Recapping a 60s Ampeg GS12R Reverberocket 2

[waldner]

I'm trying to figure out what the proper replacement is for the original cap can in this amp.  I see that Fliptops has several cap cans, but there have been so many versions of this amp.  I made a video showing a detailed look at what's going on here in the amplifier vs the schematic: https://youtu.be/nSqS90DJRXQ

Also I have attached what I believe is the correct schematic for this version of the amp as it matches the tube compliment I have (12AX7, 6U10, 7199, 2x 7591s)

Any help would be greatly appreciated!

[waldner]

Just making the video above and posting this has helped me possibly solve one piece of this puzzle.  The 10 Watt 140 ohm bias resistor that has the connection going to one section of the cap can is probably supposed to be the 25uF @ 25V cap that bypasses it.  That section of the can is measuring 45uF, so I am not sure why all of my measurements on this cap can are high relative to the values written on the can?  But at least that eliminates/identifies one cap- as nothing is written near the terminals themselves.  So that leaves the other three sections that I am getting 92uF, 60uF and 16uF and are supposed to be 60uF, 40uF and 10uF respectively. 

Given that the 92uF and 16uF were jumpered together and I assume the real values they are supposed to be is 60uF and 10uF (which would total 70uF as shown on the schematic) maybe all I need is a cap can with two values: 70uF and 40uF.  Then I can put bypass the 140 ohm output tube bias resistor with a small electrolytic on the board itself.   

Just being able to understand this level of detail is a bit new to me, so sorry if this is really obvious to everyone.

[waldner]

Ok, I may work this out by myself, but if I end up being dead wrong, someone can correct me and I will undo this.  I bypassed the 140 ohm / 10 watt resistor with a 25uF/50V cap on the board itself, leaving plenty of breathing room for the resistor not to overheat the cap or anything else.  Now it looks like all I need is a 70uF and a 40uF both at 450 or higher.  I have a 60uF/500V and 40uF/500V in stock.  Maybe I just use a couple of the open eyelets on either side of the rectifier unit and mount them there.  Leave the disconnected cap can in for looks and I'm done?

[SEL49]

I would use this 70/40/40 @ 450VDC. You'll have a spare 40µF. It'll fit the same hole. Maybe get a phenolic insulator mounting plate in case you break the original.

     https://www.amplifiedparts.com/products/capacitor-ce-mfg-450v-704040-f-electrolytic

[waldner]

Thanks Steve.  I ended up just trying the two F&Ts that I had in stock and disabled the old can.  She works like a champ now!  It sounds better than it did before. 


Now I have to order one of the opto-devices from Fliptop and try to get the tremolo working.  It was kind of working before.  Now it doesn't work at all. The trem would be strong when in the switched position, which I think they call "afterbeat," but didn't work below that.  Also, the volume goes way down as you turn the trem intensity knob up.  From what I've read, that's how it's designed?  I changed a bunch of the caps around the trem circuit but got nothing, so hopefully a new opto-device will do the trick.