Dean Markley RM-150-DR Mid-range Pot Cuts Signal

[misterc57]

I was never able to find a schematic on this one.

This is a two channel rack mount head. The gain channel mid-range pot was broke and I replaced it with a new 10K pot.

All the EQ pots also act like a volume boost (both channels) however the pot that I replaced completely cuts the signal when turned to the zero position. None of the other EQ pots do this.

Does this make any sense? It is wired correctly, I had to use a chassis mounted pot with wires to the circuit board. The readings match at zero and ten position on both of the mid-range pots.

Thank you! MC

[misterc57]

Found this schematic for the 80 version

DeanMarkley-80-DR-Preamp.pdf

[misterc57]

I think this is the tone pot highlighted for Ch 2 (gain channel)

[g1]

Sounds like maybe one of the pot lugs is connected to ground and should not be.

[misterc57]

Took it apart, inspected, reassembled. No longer a problem. Not sure what happened but maybe one of the lugs was touching ground as you mentioned.

Thank you

[g1]

If you mean you took the pot apart, there must have been a short from one end lug of the track to the casing. Maybe a little bit of wire or solder or something.
Then, with the pot casing connected to chassis, the signal is shorted to ground when turned all the way down.

It seems more common to read about these kind of issues with new pots these days, QC issues I guess.