engtaz wrote:Does this fan also work for the PM-1201?
Sorry to be almost a year late in responding to your question.
I wish that the board had a feature (like some of the other boards) where I could subscribe to e-mail notifications when this thread gets updated; then I would have known about your question a lot sooner. As it is, the only reason I found out about this question was because somebody e-mailed me to ask about buying an OEM replacement fan for their PM-1.5.
I've never been inside of a PM-1201, but I think the answer to your question is probably, "Yes."
My understanding is that the PM-1200 and PM-1201 are essentially later versions of the PM-1.5 where they added 70V line outputs and doubled the number of fans to facilitate cooling. My understanding of the situation is that just like in the PM-1.5, the fan speed is controlled by the amount of current that is passing through the power supply. This makes the fan run at a higher RPM as the demand on the amplifier increases.
Based upon the assumption that the power supply board & voltages are the same on these amps, and the fan control board's voltage dividers are the same on these amps, then the fan motors should also be the same. To get the definitive answer to this question, we'd really need to peek under the hood of a PM-1200 or a PM-1201 and compare the power supply and fan control circuitry to that of the PM-1.5. If the control circuits are the same, then its a short leap of faith to conclude that both amps can properly control the spin rate of the same fan motor.
A more forensic approach would be to remove the fan motors from both types of amps and place them in an external circuit that would allow us to measure the electrical properties of the fan motors themselves. The problem with this sort of reverse-engineering approach is that getting good data is entirely dependent upon the quality of the specimen being reverse-engineered; these types of measurements aren't that reliable with old, worn-out motors, so you have to base your forensic analysis on a good specimen.
Another option would be to look at the manuals, but I've never been able to lay my eyes on a PM-1200/1201 manual.
One thing that makes it particularly hard to source the proper OEM replacement parts from manufacturers like Carver is that like most electronics manufacturers that sold "authentic" repair parts as part of their business model, Carver's parts did not ever bear OEM part numbers. If the part bore any part number, then it was only an "in-house" part number. This locked you into buying parts from the manufacturer (Carver), and not from their supplier. If you're lucky, someone might have a crosswalk reference book that converts the "in-house" part numbers to "supplier" part numbers. That could allow you to source a generic replacement part if you couldn't get "in-house" parts.
Getting the right parts for Carver amps is particularly troublesome. Carver Parts is gone, and all of the leftover "in-house" parts inventory has been sold off. Sourcing the fan motors is particularly difficult as they don't bear any part numbers whatsoever -- there are no OEM numbers and no "in-house" numbers on the fan motors to help you. You literally have to know the specifications of the fan motor that you're looking for to find the right part.
PM-1.5, PM-1200, M-1.5t, M-500t restoration expert.