Recent content by kgmitchell

I understand what you mean...

Checked the voltage across all eight resistors located along the heat sink. It was low, averaging around .8mV. Shutdown, unplug, adjust trimpot several times before settling on about 22mV average. Installed new tubes, checked again. Full volume a few weeks ago is quarter volume today. Sounds...

Just kidding, set the bias voltage, it's still a bit low but I'm happy with it. I dropped in a new set of tubes. Sounds pretty good... Thanks guys.. lol

Just fried my ampeg guys, thanks for nothing...

Checking the resistors for DCV. 25mV being the optimal average voltage per side.

BAM!!! There it is!!! This is the reply I was waiting for!! Thank you!

Vague? I could only find a few other places on the web that talks about the bias drifting on these heads and the way to fix it. Is it classified? It just seems like theres only one or two people who can do it but I don't know them. I have found some pretty solid information here though and...

I think you may have missed the point, I do need to take the tubes out. The whole object is to replace the tubes I have. I know that they are ready to be replaced. I'm trying to clean up the sound of my head and I know that changing the tubes alone won't fix it. I want to CHECK the bias voltage...

I don't get why all this information is out here and none of it is very specific. Why can't someone just explain it instead of trying to discourage me. Someone here has done this before, stop worrying about all the dangers and just explain what needs to be done. I'm just trying to bring a little...

The head was built in St. Louis in 2007 so it's relatively new sat around for a long time, I have a combo that I grew attached to because this ampeg started to sound rough. I want to make it right again.

okay, just read through the svt bias thread, when i gator clip my ground should i use the signal ground that grounds everything to the casing? the check the + side or the - side of the resistors? thats the voltage that needs to average out to 25mV? okay, so turning the trimpot CCW increases...

Thats pretty much what I'd like to know as well. Do I ground my probe to the frame and probe each socket? Then lay out a table? What should the voltage reading be at each pin? The system has to be powered up for this so can I safely turn on the unit without the tubes installed? Where do I probe...

I'm amazed at how quickly a guy is made feel unwelcome because he has less knowledge of how or when a transformer is safe to work around. System plugged in, power on, transformer is hot, system unplugged switch on or off, system is de-energized, but is it safe plugged in with power switch off...

Thanks man, I already assumed most of what you just confirmed so I feel pretty safe. It's always good to get a second opinion.

Okay, whats the safest and fastest way to de-energize a tube head and should I de-energize all the capacitors and the transformer? If I do power down the circuits how to I keep the capacitors from surging with transiant overvoltage when powering up?