Classic Hifi Care

electra225 wrote: ↑Wed Oct 01, 2025 4:56 am What Chris said. You also need a schematic...

TC Chris wrote: ↑Wed Oct 01, 2025 10:08 pm When I was a kid, dealing with tube stuff, I always assumed that the problem was a tube. Often not that.... Always look for the simplest explanation or the most common device, like bad switch contacts or capacitors that have gone south.

I recently diagnosed and repaired a Heath receiver with one channel out. I had great help online from a very knowledgeable guy across the country who had written an article about a similar device. I actually found the problem early on, a bad resistor, a 5-cent part. But I replaced it with a mistaken one. The color code was red-red-red and I plucked a red-red-orange (very subtle color difference) from the stash. The wrong resistor meant that we worked upward on the complexity scale to--yes--a transistor replacement. But that didn't fix it, of course, since the problem was still the resistor. My advisor said to go back and check resistances again. That is, start at the beginning.

Lessons? Check resistances with the ohmmeter if there's any doubt about color, or maybe just anyway. Start with simple checks to make sure the cheap parts are OK. As Greg says, rustle up a schematic. Even if you don't grasp the full electronic circuit significance, at least you'll be able to ID parts and know their designed values.

Chris Campbell

electra225 wrote: ↑Thu Oct 02, 2025 12:08 am I have some old books I was fixing to toss. How to read schematics, how to use test equipment, books like that. Perhaps a good method would be for you to get a piece of test equipment, then we could have a discussion about how to best utilize it. There may be several differing opinions on how to best proceed, but this is a really good way to learn. A schematic may be considered simply as a road map of how electricity flows thru the device under test, what components affect current flow, then gives their locations in the circuit. You use a multimeter, set on voltage, to measure voltage at different points in the circuit in order to find faults. Then you replace a defective component, test again and note the difference in operation. I have been doing this for probably 40 years as a hobbyist, but I learn something almost every day and have experiences working on this old stuff I haven't had before. You never quit learning. Don't feel embarassed about maybe not having the knowledge more experienced hobbyists have. We all started like you are, from square one. I was fortunate to have a stepdad who had a TV repair shop and taught me a lot. The rest I pretty much learned the hard way......