Tube Amp Archive

Just as a follow-up, Today I was working on an SF Deluxe Reverb-Amp. With amp unplugged I had discharged the main caps, but didn't check the B+ on them after that. I went to re-tension the pins on the rectifier tube socket & WHAMMO! Got zapped. It's actually been years since I've gotten shocked at a...

Hello Maxkracht,
Good eye. Yeah,
I took the pic before I replaced the balance of the electrolytics just to show the main cap replacement. As I recall there was also one cathode bypass cap on V2.
Thanx, Glen - 12th Fret Music Service Dept. Boise, ID

Agreed with SteveM, If there is a more in-depth warning about the dangers of what Eurotubes is suggesting, THAT should be what is written on the 'Disclaimer' that they provide with the tubes or at that very least a link to the complete warnings that Eurotubes allegedly has on their website. STILL as...

Hello folks, Does anyone find these instructions for replacing tubes from Eurotubes troublesome? I sure do. First of all the instructions do not provide any step about being certain the unit is turned off AND unplugged! I'm sure all of you have had amps that do not have bleeder resistors to discharg...

Hello all, Posting a recent Sovtek Mig 60 recap as it was a rather involved job. The original cap-cans mount with just a hole, so using aftermarket cap-cans is infeasible. I left the original cap-cans in to maintain the originality of the amp. BTW, it took about 6hrs total to complete. Sovtek-Mig-to...

I found a few more of the battery operated signal injectors referred to as a 'Mosquito' because of the squeal noise it makes. The first one is the one I own. One of them is from the tube days. They acutally built one with a tube before transistors. WOW! Thanx, Glen - 12th Fret Music Service Dept, Bo...

Hello folks, Just sharing some repair info that might help someone: I have a Yamaha DGX640 with no sound. I tried a factory reset as usual to eliminate any weird processing glitches. All indications from the display are that everything else seems ok. There is also no sound from the headphone/line ou...

Used widely back in late 60's and somewhat in 70's. Then rendered not necessary and more or less obsolete.

Hey folks, You're basically all correct to some extent. I dicked around with this thing and determined the only way it was going to work was to install a DPDT toggle switch that would switch both tubes in with the 250 ohm cathode resistor and in the class A position cut the two cathodes apart and co...

Thanx, RG.
Most informative & reassuring.
Glen

Ah, I see.
I see where someone suggested adding 1K resistors in series with the screens. Kinda standard for most 6L6 circuits.
I always thought that was for isolation to prevent possible oscillations. Regardless, I'll have to give that a try.
Thanx, Glen

Hello folks, I have this amp that uses 2ea 6V6 tubes normally connected as Push-Pull config cathode biased. The amp is designed with a switch that disconnects one of the cathodes for approx 1/2 power and then just uses 1/2 of the output xformer. The coupling caps to the grids are not leaking. The am...

Hello RG. I do understand how the SMPS & DClass systems work and have repaired smaller less powerful types, but honestly something this powerful and complex I'd rather leave it to folks that have expertise as well as have all the correct original semiconductors AND access to service bulletins. I've ...

Hey guys, Now tell me honestly, does anyone really attempt to repair an amp like the one pictured which can be purchased for around $500.00? Look at this thing...Unless Peavey has a bulletin about some well known problem, at this point in my career, with about 20 guitar/bass amps to repair, why even...

Also, If you look closely at the volume control on the schematic which has a tap, you'll find the input jack there. The one I have for repair behaves this way: With volume control fully almost fully CCW, it cuts out the radio & engages the input jack. On the front panel there is an indication that a...