[Solved] Pioneer VSX-517 receiver repair

[max.wwwang]

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 (per manual) 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.

[DimitriP]

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.

[max.wwwang]

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.

Which 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.

[max.wwwang]

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.

[max.wwwang]

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.

[DimitriP]

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 C53

carver thread here: https://thecarversite.com/topic/17235-hr-722-wont-stay-powered-up-fixed/
C853 was the culprit on the blurry schematic

[max.wwwang]

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.

Thanks.

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.

Check before and after D55 and R53. You should have over 12V on the cathode of D55.

I was surprised I only got 5V or so DC. But for the same reason (half-wave), this seems correct.

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.

Because of the correct waveform, they should be ok.

As far as caps go, two suspects to start with : C54 and C53

I 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 this link, seems the micro is bad? If so, then no point to repair.

[DimitriP]

I 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.

It's worth measuring / replacing the caps before declaring the microprocessor dead.
Worse case you are out two capacitors.

[max.wwwang]

I 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.

It's worth measuring / replacing the caps before declaring the microprocessor dead.
Worse case you are out two capacitors.

Thanks. 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.

[DimitriP]

Thanks. 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).

If 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:

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

[max.wwwang]

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?

[ambrosia heart]

Does not power on. The power supply board relay clicks then powers off straight .  This tells you there must be some
faulty 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.84
Schematic 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 circuit
When voltage at C801&802 isn‘t balanced, Q808 off, making Q807 ON.  At the same time,  Q807 ON, charges C806
immediately, making Q808 ON shorting +5V to ground with pin 89 turning +5V to 0 V. :bullshit

[max.wwwang]

Does not power on. The power supply board relay clicks then powers off straight .  This tells you there must be some
faulty 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.84
Schematic 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 circuit
When voltage at C801&802 isn‘t balanced, Q808 off, making Q807 ON.  At the same time,  Q807 ON, charges C806
immediately, making Q808 ON shorting +5V to ground with pin 89 turning +5V to 0 V. :bullshit

Wohoo~~ 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?)

[ambrosia heart]

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.

[ambrosia heart]

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.

[max.wwwang]

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?
...
(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.

(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). OK
5V 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?!!

(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.

Fan tested is good. I've never seen a failed fan. 

[max.wwwang]

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.

[ambrosia heart]

Unable to find IC 605, otherwise, ic can be checked. :popco


The output stage of IC605 has been shorted, or, voltage amp inside the IC get damaged, resulting in
unbalanced voltage.  D.C . comes out from the speaker terminal via IC pin 8 or pin 11， triggering
protection.


Buy them at taobao.

[max.wwwang]

Unable to find IC 605, otherwise, ic can be checked. :popco
(Attachment Link)

The output stage of IC605 has been shorted, or, voltage amp inside the IC get damaged, resulting in
unbalanced voltage.  D.C . comes out from the speaker terminal via IC pin 8 or pin 11， triggering
protection.
(Attachment Link)

Buy them at taobao.

IC604-607 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.

[mzacharias]

I 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.

It's worth measuring / replacing the caps before declaring the microprocessor dead.
Worse case you are out two capacitors.

The microprocessor is only doing what it is supposed to do with a fault detected.

[max.wwwang]

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!

[max.wwwang]

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?

[mzacharias]

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.

[ambrosia heart]

How to check the power amp IC?

The output stage of IC605 has been shorted, or, voltage amp inside the IC get damaged, resulting in
unbalanced voltage.  D.C . comes out from the speaker terminal via IC pin 8 or pin 11， triggering
protection.  You can check if DC has been outputting by connecting black probe of voltmeter to heat
sink of all ICs mounted and red probe of voltmeter pointing at pin 8 OR 11.  You will see voltage greater
than 0.5V  measured.  This gives a clue which channel gets damaged.

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?

This 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.

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.

 CPU.JPG (96.48 kB. 800x600 - viewed 873 times.)

NONSENSE!    OMG, you even don‘t understand how relays of an amplifier work!!!

[max.wwwang]

How to check the power amp IC?

The output stage of IC605 has been shorted, or, voltage amp inside the IC get damaged, resulting in
unbalanced voltage.  D.C . comes out from the speaker terminal via IC pin 8 or pin 11， triggering
protection.  You can check if DC has been outputting by connecting black probe of voltmeter to heat
sink of all ICs mounted and red probe of voltmeter pointing at pin 8 OR 11.  You will see voltage greater
than 0.5V  measured.  This gives a clue which channel gets damaged.

Thanks. But by saying IC605 do you mean IC601 or 603? IC605 is only a fuselink.

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?

This 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.

Really? 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!