reverb tank?

[dugg365]

I have recently refurbed a Marlboro 132A. It was missing the reverb tank and I can't figure out which one I need to select ( input/output ohms). Can anyone here give me some info?
also it is looking for 8 ohms on the speaker output do I need to rewire my cabinet from 4 ohms back to 8??  thanks

[bry melvin]

is there a schematic?

Solid state?...probably an XbbXXX to XFBXXX reverb. BUT...without a schematic we can't probably guess... Do you have one?

anyway Accutronics(Belton) aand antique radio supply both have charts to help with reverb selection.

The orientation and physical size matter too.

[dugg365]

I can't find a shred of info anywhere. If I put in the wrong tank it will kill the amp?

[DJPhil]

I did some poking around too and info is scarce to absent. It looks like Marlboro amps were rebadged imports, so finding a schematic would be unlikely. Fair warning, from what little I could find online there weren't a whole lot of folks who were impressed with the reverb on Marlboro amps. A new tank is more likely to sound different than the original than the same though, so it's really a guess and check operation to replace it unless you happen across an original replacement.

If you're motivated I'd suggest posting good pictures of both sides of the circuit board and the chassis where the tank mounts. We might be able to come close to figuring the expected input/output impedances for a tank, as well as the physical criteria with good measurements of the mounting holes.

Using the wrong tank can be a problem. Some tanks are designed with one end grounded to chassis on input, output, or both where others have the signal isolated all the way through. If the driver is expecting an isolated input on the tank and finds a grounded one it could see it as a short, or near zero input impedance, and the amp can be damaged. Other than that an impedance mismatch will most likely just sound horrible or silent. If it's possible to reverse engineer the drive and return circuitry that should give a reasonable idea of the specs you'd need to go shopping for an equivalent at Accutronics.

Hope that helps some, sorry this old amp is such a tough nut to crack.

[Enzo]

How old is it?  Is it a tube amp or solid state?  If tube, is there a small reverb transformer or not?

[dugg365]

here are the best photo I'm able to get of the circuit board, without taking all the wiring completely loose. The small transformer which I believe to be the output transformer is numbered as:     606-10-009
                       1A 608-142