Yamaha RXV595 turns off instantly

[6ot4hr]

Hi guys, a friend brought me a Yamaha RXV595 that turns off after 3 seconds, eventually it stays turned on for longer time but if the input selector knob is turned either way it shuts off instantly.

Since i never repaired a audio equipment before, i hope someone might help on this issue.

I downloaded the service manual and this is what i get when it boots into service mode:

DVD/LD MAIN BYPAS
DVD/LD DC 18% ( <---- what does this message mean)

[goontron]

Re: Yamaha RXV595 turns off instantly

press effect + program + standby/on buttons all at once.

[6ot4hr]

Re: Yamaha RXV595 turns off instantly

press effect + program + standby/on buttons all at once.

Hey Goon, i tried what you mentioned. It says EFFECTS OFF and turns off after 3 seconds. Still turns off instantly after being turned on again and again

[goontron]

Re: Yamaha RXV595 turns off instantly

^ Huh. This one must use a different button combo to display errors...

Here's a good question. European version (240v powered) or US (110v). The 240v version is flawed across many models.

EDIT: i'll throw this out there for anybody finding this thread later on. The "Green" cap (metalized film) fim fails. The topic is well covered. https://www.youtube.com/watch?v=MwvjAtSr5t8 https://www.youtube.com/watch?v=h0j7QjriD9o

[6ot4hr]

Re: Yamaha RXV595 turns off instantly

^ Huh. This one must use a different button combo to display errors...

Here's a good question. European version (240v powered) or US (110v). The 240v version is flawed across many models.

EDIT: i'll throw this out there for anybody finding this thread later on. The "Green" cap (metalized film) fim fails. The topic is well covered. https://www.youtube.com/watch?v=MwvjAtSr5t8 https://www.youtube.com/watch?v=h0j7QjriD9o

European, 240V

[goontron]

Re: Yamaha RXV595 turns off instantly

^ Ok. barring retrieving any error codes, i would try that capacitor. What happens when that cap fails is the 5v rail goes low. 3 seconds to dead is a fault it will cause. Eventually it will get to the point of being dead totaly. C405 i believe.

[rievax_60]

Re: Yamaha RXV595 turns off instantly

Shutdown after 3 sec is likely to be excessive amplifier DC offset. Sometimes it can be a fault in the protection circuitry.
Measure the DC offsets.

[rievax_60]

Re: Yamaha RXV595 turns off instantly

Also measure the voltage at the Base of one of the mute transistors to see if it ever attempts to go negative just before shutdown. It should go to -15v in a properly working receiver.

[goontron]

Re: Yamaha RXV595 turns off instantly

Shutdown after 3 sec is likely to be excessive amplifier DC offset. Sometimes it can be a fault in the protection circuitry.
Measure the DC offsets.

Correct me if im wrong, but wouldn't it display something along the lines of "PROTECT" or "SPEAKER FAULT" If it was the outputs? Or am i giving this computerized junk too much credit?

[rievax_60]

Re: Yamaha RXV595 turns off instantly

It does say "DC 18%", I'm hoping that this might mean DC protect.
I have seen false DC protect shutdowns caused by leaky diodes causing unindented interaction between Mute, I protect and DC protect circuitry.

[goontron]

Re: Yamaha RXV595 turns off instantly

^ Huh. yeah, that could be a protect. 18% of what though? Im going to try and find a service manual for this. The CR series is easy to get documentation on, why not RX series

Mid/Late 90s Pioneer stuff has a habit of transistors going leaky in the protest circuit and intermittently cutting in, so bad SS parts wouldn't surprise me.

Found the diag mode. https://www.manualslib.com/manual/70...page=10#manual

Using the front panel keys of the main unit.Plug in the AC power cord , and, with Power OFF, hold down the "INPUT MODE" and "FM/AM" keys simultaneously(Step 1), and then press the "STANDBY/ON" key (Step 2)

Well shit, look at that.

DC % Appears when the power amp DC protection function has been activated. For the % value, the voltage at that point is shown by 5V/100%. When power is turned on in an abnormal status, power will turn off after two seconds

This computerized stuff is weird. And i guess i can't read well enough to realize OP already has it in service mode... Christ im batting 0s today. Im out before i make myself look more clueless.

[tibimakai]

Re: Yamaha RXV595 turns off instantly

I would measure for short on the finals. Just to be sure.

[6ot4hr]

Re: Yamaha RXV595 turns off instantly

Quick update, i checked all the voltages on and from the regulators and they seem okay... Interesting thing is this:
It shuts off instantly if the impedance switch is set to 8 Ohms
It only works on one speaker on channel A on 4 Ohm impedance setting, if anything else is connected to output it shuts down instantly
If the volume is turned beyond 60% it shuts down on channel A

[goontron]

Re: Yamaha RXV595 turns off instantly

^ Yeah, follow rievax_60s advice and Measure the DC offsets.

[R_J]

Re: Yamaha RXV595 turns off instantly

Like suggested above... Check the offset voltage on each channel, It can be measured at the center pin of R692,R696, R694, R690 & R688. It should be close to zero volts. which ever channel is not zero, that channel has a problem.

[6ot4hr]

Re: Yamaha RXV595 turns off instantly

Thanks Guys,

Here are the voltages:

R692 = -11mV
R696 = -8mV
R694 = -14mB
R690 = 4mV
R688 = +32V


That R688 doesn't seem to be remotely in the range, any suggestions?

[R_J]

Re: Yamaha RXV595 turns off instantly

well there's your problem channel, main Left. start by checking the transistors in that output circuit, check the R688 and see if one of the two resistors are open, Also check R598 & R602 & R599. see how those parts check out, if they seem ok (I doubt it) check Q506, Q511, Q512

[6ot4hr]

Re: Yamaha RXV595 turns off instantly

Hi guys, R J i did some testing, i think q506 might be the problem.

Resistors measured:
R688 0.18 / 0.20 Ohm
R598 5 Ohm
R599 340 Ohm
R602 5 Ohm


Q511 and Q512 seem okay, but take a look at the Q506 vs Q507 and Q509. Q506, Q507 and Q509 should have a same role, but Q506's B and Uf are both 0.



I did not measure voltages at the Q's, will do that and report soon

[R_J]

Re: Yamaha RXV595 turns off instantly

I don't use one of those, I use a meter with diode test. I guess Q506 could be bad, that amp is dc coupled so that could cause the offset voltage to be that way