YAMAHA RX-V650 shutting off

spencerbloke

Novice Member
Hello all,

I have a Yamaha RX-V650 that keeps going into protection mode, now strange thing is if you set the switch at the back to 6 ohms it will power up fine, but if switched back to 8 ohms it will shut down when powered up.
I have replaced that dreaded capacitor on the PSU and also changed ALL the output stage transistors.
still will not stay on when set to 8 ohms ( this happens with or without speakers connected )
Now i do get some slight crackling on the LEFT BACK SURROUND for around 10mins if i connect a speaker, only that channel does this.
now that channel is the only one that the output stage is located on the top PCB, if power is removed from them the amp will power up normaly into 8 ohms but
without that channel connected.
checked for cracked soldering leaking caps but nothing.
Any help on this would be brilliant thanks

cheers
 

dante01

Distinguished Member
I'd suggest that there's a hardware issue causing the receiver to overheat or encroach upon temperatures outside its operational range. Setting the impedance switch to 6ogm basically results in the AV receiver being restrained and this would result in the temperature being lowered while the unit is in use.

Sorry, no idea as to what may be causing the unit to overheat?
 

spencerbloke

Novice Member
Interesting. If i go into diag mode the therm is reading 100 when amp is cold. Service manual not very clear, also would that explain noise in that channel when powered up in 6ohms?
 

dante01

Distinguished Member
I'd suggest the issue is more to do with a problem with components or the circuitry than actual heat build up? You really need to have a Yamaha engoneer look at it.
 

spencerbloke

Novice Member
Self test mode result TRM = 100 ? Is that right and that when amp is cold.
Psu was in normal range, so was dc idle range.
Do you think its a fault temp sensor? For e.q Q301 as according to circit diagram 5v supply, ground and output pin say 0.9v but when i measure output pin it shows 0v when amp is cold.
 

dante01

Distinguished Member
Not suure why the temp sensor would on;y have issues if and when the impedance switch is set to 8ohm?
 

spencerbloke

Novice Member
Not suure why the temp sensor would on;y have issues if and when the impedance switch is set to 8ohm?
Help please.
Yamaha rx,-v650 goes into protect mode when set to 8ohms.
6ohms ok.
Now. All output stages have been replaced.
8ohms i get dc voltage on Sbl channel at power up but not when set to 6 ohms.
Any help on this would be welcome as yamaha were not helpfull at all.

Thanks
 

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