Orion 250 hcca gen 1 noise problem

[Gioba]

I think you can see from the weldings too if some transistor was replaced in the power supply.
But is necessary to disassemble the PCB from heatsink for to replace the caps, then the transistor's clamps was already removed in the past.

Maybe it's a good idea to replace all the caps, those aren't a lot, or make bypass like suggest from mr. Babin for to test.
And if you find an electrolyte loss, you must to clean very well.

If you don't resolve with re-cap i don't know, the symptoms i think are about an old amp, then caps, weldings..
It's an old model, simple and effective, not complex.
But it can to have a problem.

 

[GEM 592]

Thank you again. I think I'm going to just replace those 4 rail caps next and go from there.

I have many of these amps and like them, so I might as well try to learn about repairing them.

 

[Gioba]

Of course, and me too.
I would replace all the radials caps for to start, then try.
Maybe the axials you can test with bypass like suggest from Perry Babin.

 

[GEM 592]

You can solder a new cap across the terminals of the cap you suspect to be defective to see if it makes a difference.

Thanks Perry

I only have 3300uF, 16V on hand - probably a bad idea to use these for a brief test, what do you think?

 

[Perry Babin]

It doesn't have to be a 3300uf. A 1000uF or maybe even something smaller may be enough to bypass the ripple and tell you if you're on the right track. I wouldn't try a 16v cap.

 

[GEM 592]

I think I need to order anyhow (I have only 3300uF 16V and 470uF 35V on hand), so I will just order 10 of the 3300uF 35V Nichicons and go from there. I understand this may not resolve the issue, just learning, to me this is just an inexpensive, fun hobby and I appreciate all input.

 

[GEM 592]

Update ...

I replaced each of the 4 3300uF 25V original rail caps (shown in the last pictures posted) with 3300uF 35V caps, and the issue appears to be resolved. I am testing now, but there is no more AC on the rails, and it sounds strong and clean.

Thanks again for all help!

 

[Gioba]

Good!
I think you can to consider to replace all the caps at this point.

 

[GEM 592]

There is one tiny electrolytic in the power supply, and four small ones - two in the input stage on each channel. All the rest have been replaced. I guess there is no good reason not to do them at this point.

Thanks for your help and tips Gioba, very knowledgeable I appreciate it.

 

[Gioba]

Yes, right, all olds caps replaced, so you can be more quiet.
I'm Orion first generation owner me too, and try to maintain these in good shape.
And your topic also, can to aid me and other for to understand the moon & stars amps features.
So, thanks to you and Perry Babin also, GEM.