Ok. I want to take the easiest route on this. A former band dude has a woodworking business and he can totally hook me up with a good refin job, but because this thing weighs more than the SVT, the duratex or deckover stuff seems more suited to it. Maybe in white....

FM garthplinko dropped off four amps the other day for me to work on. I've opened two so far.Musicman 212 HD 130 (2475-130):Blown main fuse. Two adjacent output tubes were redplating. I rotated the tubes and the same two sockets did the same thing. Either way, all four tubes show signs of overheating. I'm going to put in a new set of JJ EL34Ls. My first assumption is that something in the bias circuit has given up. It needs a full recap, as one of the main filter caps is visibly leaking electrolyte. I'll also replace the 16 V zeners with 5W versions while I'm in there.PCB dates from Dec. '79. This one has a 12AX7 in the preamp and the solid-state phase inverter circuit. I can't find a schematic that matches it exactly. Somebody also added a TRS jack to the back panel labeled "pre/post" that seems to tap off the master volume pot.Sunn Concert Slave (silverface):Turns on, but no output. Found a blown 10 ohm resistor. Pretty much the same failure as one of the silverface Concert Leads I fixed last year. None of the output transistors are shorted. This one doesn't have the "stability mod" that Sunn described in a service bulletin, so I'll add that. Maybe oscillation of the output stage caused that resistor to blow up without blowing a transistor. It's getting a full recap, regardless, as one of the giant chassis-mounted caps is bulging on top.

Musicman 212 HD 130 (2475-130) (cont.):I'm thinking that somebody scammed the 12AX7 into this thing as an extra gain stage. There shouldn't be a 12AX7 in this amp, as it has the later solid-state phase inverter board. Garth did say that it breaks up earlier than other 130s.I recapped the phase inverter board and the bias supply. Somebody replaced the phase inverter transistors with Sanken 2SC3834. One of them wasn't even completely soldered in there.I tried the old tubes just to see if soldering that leg fixed the redplating issue, but no dice. I'll reevaluate after the recap and the new tubes arrive.

weezy wrote:Finished the Classic 400 make-over.SO GREAT.

WOULD

Finished the Classic 400 make-over. No more fan, and I removed the semi-useless piece of wood in the front grill and fixed the slightly bent face plate as best as possible. First time working with Duratex and ended up having plenty left over, only did about 2 coats.Trying to figure out a footswitch for it now. I got a Transtube 212 footswtich and some rando diagrams showing how to rewire it for this head, but I'm having trouble figuring it out.... kind of feeling like it's not worth it.

Messing with this Peavey Standard 260 Series right now and I cannot figure out whats wrong with it. When it came to me there was DC voltage on the output (~40V B+). I checked every transistor and diode i could on the power board and everything looks kosher. Then at some point the voltage problem went away. Plugged it in, amp works fine for ~3 minutes and the DC voltage came back. Since then i've been chopsticking it and watching the voltage on the output. I managed to make the DC go away again, but im not sure how the hell I did it. Been pushing around every component looking for anything that maybe makes it come back but I cant find it. Its driving me insane.

Musicman 212 HD 130 (2475-130) (cont.):I think I've got this one licked. Did a full recap, and replaced all of the 16 V zeners. Put a set of new EL34Ls in there, and it was still redplating the same two tube positions instantly. Started checking voltages and saw that the -16V rail was around -8V. Pulled all the socketed metal-can opamps in the preamp section and saw the same thing. The only other opamp was a 1458 on the phase-inverter daughter-board. It was screaming hot when I touched it, so I swapped it out. -16 V rail was normal.Still redplating though. The 16V zener on the daughter-board was reading 6V, so something was pulling way too much current. I checked all the resistors and the two diodes, and they measured fine, so I swapped the two Sanken transistors for some more appropriate 2N6488s. No more redplating. Biased to 25 mV across the 3.9 ohm emitter resistors, per Musicman spec. I haven't played through it yet, but I'll take care of that soon enough.

Musicman 212 HD 130 (2475-130) (cont.):Fired it up and played through it a bit. The "normal" channel has almost no output. Need to trace that out.The other channel sounds good, but it does break up pretty early due to that extra 12AX7 gain stage. The trem isn't working, but I think I may have bumped the internal trimpot. I'll play with that later.It's LOUD AF!

Nate Dort wrote:Musicman 212 HD 130 (2475-130) (cont.):Fired it up and played through it a bit. The "normal" channel has almost no output. Need to trace that out.The other channel sounds good, but it does break up pretty early due to that extra 12AX7 gain stage. The trem isn't working, but I think I may have bumped the internal trimpot. I'll play with that later.It's LOUD AF!Got this sorted today, after taking some time away to mix a record. I pulled and reinserted the first opamp in the "normal" channel circuit and it came back to life.I was also right about the trem trimpot. Dialed it in for maximum intensity with the front panel control set to 10.Gonna call this one done.