power section pops like frying bacon

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I am attempting to repair a guitar amp that belongs to a friend of mine. I isolated the power section and power supply from the preamp and tone controls. Its making random pops and crackles as if I am wiggling a loose connection. The power supply is a simple unregulated bridge rectifier and 2 caps. The amp is a TIP35 and 36.

I have re-soldered all of the component connections and changed all of the electrolytic caps with no success. What you recommend next?
 
Although the other causes are more likely I am sure, I had a frying bacon noise (low) on both channels in a power amp from some tantalum input caps (5.0 uf) I installed. Caps were purchased at RK distributing, a local parts store. Had it from the day I activated the purchased dead amp until 20 years later when I replace the caps again. Wasn't any internet in those days, didn't know what to expect from a transistor amp. This replacement time I used 4.7 uf 50V CPO ceramic caps. Much better! Still have the OEM (original equipment manufacturer's) 1970 transistors on one channel.
 
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I think that popcorn noise is intrinsic to the device. i.e it would have sounded that way from the time of manufacture.

It is intrinsic to the device - but it can get worse over time if a defect causes the device to continuously degrade. I've had input stages start out quiet and just start that crap up one day, and then get worse and worse and worse till I get fed up and replace it. Never had one in a hermetic package do this - so I suspect it's die attach or contamination issues.
 
I've been around the whole amp. There is nothing that I can influence physically.

If I could figure out what this is, I would buy a pair and a 506 to match.
524.jpg
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I think 524 is the date code. I'm sure someone on here can tell you the make from the logo in front of the 5.

Decoding component marking is something of a black art; it relies on some guesswork and some pre-existing knowledge. I happened to have heard of transistors called MPSA-something, and google confirmed that MPSA05 is a known transistor type. In an extreme case I could still be wrong, but in this particular case I think I have it right.
 
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