Yamaha HTR 5650 - Power on Immediate Power Off

[Rebel]

I inherited a Yamaha HTR 5650, looks pretty good. Powers on (relay clicks and lcd screen turns on) then Immediately powers off. Unit does not flash a message when it powers off, just blanks out. I went through a reset procedure I found, I tried it twice it does the exact same thing afterwards. It will stay on in diagnostic mode but other than that nothing much. I have a pretty good meter and know how to diagnose some stuff, also have a capacitance meter. Any help is appreciated, Thanks.

 

[mbz]

The amp is in protection mode, immediate power off indicates over current,
typically caused by a failed/short output transistor. Power off after 1 sec
indicates a fault in the power supply.

Are you able to see what protection mode it is eg, "I PROTECT" or "PS PRT xxx"
refer page 24, 25 of sm

Since LEDs light up probably PS PRT, need the numbers xxx, might be zero.
This could be due to tired caps in the regulated supply. Lift the lid and take
a pic of the caps of the larger caps near the heat sink (voltage regulators and
output TR's) Might also be a failed voltage regulator.

Without doubt these are extremely difficult/time consuming to repair. Sometime
you can be lucky.

 

[Hamish119]

...It will stay on in diagnostic mode but other than that nothing much.

Congrats... You've reached the advanced troubleshooting stage, but you haven't stated what fault is displayed on the front panel display when you power-on in 'DIAGNOSTIC MODE'. (MBZ has provided some hints...)

Whilst in 'DIAGNOSTIC MODE', scroll through the menu and note the fault(s) in the 'PROTECTION HISTORY' log. Here's an example...

Troubleshoot from there...

I received a DSP-AX757SE (HTR-5860) with a label that stated "Needs new fuse". It didn't...
The symptoms were similar to those exhibited by your HTR-5650.
'DIAGNOSTIC MODE' stated 'PS PRT' and the fault history was repeatable.

...Might also be a failed voltage regulator...
...Sometime you can be lucky.

I was lucky - it was a duff 7805!

Good Luck!

 

[Rebel]

Hey guys, got a chance to look over the unit again. when force starting it into the Diagnostic menu it says PS PROTECT 5% D. Im just guessing that means a power supply fault and that it is maybe outputting only 5% of the DC Voltage? Am I anywhere close?

 

[mbz]

Hey guys, got a chance to look over the unit again. when force starting it into the Diagnostic menu it says PS PROTECT 5% D. Im just guessing that means a power supply fault and that it is maybe outputting only 5% of the DC Voltage? Am I anywhere close?

That would be my intrepretation. Check each of the voltage regulators. You might be lucky with a simple fix...

 

[Jube marsh]

Has anyone figured out what the culprit was?
I have a htr-5650 & a htr-5640 doing the exact same thing.

 

[mbz]

Has anyone figured out what the culprit was?
I have a htr-5650 & a htr-5640 doing the exact same thing.

Need to check the protection history, also subtle differences when attempt to power on.
Over current/I-PROTECT, amp immediately turns off
Power Supply/PS PROTECT, amp shuts down after 1 second
DC PROTECT, amp shuts down after 3 sec.

Check protection history by entering diagnostic mode by pressing the three keys simultaneously
"8CH" + "STEREO" + "STANDBY/ON"

Protect info should then be displayed, eg, PS PROTECT 005
make a note of this info

These style of amps are difficult to diagnose/repair almost cost prohibitive. The easiest repair is the
PS PROTECT typically caused by failed voltage regulator or caps...

 

[Jube marsh]

Hello and thank you for your valuable information!

I found shorted voltage regulators and resistors on both of them. I see that +5 & -5 effects the protection circuit from the chip(stand by).

I also see that if it isn't perfect and it senses trouble it won't turn on.
Other than that all the outputs are good.

Since both are plagued with the same issue I've ordered the replacements.

But as directed, I will get the codes and post back with them.

Thanks again my fellow holic!

 

[mbz]

Certainly replace the failed regulators, resistors. The amp checks all key voltage supplies and wont power up
if they are not within spec.

 

[Jube marsh]

Certainly replace the failed regulators, resistors. The amp checks all key voltage supplies and wont power up
if they are not within spec.

Thank you!
I'm waiting on parts from digikey

 

[Jube marsh]

*UPDATE*
Well after lots of testing I have figured out the problem in both of the 5650 and 5640.

Turns out the 5 voltage regulators were in question....

The 5640
3 of 5 were shorted
2 x 78m05
1 x 78m12
No resistors were shorted
No outputs were shorted

The 5650
All 5 are shorted
No resistors are shorted
No outputs are shorted

Waiting on parts.....

 

[Audiokingman]

*UPDATE*
Well after lots of testing I have figured out the problem in both of the 5650 and 5640.

Turns out the 5 voltage regulators were in question....

The 5640
3 of 5 were shorted
2 x 78m05
1 x 78m12
No resistors were shorted
No outputs were shorted

The 5650
All 5 are shorted
No resistors are shorted
No outputs are shorted

Waiting on parts.....

Well? Ever get the parts in and perform the repair?

 

[Jube marsh]

Well? Ever get the parts in and perform the repair?

Hello again!
Sorry for the delay!
Yes after replacing all the shorted regulators both powered on and work perfectly.
I went ahead and replaced the resistors as well.
I use one on my test bench and the other was sold.

 

[AstarOfDavid]

Hello again!
Sorry for the delay!
Yes after replacing all the shorted regulators both powered on and work perfectly.
I went ahead and replaced the resistors as well.
I use one on my test bench and the other was sold.

While I understand this is an older post but I too have the 5640 here and it's powering on then off after 1 second. Could you tell me which transistors you replaced so I can know where to look? I don't really see any near the power supply only on the upper and lower amp boards. (Perhaps you have a photo of the location or the part # off the board so I can narrow it down where to look on the PCB.) It would be greatly appreciated if you're still around and could point me in a direction to look. Thanks!

 

[mbz]

While I understand this is an older post but I too have the 5640 here and it's powering on then off after 1 second.

Cause could be almost anything though failed power regulated power supply (caps and regulators) have occurred. You should enter diagnostic mode (see service manual) and confirm a PS fault. The regulators are typically on a top board (above main board) with heat sink mounted regulators and plenty supporting caps.

 

[AstarOfDavid]

Cause could be almost anything though failed power regulated power supply (caps and regulators) have occurred. You should enter diagnostic mode (see service manual) and confirm a PS fault. The regulators are typically on a top board (above main board) with heat sink mounted regulators and plenty supporting caps.

View attachment 2453094

Thanks for the reply but the guy who reported which ones he replace stated the part #'s for the
5640 that had failed were:
2 x 78m05
1 x 78m12
And the 78m05 and the 78m12 are small 5v regulators not the main power IC's attached to the massive aluminum heatsink as you've highlighted in your schematic. I assume these that you pointed out are in fact the actual audio amp IC's.
From what I can tell from the quick diagnostics mode look I did - the DC voltage reported on the screen it's around 94% to 95% so I assume this is why the unit powers off not reaching the full 100% DC voltage it's looking for. Which to me sounds like the same issue Jube Mash reported and solved by replacing those smaller regulators. I looked them up and I know what they look like but I cannot seem to locate them inside the unit anywhere.

As a side note - the diagnostic screen also blinks the world "sleep" in red.

 

[mbz]

Thanks for the reply but the guy who reported which ones he replace stated the part #'s for the
5640 that had failed were:
2 x 78m05
1 x 78m12
And the 78m05 and the 78m12 are small 5v regulators not the main power IC's attached to the massive aluminum heatsink as you've highlighted in your schematic. I assume these that you pointed out are in fact the actual audio amp IC's.

Thinking you would be wrong in your assumption.

From the service manual, shows +/-5,12V regulators

From what I can tell from the quick diagnostics mode look I did - the DC voltage reported on the screen it's around 94% to 95% so I assume this is why the unit powers off not reaching the full 100% DC voltage it's looking for.

Exactly what was the diagnostic message, ie PS PRT nnn
A voltage of 94-95% unlikely to be regulator failure, more likely to be a leaky cap, maybe post a pic of that board highlighted above, showing caps. I'd be surprised if 95% voltage would trigger protection, considering mains AC drift.

 

[mbz]

I'd be looking behind metal clamp below

 

[AstarOfDavid]

I'd be looking behind metal clamp below
View attachment 2453509

Oh yes - there they are! I did not think to look under that metal plate I assumed that was just another of the larger audio amp power transistors under there. Thanks!

 

[AstarOfDavid]

Thinking you would be wrong in your assumption.

From the service manual, shows +/-5,12V regulators
View attachment 2453502


Exactly what was the diagnostic message, ie PS PRT nnn
A voltage of 94-95% unlikely to be regulator failure, more likely to be a leaky cap, maybe post a pic of that board highlighted above, showing caps. I'd be surprised if 95% voltage would trigger protection, considering mains AC drift.

After the comment mbz made I realized the schematic you included was in fact focused on this same location. However I was looking at it "mirrored" because I was not thinking this schematic was being seen from underneath. So I thought you were highlighting the much larger audio amp power transistors that are on the right hand side of the location you actually indicated. After mzb pointed on the actual physical layout image - I took the metal plate off this location and there they are! So I will pullout the multimeter in a bit to check them. Sorry about that! And thanks for the quick reply!

Also the first thing I looked at when I noticed the unit powering off was the small daughterboard that the AC power connects to. And I did in fact find multiple broken solder joints which I repaired. I then took the entire unit apart and went over it with a magnifying lens checking all solder joints on every board to find no other physical issues.