Rickenbacker International Corporation - Forum

B16A troubles
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Author:  geejayeff [ Mon Feb 15, 2016 12:08 pm ]
Post subject:  B16A troubles


I have an old B16A Rickenbacker with tremolo circuit and after not playing it for a few years there is no sound except for some serious hum. Tubes test ok and the filter caps are in spec but I noticed that only 3.3 V AC is going to filaments (checked out of circuit). The B+ seems ok though. Possibly failed transformer? The transformer in there now has "PT564" stamped on it and no other information and it may not even be the original. Searching for PT 564 has not yielded any useful information.

Any ideas on getting a replacement transformer or other diagnostic ideas greatly appreciated!

Thanks in advance.

Author:  geejayeff [ Fri Feb 19, 2016 1:02 pm ]
Post subject:  Re: B16A troubles

Does anyone out there have a Supersonic B16A Amp? If so, can you take a look at the power transformer and tell me the model number or any specifications/wiring diagrams on the casing? It's visible without dismantling anything.

Mine is blown and other than "PT564" stamped on the top, it has no information or specs of any kind. A search for PT564 comes up with no helpful information. Also, I'm fairly certain it's not the original, so getting the original model number would be fantastic.

Any help greatly appreciated!

Author:  JohnHall [ Tue Mar 01, 2016 10:33 am ]
Post subject:  Re: B16A troubles

That part number is consistent with the way original parts were labelled. Both the power and output transformers were custom made parts but I would imagine would be similar to many other amps that had a dual 6L6 tube design.

Author:  geejayeff [ Mon Mar 07, 2016 2:39 pm ]
Post subject:  Re: B16A troubles

Thanks John. I'll look around and see if there is something comparable.

The confusing thing (and I saw you helped someone on another Rickenbacker forum about this) is the schematic shows a power transformer with three outputs:400 V B+, 6.3V for the heaters and a third (with unspecified voltage and without a grounded center tap) going to a 5AR4. But on the amp there is no 5AR4 rectifier and the transformer only has two outputs. Instead there are two solid state rectifiers by the filter caps.

Was there a late modification to the amp or something? Thanks again for the help!

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