"The reverb doesn't work. I think it has dirt in it. You should maybe try...

[JHow]

... to blow it out with compressed air."

That was the advice from the craigslist seller, parting with his brother's very dirty 1983 Randall RG80.

So I spent a lot of time cleaning this thing, fixed some trivial stuff like loose footswitch connector, etc. and finally I turned my attention to the reverb.

I guess the reason I got the "compressed air" advice was because of all the filth in the bottom of the cabinet, but fortunately, the reverb pan was in its bag and was actually very clean, so I had a look at the circuit. It is very basic, just one 1448 or 4558 according to the schematic. I check the voltage on pins 8 and 4, looking for +12V, -12V respectively and I get crap. The chip that's in there is an NE5532, and, interestingly it's in a socket. I thought, maybe I'll just stick another chip in there - so I pull it out and realize its upside down! I flip it over, I have reverb!

Weird. The interior of the amp is pretty unmolested. Who flipped the chip over like that? Mr. Compressed Air didn't strike me as the type to go poking around in his amp guts (although I'm glad he didn't go waving his compressed air around the speaker). Besides, the amount of dirt on this thing seemed like it hadn't been touched for a while. Oh well. His loss, my gain.

[Euthymia]

Funny.

If only that IC was socketed, my guess is that years ago the reverb died and someone pulled the original IC and put in a socket, then proceeded to screw the pooch by installing the replacement IC backwards.

[JHow]

That's why it made me laugh, because anyone should be able to tell that their "fix" didn't take, but they weren't curious enough to re-examine their handi-work.

As to the IC, it is actually the only chip on the board, all the other semis are discrete devices - so it is also the only chip with a socket. If it is a later addition, I should be glad they didn't reverse the socket.