Onkyo TX-2500 no power

[rickl]

TX-2500 here:

Oops. Thanks. The file says 2500. I'll rename it.

Let me look again.

 

[kwayde]

Oops. Thanks. The file says 2500. I'll rename it.

Let me look again.

The service manual I have is for both the TX-4500 and TX-2500. They list the 4500 schematics first, then the 2500 after that.

 

[rickl]

The service manual I have is for both the TX-4500 and TX-2500. They list the 4500 schematics first, then the 2500 after that.

*now* I see that. I'm a bone head. But i'd like to get the 2500 working!

I tried to update my posts with 2500 voltages. Thanks for pointing out the mistake.

 

[bzb882]

It was pretty easy to remove the outputs, so I did that rather than desyolder the pins. Looks like the thermal grease has been replaced at some point, not dried out at all. I tested all 4 on a Peak DCA55; they all tested good. I then tested the voltage on the filter caps again. Back filter cap is still pretty much 0 VDC, but the front one is now reading 31 VDC. Not sure where to check those other voltages,

 

[sregor]

Back filter cap: 0.5 mV DC (positive terminal to ground)
Front filter cap: 272 mV DC (positive terminal to ground)

Back filter cap is still pretty much 0 VDC, but the front one is now reading 31 VDC. Not sure where to check those other voltages,

The voltage on the filter cap for the negative supply is on the - terminal, the + terminal is connected to ground....

 

[curtisw99]

I bought a 2nd TX-2500 for the faceplate glass and the bonnet. It looks so pristine I don't want to use it as a parts unit. As advertised it does not power up. All 4 fuses test good as does the power cord. I tried cleaning the power switch with deoxit and used a jumper wire between the two wires attached to the power switch. No go. I removed the jumper wire and verified that I have 120 VAC at the two wires connected to the power switch. However, when I engage the power switch that drops to either 0.022 VAC or 5.022 VAC. There's no relay, but I'm guessing some sort of protection circuit is doing that. Any ideas as to where to look?

check the voltages at these 2 transistors, you can first try touching the heat sink, I think they are not insultated. On mine, the resistors associated with these were blown and replacing them brought it back to life

sorry for the bad picture, it's all I can find on line

 

[bzb882]

check the voltages at these 2 transistors, you can first try touching the heat sink, I think they are not insultated. On mine, the resistors associated with these were blown and replacing them brought it back to life

sorry for the bad picture, it's all I can find on line
View attachment 3842966

Looks like you have the MK II, mine is just the TX-2500. Thanks for replying,