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MF-104 PROBLEM

Posted: Thu Dec 19, 2019 9:01 am
by the art of noise
I recently bought a used MF104 Delay and it didn't work properly until a tech replaced the MAX761CPA chip. Now everything works but there's this 1,6 kHz sine oscillation bleeding into the output, which is especially apparent on the SHORT setting. The tech measured the pedal with an oscilloscope and he says it's across the whole power-rail.

Any suggestions where to look or even better, can you provide a service manual for it?

Thanks a lot !!!

Re: MF-104 PROBLEM

Posted: Thu Dec 19, 2019 7:10 pm
by stiiiiiiive
Do you power it with the original PSU?
Do you power it along with others FX units or instruments on a power-strip?

If so, consider testing to power it alone. I had this kind of anoying noises when I used several MFs on a power-strip.

Re: MF-104 PROBLEM

Posted: Sat Dec 21, 2019 5:00 am
by the art of noise
I use the original Moog power supply. I borrowed the same pedal from a friend and his works great with the same PSU.

Something is wrong with the pedal and it's really hard to figure out without a schematic.

Any tips appreciated, thanks!

Re: MF-104 PROBLEM

Posted: Mon Dec 23, 2019 12:02 am
by ummagumma
you may have to send it back to the big M