Pioneer VSX-933 Died - looking for guidance on repair or ...

briank5400

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Hi,
I've been lurking in these forums for a long time but never posted so hope someone can help or advise me.
I bought an Pioneer VSX-933 from Richer sounds back in Nov 2018 but a few months ago it suddenly stopped turning on. They advised that it unfortunately was no longer under warranty and would need to charge to look at it and it would take a while. They then suggested it may be better for me to find someone local to me to take a look.

Having scanned forums I have tried all the various reset options to see if it was related but seems completely dead. I have since taken the cover off to see if there was anything obviously blown or otherwise but everything seems fine. A quick volt-meter reading confirms that power is flowing in nicely, and 12v out the black ribbon.

So my first question is this. There is a small power board (see pic) - is this something which fails and can be replaced or are these issues normally more complex (i expect i know the answer!) - and any guidance if its something worth exploring further with some but basic electronics skills!
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IMG_3136.jpg

related question then is, does anyone know someone they can recommend to repair near Chippenham, Wiltshire? ;)

Thanks,
Brian
 
Have you tried [DIMMER] + [ON/STANDBY] x 2 key command?
 
think ive tried most combinations but just tried again. I assume its a case of just holding the 2 buttons pressed for 10 secs or so with the power on? no sign of any change so far.
 
Did you hold down Dimmer and then hit the On/Standby twice?
 
Ok, get this service manual (it's for vsx-1131 but hdmi is the same as 933) Check if MPON on the psu board goes low voltage when you press on/standby button. Also, check if 3.3V is present at KEY0, pin 1 of the P7001A connector (see photo below). It should go to 0V if on/standby button is pushed down.
 

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MPON stayed at 3.3v when I pressed/held the power/standby.
before going on to check the P7001a connector I also checked the +12v out (pin4) again which was now also reading 3.3v?
so I disconnected the black ribbon and check again and then it read +11.8v
I then plugged the black ribbon back in and went to read the voltages again and both the MPON and +12v were reading +11.8v
I pressed the power button on the front and its turned back on :) :) :)

I'm not quite sure what happened but I owe you a beer :)
 
Hi everyone,
I know, it's an older post but I quite have a similar problem.
In fact mine VX-933 power on then shutdown. I can ear a relay on the power board clicking.
I verified the 3,3V on the MPON like @dobrykamil said. I have the 12V on the little 4 pins black cable.
I can't see any damage on boards.
I have a basic knowledge on electronic, so I am lost ;-)
Is there someone to help me ?

Regards

JonaSan
 
If the power board relay is constatnly clicking on and off, then you might have a major short on amplifier's two power rails. Check each power transistor but start with looking at the +55V and -55V rails, make sure they aren't shorted.
 
Thank you for your quick reply @dobrykamil !
Do you mean the transistors with massive heatsink on bottom front of the unit ?

JonaSan
 
Hi everyone and @dobrykamil ,
I tested each transistors with massive heatsink on circuit, solderded on the board. Is it good or I have to unsolderded them to check them out ? They seems died actually. The other little transistor are ok.
I tested the rectifier bridge 4 pins too and it seems died.
I'm not sure of my measurement though. Not that easy to me ;-)
 
Hi everyone and @dobrykamil ,
  • I replaced all amplifier transistors: The toshiba A1941 one and the C5198 one. 14 in total.
  • I replaced the 2 transistors: a 78M15A and 79M15A.
  • I replaced the TS10B06G rectifier (diode bridge)
But it still the same. The relay on power board clicking on and off and the display, display nothing.
I saw an other rectifier 4 pins "D2000" on the "speaker connector" board, I replaced it with a TS10B06G just in case. But no, the same.
If someone have an idea, I'm interested.

Thank you
 
Ok, get this service manual (it's for vsx-1131 but hdmi is the same as 933) Check if MPON on the psu board goes low voltage when you press on/standby button. Also, check if 3.3V is present at KEY0, pin 1 of the P7001A connector (see photo below). It should go to 0V if on/standby button is pushed down.
What should I do if I don't have a 3.3v power source? Please
 
Hi, hope this forum is still active.
I have a pioneer vsx-1131, same as in this thread, mine just went into protection mode while playing one day. Shows the error "DET.PROTECT:I" on the screen. From what I understand this is some over current issue? I checked the PSU board connector P9011A on board/diagram. Pin +12VST shows 11.8V when in standby. When I turn the receiver on this goes to 17.3V is that too high?
Could the high voltage on PSU be the reason for it going into protection?
If I manually disable the diagnostic mode on the receiver, it powers on OK, and works, but is it safe to run it with the diagnostic disabled?
Any insight would greatly be appreciated.
Thanks
 

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