Wednesday, April 18, 2012

Crate PA-B8350

I roadside rescue, picked up on my way home from a gig a few months back. This PA head  has been taking up my guitar workbench the entire time since. While I'm occupied with digging out, it's time to finally see what's going on with this thing.

I came for the brightly colored knobs, but I'll stick around for the built in spring reverb and effects loop.

Obstacle number one. While I often see devices that have had their power cords cut to keep people from using them due to some perceived or actual danger, the wear pattern here suggests a violent and unexpected disruption of power, i.e. an accident.

Nothing unusual inside, and no evidence of prior tampering. Everything seems in good order on visual inspection, but one of the three fuses fails a continuity test.

Not exactly burned out, but certainly not operational. Searches for schematics, parts lists and the like don't turn up anything that doesn't cost money, so I'll assume that the 1/4A 250V label on this (and the other non mains power fuse) is accurate, which is an easy thing to fix with a trip to the hardware store.

I also grabbed some crimp-on connectors to replace mains using an old IEC cable, but failed to realize that I didn't actually have the appropriate crimping tool, as I had thought.

Not optimal, but okay for now.

Nice big pop on power on, and the transformer hums like a beehive, but it works well enough to consider it salvageable. Since these guys are around 20 years old now, I'm gonna take a wild guess that electrolytics are at least part of the answer. Without a schematic, I'll need to just poke around and write down everything I see to make an order. Luckily there's not too much, really just the big guys in the power supply.


crochambeau said...

Nice haul! I love the roadside rescues.

Casey Edwards said...

Just was given the same unit with the plug cut. Opened it up and checked fuses. Attached a new plug and turns on O.K. Don't know really much of anything about this stuff. Kind of concerned that the speakers I own will not handle power from this unit. Would you know how I can make sure speakers are large enough ?

matthewjosephpayne said...

Good thing I still have comment notifications on!

To my knowledge, unless there's some kind of serial or model number on the speakers by which you can track down the original manufacturer's info, the only way to determine at what point the speakers will break is to break them.

That being said, there's definitely a point of "sounds like it's gonna break" that comes before "it's broken", so if you're just cautious at first (a full volume square wave is probably not the optimal first test), you should be fine.

Good luck!