I was talking to a fellow who was interested in doing some DIY work on his own amp. Naturally we ended up talking about what he needed to be successful in the endeavor. At the heart of things, it best to have a clean, safe place to do electrical experimentation!
We’d need to have a space to do it in that is secure and equipped to safely deal with quantities of electricity that will knock your ass into next week. Now this space doesn’t have to be big. It can probably be done in a large closet-sized place. Of course you’d have to have electricity, preferably one or more dedicated 20A circuits. A powerful amp can pull some juice! 10-15 amps or more!
OK, so there’s a space with a good electrical outlet. You’ll need a bench. An inexpensive flat interior door on a couple sawhorses would be good. Put one of those power strips near to hand where you can shut it off easily – where you can lean away from the gear and still turn it on. And off quickly! The bench should be a bit higher than a table so you can sit properly and not be all hunched over. A Magnifier-Light is really nice, and puts something between your face and anything coming your way.
We need to be able to measure and control the electrical supply that’s being used on the unit under testing. This could be something like a Variac or a 100W incandescent light bulb. I have both for testing gear in my shop. My Variac has an A/C ammeter so I can see how much current is being drawn. I also have a voltmeter attached to the Variac, and run the whole thing through the light bulb, which is bypassed with a switch.
We’d need some compartmented storage space, not only to store all our parts, but also to hold the nuts, bolts & screws as they come off whatever we’re taking apart. The bench would need some kind of mat, too.
And now, we can go really overboard with tools and test equipment. Well no, not really. A serviceable soldering station, with accessories, like solder, flux, a solder-sucker, tip cleaner and pad, etc., is essential. Ask someone who is experienced what he or she uses. A few small hand tools like needle-nosed pliers, diagonal cutters, a wire stripper, along with a good assortment of screwdrivers are a must. With test equipment, you’d be surprised how little you really need. A good Digital Multi-Meter (DMM), something that injects a known signal, and something that reads that signal safely, are about it. We’ll gather more, as we need it.
As you’re getting all this stuff together, you also feed your head. Electricity is deadly. The only thing that stands between you and deadly shock is your knowledge and experience. Know the safety protocols and follow them as you gain experience. Being shown by someone who knows already is invaluable. Check everything with your meter and watch out for being grounded. Learn the properties of electricity, starting with Ohm’s Law. Learn the symbols for both the schematics and the math that they represent. Feed your head.
Plate voltage on a 6550 output tube is nothing to fool with. It’s very serious stuff, so I would learn on some low voltage solid-state circuitsubel no, not really. A , first, and then a small vintage tube amp before trying on that old SVT in the garage…
Armand Blake, Owner: AMPWERX Repair
1935 E. 7th. St.Long Beach,CA90813
Tel: 562-591-1423 Fax: 562-591-1423