Ampeg Gemini sounds like a ring modulator

[shanetram]

I bought an Ampeg Gemini II on eBay in supposedly working condition that had been cut down to a head for next to nothing.

When it arrived the foot switch had bounced around inside and wound up breaking the mounts off of the power supply capacitor. My buddy and I fixed the mount and re soldered the connections. When we fired it up it made an awful loud hum and any signal fed through it sounds like a ring mod. It's not the same pitch, it's very weak, and it sound like it's on very fast vibrato even in the non vibrato channel...

Thoughts?

Thanks in advance.

[Blue Strat]

Sounds like it needs a cap job. If this has never been done you're about 30 years overdue.

[GuitarsFromMars]

replace the filter caps...

[slider313]

If your replacing that twist-lock can, it may be a task finding the correct values. I believe the values were 70/40/20/20. I believe Ted Weber is making custom cap cans.

[soldersucker]

Looky here- http://www.fliptops.net/catalog/product_info.php?cPath=25_76&products_id=478

[AL30]

http://www.fliptops.net/

All things Ampeg. Including re-cap kits. I've ordered from there a few times. Don't forget to pick up a clutch head screwdriver bit. :AOK

AL

[donnyjaguar]

When you ship tube amps they really are in the hands of the gods!

[shanetram]

Thanks gents.

I was planning on getting a cap set from fliptops. There's 2 different ones though, anyone know the difference?

Also, if there's any one who has one of these and can take a picture of the power supply cap area for me I'd greatly appreciate it.

I cant seem to find a schematic that specifies how that area should be wired.

[AL30]

You're gonna have to open it up and see which caps you need. There is usually a schematic on the chassis of those amps. Is yours still there or did they remove it?

Try this schematic.

http://www.schematicheaven.com/ampegamps/g15_gemini_ii.pdf

AL

[shanetram]

I should also add that the power supply cap (the cap can) is not originally, it looks quite new actually...

[shanetram]

There's no schematic in the amp itself as I recall. It was a combo that's been cut down to a head.

That schematic is the same one I keep coming across but I can't determine from that which wires connect to which tabs on the power supply cap.

Am I missing something?

[brad347]

look for shapes on the can, like a square, triangle, half-moon, etc. These indicate which values are which tabs.

[TopBooster]

There's no schematic in the amp itself as I recall. It was a combo that's been cut down to a head.

That schematic is the same one I keep coming across but I can't determine from that which wires connect to which tabs on the power supply cap.

Am I missing something?

Well, the can caps have shapes next to each section usually engraved on the outside of the can, and the shapes are shown on the underside of the can next to each tab. That's how you know what cap each tab is connected to...

Not sure if this is what you were asking, though.

These caps can be seen at the bottom right of the factory schematic if that's what you were asking. The ones just past the rectifiers...