Yamaha RX-V800 strange issue

miltown · Joined: 01 Sep 2009 Posts: 9

Hey all . I have an RX-V800 that shuts down every time an input is selected or the program button is pushed, or the DSP switch is turned on/off or the 6ch input switch is turn on/off. Now the details . If 6ch input is on I can select inputs without it shutting down. I can press the program button if the effects(DSP) is off. If I press input though it will still shut down. Sometimes it will not turn on at all but usually after 3x it will turn on with the above stated issues. Any takers. I have a manual for the unit and the voltages all look like they are there I've checked voltage reg IC's on Function card and they look fine. I have not checked their output voltage yet as they are in an unreachable space but I'm looking to check it at the phono IC. Anyone with some ideas or someone who is familiar with these. I'm not. I also have not checked any caps yet I have to grab the ESR tester from work.

paul

Drdave · Joined: 11 Jun 2009 Posts: 24 Location: South Florida

For starters, I would check the muting transistors (Q-515 thru Q-528) on the function pcb. One might be leaky and could cause it to shut down when you change modes. Also check(C-633) the memory backup cap, that's known to leak.If it has clean the board real good around the cap and replace it. Even if it hasn't leaked yet replace it anyway. Let us know what you find. Good luck.

miltown · Joined: 01 Sep 2009 Posts: 9

I have checked out the transistors and they are fine. Have not checked out the caps yet. I did notice before the speaker relay clicks the buttons will work without shuting down the unit. Once they click though it is all over.

Drdave · Joined: 11 Jun 2009 Posts: 24 Location: South Florida

You said you could change inputs without shut down until the protect relay kicks in. That maybe normal.
Are you testing with or without speakers hooked up?
If it is with, remove all of them and see what happens.If it does not shut down then check the speaker jacks one by one to see if you have DC offset on any or all when you change inputs, and let us know.
Then we can go to the next step

miltown · Joined: 01 Sep 2009 Posts: 9

Yeah that was my 1st step to remove speakers. I'm in service mode now. I currently have nothing plugged into the unit as it is being serviced. The same thing still happens with or without speakers. I get to take the ESR from work this weekend so I can get on the caps. I'm really puzzled on this one. I haven't found a bad voltage anywhere yet. With time it will come though.

paul

miltown · Joined: 01 Sep 2009 Posts: 9

New discovery. When I leave the unit on for more than a half-hour I can press the buttons a few times before it will shut down instead of just once like it was doing when it is first powered on. Would that lead me to caps?- Maybe that memory battery/cap?

paul

miltown · Joined: 01 Sep 2009 Posts: 9

Well an update. I tested the caps pretty good. I did find a bad cap at C633 so that was replaced . (That is what to so long to reply waiting for parts.)Goood call D. ,But that also did not solve the problem. So any new guesses?

paul

miltown · Joined: 01 Sep 2009 Posts: 9

Well I found it. A cold solder on the front board. Not exactly sure where on the board but resoldered the whole thing and all is good. Probably on the display those get some heat. That is always my last ditch effort and 98% of the time works.

PS I did not resolder the chip. I would of if the unit still did not work.

PAUL