My Marshall amp has been sitting unused for a long time because it doesn’t make any noise. Recently I’ve been wanting to get it going again so that I can play electric guitar from my couch instead of walking all the way downstairs (i.e. ten feet). Any old amp will do this task as I can use my POD for effects. But I have the Marshall so why not put it to use? Incidentally, I can just connect the speakers directly to the POD’s headphone amp, but that’s no fun.
Vacuum tubes are notorious for being flakey, so I figured a new set of tubes might make it work again. I ordered a new set, plugged em in, no go. The power tubes heat up but the preamp tubes do nothing. That’s about the extent of my expertise on amplifier repair, so the only other thing I can do is open it up and look for cold solder joints or blown fuses. Alas, I found nothing obvious when I did this.
Working on any high power AC gear is dangerous. In fact, today while discussing my broken amp with a coworker, I said that despite my many hours logged in EE labs in school, I was not at all comfortable working on it myself. Perhaps I should have listened to me.
I was smart enough to unplug the amp, and careful enough to keep a hand in a pocket. But still, I was sloppy when putting it back together and managed to discharge a high voltage cap with my fingers. Holy hell that hurts! I dropped back a couple of feet and let out a loud scream. Youch. I will not be doing that again anytime soon. Luckily, I don’t have any permanent damage: I got a tiny electrical burn on my middle finger (that probably would be worse if I didn’t already have a half-inch callus on it from playing guitar). And I earned a healthy fear of high powered electronics.
So, people of the internet, don’t do what Donny Don’t does. Discharge those caps!
You pretty much have to buy vacuum tubes from the third world or eastern bloc these days since they aren’t much in demand over here. The ones I bought were all Sovteks. I love the Soviet iconography on the box:
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