Help me ID my 112 RP model
I bought a 112RP on German eBay a few years back. When I got it, it had numerous (awful) mods:
1. Tolex had been removed and it was re-covered in aluminium foil (!!!)
2. Its grill cloth had been removed and a generic black cloth installed in its place
3. The area on the back panel which usually has the serial and model numbers had been filed off.
4. Both MM logo plates were gone
5. It had a weird reverb tank in a hand-made bag which was flopping around in the bottom.
So all I knew is that it was a 112RP, nothing more about specific model/chassis numbers etc.
I had it re-covered in black tolex and new grill cloth installed. I also found an upper-left-corner MM logo plate which I re-attached. So it's at least looking a bit like it once did.
The reverb tank doesn't work and I'd like to get a replacement but it seems that different models of the RP series require different tanks. I've not been able (since the model info are was filed off) to determine with any degree of certainty which model I actually have. Once I know that, I'll print up the schematics and take it to my local amp guru and have him give it a once-over. I'd like to buy the tank in advance so I'd like to figure out the exact schematic to use.
I was able to read the transformer code. It is EIA606-81x (can't quite read the x). A post on the old site suggested that EIA606 was the manufacturer (Woodward-Schumacher) and the 8 after the hyphen would tag it as being made in 1978.
The number above that is 100 - 65 - 250 (note to my North American friends - I'm in Europe so this is a 250v "export" voltage). But the 100-65 part doesn't tell me whether this was one of the 100w models or the 65w. Or it could even be one of the later EV models (I have no problem believing that the speaker in mine is non-original).
I see one tube is a 6V6 GTA. I can't read the code on the other but I'll post later when I have a chance to take it out and examine it.
Any ideas/clues as to which model I've got?
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Thanks for those comments!
I'll try and get some shots of the chassis in the coming days. I'll attach a few photos including the "as received" one with the aluminium foil covering (eeek!) along with what it looks like now.
I actually found a MM logo on ebay. It's not in the photo I attached but it is now installed. It's one with a black background and silver logo. Is that correct for a '78-ish model? Or did they use the grey/silver background logo plates then?
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Another (related) issue - identifying plugs
I've attached a shot of the bottom of the chassis where the footswitch and reverb plugs are. Right now the footswitch is plugged in but I don't know if they're in the right set of inputs. Which are which? A previous post I wrote in another section received an answer that the footswitch plugs were more towards the center of the amp. I'm only bringing it up in case some new member sees this thread and wants to chime in/confirm...
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10 years 7 months
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Photos added - my 112RP
I finally took the chassis out and took some photos. For anyone who's interested, the online album is here:
My main issue still remains - I can't figure out which chassis model my amp is. Some previous owner scratched off the numbers/letters on the back panel so that's no help. I can't determine whether it's a 2100 chassis or a 2165. The tubes that came with it (from the eBay seller) are 6V6 GTAs which are wrong (and it give me no clue as to what *should* be there. The 2165 chassis uses, if I read the charts correctly, 6CA7/EL34 tubes, whereas the 2100 uses 6L6GC tubes. I don't know if the speaker is original so the amp could be a 100w EV model with a different speaker in place now. The more I figure out, the more I get confused.
There is a September 1978 date written in marker on the PCB so I've at least got that mystery solved.
If anyone can take a look at the photos and offer any suggestions, I'd appreciate it!
http://s244.photobucket.com/user/mjet260/library/MM_RP112_Guts
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10 years 7 monthsFoot Switch Connectors
Hi Mjet,
I'm confirming the footswitch connectors are towards the middle of the board. Black goes to the outside middle and red next to it. The other two connectors are for the reverb tank. Reverb red goes next to the red footswitch cable and black next to that. From right to left they go black, red, red , black. I have and RD 65-112 and it probably uses the same reverb tank. I checked the schematics and the reverb circuits use the same driver and summing components for RD's and RP's, The OEM ones are no longer made, but there are replacements. I used a ReVisit model 8FB2A1B from Studio Sound Electronics http://www.amprepairparts.com/reverb.htm. One last note...if you're brave enough to unscrew the PC board from the chassis, you will find the version number of the board with the circuit traces. Based on the mfg date of 1978, it's probably a GP1, but seeing is believing if you know what I mean. Good Luck.......... mgriffin
AMP
OK-so I'm confused. First off, they didn't MAKE a 1-12RP in 78 that I am aware of. They didn't come around until later. Second, they NEVER used a 6V6 in ANY MM amp so THAT needs to go bye bye. SOMETIMES, there will be dates written on the PC boards inside but that's not a given either. Maybe Lars can help here as I'm not versed in exports but I'm fairly sure it will be 1980 or later. I'm thinking 81 and the rest of the number that you can't read is the week code. Mike.