quality electronic spray from the front panel... still exists... do you happen to have any bloody hell recommendations on cleaning that up OR replacing if the part is even out there anymore... might you have a part number? Your a brain child repairman and amazing one at that.
Just love the time lapse repair thanks to editing. That was some good troubleshooting, your eyes are doing better than mine. Would have a difficult time counting the leads on that controller, yikes.
I own the AVR-600RD, which looks very similar, and when I don't have it plugged in for some time, the same standby light appears. I then keep "video select" and "Tuner" buttons pressed while powering it on, which magically resets the entire thing, and all is good
Nice to see the use of an Aldi screwdriver, I must have missed when that was for sale! I have a Lidl one, branded 'Parkside' - bloody brilliant, has survived use and abuse over several years. Lithium Battery is getting a bit weak now, but only to be expected after all this use. As a hobby user, I wouldn't spend the money on 'De Wilt - sic' etc...
The microcontroller is reprogrammable, and still available. The Denon allows for DFU ( direct firmware update ) using a DOS/Windows program to perform the first update. It is an older Denon ( being 20 years old indeed ) which doesn't support many modern features that are needed for HDTV's ... but it is a pity that it's for the bin.
I repaired a similar vintage receiver the other week. What was odd is that the reset was not clean / fast enough with the "dim lamp" in series with the mains and the micro failed to start. As soon as I went back to straight mains the unit it worked fine. It had me flummoxed for a minute!
Can't win them all. But this video is a great example of investigating and finding the source of the problem. I have a Denon DRA-325R from 1989. Was given to me. Lightly used in an office (they guy listened to AM radio through some fairly expensive speakers).. I got it some years ago and just started using it again when my NAD C368 failed. Died in 3 years yet the old Denon still works. Go figure!
Thanks fire the video. Been looking for a solution for my Denon 1709. All function working great, just don't have any sound on any input. Any tips please?
I repair electronic equipment for a hobby (self taught) and I usually get everything working, but when I start to open some device to repair, I always dread that an unobtainable IC has failed in it. For example, in this video, where you will have to bin the Denon. That's why I enjoy working on pre-IC equipment like old Dansette record players, where the parts are still easily available.
Hi Mark, Thanks for sharing your great knowledge with us! I've recently bought Denon PMA SX11 (online order from Japan) and the day I received (last week) , I powered it on through my existing step-down transformer which says 500Wt but continuous 400 wt. The moment I tried to turn on my unit, it started blinking (power button blinking green) and clicking but not turning it into solid green. I asked for help from my supplier who told me use 5000watt transformer which I ordered through amazon. Now, when I connected it through the new transformer which can handle up 5000watt (continuous 4500watt) , the power button is not green but it stays red for a while without any clicking noise and then goes off afer a while. I was so excited when I got it and now I am worried thinking to send back to Japan for repairing. Any advise so that it can be seen and resolved the issue in the UK? Would appreciate your advice! Thank you so much!
Onkyo TX84. I have a similar-era setup I love. I live on a half an acre, and out in my shop I have my shop-laptop that I download Pandora Music from the internet, and send it into the Onkyo for the amp, into some rather large (very) JBL speakers. Even tho my property is larger (as are all my neighbors), I dare not turn the volume much past half. Beyond that I DO get a little distortion (and it is LOUD --- my neighbors are accommodating, but I don't want to push my luck with them). I do have one question for the electronics-savy: I have to turn the Bass all the way down, otherwise the bass gets overwhelming. Could that be the amp, or is it more likely the speakers?
I own a DRA 45 that was dead after power switch cycle! The only repair shop wanted more in a bench check charge than what the receiver was worth ! I decided to at least try resetting board connections , and clean internal power switch ! The receiver powered on with no other apparent issues !😁
I have a question for you Mark about your favorite brand, Denon! I bought a Denon AVR-2802 new about the year 2000. Used it for a couple of months, and then stored it away for about 24 years. Pulled it out the other day, and it does turn on. Just doesn't make any sound through speakers. The headphone function works marginally but pretty low. It's not muted, not on the wrong input, working speakers and connection. It even outputs a signal through rec out to a sub with a cd player connected to it. I imagine other functions work short of playing through speakers. What do you think from afar?
I am planning to do a full service on our Denon PMA-450. It is still working OK and luckily it has not got any microprocessor. There are 4 op amps NJM5534DD, which are now discontinued but still available. Are these worth upgrading to something better?
I use car polish compound on the display screen. Fix almost any scratch. Also, you can use wetsand and try to cut down the scratch as much as you can and repolish the surface with again car polish compound. Thanks me later.
I had a fair share of such repair attempts. Most of the time I ask the customer if they want the amplituner back with just the "amp" functionality, bare minimum, and most of them say "yep", so I just disconnect everything that is not related to the amp/preamp or power supply, and add an "AUX in" functionality. But it's sad to do such a thing, only because the IC that died is no longer being made, and it has to have proprietary software on it...
12:02. When most of the budget for the product is spent on screws... Might show the evolution of design as now, there are clips molded into the plastic and only 1-2 screws to hold it down... not 1000...
6:43 - I'm not familiar with -27v driving the VFD. Normally, I think of the filament being driven by a low voltage and the anodes and grids with a much higher voltage.
Soooo much screws, you definitely need a DeWalt DCF680. I enjoy your videos very much. I am a hobbyist from Vienna Austria. I try my best an learn from you. Rock on and best regards.
I had wondered about the new lead-less solder, is the new stuff any better? Frankly I that they went to far about going lead-less. So far as the receiver? another black weightless box with tiny print or labeling. Give me a Pioneersx650 or Kenwood KR6030.
Hello I have a quick question. When opening these up and poking around arent you afraid of the big capacitors shocking you? Can you acciddentally touch another component that traces back to the capacitor and it shocks you? Or do you have to actually get underneath the cap and touch when of the leads for it to shock you?
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I want to try something new. Something more live.
So I’m running a 3-part live workshop that takes us on…
A Time Travel Through Vintage Electronics.
We’ll rewind the clock, dive into the tech of the times…
(and study the very history of how things were broken and repaired has evolved)
From the 1950s all the way to 2020s.
It's still just an idea. The dates and times are to be confirmed.
But if you're reading this, then the workshop hasn't yet taken place.
So if you're interested and don't want to miss out, you can sign up here:
menditmarkk.ck.page/6e8fbd9521
P😊
Excellent video, I love the ‘Hal 9000’ quote at the end. I’ve been repairing vintage and modern electronics for a long time now and I find your videos extremely informative.
While I enjoy a successful repair as much as anyone else, what I most enjoy is the process of trying to find the fault in the first place. In that regard, this video did not disappoint.
You need repaired 2000 gear, you can have it all !
Radio's, HD HDD recorders, DVD, come and take some trash if you need it, i did repair it all, not needed by anyone, so come and take them please !
Totally agree! I don't know why, but finding the root cause, regardless if it's repairable or not, is very rewarding.
Fully agree. It's great to see some old school diagnostics AND explaining what is going on for a semi noob like myself. Thank you.
It's really the only interesting part for me. And I did a few thousand of them between 1986 and 2000.
Before I went back to school and then medical school and became a surgeon, I was an engineer who did some service work on the side. It didn't take me long to figure out that I wouldn't work on Denon equipment. They have a terrible service history. They are the electronic version of Range Rover. I once repaired a 400-watt RMS mono block amp whose only problem was a cold solder point on a component. The owner sent it into the maker and they said that they couldn't find the problem. The whole repair took me about 10 minutes. Stunning.
Best tech repair channel on the tube.
Another one, if you're into vintage computers (Amiga / Apple 2 / IBM XT), is Adrians Digital Basement. Can be quite interesting and in depth.
Cutting your losses with a smile, thats a great attitude. Thanks for uploading the dead ends too.
This guy..and theres a guy who cooks pies on here.both i think are from the same place and both are amazingly happy all the time..must be idilic
@@luminousfractal420 I know the channel you mean, Is it 'Bald Foodie Guy'?
That ending with the red led dimming, definitely like the death of the Terminator in the first film!
That's exactly what I thought
It was cool!!!
I like that you don't faff about unnecessarily testing unrelated stuff to find the fault, you get right to the issue. Excellent work, as always.
And he doesn't start talking about something that is barely related to the unit being looked at or spends 30 seconds trying to get the camera to focus on something we can just take his word for. Other repair channels really bug me with 20 minutes of actual related repair and 10 minutes of faff. As Monty Python used to say "Get on with it!"
Yeah, it's very well edited.
I have this excat denon amp from over 20 years ago it's my baby I actually cleaned it out recently and it's still alive after all this time I'm sad to see this one has died this was my first ever Amp it has a special place in my heart ♥
After watching this video I pray it's got many more yrs to live
Reminds me of my 1974 Sansui Radio / Amp. Bought 2nd hand from my boss . He bought a newer one. Mine had a green radio valve on one side. The full valve lit up when you were on the radio channel. It also got brighter with the volume.
A solid steel chassis. Part transistors part valve. Stunning sound. The handbook gave you the full circuit diagram and possible faults and how to repair them.
You are one of the best electronic repair channel on RUclips. I definitely learned more about electronics with you than in school. Thank you for sharing your passion with us.
That receiver may be repairable. The RESET MCU line is two-way. It can be a watch-dog timer output if the MCU is stuck in a loop.
According to the MCU TMP87CM71 datasheet section 1.11 "Reset circuit", in watch-dog activation mode the RESET line can be a pulsed output
with a period of 2^20 / Fc [s] = 131ms at Fc = 8Mhz. In this unit the crystal gives Fc = 4MHz.
Thus the watch-dog output period here is 262ms which gives 3.8146 Hz, which is virtually exactly what you are seeing at 9:32.
Therefore the MCU may be stuck, glitched. This can be a classic case of supercap holding up the stuck MCU.
I recommend you gently fully discharge the memory supercap which seems to be C401. Don't bother with reset procedures, the supercap is THE reset procedure.
Simply pressing power a few times is NOT the official reset procedure.
And check for shorted outputs. That (protection mode) and other reasons may also be why the MCU does not come up.
Please keep trying. It is highly probable that the unit can be fixed. It is highly unlikely that the MCU is bad.
Good luck. Let me know if I can be of further assistance.
[ Edit ] One more thing: Please be aware that for complete grounding often the complete back panel must be attached or jumper wires
connected to fully connect all grounds. Failure to do so can often lead one down the wrong path. Perhaps not in this unit, but still good practice.
Hope Mark tries this
Nice detective work Tim. It never would have occurred to me that the reset line was bi!
@@marcseclecticstuff9497 Me neither. But something was odd. There was nothing else connected to that reset line.
I don't know why I took the time, but I was just very suspicious. I have never seen that or at least bothered to look it up before.
I should look closely when examining datasheets. Likely more of them do that. Hope it helps. Happy listening ... yet ... ?
I was just about to post this. Something making the MCU go to reset loop. Does not mean MCU itself is dead.
Thanks Tim. I dig a little bit deeper and as far as I understood according to the TMP87CM71F datasheet (1.10) the watchdog behavior must be initialized after reset. So my guess is a "Adress Trap Reset" caused by degraded rom (for example cant find qualified reset vector) and matches the timing diagram. There is also a OTP replacement part (TMP87PP71F) but without firmware and special programmer (example: Xeltek ~1k$) I think is hopeless.
Back in the 80s, when these computer controlled audio receivers became popular, we had a lot of success "discharging" the MOSFET inputs by power off, connecting a jumper to ground and swiping it across all the legs of the MCU. Not exactly sure, really didn't care since it worked, this worked, and I hadn't thought of it in 30 years. It might be worth a try, if you haven't trashed the Denon yet. I enjoy watching you work. I've been away from component level repair for more than 20 years, having gotten into IT when I saw the repair business disappearing, with "swap while in warrantee, and trash when out" manufacturer philosophy. Thanks for sharing.
Your opening sequence is such a joy. The subsequent repair etc is the icing on the cake.
Amazing, I got a Denon AVR receiver just last week with the exact same issue -- only the standby light on, no other display and no reaction from the power switch or any other switches no matter what -- AND all of the output voltages were there so it acted like it was on. I came to the same conclusion -- dead CPU. I learned a lot in the troubleshooting though, and also learned never to bother with a Denon showing only a standby light again. Thanks for the video, now at least I have some confirmation I wasn't way off base!
maybe a common issue with these? premature failure of the cpu? or killed by that dry jointed regulator
@@andygozzo72 In my case, there were no dry joints or any power issues so I don't know what killed it.
I have a Denon amplifier PMA 1500 R where the microprocessor of the interface PCB appeared defect. Cost of the ampiifier € 1600 .... Contacted Denon in Japan. Interface PCB is not available as spare part. Shame to Denon !!!!!!
I have the predecessor to this model and, fortunately, it's still running fine. Good video: very illuminating!
I learn so much just by watching and listening. Thank you!
One of my favourites from you Mark this one! Love the detective work more than anything. Fix or not, it's always an education.
What a knowledgeable and friendly man! I just found your channel and been bingeing on your content lately!
Be like telling someone a Family member has died. You can't win them all Mark. Keep 'Em Coming.
"" be like"", im glad I don't speak like this.
Thank you for this educational video, very nice to learn more about electronics.
Great detective work Mark! At least there was a datasheet and schematic for you to use to try to fix this. (Unlike so many computers I try to fix)
Your that 2-bit guy
Ho letto i messaggi di alcuni utenti su queste discussioni per il raggiungimento della riparazione finale, per far tornare in vita l'apparecchio.
E sono sempre più convinto che 40anni fà ho fatto la scelta giusta, per aver deciso di studiare l'elettronica. Il mio indirizzo di studio era radio e tv.
Grazie a Mark e a TUTTI QUANTI VOI, per aver conosciuto anche soltanto leggendo, le vostre assolute grandi capacità di arrivare fino in fondo alla riparazione.
Mark è assolutamente eccezionale nel riparare di tutto, ma leggo con mia grande gioia che ci sono altrettanti Mark a cui poter tranquillamente affidare in riparazione i propri gioelli elettronici.
GRAZIE A TUTTI VOI
❤
best repair channel ever i may just take classes as i like this stuff not to new not to old like tube only channel . i love Mr Carlson a lot to but not much newer stuff presented to learn about
I've never seen anyone proceed with electronics disassembley with such evil delight. Charming!
I don’t know how I got here. I have no idea what pins and transistors are advocating signal and voltage drop is. But I find it very relaxing and helping fall asleep. Typing is making me sleepy too
Iam so glad your Channel came up on my RUclips. It was great to see you go through diagnosing the fault .I Have Subscribed and will be checking some other videos of yours, Great work Mark.
Absolutely fascinating. I detest the way we have to throw away stuff now. I recently repaired my 1994 akai integrated amp. Cost 17p for a couple of capacitors and resistors . Sadly went again 6 months later so beyond my skill to fix. I then wnet for a marantz costing over a grand. Sadly I know some day maybe ten years from now something will go and it will be another bin job. It is crazy. Thanks for the video, I am subscribing.
I have a Denon 35 watt am fm receiver I bought in the eighties. It's class A and can be cranked up to maximum volume with little distortion. Great video on this one Mark............
electrical appliance repair It's a stressful job. But you're playing for fun. ..extremely appreciated
well tried I forgotten a lot I learned since my stroke so admire you and being a radio ham i need to repair things but often i just leave them , thanks for the video
Excellent!. Had I seen your vids when I was 15 or 16 I would have surely chosen a different career ... still find it a bit of a 'Magicians apprentice' job. Went into Mainframe software development and OS instead but now (over 70) the old hardware still calls to me. Well done!
Look at it glowing away like the saddest Hal 9000 - what an epic statement right there sir!
Worlds, happiest component level, electronics repair person.
I have a similar era Denon receiver, an AVR 2500 that I bought new in 1996 or so. I've used it heavily and it's my favorite receiver ever. It has the ability to make any set of speakers you hook up to it sound fantastic. It ran a pair of Klipsch Chorus IIs for about a decade, it lived through 8 years on a modified sine wave power inverter in my cabin, now it runs a sub/satellite Bose speaker system in my office. It was my 2nd "big" audio purchase ever and I hope it lives another 27 years. Only quirk it has is sometimes the buttons on the unit will act like you pressed a totally different button.
"That 80-pin rectangular bastard has all the answers"
LOL
It was an illegitimate repair ... almost :-)
😂😂 that tickled me too .
Showing things that can't be rejuvenated is assume. Most tubers don't do this.great job sir
Have repaired thousand of thousands of Denon Hi-Fi between late 80's to early 2000. Do even have a DRA-275 for my pc.. :P It's was a very very reliable receiver. Most common thing was blown inputs (due to user connecting/disconnecting stuff with all stuff turned on) or a cooked mains transformer because of stacking things on top and drive it hard. The transformer has a temp fuse you can locate and wiggle out and replace with some handywork. Your thing is rare and seems more of just get the remote and turn it on or manual reset by first discharge all caps completely then use a solderwick and ground all legs on the mc by drag the grounded wick over the legs of the mc. Feel free to holler if you need Denon tips.
Yes when AV Receivers and the like are controlled by a Microprocessor it's a ticking bomb. Onkyo AV receivers are also notorious with similar problem in their Syscon boards. With this Denon you may succeed in fidling for the On/Off control to power up but other function like source selection, etc. may not work either so yeah it's parts out unit then. I love watching videos on this channel which give good information. Mark is really patient at work and always smile.
Great video - I worked in a Hifi shop at weekends 30 years ago when I became interested in electronics and building amps and active crossovers. I was horrified at the amount of nasty cheap components in the signal path - stuff I would never put in my own builds - carbon film resistors in the signal path - even in the NFB in amps costing a months wages!
Marketing, Gimmickry, proprietary protectionism and planned obsolescence, not much has changed.
@@mikw1809 You can't possibly have a clue about the application or topology I'm talking about and you've gone out of your way to prove it.
John Linsley Hood described it as "as any component that directly affects the amplitude, phase, or frequency of the signal, then this resistor qualifies, as it influences the gain and linearity of the amplifier's output signal".
I've done the experiments with measurable and audible differences. Rod Elliot has a website where he shows the differences.
At RF as Siegfried Linkwitz describes it, it becomes so critical it's the difference between a design that works or doesn't at all.
Bummer...
Nice job chasing it though. Your logic is sound, it was interesting following along and you're tenatious.
Excellent work.
The comment, "That's weird?" .........is something I have muttered a hundred times when trying to debug a circuit.
I know the unit is old, but to be unable to fix a receiver because of software in a discontinued chip is very disappointing.
That software/chip is just an unnecessary (control) wart in the circuitry: I am old school....all you need is:
input jacks, selector switches, preamp, amp, speaker jacks.
Leave the software to iPads.
Great to see, hopefully further advice from comments will see this working. I used to work at Marshall Amplification in test & service (88-93), then Alpine Car Audio (93-97), before the days of in-circuit firmware upgrades so regularly replaced similar controllers.
I am just so amazed by your knowledge. Complete noob myself I woudn't even know where to start. Fascinating. Would like to be like you...
Every identifiable date code in that is from 1996. That’s way before the transition to lead-free. But cracked joints (not “dry joints” - dry joints are a specific type of soldering error, which does not include thermal cycling induced fracture) happen to thermally cycled joints with leaded solder.
This is why I steer clear of all Denon receivers. I've seen way too many broken ones and I'm not a skilled enough technician to keep them alive. Thanks for sharing this video Mark!
I have a Denon receiver that I bought about 10 years ago as a 'demo' unit. Was the last one on the shelf at the store, it had been a powered display unit for awhile. It's been a great unit, sound quality is fantastic, the 5 channels inside are separate. Only thing I've had to do once in awhile is take the remote apart and clean the button pads, especially for the volume up/down etc. But since it's going to be over 10 years old soon, if it ever dies, I'll chuck it. Was on sale at a pretty good discount since it was 'open box'.
I quit buying Denon products many years ago when they were known as a somewhat "high end" brand and all I seemed to have was bad luck with them. Too many better options out there to take the risk in my opinion.
If I still may suggest, provided it is not yet scrapped, I would suggest you to check main Vcc pins on MCU on an (fast DSO) scope during power on. If some capacitor on power rail is dead, which I can imagine there may well be some, the inrush current to MCU will cause a voltage drop, simply causing MCU to reset. All I am saying this could be as simple as power supply issue.
I'm surprised he didn't notice or mention the multiple, easily visible puddles in the dust at the beginning of the video, where things have obviously gotten wet at some point. I'm betting a lot of the caps have leaked onto the board and are now effectively nothing more than resistors to the circuit
I’ve fixed more older inoperative electronics with recapping then anything. They loose their value with age and they short other components when they leak.
@@Knaeckebrotsaege Yes, there were some tell-tail signs of leakage on that board in the beginning of the video.
Maybe not the inrush current, however you can get shorts, oscillating power regulators, etc. Electrolytic caps tend to die with age, as Fireship1 posted earlier.
@@Knaeckebrotsaege or, someone clueless used spray cleaner (shudder).
Hey Mark, I have one of the same model that is also dead. I hope you can solve this.
I look forward to seeing your second episode. I get motivation from your smile. Go ahead.
Excellent channel on the topic of repairing electronics, on par with NorthridgeFix, which is based exclusively on microsoldering. Mark seems to be much more versatile and modest than NorthridgeFix guy. At the same time Mark shows his work very entertaininly...
What a shame !!
I love your channel-and your good and cheery humour,I’ve watched you successfully fix quite a number of products-but sadly ‘you can’t win ‘em all’ !!
Age-wise, according to HiFi Wiki, the manufacturing years for that Denon receiver was from 1996 - '98.
I have a 'DRA 425-R' receiver that's older, but still runs fine. Maybe one aspect that has kept it in shape was using a power-strip as a power-on/power-off switch; as I am suspect of push-button on/off switch's lifespan.
I have a moderate, at best, interest in this subject but was incredibly drawn in by your positive expertise and am now a loyal subscriber
I had this exact amplifier, I'm fairly sure from memory that you need it's remote control to bring it out of standby and that was the only way you could do it. I assume the processor is generating it's own reset cycle. Thanks for the excellent continue, reminds me of my TV and audio repair days.
Ohh I love a quick troubleshot without 5 min watching how you unscrew a box, I love it. You have a new subscriber!
Recently found your channel Mark and love it. A true engineer at work. Keep up the amazing work. Cheers. Matt
Thanks for showing us the ones that got away!
Great analysis of the problem. I would never have found it.
i picked up the same reciever about 9 years ago for 30$cad at a yard sale. It's been my bedroom radio for quite some time. I always thought there was more on the inside. So far i been lucky no issues yet
open it up and check for dry joints!
You poor little Denon, I will always carry you in my heart 😞
You still do Radio in 2023, muhuhahahahahaha
As usual excellent video. Thanks 👍
My compliments for your endurance anf skills.
A pitty to waste a Denon.
I still have an AVR 1000 pro logic recoevet with excellent audio quality.
Build around 1992 and still going strong.
Greetz from 🇳🇱
I can not stop watching your videos! I have no words! Just brilliant! Perfect! I am not sure about your background. Priest? School teacher? Bilioner hobbiest? All together?
I happen to have a DRA335R unit. very similar to this model. My problem with it is the pull out knob for the variable loudness has a nasty crackle to it and it will cut out randomly. I have tried to rotate the knob in every position pushing and pulling etc to try and clear the static (carbon build up?) tried a quality electronic spray from the front panel... still exists... do you happen to have any bloody hell recommendations on cleaning that up OR replacing if the part is even out there anymore... might you have a part number? Your a brain child repairman and amazing one at that.
Got one of these - if it fails, chuck it I guess. Rare that something evades Genius Mark.
That was awesome. I figure my Denon amp will stay dead. love your work Mark
Just love the time lapse repair thanks to editing. That was some good troubleshooting, your eyes are doing better than mine. Would have a difficult time counting the leads on that controller, yikes.
you all say weird things here, why you people need Radio in 2023 ?
you did not read what you already types here, you all say the same thing .......
I own the AVR-600RD, which looks very similar, and when I don't have it plugged in for some time, the same standby light appears. I then keep "video select" and "Tuner" buttons pressed while powering it on, which magically resets the entire thing, and all is good
I enjoy so much your very interested channel. Thank you so much, please never stop to make fantastic videos. Thanks so lot !!!
It might just be the watchdog timer resetting the processor, so it might still be caused by some other external circuit.
Nice to see the use of an Aldi screwdriver, I must have missed when that was for sale!
I have a Lidl one, branded 'Parkside' - bloody brilliant, has survived use and abuse over several years. Lithium Battery is getting a bit weak now, but only to be expected after all this use.
As a hobby user, I wouldn't spend the money on 'De Wilt - sic' etc...
only came across this channel, absolutely brilliant!!!!
The microcontroller is reprogrammable, and still available. The Denon allows for DFU ( direct firmware update ) using a DOS/Windows program to perform the first update. It is an older Denon ( being 20 years old indeed ) which doesn't support many modern features that are needed for HDTV's ... but it is a pity that it's for the bin.
really enjoy learning from you, Thanks
I repaired a similar vintage receiver the other week. What was odd is that the reset was not clean / fast enough with the "dim lamp" in series with the mains and the micro failed to start. As soon as I went back to straight mains the unit it worked fine. It had me flummoxed for a minute!
Can't win them all. But this video is a great example of investigating and finding the source of the problem.
I have a Denon DRA-325R from 1989. Was given to me. Lightly used in an office (they guy listened to AM radio through some fairly expensive speakers).. I got it some years ago and just started using it again when my NAD C368 failed. Died in 3 years yet the old Denon still works. Go figure!
Thanks fire the video. Been looking for a solution for my Denon 1709. All function working great, just don't have any sound on any input.
Any tips please?
I repair electronic equipment for a hobby (self taught) and I usually get everything working, but when I start to open some device to repair, I always dread that an unobtainable IC has failed in it. For example, in this video, where you will have to bin the Denon. That's why I enjoy working on pre-IC equipment like old Dansette record players, where the parts are still easily available.
Thanks Mark, lovin' the content of your videos.
Really enjoy the logical approach and tips.
My 40 year old Sansui Amp is still working with the only issue is scratchy pot’s. Some of the good stuff are still Made in Japan!
I've thought about learning electronics for a while now. I think this guy would be a great teacher
Hi Mark, Thanks for sharing your great knowledge with us! I've recently bought Denon PMA SX11 (online order from Japan) and the day I received (last week) , I powered it on through my existing step-down transformer which says 500Wt but continuous 400 wt. The moment I tried to turn on my unit, it started blinking (power button blinking green) and clicking but not turning it into solid green. I asked for help from my supplier who told me use 5000watt transformer which I ordered through amazon. Now, when I connected it through the new transformer which can handle up 5000watt (continuous 4500watt) , the power button is not green but it stays red for a while without any clicking noise and then goes off afer a while. I was so excited when I got it and now I am worried thinking to send back to Japan for repairing. Any advise so that it can be seen and resolved the issue in the UK? Would appreciate your advice! Thank you so much!
Onkyo TX84. I have a similar-era setup I love. I live on a half an acre, and out in my shop I have my shop-laptop that I download Pandora Music from the internet, and send it into the Onkyo for the amp, into some rather large (very) JBL speakers. Even tho my property is larger (as are all my neighbors), I dare not turn the volume much past half. Beyond that I DO get a little distortion (and it is LOUD --- my neighbors are accommodating, but I don't want to push my luck with them). I do have one question for the electronics-savy: I have to turn the Bass all the way down, otherwise the bass gets overwhelming. Could that be the amp, or is it more likely the speakers?
First time I see this channel. IT IS GREAT. Love the old HiFi stuff.
I own a DRA 45 that was dead after power switch cycle! The only repair shop wanted more in a bench check charge than what the receiver was worth ! I decided to at least try resetting board connections , and clean internal power switch ! The receiver powered on with no other apparent issues !😁
Love your channel Mark, keep em coming.
I have a question for you Mark about your favorite brand, Denon! I bought a Denon AVR-2802 new about the year 2000. Used it for a couple of months, and then stored it away for about 24 years. Pulled it out the other day, and it does turn on. Just doesn't make any sound through speakers. The headphone function works marginally but pretty low. It's not muted, not on the wrong input, working speakers and connection. It even outputs a signal through rec out to a sub with a cd player connected to it. I imagine other functions work short of playing through speakers. What do you think from afar?
Mark is like the Bob Ross of electronics.
I like his jovial nature
I am planning to do a full service on our Denon PMA-450. It is still working OK and luckily it has not got any microprocessor. There are 4 op amps NJM5534DD, which are now discontinued but still available.
Are these worth upgrading to something better?
You have an air about being a cheerful and casually omnipotent electronics tech. Refreshing to see real skill and acumen with a positive bias....
I use car polish compound on the display screen. Fix almost any scratch. Also, you can use wetsand and try to cut down the scratch as much as you can and repolish the surface with again car polish compound. Thanks me later.
I had a fair share of such repair attempts. Most of the time I ask the customer if they want the amplituner back with just the "amp" functionality, bare minimum, and most of them say "yep", so I just disconnect everything that is not related to the amp/preamp or power supply, and add an "AUX in" functionality. But it's sad to do such a thing, only because the IC that died is no longer being made, and it has to have proprietary software on it...
12:02. When most of the budget for the product is spent on screws...
Might show the evolution of design as now, there are clips molded into the plastic and only 1-2 screws to hold it down... not 1000...
Found this channel at random. Very interesting and more views to you, very educational.
Did you try removing the big yellow super cap C401 next to the large ribbon cable? Maybe that is storing the memory.
If the memory is with the processor on the front panel (where it should be), unplugging the ribbon cable certainly disconnected it.
6:43 - I'm not familiar with -27v driving the VFD. Normally, I think of the filament being driven by a low voltage and the anodes and grids with a much higher voltage.
Soooo much screws, you definitely need a DeWalt DCF680. I enjoy your videos very much. I am a hobbyist from Vienna Austria. I try my best an learn from you. Rock on and best regards.
I had wondered about the new lead-less solder, is the new stuff any better? Frankly I that they
went to far about going lead-less. So far as the receiver? another black weightless box with tiny print or labeling. Give me a Pioneersx650 or Kenwood KR6030.
Hello I have a quick question. When opening these up and poking around arent you afraid of the big capacitors shocking you? Can you acciddentally touch another component that traces back to the capacitor and it shocks you? Or do you have to actually get underneath the cap and touch when of the leads for it to shock you?
Very interesting video. Thank you very much.