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Hello folks,
I thought I'd post this cap replacement on this Ampeg V-9 SVT from the 70's. I think it was the most efficient use of the cap-cans that were insulated as well as placement of the extraneous Stick-o-Dynamite caps.
The 50-50uf @ 450V cap-cans are only replacing the 2ea 100uf @ 450 caps (C10 100uf @ 450V brown Stick-o-Dynamite) and (C-12A in the cap-can). I used these blue bracket mounted cap-cans the one needs to be electrically insulated from the chassis as well as insulated from anyone touching it...ZAPP!
The other half of the cap-cans that are 40uf @ 450v are replaced in the lower right corner on the terminal strips.
The 30uf @ 600V Stick-o-Dynamite cap is replaced by those two 100uf @ 350v blue caps in series with the divider resistors across them.
The bias filter cap is the Radial cap on the terminal strip.
It was a bit tricky to get all the floating grounds connected to each other and isolated from the chassis. The power amp chassis is grounded thru a 10ohm resistor at the preamp out jack and that ground line is eventually grounded at the input jack of the preamp chassis.
Ampeg's original method of preventing ground loops. Seems they did that as it was the easier method of dealing with ground loops. I've had issues with even this method in some of their combos of the same era where a previous tech replaced the filter cap, but did not use the phenolic wafer to isolate the can ground from the chassis. I generally had to split the black ground wire and ground the preamp at the input jack & the cap-can at a star ground at the cap-can. Interesting that Ampeg didn't think to do it that way.
I watched a few videos by The Guitologist on the older Ampeg combos where he couldn't figure out the ground-loop issue, and ended up reaming out the input jacks so he could add insulated washers. Not the way I would have approached it, as you now a grounding system that relies on the equipment attached to the input jacks to keep the integrity of the grounding system of the amp. Although I give him a lot of credit for shooting his methods & real time repairs for all to benefit from, I tend to not want to deface vintage equipment that way and endeavor to ferrite out the real cause or develop a different way of going about it.
Glen
I thought I'd post this cap replacement on this Ampeg V-9 SVT from the 70's. I think it was the most efficient use of the cap-cans that were insulated as well as placement of the extraneous Stick-o-Dynamite caps.
The 50-50uf @ 450V cap-cans are only replacing the 2ea 100uf @ 450 caps (C10 100uf @ 450V brown Stick-o-Dynamite) and (C-12A in the cap-can). I used these blue bracket mounted cap-cans the one needs to be electrically insulated from the chassis as well as insulated from anyone touching it...ZAPP!
The other half of the cap-cans that are 40uf @ 450v are replaced in the lower right corner on the terminal strips.
The 30uf @ 600V Stick-o-Dynamite cap is replaced by those two 100uf @ 350v blue caps in series with the divider resistors across them.
The bias filter cap is the Radial cap on the terminal strip.
It was a bit tricky to get all the floating grounds connected to each other and isolated from the chassis. The power amp chassis is grounded thru a 10ohm resistor at the preamp out jack and that ground line is eventually grounded at the input jack of the preamp chassis.
Ampeg's original method of preventing ground loops. Seems they did that as it was the easier method of dealing with ground loops. I've had issues with even this method in some of their combos of the same era where a previous tech replaced the filter cap, but did not use the phenolic wafer to isolate the can ground from the chassis. I generally had to split the black ground wire and ground the preamp at the input jack & the cap-can at a star ground at the cap-can. Interesting that Ampeg didn't think to do it that way.
I watched a few videos by The Guitologist on the older Ampeg combos where he couldn't figure out the ground-loop issue, and ended up reaming out the input jacks so he could add insulated washers. Not the way I would have approached it, as you now a grounding system that relies on the equipment attached to the input jacks to keep the integrity of the grounding system of the amp. Although I give him a lot of credit for shooting his methods & real time repairs for all to benefit from, I tend to not want to deface vintage equipment that way and endeavor to ferrite out the real cause or develop a different way of going about it.
Glen
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