BeePre (gen1 - 300B) volume control

[rkoonce]

Hi all,

I got a BeePre gen 1 in for repair. It has the upgraded switched attenuator with two switches, one for coarse and one for fine control. The schematic I have does not include the upgrade. On the attached image, the two resistors noted by red arrows, are burned black and I'm unable to read the value. One measures 820 ohms and the other is 940 ohms. From what I can by blowing up the pic, they appear to be 1K parts. Can anybody confirm that for me please?

Part 2: What could possibly cause a resistor in a volume control to get that hot?

Customer says the unit ran hot, maybe the regulators boards?

I'm not familiar with this unit, so I don't want to just plug it in. It has some age on it, so I'm going to replace all of the electrolytic caps.

BTW, the contacts on the switches on the actual unit (not in the pic) were black and when I sprayed some contract cleaner on them, the stuff liquified and was a tar-like material. I removed as much as I could, but I could only get the wipers clean.

Any advice will be appreciated.

 

[astouffer]

Maybe something with a large voltage on the output was plugged into the attenuator?

 

[Suncalc]

An upstream preamp plugged into the input can cause this type of failure if the output capacitor fails short. You might want to query the owner about the system configuration at time of failure.

 

[rkoonce]

Possible, but it doesn't make a lot of sense to plug a preamp into a preamp.....