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Fisher X-100-2 safety mods and maybe more???

Steve,
Those voltages are typical for the design. You might get it to rise a little with the zener diode mod - if you care. If it sounds good and it works well, you might want to just leave it.

Running it without a load isn't a good idea, but if it is still working alright then probably no harm this time. I can't comment on what are the odds of damaging it by running without a load.

The phase inverter pots are for split of the signal for the phase inverters. I didn't mess with mine because I think you need a scope to set them right. If you think you messed with them you can get close with a multimeter by measuring their resistance The KX-90 is almost identical except that it replaces those with a fixed resistance. Anyone that might have moved the pots should be able too get them "close enough" by setting the pots to the same resistance as installed in the KX-90.

I was planning on etching the PCB for the IBAM. I have all the parts and just need to get the toner transfer to work right. I think my thread might point to another thread that has the circuit diagram for the IBAM. If not I can send you a PDF of the actual circuit I plan on using, but I haven't tested its myself yet.
 
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Signal is AC. The driver tube splits the sinewave into upper and lower for "PUSH PULL" operation. The 1/2's have to be aligned at the 0 voltage point so one tube shuts off as the other output tube is turning on. And they do this every cycle on all frequencies. If the transistion is not lined up right (too early or too late) distortion occurs and is quite obnoxious. To do it Right (according to the manual) you need a intermodulation distortion analyzer to basically null out the differences. There is another way (Dave came up with it, and if it can be done on a X-100-2 Tim would probably know how) that's not as accurate as the analyzer, but gets you very close. If your's hasn't been mucked with, leave it alone for now.
 
+1 on what Larry said.

BTW, I don't know how, but if its is in a thread somewhere I could probably figure it out. I think I have a vague recollection of seeing that somewhere but cannot remember where. As Larry seemed to indicate - Dave has probably spoken about it somewhere and I listen to what he says.
 
Thanks guys. I'll definitely follow your advice and leave those adjustment pots alone. I did mark them with a sharpie just in case they got bumped during the rework, being very careful not to exert any force.

I'm probably going to be entering a reading phase for the next few days while I familiarize myself with the IBAM circuit. Is there only one approach for amps like this? Or will I find different designs that folks have tried? Just want to make sure I'm on the right "path". I'll start with your thread, Tim.

Thanks again,

-Steve
 
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