Orion HCCA 2100 no rail voltage.

[Perry Babin]

Those probes are cheaper on ebay. Find a US seller. You can buy 4 for about $20.

Don't buy from anyone who claims that those are P6100 probes.

If it's OK out of the sink, look for something shorting to the sink.

 

[Chopperbuilder]

I'm confused. I apparently didn't understand your question in post #119. So to maybe better answer it, the DC voltage is exactly the same in or out of the sink.

 

[Perry Babin]

Does anything other than the PS FETs heat up if not clamped tightly to a heatsink?

 

[Chopperbuilder]

With the lamp connected none of the PS FET's are heating up. However the five 6488's and two voltage regulators circled in the photo are heating up.

 

[Perry Babin]

The voltage regulator heating is likely normal.

Its not normal for the 6488s to heat up in this amp.

Are you 100% sure that the DC voltage across ALL 10 emitter resistors on that side of the amp is 0.000v DC?

 

[Chopperbuilder]

There are now a several emitter resistors that are not reading 0.000v DC, see attached photo

 

[Perry Babin]

The transistor with the emitter reading 0,032 is likely defective.

 

[Chopperbuilder]

Is the MPSU57 circled in the picture the transistor that you're thinking is likely defective?

 

[Perry Babin]

No. The output.

 

[Chopperbuilder]

That is a photo of the audio section of the amp. Will you please show me which transistor you are talking about?

 

[Perry Babin]

See attached.

 

[Chopperbuilder]

Oh the 6491, okay. I'll pull it and check it. It is brand new.

 

[Chopperbuilder]

It was bad. Replaced it. Voltage reading across all the emitter resistors is now 0.000v. Amp power light now lights up and the lamp bulb is not lighting up.

 

[Perry Babin]

Did you buy them from a reputable distributor?

 

[Chopperbuilder]

Yes, or at least what I thought was a reputable distributor. I bought them from Arrow.

 

[Perry Babin]

Arrow is OK.

You need to determine why this didn't show up back in post 78. Why you read 0.000v across the emitter resistors. It would have saved a lot of time if it would have been caught back then.

 

[Chopperbuilder]

Yes, it would have saved a lot of time. Sorry, I didn't catch it back then because I misunderstood and thought you were taking about the resistors on the PS FET's.

 

[Chopperbuilder]

I put the amp pack to it's normal state (removed the lamp and soldered the red wire that feeds the audio circuit back into the board).

Took the limiter off and powered up the amp. Nothing appears to be heating up and it is producing clean audio however it is not producing full audio output.

 

[Perry Babin]

Are you saying that it's producing audio but the output never reaches full rail voltage (clips)?

What is the DC voltage on leg 3 of the muting transistors?

 

[Chopperbuilder]

Yes.


Both 2N5639 DC voltage:
1. -0.095v
2. -0.095v
3. -0.348v