[Solved] Pioneer VSX-517 receiver repair - Page 1
Forum section: electronics / repair

author: max.wwwang
author_rank: Frequent Contributor
timestamp: August 22, 2020, 07:44:29 am
content: Does not power on. The power supply board relay clicks then powers off straight (the far right end of the display lights up very briefly then off). The standby 5V is ok. By manual shorting the relay connectors, the main transformers works and secondary voltages all ok. When pressing (and holding for 2 sec) both Enter+Auto Surr/direct (permanual) the relay works and the display lights up (far right end) briefly then goes off as well.Also, by pressing the power switch the relay clicks. Then I have to wait for some good time before I have a relay clicking when pressing power switch. Before that, nothing happens when pressing the power switch. This 'recovery time' does not happen to Enter+Auto Surr/direct.Appreciate any thoughts.

author: DimitriP
author_rank: Super Contributor
timestamp: August 22, 2020, 08:41:56 am
content: My Carver receiver had a similar symptom. Turned out to be a degraded capacitor that is kept charged by the standby voltage. Wasn't large enough ( it was supposed to be 220 uF and measured around 20uF ) to provide power long enough for the main power supply to power up.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: August 22, 2020, 08:46:49 am
content: Quote from: DimitriP on August 22, 2020, 08:41:56 amWhich capacitor and whereabout in your case? The symptom (time for recovery) of mine seems to have something to do with the charging or discharging of a capacitor.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: August 22, 2020, 08:56:20 am
content: Before this I already sorted a voltage selector problem - no proper contact inside. I have taken it off and replaced it with direct wire connections (fixed mains voltage without multi-voltage options now). This makes the main transformer working when manually 'clicking' the relay.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: August 22, 2020, 09:27:13 am
content: The power assembly schematics is as attached.Manually shorting pin 4 (STBY +5V) and pin 2 (AC RY) can make the relay click, which is correct.Should the voltage at pin 3(AC WUP) be 5.1V? I got around 2V.If 5.1V, then shorting pin 2 and pin 3 should also make the relay click. But now it only causes it to click but not holding, ie quickly and intermittently click.

author: DimitriP
author_rank: Super Contributor
timestamp: August 22, 2020, 07:00:00 pm
content: Regarding AC WUP and only getting 2 Volts on pin 3 , since they have a 5.1V Zener D58, that rectifies AC with D55, I'd expect 5.1 Volts, not just 2V.Check before and after D55 and R53. You should have over 12V on the cathode of D55.Remove and measure R53 to make sure it's 3.3K.If D58 decided to hold the voltage down, R53 might look a little "cooked" too.As far as caps go, two suspects to start with : C54 and C53carver thread here:https://thecarversite.com/topic/17235-hr-722-wont-stay-powered-up-fixed/C853 was the culprit on the blurry schematic

author: max.wwwang
author_rank: Frequent Contributor
timestamp: August 23, 2020, 02:32:27 am
content: Quote from: DimitriP on August 22, 2020, 07:00:00 pmThanks.Thought the same way. But with a closer look and measurement, it seems working ok. The reason is D55, along the full bridge, is only working as a half-wave rectifier (the other half is cut). Checking the wave form of AC WUP, I got as attached (1 div=2V), so the peak voltage is indeed around 5-5.1V. Because of the half-wave, the reading of DC with a DMM of around 2V (RMS) should be correct.This also explains why shorting pins 2&3 makes the relay rattle.Quote from: DimitriP on August 22, 2020, 07:00:00 pmI was surprised I only got 5V or so DC. But for the same reason (half-wave), this seems correct.Quote from: DimitriP on August 22, 2020, 07:00:00 pmBecause of the correct waveform, they should be ok.Quote from: DimitriP on August 22, 2020, 07:00:00 pmI measured the voltage across both C53 and C54 with DMM and oscilloscope, I got 12V and 5V straight lines, so they are working as expected.To this point, I think this board is working ok.According to thislink, seems the micro is bad? If so, then no point to repair.

author: DimitriP
author_rank: Super Contributor
timestamp: August 23, 2020, 03:29:11 am
content: QuoteIt's worth measuring / replacing the caps before declaring the microprocessor dead.Worse case you are out two capacitors.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: August 23, 2020, 04:38:43 am
content: Quote from: DimitriP on August 23, 2020, 03:29:11 amThanks. But my question is--if the outcome is as expected (i.e. straight line DC voltages at the right level), do I still need to desolder and test them? What I mean is, even if they were broken, the board is doing what it's expected to do (of course, this should then mean they are good).Am I missing anything in this logic?One thing is--even when the power supply board is good, before declaring the microprocessor is dead, there may still be many other possibilities.

author: DimitriP
author_rank: Super Contributor
timestamp: August 23, 2020, 10:26:55 am
content: QuoteIf the circuit in the Pioneer works the same way as it does in the Carver, the capacitors are supposed to provide power long enough for the main power supply to power up. If they have lost capacitance due to age they discharge too quickly.It seems thats's what is going on in your case too since you mentioned:Quote

author: max.wwwang
author_rank: Frequent Contributor
timestamp: August 24, 2020, 08:06:38 pm
content: Thanks, I will have a closer look at these two capacitors, especially when the switch is pressed, and both when the relay clicks and when it doesn’t.The wait time symptoms indeed seem to have something to do with the capacitor charging or discharging.More questions—Do people have any idea of how the AC WUP pin would work from its name, its wave form, and your experience?Also, what’s the best way to check whether the micro is good or not in a somehow definitive way?

author: ambrosia heart
author_rank: Regular Contributor
timestamp: August 26, 2020, 01:20:31 pm
content: Does not power on. The power supply board relay clicks then powers off straight . This tells you there must be somefaulty in your amp, including over-current: defected power transistors , dc outputted(dc offset caused by small power transistor leakage: current leaking from collector to emitter) from speaker terminals, temperature or any voltage problem in your amp, preventing you from turning it on. I am very sure that it is not related to the schematic you posted.Read p.83 to p.87.According to your symptom, Xprotect occurs. See service manual P.83 & P.84Schematic analysis p.83: fan switch on.When fan is ok, Q252 on, NO current flowing through R438&445. Q253 is off making pin89 +5V. All go reversed, if fan is NO GOOD.Schematic analysis p.84: voltage balance circuitWhen voltage at C801&802 isn‘t balanced, Q808 off, making Q807 ON. At the same time, Q807 ON, charges C806immediately, making Q808 ON shorting +5V to ground with pin 89 turning +5V to 0 V. :bullshit

author: max.wwwang
author_rank: Frequent Contributor
timestamp: August 29, 2020, 12:04:58 am
content: Quote from: ambrosia heart on August 26, 2020, 01:20:31 pmWohoo~~ This is really helpful. Thanks. I'm pleased to hear the PSU module is probably ok.Indeed pin 89 of IC9001 is 0V.More questions -- Does this mean the fan is faulty? Probably no. Because on p.84 there are more situations that can make this happen. Correct?"fan is NO GOOD". It thought fan would be one of the last parts that fail.Also, how does 'Fan stop' work? How is it wired internally in the fan (conceptually)? Is the fan always running when the unit is on or only when temperature is high? Is 'Fan stop' only a signal (output) or a switch (input) (for this one, I guess is the former)?An observation -- by 'forcing' the relay to click, the voltages at the output pins of D801 are +/- 19.5V. Seems balanced.(This is one concern, since I have overridden the protection mechanism by doing this, would this have caused more serious damage already?)

author: ambrosia heart
author_rank: Regular Contributor
timestamp: August 29, 2020, 11:54:26 am
content: Study service manual from p.82 to p.87 carefully. It gives you a lot of hints of troubleshooting.There are several points needed to be checked.(1)P.84 D702 Is this voltage balance in spite of D801 balanced as you mentioned.(2)P.83 Is +5V supplied to IC9001 of fan stop protection presence?(3)p.83 Did +24V supply to fan presence?(4)p.83 Is your fan OK?, giving +24V to fan to test its rotation.(5)Check overload, dc-detect pin voltage if +5V presence.(6)Check ALL protection circuit TRANSISTORS serving as switches, for instance, in fan stop protection circuit Q252 & Q253.Good luck.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: August 30, 2020, 09:06:40 am
content: Correction:(4)p.83 Is your fan OK?, giving +5V to12V to fan to test its rotation.Read service manual P.19 Q252, D253 & D255 form a electronic filter to give power to fan.Measure Fan+ voltage with respect to ground to confirm voltage used by the fan.To make fan rotate, fan drive voltage must be presence obtained from C740. Read P.27 right hand side bottom.It maybe +12V obtains from relays.Good luck.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 05, 2020, 05:09:55 am
content: Quote from: ambrosia heart on August 29, 2020, 11:54:26 am(1) Yes D801 balanced +/-19.5V. All good.But D702 is not, +36.5V, -24.5V. The negative is bad. (***)I then suspect the filter capacitor on the negative rail. Replaced one but the no effect.One thing interesting, when I measure with oscilloscope, is that when using the DC mode o the scope, I can see the voltage is not properly filtered. The waveform is like this-Base is at the top of the screen, 5V/div. So peak V is around 36V.However, when I switch to AC mode, it turns to almost a straight line. Should I have the same waveform only in a different vertical position? All other settings of the scope are the same.This is when the relay contacts are mannully shorted. It's similar for D701. +/- not balanced and similar strange behaviour of scope on -ve rail.(2) 5V presents in the fan stop circuit (top end of R727 on p.83). OK5V also prestns on R725 for overload detection circuit. OK(3) +26V presents on the collector of Q252.(5) IC9001 pin73 / R725 (bottom) is 0V. Bullshit, overload! (***)But looking at 2 of p.83, without even connecting a speaker as load, how can overloading happen?!!Quote from: ambrosia heart on August 30, 2020, 09:06:40 amFan tested is good. I've never seen a failed fan.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 05, 2020, 10:44:21 am
content: Putting the repair of the unit aside, does anybody hava any idea of why the oscilloscope can behave this way? I've never come across this before.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: September 06, 2020, 11:09:28 am
content: Unable to find IC 605, otherwise, ic can be checked. :popcoThe output stage of IC605 has been shorted, or, voltage amp inside the IC get damaged, resulting inunbalanced voltage. D.C . comes out from the speaker terminal via IC pin 8 or pin 11， triggeringprotection.Buy them at taobao.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 07, 2020, 09:08:48 am
content: Quote from: ambrosia heart on September 06, 2020, 11:09:28 amIC604-607 are all fuse resistors. They are all good.You mean the STK bricks are possibly bad? I cannot find the datasheet for them online. I have spares but don't know how to test without datasheet.Possibly I would stop if I have to buy new STKs from taobao.

author: mzacharias
author_rank: Frequent Contributor
timestamp: September 07, 2020, 02:36:19 pm
content: Quote from: max.wwwang on August 23, 2020, 04:38:43 amThe microprocessor is only doing what it is supposed to do with a fault detected.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 09, 2020, 08:53:45 am
content: Progress---This should really have been detected earlier. It turns out the two full bridge rectifiers D701 and D702 are both not properly soldered properly (the DC- pins)! In the photo, between the black crocodile clip and the red probe an electric connection cannot be detected and it's the same for the one next to it!These two legs were cut short, so not soldered, but long enough to appear to have been properly soldered. This looks like some deliberate sabotage!Have them soldered, and it works!But wait, no sound from the speakers. The reason is the relays are not clicked. By connecting one speaker before the relay, music comes out!

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 09, 2020, 09:02:55 am
content: A bit more study of the schematics. The reason why the relays have not clicked is because the pins 54-56 (SPB_RY, R/C_RY, SPA_PY) are low (should be 5V to click I think). Any idea why this happens?

author: mzacharias
author_rank: Frequent Contributor
timestamp: September 09, 2020, 02:53:33 pm
content: Receivers of this sort have a switch built into the headphone jack which can and often do malfunction, telling the microprocessor to shut off the speakers.This is due to a plating problem on the internal contacts which result in a short or near-short of the internal switch connection.Try disconnecting the headphone jack inside the receiver, probably at or near the front panel; there should be a plug near it which you can simply unplug to confirm the problem.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: September 09, 2020, 03:07:19 pm
content: How to check the power amp IC?The output stage of IC605 has been shorted, or, voltage amp inside the IC get damaged, resulting inunbalanced voltage. D.C . comes out from the speaker terminal via IC pin 8 or pin 11， triggeringprotection. You can check if DC has been outputting by connecting black probe of voltmeter to heatsink of all ICs mounted and red probe of voltmeter pointing at pin 8 OR 11. You will see voltage greaterthan 0.5V measured. This gives a clue which channel gets damaged.Quote from: max.wwwang on September 09, 2020, 09:02:55 amThis is normal. Whw? Your amp is now under protection mode. CPU tells ALL relays in off-state. If not, outputting DC from the damaged channel will flow through the speaker terminal making your speaker get damaged.Quote from: mzacharias on September 09, 2020, 02:53:33 pmCPU.JPG(96.48 kB. 800x600 - viewed 1198 times.)NONSENSE!OMG, you even don‘t understand how relays of an amplifier work!!!

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 10, 2020, 07:05:56 am
content: Quote from: ambrosia heart on September 09, 2020, 03:07:19 pmThanks. But by saying IC605 do you mean IC601 or 603? IC605 is only a fuselink.Quote from: ambrosia heart on September 09, 2020, 03:07:19 pmReally? if in protection mode, the power should go off but it didn't and remained on. By jumping the relay I had the music playing well without damaging my speaker!

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 10, 2020, 07:25:41 am
content: Trying to figure out how Q801-806 works which control the relays, I turned the whole thing over and it stopped working again. Plus some issues with the power assembly board, I lost my patience and am now scrapping this one.But it's almost done and I learned a lot in the process. Thanks all for your help.

author: mzacharias
author_rank: Frequent Contributor
timestamp: September 10, 2020, 05:27:25 pm
content: Quote from: ambrosia heart on September 09, 2020, 03:07:19 pmNonsense. I did factory service for Pioneer and others for over 20 years. The headphones jacks DO have an internal switch to TELL THE MICROPROCESSOR that headphones have been inserted.How else would the micro know to shut off the speaker relays?I have replaced dozens of these and similar headphone jacks for EXACTLY this problem on Pioneer, Denon, Marantz etc receivers.Here is a pic of the switch in the schematic. Pioneer, as usual, ran over onto two pages, but you can see it. The sense line is pin 2.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 11, 2020, 05:32:23 am
content: Quote from: mzacharias on September 10, 2020, 05:27:25 pmMakes sense!I should have realised this earlier. Actually I didn't even have the headphone jack module plugged in (I totally forgot about it because two many wires made it very difficult to work) so the switch 'is off' even if it's fault-free.But no worries -- I planned to scrap it even after it's repaired (I planned to use the main transformer, with another same one, as an isolation transformer without having to fiddling the wiring at all. It's only a 240V->80V or so->240V transformation). So it's 99.9% probable it should have worked perfectly if I have had the module plugged in. So I can justifiably mark this one as "".Thanks very much! One more lesson learned.Can you please explain a bit more on how this switch will pull the level at SPB_RY, R/C_RY, SPA_PY all to low? Is it through the HPDET pin of IC9001?

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 11, 2020, 05:44:33 am
content: One more question only for learning purposes. There are two rotary encoders on the front panel. Schematics attached. How can these be used as parts?Thanks!

author: mzacharias
author_rank: Frequent Contributor
timestamp: September 12, 2020, 01:18:47 am
content: Quote from: max.wwwang on September 11, 2020, 05:32:23 amI don't recall ever tracing back as far as the microprocessor for this; I simply take voltage readings at the connector and if the DC voltage at that point is pulling down with no headphones inserted, the switch is bad. I have dis-assembled the headphone jacks and it's remarkable that you can see the plating flaking off almost at a microscopic level but enough to cause a false or intermittent sensing signal.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 12, 2020, 07:29:03 am
content: Quote from: mzacharias on September 12, 2020, 01:18:47 amThanks. I think it's probably as what I said. HPDET should mean "headphone detection", and this pin of IC9001 has an inward arrow which I understand should mean INPUT. Obviously, the logic is in IC9001 itself.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: September 13, 2020, 09:07:03 am
content: So this is my isolation transformer, using a case of a UPS which is perfect and two identical main transformers of Pioneer VSX-517 (the quality is good!). The power assembly module is also used (hanging under the white plastic board) which is handy and makes the project looking more sophisticated.