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New to me 112RD EV Ivory

I just bough this amp from the second owner who had not used it for the past 14 years for $350. It still has the original Phillips 6L6GC tubes. I am going to take it to a local amp tech for check over. I have played through it and all seems fine but better safe than sorry.

mm210's picture

Played with a guy that had

Played with a guy that had one of these. It was, I am sure, the LOUDEST single speaker amp I ever heard. AND clean. Mike.

bill_moore's picture

You're "Pinwale" tolex is a little better than mine!

I have a 115RD, and it is great! I bought a Sho-Bud steel guitar from a friends widow, and she also brought me the (dead) amp. Mainly rebuilt the high and low voltage power supplies, new tubes, and one of the protection diodes was shorted, it too sounds great! (I'll tell you, with the stock EV, and an extension cab with a JBL D130, the sound is glorious!)

RD112's picture

Check R42 and R43 for overheating

The two 390 ohm 3watt R42 and R43 (cement wire wound) resistors get really HOT!. Check to see if these parts and the underlying PCB have been damaged by the heat. You can easily swap these out and raise the new ones off the PCB by a centimetre or two to dissipate the heat. The resistors are right beside the two Zener diodes than control the 16 volt section. You can replace these Zeners as well and raise them off the PCB. They also get hot. And the Zener diode operation is key to the entire low power section. These parts should have been provided with a heat-sink of some kind, or at least been given more room on the board. They are jammed in really tight.

My RD112 100 watt amp picks up lots of rogue EMF... so it can be a bit hissy...not much you can do about that... other than grounding yourself out.

High power electrolytics must be replaced.

All cheap parts...just maintenance.


Thanks for the impute. I took

Thanks for the impute. I took the amp to a local (well regarded tub amp tech / builder) and he found that he caps all need replacing. No surprise there. The 6L6 tubes although not perfectly matched are close enough and still in great shape. Sadly as you predicted the pre-amp board is very badly burned to the point of scorching / possibly melting the fiberglass. He is recommending rebuilding a new pre-amp instead of trying to rebuild the old one.

I have $350 in the amp and he is estimating $250 for the repairs. Does that seem about right?


My tech also found these

My tech also found these codes on the transformers and I have been able to determine that the transformers were made by Woodward-Schumacher EIA606-134 & EIA606-212. What I learned is that the three number after the dash are, the first digit (in this case 1) is the year and the next two are the week of the build. So 1981 12 and 34 weeks of the year.
He also found a small note with the initials RA and 82581. Could it be builder or QC Aug 25th 1981? Seems about right.

RD112's picture

Repairs to the RD 112 100

Sure, $250 would be right for a full rebuild... around 7 hours of your tech's time.
If the board is only heated but not damaged, then you may not need to start over. Just replace the parts that are bad, and provide some heat protection.

You are in for $700 total after repairs... so that is not bad. That's what the amp is worth, give or take $50...imho.

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