Orion 250 hcca thermal tape right?

[GEM 592]

Hello,

This is another working gen 1 250 hcca that sometimes produces static when very hot - if I keep a fan on it, no problem. It will do this without shutting off. The thermistor is present, the amp has obviously been worked on (looks like all power supply devices at least, soldering is not good), it seems to be an older board than the others I have (slight board differences).

Anyway, I'm wondering if the thermal tape looks right, or might be related to the problem. It doesn't look like Kapton or equivalent to me, maybe more like plumber's tape, it has a soft spongy feel.

Thank you

 

[Perry Babin]

It looks like fiberglass reinforced silicone rubber tape. It was used in some amps. Many times (if it'e the blue tape), it will stick to the back of all of the transistors and will have to be scraped off or the transistors replaced.

The noise may be leaked electrolyte. touch your scope probe to the board near the capacitors. T scope should not deflect any (set to about 1v/div). If it does, it means that electrolyte has leaked from the caps.

 

[GEM 592]

It looks like fiberglass reinforced silicone rubber tape. It was used in some amps. Many times (if it'e the blue tape), it will stick to the back of all of the transistors and will have to be scraped off or the transistors replaced.

The noise may be leaked electrolyte. touch your scope probe to the board near the capacitors. T scope should not deflect any (set to about 1v/div). If it does, it means that electrolyte has leaked from the caps.

The four 3300 uF rail caps (I think) look to be new or recently replaced (although I guess they still could be leaking). The 3300 uF "input" caps (2 of them right on the +12V input) look like maybe not. Did you mean to check either of these, both, or generally any electrolytic in the amp?

Thank you!

 

[Perry Babin]

Leakage could come from any of the electrolytics. There is no guarantee that the person who changed the caps cleaned the electrolyte, which can be very hard to see. You don't have to do anything with the caps for now, just check for leaking voltage on the board.

 

[GEM 592]

Thanks once again Perry.

I am not going to do anything other than measure, etc, with this one for now. If it ain't broke ... right? Unless I allow it to get blazing blazing stove hot, it definitely sounds right. The problem I mentioned might be down to install.

Anyway, I need to get a scope so I am looking around for that. Like you said, a real one with dials that will make me remember engineering school. I will update, any recommendations are appreciated.

 

[Perry Babin]

You may be able to do it with a multimeter but with a scope, it's easier to find the electrolyte.