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Topics - Bill Moore

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Amplifier Discussion / Match Output Transistors?
« on: August 14, 2019, 11:20:18 AM »
I have a Peavey Special 150 that a friend gave me years ago, (dead). He already had replaced some parts, and had given up, (blowing fuses). I repaired some open traces on the board, but it still had a draw on the power amp side. The original outputs were replaced, but with replacement numbers, I tested them all, and one is shorted, (they were incorrectly installed)! I'm not sure if I can find the replacement number of the dead one, and was considering replacing all, is that really necessary?
If I have a bad output tube in push-pull, I always replace them all, but I'm only wanting to get this project working, not rebuilt!

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Amplifier Discussion / Peavey Reverb Cable.
« on: September 10, 2015, 01:25:36 PM »
Thought I would share this. Some Peavey amplifiers have a 5 pin Molex connector that attaches to the circuit board to connect the reverb tank. I had no luck finding one anywhere, but found that 2 2 pin connectors will work.
Molex Recepticle  03-09-1027
Molex Terminal     02-09-1119





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Amplifier Discussion / Another "Bedroom" amp.
« on: April 04, 2014, 12:08:12 PM »
Just had to post about the latest orphan to find my house. One of my brother in laws was cleaning out his rent house, and brought me a little Marshall Lead 12 that was in pieces. I replaced all the pots, input jacks, and PS caps. Cleaned the thing up, and made a full cover for the rear, (with an oval cutout). I put it together last night, and got to play it some, even with the stock speaker, it sounds pretty good. I added a speaker out jack, and also played it plugged into a single 15" JBL cabinet I have, seems louder that 12 watts!
It really can sound like a real Marshall!

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Amplifier Discussion / Great little amp!
« on: August 01, 2013, 05:46:53 PM »
Some of my customers have a shop that buys estates, and I tell them to find old amps for me to tinker with. A few weeks ago, one of the fellows came in with an "old" amp, and gave it to me. I guess it's probably 80's, Dean Markley, K20. It's really clean, (brown tolex), but would cut in and out while playing. I pulled the chassis, and cleaned the pots, now as good as new! Surprisingly good sound, with a little 8" speaker, and has decent built in OD. Now if I can get my grandkids more interested in guitar, I have an amp for one of them!

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Tubes and Hybrids / Music Man hybrid
« on: May 16, 2013, 05:32:52 PM »
I am no tech, but enjoy tinkering. I recently picked up an 81 Music Man 100RD amplifier that was dead. Replaced the caps/diodes in the HV, and LV power supplies, and retested it with a bulb limiter. Still had a problem, finally figured out that one of the 5KV diodes at the output tubes was shorted. Found out the function was to protect the OT, and eventually settled on some availlable 3KV diodes.
My question is, how does it generate 100W with only 2 6L6 tubes. The PI is a pair of transistors that are biased at 25mv. The center tap of the OT shows 715V, (in high power mode), but only 350V feeds the power tubes. It is loud!

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Tubes and Hybrids / Drive channel is too dirty!
« on: October 30, 2009, 11:28:29 AM »
I ended up with my nephews dead Champ 25, and replaced a few parts, and got it working again. I replaced the speaker with a Mojo heritage clone, and the clean channel is almost Twin clean, really a great sound. The problem is the other channel, even with the gain at zero, it is gritty. Looking at the schematic, there are no less than 7 diodes after the gain control. Has anyone bypassed/removed some of these, or replaced some of them with LED's, or maybe have another fix to get a cleaner sound from this channel? I would like to get it to sound like a single 6V6 amp dimed into a Weber vintage AlNiCo.
I think maybe here at the SS Forum, you guys will have a little more knowledge about the SS preamp, and maybe modified a few. My friend/amp tech, can really make a tube amp sing, but is ambivalent about SS devices. (Although most pedals are not tube!)
Thanks for your help, Bill.

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