Early Ampeg Reverberocket R-12-R Chassis Restore

[misterc57]

I'm leaning towards this being a R-12-R, apparently there are different output versions, this one being a 6V6. Odd that there is no model number under the model name as I have seen on others.

I only have the chassis as seen in the pictures. No cabinet, etc.

This is a 7 tube circuit with 6V6 output tubes.

V1 6SL7 GT, (Ampeg)

V2 6??? GT, maybe 6SN7, (Sylvania)

V3 6SN7 GTB, (Ampeg)

V4 6SL7 GT, (Ampeg)

V5 6V6 GT, (Sylvania)

V6 6V6 GT, (Sylvania)

V7 5Y3 GT, (Ampeg)

All tubes test good. OT tests good. Power switch is not good and removed/bypassed for now.

A chunk of fiber board and a wire wrap resistor (250R 10W per schematic, power tube cathode R) is missing (portion of resistor in picture) by the PS. I have clipped in a cement 400R 10W in its place for now.

At this point after gradual dial up on a variac (not to full power) the current starts getting jumpy as I reach 20 VDC at the rectifier HV output.

Attached is a schematic that looks possibly correct but not an original. Some items do not match. Does anyone have an official version schematic they can share?

[g1]

This one?

[mozz]

Really looking for one of these chassis. I have a cabinet. Let me know if it's available as-is. I will give it a good home.

Here's the story.
I put a local ad wanted to buy empty cabinets, as i was building a few amps and didn't want to spend for a new one. So this guy about 40 miles away answers and has a empty Ampeg cabinet. I drive there and pick it up, he tells me years back he brought it in for repair and was told the chassis was not worth fixing. So he took the cabinet back home and used it as a extension speaker. So i got home and built a 6973 Supro type amp on a old metal chassis and bolted it in there. I figured i would never find anything close to the original. Ampeg made so many models and variations.

Browsing Reverb, I see the proper chassis R-12-R-T, with the 7868 tubes, it was marked "item has been sold". The seller happens to be 5 miles away from the guy i bought it from and is a semi well known local music shop. So i am taking it the chassis was sitting in the repair shop for years, and was eventually fixed and sold on Reverb.

[Justin Thomas]

This was my first Ampeg!
The Piazza schematics are good general guides, but these amps are from a time when changes were often made on the fly. My old Reverberocket 2 had elevated heaters; the addition was penciled in on the schematic on the back panel. If nothing seems too out of whack, it should be close enough. Otherwise the schematic g1 posted is right. It's the first version of Reverberocket, so that might be why it doesn't have a model number - there were no others. As far as I can recall, there was the R-12R, R-12R-B, & R-12R-T. There may be a D version too.

These are great old amps... I love the reverb in them. And even though they were the "budget" line, Ampeg never used a speaker smaller than a 12" until the SVT.

Jusrin

[misterc57]

I'm suspecting the PT has issues.

With rectifier tube removed I see very little AC HV on the secondary side and the current starts to jump quickly.

Seeing 117 and 161 R on the HV to ground and 272 R across the HV ends.

1R across the 5V winding

7R across the primary

[misterc57]

Hey Mozz,

I am trying to reach you. Left you my phone number in the messages section.

Thank you, Mark

[mozz]

Will try to call when I get home today.

[g1]

Seeing 117 and 161 R on the HV to ground and 272 R across the HV ends.

1R across the 5V winding

7R across the primary

If HV CT is connected to ground, those numbers all sound ok. Maybe try disconnecting the heater winding.