Onkyo M5000 Goes into protection mode

saturnfive

New Member
I just bought an Onkyo M5000 power amplifier from local sales and when I plug the amp in it immediately goes into protection mode. Nothing is connected to the speaker terminals or the inputs. Any ideas where I should start looking for solutions?
 
May have a bad STK amplifier chip. Would need to test voltages on the STK power Packs.
 
Need to know what voltage is on pins12,14 and 13 of Q501 and Q601 ( STK4044V)
 
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That’s what I was afraid of. They guy said it worked fine, I got it with the matching preamp and tuner. He said he didn’t know if the tuner worked, that didn’t matter to me.
 
Thanks. That will give my multimeter something to do.
Be careful not to short two or more of the pins together. Pin 13 is output. Pin 12 and 14 are +/- 60vdc rail. If you short out 13 to either 12 or 14 Chip will be history if it wasn't already.
 
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Ideally, there should be only a few millivolts on pin 13.
 
Be careful not to short two or more of the pins together. Pin 13 is output. Pin 12 and 14 are +/- 60vdc rail. If you short out 13 to either 12 or 14 Chip will be history if it wasn't already.

I popped the cover off and the STK pins are difficult to get to! I need smaller probes or I’ll need to remove the cover, heat sink and main board to to access the bottom traces and check solder joints.

Update: the bottom metal cover came off easily. The pc board is exposed, so I can test from the bottom.
 

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Be careful not to short two or more of the pins together. Pin 13 is output. Pin 12 and 14 are +/- 60vdc rail. If you short out 13 to either 12 or 14 Chip will be history if it wasn't already.

Is it ok to ground the multimeter to the chassis?
 
Should be OK. Need to reference all test voltages to ground.
 
i would monitor pin 1 at power on then if input looks ok look into replacing the differentials in the ic .
this i have never done but looks possible if you can work with smd .
edit .. i was jumping the gun here assuming it took a long time for the 1v to subside .. manuals usually state a few seconds for the circuits to stabilise and allow the relay to click in .
stk4044v_6690.jpg
 
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Is there an illuminated LED light that indicates "protection" mode? If so. Does it extinguish when the relay "clicks"?
 
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