Where can I find repair manuals and exploded diagrams for valve amplifiers?

January 21, 2009 4:59 AM

Where can I find repair manuals and exploded diagrams for valve amplifiers online?

A while ago, I needed to find a repair manual for a vintage Twin Lens Reflex camera... then come across a website that had PDF after PDF of scans of exploded diagrams of cameras of all ages. Since I knew exactly what I was looking for it wasn't too hard to find.

However, I now need to find similar diagrams for valve amplifiers. I just need to see what they look like inside but since I know nothing about them... I don't really know what I'm looking for.

Ideally I'd be looking for guitar amplifiers but anything that has big glass valves that glow and make things louder would be suitable.

posted by stackhaus23 to technology (3 comments total)

I doubt you'll find exploded diagrams. There really wan't any much for a visually accurate representation - normally what you'll find is a schematic showing how the various components are connected.

And my advice would be to stay out of the insides of valve amps if you really don't know what you're doing. The voltages can be lethal.
posted by le morte de bea arthur at 5:31 AM on January 21

You might want to ask for advice about specific amplifiers from the nice people at audiokarma. They'll be able to point you to what you are looking for if it is to be found, and if you describe the symptoms of your amp they can point to likely fixes.
posted by Killick at 7:59 AM on January 21

Triode Electronics has an archive of schematics for vintage amps, including guitar and hi-fi types. There may be some mechanical layout diagrams within them.

I'll try to give you a picture in words here, too. Older guitar amps share a relatively 'standard' construction: if there's an integral speaker, its cabinet forms the bottom of the unit. Above this compartment is the somewhat smaller one where the amp electronics are held. These consist of a power transformer, an output transformer, maybe a choke (which looks like a transformer) and several tubes, including output, small signal, and probably a rectifier, which are mounted to a box-like metal chassis with an open bottom. On the underside of the chassis, where the tube sockets poke through, tag boards are are attached to which the individual resistors and capacitors are soldered and wired. The front of the metal box has the controls and inputs/outputs. This metal chassis slots into the electronics compartment in the cabinet, often upside down so that the tubes hang down.

As bea arthur says, be aware of the danger that this kind of amplifier represents- there are very high voltages inside, often on the order of 600 volts. Doing some reading about safety practices would be a good idea if you intend to service one of these yourself.
posted by monocyte at 11:57 AM on January 21