RM100 anything I can check before sending it in?

[Lespauled]

I bought an RM100 along with 2 modules for a stupid price. When the amp didn't work, I really didn't care much, because the modules are worth much more than I paid.

Anyway, the RM100 turns on, and the power tubes light up, but there is no sound. Removing a module makes some crackling sounds, like removing a guitar jack. I'm leaning towards a dirty jack. So, I did the old 600 grit sandpaper rolled up trick. Same result.

Anything else I should try before considering getting it looked at by a professional?

 

[KernelSanders]

Bad phase inverter tube maybe? Total shot in the dark but it's possible.

 

[Mattallica]

Have you checked all the fuses? Including the internal ones?

 

[9985]

Agree about checking fuses. I would rule out other silly stuff, like confirm the guitar & instrument cable works on another amp, same thing with the cabinet & speaker cable. If you have a known good module (not one that came with the RM100) , I'd test that out too, RM100 will work with just a single module. Try all 3 slots in case there's an issue with one of them. If it was shipped to you , or even bounced around in a vehicle for a long trip from wherever you purchased it, there's a chance one or more tubes wiggled loose - with the amp cool & powered off, check that all the tubes are fully seated. This is a long shot, but with it powered off, toggle the ohm switch on the rear and the standby switch on the front back & forth a few times, and do a few vigorous 0 to 10 sweeps of the master volume & other pots on the head. If any of the pots or switches feel wobbly, it could be a short - power off immediately. If you have 2 cabs (or a stereo cab) try connecting them to both main and extension speaker jacks.

If you have another preamp (or any other amp with a loop), connect send to the series loop return on the RM100 with no modules inserted - which turns your RM100 into a power amp, if that works, issue isn't the power section or any of the tubes.

You can try swapping out the 12AX7 tubes in the head if you have known good spares. If you have spare power tubes, can swap those as well if you are comfortable biasing. From there, I think you might need to take to a tech. Keep in mind used RM100s are pretty widely available in the $500 range before you pay a lot for repairs.

That's all I can think of, somebody else can chime in.

 

[Lespauled]

Thanks all. After checking everything I could, I brought it in. There were a couple of things that needed to be resoldered to the board. Way beyond my (complete lack of) skill level.

It only took them a couple of hours to diagnose and fix it. Works perfectly now.