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Louie
Louie, Technician
Category: Home Theater-Stereo
Satisfied Customers: 11428
Experience:  Have been in the business 25+ yrs., down to component level.
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I have a Yamaha Rex v659 that does not power up.

Customer Question

I have a Yamaha Rex v659 that does not power up.
Submitted: 17 days ago.
Category: Home Theater-Stereo
Expert:  Nathan replied 17 days ago.

Hi, I'm Nathan.
Sorry to hear that you're having trouble, but I'll do my best to help you. Please give me a few moments to review your details here.

Expert:  Nathan replied 17 days ago.

Hello Pierre,

Are you getting any error messages, flashing lights, or clicking sounds?

Customer: replied 17 days ago.
Nothing. The relay does not switch on.
Expert:  Nathan replied 17 days ago.

If you turn it off (using the small on/off button, not the larger standby button), then press and hold the STRAIGHT button on front, and try to power on with the small on/off button (still holding straight) is there any response?

Customer: replied 17 days ago.
No response.
Expert:  Nathan replied 17 days ago.

Thank you for checking.

Unfortunately, the issues you are experiencing are symptomatic of an internal hardware defect, meaning a faulty power supply or main/control board, though there are many possible failure points. This issue could be a manufacturing defect, but is also often caused by a power event (shock/surge, prolonged over/under voltage condition, etc).

This could also be the result of age related wear and tear; as a 2006 model, that type of failure wouldn’t be surprising; this amp is at twice its designed service life at this point.

There is one further step you can take here, both as a possible fix, as well as a diagnostic evaluation:
1) Unplug the power cord from the outlet

2) Wait at least 1 hour (60+ Minutes)

3) Press and hold the power button (on the set, not the remote) for 60 seconds
4) Keep holding power button while plugging back in, and for another 60 seconds after. When plugging back in, go directly to the wall outlet, bypassing any power strips or surge protectors.

If this reset process does not work, it would unfortunately confirm an internal hardware failure.

This is something that would require repairs to correct; however repairs for these units are generally not practical. There are no parts available for them any longer.

If you’re considering repair at a local shop, you’ll find a typical repair to be around $300-400 for diagnostics, parts, and labor.

For an amp of this age however, replacement will make more sense. You can get a brand new receiver with a fresh warranty and updated features (hdmi, networking, 3d, 4k, etc) for the same price or less than you'd spend on repairs.

Depending how you’d like to proceed here, I can help with finding a repair shop, or recommending replacement options. Just let me know.

Best regards, ***** ***** for the news,

Nathan

Customer: replied 17 days ago.
Uhm, I think we should dive a little deeper into diagnosing the problem. I have the cover off and the service manual handy.
Expert:  Nathan replied 17 days ago.

Thanks for noting that, I would have skipped ahead if you had mentioned attempting to repair it yourself in the beginning.

Are you getting any voltage at all out of the power supply?

Customer: replied 17 days ago.
Both leads at the relay coil are + 1.2v
Expert:  Nathan replied 17 days ago.

You should have some additional standby voltages out of the transformer, are you getting those?

Customer: replied 17 days ago.
S10 10.4v
PRY .077v
E 0v
PDET .06v
+SM 5.1v
RES 5.1v
Expert:  Nathan replied 17 days ago.

Some of those don't look quite right, but I'm away from my pc at the moment and don't have the service documentation accessible to go through the details with you right at this time, so I'll opt out at this point and let another tech jump in to go through those details with you. Best of luck to you.

Customer: replied 17 days ago.
Thanks
Expert:  Louie replied 17 days ago.

Hi Pierre and welcome to the site, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.

Initially, the description of "...Both leads at the relay coil are + 1.2v..." would be a concern as both should read +10.5V during standby and one terminal would go down to nearly 0V when attempting to switch On.

Can you confirm and recheck please?

Customer: replied 17 days ago.
Hi Louie,Correction, 10.4 both leads.
Expert:  Louie replied 17 days ago.

Appreciate the information.

Please do the same and confirm / recheck:

  • S10 10.4v - present and consistent;
  • PRY .077v - should be 0.0V during standby and pulse up ~5.0V when attempting to turn on;
  • E 0v - is the common / reference ground
  • PDET .06v - is from D767 of the CPU board;
  • +SM 5.1v - should read as +5M which is memory +5 supply from IC673 through a D769 and also at the CPU board;
  • RES 5.1v - is a power on/plugging in RESET.
Customer: replied 17 days ago.
S10 is 10.39v and stable
PRY now reads .077v and does not increase when attempting to turn on
+5M 5.1v
Expert:  Louie replied 17 days ago.

Based on "...PRY now reads .077v and does not increase when attempting to turn on...", it would appear that the Yamaha has kicked in auto-protect mode.

A little more background info please:

  • • did the RX-V659 die while in use;
  • • or it has been in storage / off for some time and this came up when attempting to use again;
  • • if died while in uses, was there any power failure or fluctuations / interruptions during that time?
Customer: replied 17 days ago.
Died after prolonged storage.
Expert:  Louie replied 17 days ago.

I understand.

Proposed preliminary checks (if have not been done) if attempting a component level repair:

  • capacitors in the standby power supply board and the CPU regulator circuits including but not limited to C651, C654, C655, C7643 ~ C7646, C7648;
  • zener diodes of the standby power supply board;
  • regulator transistor Q768 of the CPU board as well as switching transistor Q769;
  • and if & only if comfortable with, what happens when the collector & emitter of Q652 are shorted together.

Please post back results / observations of the above once tried.

Customer: replied 17 days ago.
All caps on power supply checked good.
I'll have to test the Zeners (which ones are they?). Q768 and 769 checked god previously.Shorting q652 turns the relay on but not the display.I will test and retest the components you've sggested tomorrow.
Expert:  Louie replied 17 days ago.

The zeners would be D654, D655, D656 and D658 (if installed).

"...Shorting q652 turns the relay on but not the display...", check the voltages at the CPU board and re-check the capacitors there. Further, please determine if there is filament voltage from the main transformer.

Customer: replied 16 days ago.
Good morning,
All zeners OK, including D658
Q768 and 769 OK, but replaced 769 anyway.
C7643, 7646, 7648 OK but replaced them anyway.There are 128 pins on the CPU, should I check them all?
Expert:  Louie replied 16 days ago.

Interesting question; what makes you think something is wrong with the CPU and/or any of its 128 pins please?

Customer: replied 16 days ago.
You asked me to check the voltages at the CPU board. I assumed you wanted those from the CPU.
Expert:  Louie replied 16 days ago.

The CPU would need a logic prove for tests on most of its pins and rarely done.

In most instances, it would be the different +5Vs that are checked and in this particular model; +5BU, +5M, +5S, PDET and PSV. Please note that all of these are derived from a 3-pin regulator IC located at the CPU board.

Additionally, PDET (power detect) and +5M (5V memory) are supplied back to the standby power supply board also from the CPU board. Turn on signal PRY is the only logic voltage supplied by the CPU to the standby power supply board that is needed to turn on the relay RY651 hence the above post of "...PRY .077v - should be 0.0V during standby and pulse up ~5.0V when attempting to turn on..."

The /RES (reset) is logic state supplied by the standbypower supply at the moment it is first plugged in and is an input to the CPU's pin 17. There should be a +5V pulse on /RES when the Yamaha is plugged into an outlet..

With these in mind and as earlier posted, please re-check that:

  • PDET .06v - from D767 of the CPU board should have +5.2V;
  • RES 5.1v - is a power on/plugging in RESET and should pulse up ~5.0V when plugging the RX-V659 to an outlet after a bit of a delay.
Customer: replied 16 days ago.
D767 0.66v
RES highest 0.3v when device plugged in
PRY fluctuates between.077v and .008v. Pushing the power button doesn't seem to affect it's reading.
Customer: replied 16 days ago.
It seems that the RES is not signaling to the CPU. So, PRY is never sent to the power supply board?
Why is PDET so low?
Expert:  Louie replied 16 days ago.

Let's start with "...Why is PDET so low?..." which could either be:

  • the expected +5.2V is clamped down by Q769 - temporarily remove D767 and test for PDET again;
  • the +5.2V was never there to start with - check Q653.

Incidentally, was C654 on the standby power supply board checked and/or replaced ?

Customer: replied 16 days ago.
C654 Ok, but replaced again
Q653 4.9v at collector
Removed D767 with the following results:
S10. 10.5v but jumpy
PRY 0.092v
E. 0v
PDET. 0v
+5M. 5.1v
RES 0v and no change when plugging in device
Expert:  Louie replied 16 days ago.

Sorry but my initial understanding was that "...RES 5.1v..."

Did "...Removed D76..." resulted to "...RES 0v..." ?

With "...Q653 4.9v at collector ...", determine the voltage at both legs of R655 & D653 and R654 & D652.

Customer: replied 16 days ago.
RES was always close to 0v. My initial reading of 5.1 v was an error caused by shorting RES with adjacent +5M.
D653 4.9v and .007v
R655 jumpy reads:
1.02v- 1.09v on one side
1.2v- 1.9 on the other.
These values were triple checked. I'll be more careful with my measurements.
Customer: replied 15 days ago.
R654 5.1v and 5.1v
Expert:  Louie replied 15 days ago.

Thanks.

On "...D653 4.9v and .007v ..."; which voltage was tested at the anode? ...at the cathode?

Customer: replied 15 days ago.
Cathode 4.9v
Anode .007v
Expert:  Louie replied 15 days ago.

Do you have a copy of the Service Manual? ...or at least the schematics?

Customer: replied 15 days ago.
Expert:  Louie replied 15 days ago.

Please see the schematics of the standby power supply.

Note that the connections would be PDET -> anode D653 cathode -> R655 -> collector Q653.

If "...D653...Cathode 4.9v..." and "...Q653 4.9v at collector ..." then "...R655 jumpy reads:...1.02v- 1.09v on one side...1.2v- 1.9 on the other...." could not be true.

Customer: replied 15 days ago.
Sorry, that was R665!R655
5.1v on one side
4.9v on the other
Expert:  Louie replied 15 days ago.

Let's start again.

Please determine the voltages at connector CB651 of the standby power supply board with the Yamaha just plugged in (standby condition):

  • S10 - ??;
  • PRY - ??;
  • PDET - ??;
  • +5M - ??;
  • /RES - ??.

Repeat voltage measurement when attempting to turn on:

  • S10 - ??;
  • PRY - ??;
  • PDET - ??;
  • +5M - ??;
  • /RES - ??;
  • base of Q652 - ??;
  • collector of Q652 - ??.

During standby condition, what are the voltages of:

  • collector of IC651 - ??;
  • collector of Q653 - ??;
  • emitter of Q653 - ??;
  • base of Q653 - ??;
  • collector of Q651 - ??;
  • base of Q651 - ??;
  • collector of Q768 - ??;
  • emitter of Q769 - ??;
  • base of Q768 - ??;
  • collector of Q769 - ??;
  • base of Q769 - ??;
  • pin 2 of IC763 - ??;
  • pin 3 of IC763 - ??.

Carefully / cautiously consider performing:

  • shorting collector and emitter of Q652;
  • then determine if there are voltage on pins 1, 3, 5 & 7 of connector CB354 of the power board;
  • shorting drain and source of Q654;
  • then determine if there is a significant change in the voltage of S10.
Customer: replied 15 days ago.
Good morning,The voltage across C661 is less than 1v AC. According to the manual, it should be 7.9v AC. C661 checks OK.Should D767 be reinserted for the next tests?
Expert:  Louie replied 15 days ago.

Hi again,

Should D767 be reinserted for the next tests? - since we are starting again, yes.

The voltage across C661 is less than 1v AC. According to the manual, it should be 7.9v AC. C661 checks OK. - hence the above "...shorting drain and source of Q654;..."

Still, IF The voltage across C661 is less than 1v AC, THEN ...Both leads at the relay coil are + 1.2v...Correction, 10.4... would then be suspect.

Customer: replied 15 days ago.
Ok, I'll reinsert D767 and proceed with testing right away.
Expert:  Louie replied 15 days ago.

And would look forward to an update when able.

Customer: replied 14 days ago.
Just about done testing. Can IC763 be accessed top side of PCB?
Customer: replied 14 days ago.
STANDBY
S10 - 10.38v
PRY - .007v
PDET - .060v
+5M - 5.14v
/RES - 0.153vATTEMPT ONS10 - 10.38v
PRY - .007v
PDET - .060v
+5M - 5.14v
/RES - 0
base of Q652 - 0.014v
collector of Q652 - 10.37vSTANDBY
collector of IC651 - 58.8v AC
collector of Q653 - 4.84v
emitter of Q653 - -0.002v
base of Q653 - -0.001v
collector of Q651 - IN -0.002v; GROUND -0.002; OUT 0.001v
collector of Q768 - 4.9v
emitter of Q769 - 5.0v
base of Q768 - 4.3v
Q769 - IN -0.001v; GROUND -0.002; OUT 0.666v
pin 2 of IC763 - ??;
pin 3 of IC763 - ??.C661 leads. 4.67 AC
Customer: replied 14 days ago.
IC763Pin 2. 10.35v
Pin 3. 5.8v
Customer: replied 14 days ago.
34;shorting collector and emitter of Q652;
then determine if there are voltage on pins 1, 3, 5 & 7 of connector CB354 of the power board;"
1: 9.75v AC
3: 9.76v
5: 15.49v
7: 15.5v
Customer: replied 14 days ago.
34;shorting drain and source of Q654;
then determine if there is a significant change in the voltage of S10."S10 went from 10.36v to 15.9v
Expert:  Louie replied 14 days ago.

On:

  • S10 went from 10.36v to 15.9v - good;
  • shorting collector and emitter of Q652 - good;
  • IC763 - good;
  • collector of IC651 - 58.8v AC - please re-check;
  • collector of Q653 - 4.84v - how about anode of D653?
  • collector of Q651 - IN -0.002v; GROUND -0.002; OUT 0.001v - ???
  • emitter of Q769 - 5.0v - re-check
  • Q769 - IN -0.001v; GROUND -0.002; OUT 0.666v - ???
Customer: replied 14 days ago.
IC763 Collector. 0.414v ACD653 Anode. 0.60vQ651 Collector. 0.001vQ769 - Base -0.001v; Emitter-0.002; Collector 0.666v
Expert:  Louie replied 14 days ago.

Thanks.

Still and on IC763 Collector. 0.414v AC - might it perhaps be IC651 ?

Customer: replied 14 days ago.
Sorry,
IC651 Collector 0.414v AC
Expert:  Louie replied 14 days ago.

Confusing diagnosistics.

Please reconnect everything.

Then determine if the Self Diagnostic Function (DIAG) can be performed. If not force/bypass by performing DIAG in the protection cancel mode.

Please be forewarned, bypassing the protection mode would serve as a test but as it implies, the Yamaha would not be protected hecne it is equally possible that other components may also go bad.

Customer: replied 14 days ago.
Should the cover/screws go on before performing diagnostics?
Expert:  Louie replied 14 days ago.

Hi again,

Cover not necessary, screws at the back/rear yes (if were removed)

Customer: replied 13 days ago.
Hi Louie,No response when DIAG attempted. Apparently, DIAG protection cancel mode works only if DIAG worked to begin with.
Expert:  Louie replied 13 days ago.

Please confirm that it has also been tried with the protection function cancelled.

Customer: replied 13 days ago.
Good morning Louie,What is the procedure for protection function cancellation?
Expert:  Louie replied 13 days ago.

Hi Pierre,

Sorry but procedures is also in the Service Manual. Please see the paragraph "Starting DIAG in the protection cancel mode". Please note that there is also a caution that such procedure may and can cause (further) damage. Proceed if have not been tried and only if comfortable with the idea.

Customer: replied 12 days ago.
Good morning Louie,No response from the unit withe the DIAG procedures. The master on/off switch doesn't appear to have any influence over the unit. The switch itself functions. I suspect there may be a problem with operation1 PCB . Do you think it's reasonable to explore this further?
Expert:  Louie replied 11 days ago.

Apologies for the delays Pierre; mobile/field. Appreciate your understanding and patience.

Still and based on all of the above, I am tempted to suspect that the CPU is halting the turn on signal hence no PRY. It has kicked in auto-protect mode.

Primary suspect would be any of the output transistors.

If these checks good, then the CPU is false sensing and/or has gone faulty itself.

If the output transistors indeed check good, then replacing the CPU board would be a major challenge due to availability.\

I realize that the above information may perhaps be not what was expected. Unfortunately, there is no quick-n-easy fix and neither is there a workaround; sorry for having to be the bearer of bad news.

Customer: replied 4 days ago.
Hi Louie,I've been overseas for the holiday.
Better to know now than to spend more time on it.
Thanks for all your help!
Expert:  Louie replied 4 days ago.

I understand this may not be what you are hoping to hear, and I'm sorry but I don't have better news.

Still, good luck and thank you too for the opportunity to share the information.

...and Happy Holidays!