Resistor Heat

[swelebny]

Electronics are still new. I'm learning terms, and how things work. The R17 resistors on my board are really hot. Too hot to touch. I had some junk box SE output transformers I did the initial run with. The resistors were hot, but I figured I'd wait until running with the good transformers, before being concerned.

Well with the new 3.5K transformers, the resistors are still really hot. But I don't know what would be normal. The unit plays just fine. The resistors I believe are correct at 3W.

How hot is normal, and how hot is damaging?

Thanks,

Steve

[TomMcNally]

The resistors do run hot, if you have them spaced up
from the board, and on the opposite sides of the board,
it's fine. No problem.

[swelebny]

Thanks much, Tom. Out of all the resistors I soldered, those two just ended up closest to the board. But I did order duplicates of the less expensive components, figuring this would be a good way of building up a little stash of common ones.

I think I'll solder in another pair, higher off the board. Sounds like you're suggesting opposite sides for these two, and that seems to make good sense.

This is still fun.

Steve

[TomMcNally]

Hi Steve -

There is a quick note in the manual about putting the
paired resistors on opposite sides of the board, and
spacing them of about 1/8" for cooling.

I do the same thing you did - grab extras of parts
for the junkbox ... the little stuff is so cheap it
makes sense. You can probably just snip them
close to the board, pull out the lead and re-do them.

I've built a bunch of GSG's - it's a nice amp.

... tom

[swelebny]

HaHa! I feel a little dumb...... I put some of the pairs and triples on the opposite side of the board. All of them! Oops........ I figured it was because heat shed from the top of the board better than underneath! Ignorance has its own genius......

You do nice work Tom. I've been to your webpage. It was part of my inspiration to pick up an old Heath AA-100 for the transformers. Before stripping it for transformers, I thought lets see if we can get the thing to work. The workmanship was so nice. It didn't take much at all to get it sounding really nice. I didn't have the heart to take it apart. It's sitting in the cellar shop to keep me company when I work, headlights blazing.

Steve