Yamaha RX-V 550 turn on 1-2 seconds and then turn back off

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manolete

Member
Joined 2020
#1
Hi my friends,

I have a problem with my Yamaha RX-V 550, the amp turn on 1 second and then turn back off.

When I started on the diag mode, I have this message : PS PRT : 000 D

I guess that the problem came from the power supply board or from the big transformer, because when I unplugged the cable that come from the transformer to the front up lever board the amp turn on normally in straight mode.

It's difficult to me to explain my case, I did a little video that explain all that :

YouTube


Any idea ? I'm really lost :/

Thank you so much
 
#2
As a first guess I would say the amp is in protection because of an unexpected power supply voltage (0%) meaning one of the voltage regulators is down, could also be a filter cap on the regulator. Give me a moment to track down the service manual.
 
#4
Yeah, power supply problem. Suggest open the unit up (unplug power first) and check the power board, Should be the top board connected to the large heat sink. The board has 5/6(?) voltage regulators for supplying +/- DC voltages. First check for any physical damage like charred/burnt resistors, stressed capacitors or... Are you comfortable taking voltage measurements on a live unit (lethal voltages inside). Next step would be to test each voltage regulator by measuring output voltages. Good news is that it's repairable and probably a simple fix. Maybe 2 hours work for a tech if you don't have diy skills. These items are fairly cheap, you could probably buy a replacement for $50-
 
#6
Hi my friend, thank you very much for your response! So if I understand the problem came from a regulator in the power supply board ?

I tested each pin of this cable :

20/16/3fi3.jpg - Visionneuse Zupimages

They give me 0 volt :/

Is it possible to use an external power supply (5v or 12 v) to power this compartment instead of this cable?

I'm really sorry my knowledge in electronics is weak :/ And it's so difficult to find technician right now with the COVID crisis...

Thank you again
 
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#7
manolete said:
I tested each pin of this cable :

20/16/3fi3.jpg - Visionneuse Zupimages

They give me 0 volt
Click to expand...

The cable is the outputs from the power transformer.

You should measure them with AC and the values in green color.

Your problem maybe there is some bad capacitors if you never replaced any capacitors in this supply board.

Please check the all voltages in the red circles if they are correct as the schematic, you can consider to replace the capacitors in blue color.
 

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#8
Hi

Ok I tested the voltage regulators who are next the heatsink...

1 - It was so difficult to test and I'm not sure of the result :

20/16/dkz1.jpg - Visionneuse Zupimages

2 - As I told you I'm very weak en electronics 🙁 And I think that I burned a voltage regulator during my test beacause I have a feeling that the voltage is going very high now🙁

YouTube

My question now, Can I test again those voltage regulators with the amp off to find out which voltage regulator has fallen? Otherwise, I'm sur that the problem come from this part.

Thank's again
Best regards
 
#9
the video seems a bridge rectifier smoking.

Yes, you can measure those voltage regulators for shorted pins checking when the amp off.

If you really weak in electronics, I suggest you to buy all the new bridge rectifier, voltage regulators and caps to replace all of them(should be not much money) and hope that will solve your amp problem.

Good luck!
 
#11
Not clear to me what you've done. Suggest go back and measure the DC voltages
from the regulators. Black meter probe connected to chassis/ground. Measurement
points highlighted below (need to be careful/don't slip, maybe strip some
insulation from some wire and put it on your probe)

+5V Digital Measure at R361
+5V analogue R358
-5V J366
+12V R359
-12V R360


F+6W89oVRHGFcssuw8o7v4bO116DjerDUJMYiCbmaFUNj+SNF2L7N9LXw6jIxwwTAAAAAElFTkSuQmCC
 

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#12
manolete said:
If I have tested well I must change the two (+5v) regulators ?
Click to expand...

Your amp is not a simple power amp, there are lots of digital chips, if these chips damage, you have to pay high cost to a pro to repair it.

You have already expanded your amp damage to the regulators and rectifier, possible damage to the digital circuit after the power supply, I think you should consider a safe/better way to handle your amp, otherwise you will lost your amp if you continue to fix it.
 
#13
mbz said:
Not clear to me what you've done. Suggest go back and measure the DC voltages
from the regulators. Black meter probe connected to chassis/ground. Measurement
points highlighted below (need to be careful/don't slip, maybe strip some
insulation from some wire and put it on your probe)

+5V Digital Measure at R361
+5V analogue R358
-5V J366
+12V R359
-12V R360
Click to expand...

Hi my friend,
Thank you for your response,

As I told you on my previous post,

I did not manage to properly measure the voltage regulators with the amp on.

Apparently I lost a regulator by mistake because another component has burned out during the test with amp powred on, please see this video:

YouTube

Before the accident, I managed to get this values :

20/16/dkz1.jpg - Visionneuse Zupimages


I dont know if I can test the voltage regulators directly with my multimetre on diode mode to detect damaged regulators? Because is so diffcult to do the test now with the amp powred on...

Thank you!
 
#14
patrick101 said:
Your amp is not a simple power amp, there are lots of digital chips, if these chips damage, you have to pay high cost to a pro to repair it.

You have already expanded your amp damage to the regulators and rectifier, possible damage to the digital circuit after the power supply, I think you should consider a safe/better way to handle your amp, otherwise you will lost your amp if you continue to fix it.
Click to expand...

Thank you again my friend,

If I find the damaged voltage regulators I will change them and I'll test the amp, It's the only thing that I can do 🙁


If it doesn't work, I will order a new amp in the future...

I can not do more Unfortunately 🙁

I bought this amp in 2004... I would like to keep it but if the repair is expensive and complicate, I give up!

Thank you angain
 
#19
manolete said:
The idea is to replace the power supply board of my YAMAHA RX-V 550 by the YAMAHA RX-V 450 PS
Click to expand...

The power supply board can not interchange.

To repair and testing the regulater IC for your amp, to keep the other circuit safe, you should disconnect these two cables first, the left hand cable unplug in the power supply board, the right hand cable unplug it from the other end of the cable, after that it is very safe to test the board with power on and do not afraid any damage in the power supply board when testing.
 

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#20
Thank you again patrick101

I did what you told me, I made a video showing my test :

YouTube


I think I burned some IC regulators because of my bad test of yesterday,

The values ​​received seem to be wrong, for example yesterday on the first IC I geted the correct value which is "+12V" and now I get 1.30 ...


I think it's getting more and more complicated for me 🙁

Best regards
 
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