Danelectro 6sj7 Vibrato

[Deric]

Working on a Danelectro Commando. Pretty cool amp - 2 piece suitcase design that folds open.

Anyways, found schematic for a later version here...

http://www.blueguitar.org/new/schem/mis ... mmando.gif

This one is an earlier version that is the same but uses a 6sj7 for the vibrato. Anybody happen to have a schematic?? Sure enough it's the only part of the amp that has been worked on / modified. Vibrato doesn't work. Found a schem for a Model 98 with 6sj7 vibrato. It's a little different than what's been done to this on. Thinking of just converting to the Model 98 version and see what happens....

Any tips/suggestions?

Thanks

file:///C:/Users/D/Desktop/danelectro-model-98-schematic-diagram[1].pdf

[10thTx]

http://el34world.com/charts/Schematics/ ... pecial.pdf

Maybe this one would be useful to you?

[Deric]

Thanks for sharing. That's pretty much what is in there. Only difference is a 1M resistor feeding a .05u cap (in place of the .02u) from the plate to the Depth/Intensity pot. Those parts appeared stock to I replaced them with same. Had to order 390K and 560K resistors so can't fire it up yet.

Another question: There's a 2k2 10w resistor between the first two filter caps. It does not appear to be stock and is HUGE. Would a 5w be OK here or should I stick with 10w?

[jjman]

Should be about 8ma thru that resistor at idle. Screens would draw more at louder outputs since class AB.

2200=v/.008

.008x2200=v

v=17.6

w=va
w=17.6x.008
w=0.14

No way that resistor needs to be that big. I like a ~3watter early is a PS that small.

[Deric]

Getting ready to test fire...

The 12ax7 filaments are powered from the 6v6 cathodes. If I want to eliminate the preamp for test purposes - what value resistor should I sub for the filaments? If the filament draws 150mA at 6.3v then I'm guessing 42ohms per 12ax7. Two 12ax7 in series would be 84ohms. Should be OK with 100ohms for test purposes???

Am I missing anything?

Edit: Second question...

Is it OK to ground the grids of the 6SN7 for testing??

Second edit:

Fired it up with a 100r resistor 10u cap on the 6v6 cathodes and the grids of the 6SN7 grounded. Nasty hum is gone and Vibrato works - yay!! Lots of frying bacon that goes away when I pull the 6SN7 - will replace the plate resistors and try again...

[Deric]

Finished this up today. Replaced all the resistors and caps around the 6SN7 and the frying bacon sounds went away. Hum was gone, vibrato worked but still had something weird going on. Found a broken pin on the phase inverter socket. Was able to steal the unused pin 9 from the socket and move it to where the broken one had been.

Pretty cool amp. Thanks for the help!

[Deric]

Couple more...