Yamaha RX-V359 troubleshooting, turns on and off

[Jooo]

I got this amplifier, it turns on, lcd displays for a second or two and then relay clicks and it turns off. Clearly goes to protection mode.

I got to diagnostics mode and it says "DC PRT 100% E" which means "DC output of the power amplifier is abnormal." aka overvoltage.
"Turning on the power without correcting the abnormality
will cause the protection function to work 3 seconds later
and the power supply will be shut off."

Can anyone help me with troubleshooting this? Any common faults in these models? Thanks in advance.
I have ESR meter, soon two oscilloscopes (just waiting for probes to come in mail) and multimeter ofcourse. Just not too much hands-on experience.

[Jooo]

Re: Yamaha RX-V359 troubleshooting, turns on and off

Some pictures.

And here's link to the service manual:

[Th3_uN1Qu3]

Re: Yamaha RX-V359 troubleshooting, turns on and off

"DC PRT 100% E" which means "DC output of the power amplifier is abnormal." aka overvoltage.

That doesn't mean overvoltage of the power supply, it means DC on speaker output which is likely caused by one or more shorted output transistors. Check those first.

[tom66]

Re: Yamaha RX-V359 troubleshooting, turns on and off

Looks like it uses hybrid modules, but the idea is the same.

[Jooo]

Re: Yamaha RX-V359 troubleshooting, turns on and off

Thank you. There indeed was an short: a tiny piece of wire in the legs of IC101 (STK404-130Y).
Removing that sadly didn't fix the problem, but the percentage on the error dropped to around 35% (from previous 100%), which means that it says now DC PRT 35% E.
IC102 and IC103 are Sanyo STK433-130-E.
I'm not quite sure how to measure those hybrid modules... Haven't played with them before.

I wonder if the IC101 STK404-130Y is now damaged from having a short in the legs?

[tom66]

Re: Yamaha RX-V359 troubleshooting, turns on and off

You can measure each of its OUT pins to GND. They should all measure 0V, within 0.5V.

[Jooo]

Re: Yamaha RX-V359 troubleshooting, turns on and off


This is what I measured. The current DC protection value is 40%, which equals 2V according to the service manual. (100% = 5V). And 2V is exactly what I get after STK404-130Y.
The service manual also says that normal range is 17% to 29% which translates to a voltage of 0.85 to 1.45.
Did I get it right? If I'm correct, IC101 = STK404-130Y is bad.

Then another question, are STK404-130 or STK404-130S the same parts, can I use them as replacement? I assume that Y could just mean that it is for Yamaha, but then again I'm not 100% sure.

[tom66]

Re: Yamaha RX-V359 troubleshooting, turns on and off

Obviously, this Yamaha is a lot more tolerant than I would expect, normally 1V on speaker outputs would be considered a failure.

It does look like that IC could be bad but first check for any bias adjustment pots (potentiometers) which may allow adjustment of the zero point.

[Jooo]

Re: Yamaha RX-V359 troubleshooting, turns on and off

I couldn't find any potentiometers. Is there any other way to adjust it? DC protection value was last time I checked 34%, which means it is only 0.25V over the maximum limit.
Any clue if I can use STK404-130 or STK404-130S for replacement of the STK404-130Y?

[tom66]

Re: Yamaha RX-V359 troubleshooting, turns on and off

I looked at the schematic, and I don't see a way. I'd guess the only thing you can do is replace it.

As long as you replace it with a part which has identical pin out and identical or closely matched parameters, it should be fine.

[Jooo]

Re: Yamaha RX-V359 troubleshooting, turns on and off

Thank you. Ordered one of those STK404-130S. They seem to be the same to me. I found this which finally convinced me: "Drop in compatible with the entire series of STK404 IC's from Sanyo." I hope it is true. I will let you know how it goes.

[tom66]

Re: Yamaha RX-V359 troubleshooting, turns on and off

-130 suffix indicates maximum output power of 130W. You could use a -150, for example, which has a maximum 150W output. It won't make the amp louder on that channel, because it's not designed to use the additional power capability.

[rhomanski]

Re: Yamaha RX-V359 troubleshooting, turns on and off

I don't know about your particular unit but there are a lot of counterfeit STK modules out there. If it burns out quickly again, keep that in mind.

[Jooo]

Re: Yamaha RX-V359 troubleshooting, turns on and off

I received the new IC today and soldered it in, unfortunately that did not fix the problem
It does exactly the same and there is still 2 volts after the IC... Any suggestions?

[tom66]

Re: Yamaha RX-V359 troubleshooting, turns on and off

Do the input pins read 2V too?

[Jooo]

Re: Yamaha RX-V359 troubleshooting, turns on and off

So this is what I measured:

Pin 1: 0,4V
Pin 2: 0V
Pin 3: 1V
Pin 4: 2V
Pin 5: 0V
Pin 6: 0,6V
Pin 7: 12V
Pin 8: 3,1V
Pin 9: 0,9V
Pin 10: -52,3V
Pin 11: 52,3V
Pin 12: 2V
Pin 13: 2V

[rievax_60]

Re: Yamaha RX-V359 troubleshooting, turns on and off

So this is what I measured:

Pin 1: 0,4V
Pin 2: 0V
Pin 3: 1V
Pin 4: 2V
Pin 5: 0V
Pin 6: 0,6V
Pin 7: 12V
Pin 8: 3,1V
Pin 9: 0,9V
Pin 10: -52,3V
Pin 11: 52,3V
Pin 12: 2V
Pin 13: 2V

I would expect pin 6 to have a much higher voltage. Check for a resistor applying rail voltage to it.

[Longbow]

Re: Yamaha RX-V359 troubleshooting, turns on and off

Input pins 3 and 4 should not have any d.c. voltage on them. Pin 6 is missing the -49 volts (check Q109 and R144. Pin 8 is high. Check Q106 and R119. Is it possible that traces cracked during IC replacement? Assume that the stray piece of wire took out a number of other parts, which are directly connected to the output IC.

[Jooo]

Re: Yamaha RX-V359 troubleshooting, turns on and off

Input pins 3 and 4 should not have any d.c. voltage on them. Pin 6 is missing the -49 volts (check Q109 and R144. Pin 8 is high. Check Q106 and R119. Is it possible that traces cracked during IC replacement? Assume that the stray piece of wire took out a number of other parts, which are directly connected to the output IC.

Thank you for your message.

- Q109 seems bad, ordered a replacement for that

- R144 is open, ordered a replacement

- Q106 is ok

- R119 is ok


Replacing the IC went smoothly. The traces are still good.
I will let you know how it goes when the new parts arrive.

[Longbow]

Re: Yamaha RX-V359 troubleshooting, turns on and off

A faulty Q109 accounts for the missing -49 volts. A missing 1.2 volts on pin 8 might be caused by missing +48 from Q108/R133. Q106 serves as the 1.2 volt regulator.