Rheem MKVII repair

[joelindsey]

Hey all,

So I got my hands on a Rheem MK VII organ last week, and I thought I would share my progress on repairing it for any other Rheem owners. The second to lowest D wasn't working, the lowest 16' octave didn't work, and none of the bass voices worked. Half the time the organ wont even power up; the light wont even turn on. It intermittently shuts off as well. Still investigating that issue...

First thing I tackled was the D card. After removing it and hooking it up to my power supply (the tone generators run at 12 volts, by the way.) and reading the voltages on the transistors, I noticed the pair of transistors for the lowest divider weren't receiving any voltage from the power supply at all. I noticed some corrosion on the trace going from the positive supply to the emitter. I put a jumper wire between those two points, and it worked!

Next was the bass issue. I replaced all the electrolytic caps, just because thats a good thing to do anyways, and the bass voices and lowest 16' octave work now... most of the time. They will cut out intermittently, save for the low C and C#. I've poked around the board for loose joints, but I can't locate the problem. Any suggestions?

As far as the power issue... I have no idea. I'm thinking maybe it's a dirty switch or loose power cord. Haven't looked into it enough.

If anybody wants photos of the Rheem, interior or exterior, just send me a PM.

[cady]

Hey Joe, like you, I too have a "Rheem Mk VII" combo organ. It works (pretty good) most of the time, but after it's been on for a few minutes, some of the voices change tone & aren't in proper sequence. Also, the "fuzz bass" tab sounds very "raspy" when turned on. Even after attempting to use actual "contact cleaner" on it. I didn't get a power cord with mine when I bought it, so I used a "receptical" from an old (scrap) pc & a pc power cord to replace it. I will also need to replace the "expression pedal" connector socket as the "Lafayette C.B." type cords or "recepticals" aren't made any more or obtainable any where.

[joelindsey]

www.kenselectronics.com/lists/micplug.htm

Part no. CBC4Y for the plug. The site may seem a little sketchy. I was a little nervous about giving them my credit card info, but I received my parts in a couple days no problem.

Have you replaced the filter capacitors? Those are the large ones on the right side of the organ. That could cause your intermittent failures. I don't know what to tell you about the raspy fuzz bass. Maybe it's supposed to sound like that? It is "fuzz" after all. As a general rule, replace all the electrolytic caps and if it still has issues, you can go from there.

[cady]

Joe, what I was refering to is; a "staticy crackleing" when I turn the tab on or off. Also, at times, the static continues when the "Fuzz Bass" tab is in the "on" position.
Also, thanks for the info on where to find the "Lafayette C.B." parts. I haven't (yet) tried to purchase them. I don't use credit cards at all & will only deal with cash or postal money orders to purchase anything, even cars. As for doing the capacitor replacement thing; should I replace most every cap I can on every board? I happen to have an entire schematic from the "official" Rheem Mark VII web site & all of the photo's of the Rheem Mark VII's "inner workings". So, I hope to get my "old t.v. repair skills" dusted off & get to doing a "overhaul" of the Rheem's circuitry. I've been real busy with outdoor projects lately, so my time to spend on the organ has been at a "stand still". Once the snow starts sticking around for the winter, then I'll get working on the Rheem. For now, though, to not risk major damage, I don't run it much. These old "combo organs" are getting hard to find & expensive, so I don't run the risk of causing damage unnessearilly.
Any way, thanks Joe.