RM100 help! No output.

[uglykidjohn]

I've had my rm100 for about 2 years. No problems until last week. Head was getting dusty, so I thought I'll dust it. Afterward, I can't get an output signal. All the tubes seems to be fine, no tube failure light on. New to tube amps, can't figure out what's wrong.

When switching from standby to play, I can hear the speakers power on, but no guitar signal. Instrument cables are okay.

If anyone can help I'll appreciate it much. Thanks.

 

[JKD]

First guess would be that you dislodged something while cleaning..if you didn't remove the pre-amp tube covers (metal cylinders) then chances are it's not a pre-amp tube.

Make sure the power tubes are all seated.

Another place I'd look would be the output load (ohms) selector...make sure it's not 'inbetween' settings....other than making sure the cab is still connected to the Main output...can't think of much else externally.

You could power off and pull the tube fuses..sometimes they go and no failure light....it's best to test them with a meter rather than rely on visual.

 

[uglykidjohn]

First guess would be that you dislodged something while cleaning..if you didn't remove the pre-amp tube covers (metal cylinders) then chances are it's not a pre-amp tube.

Make sure the power tubes are all seated.

Another place I'd look would be the output load (ohms) selector...make sure it's not 'inbetween' settings....other than making sure the cab is still connected to the Main output...can't think of much else externally.

You could power off and pull the tube fuses..sometimes they go and no failure light....it's best to test them with a meter rather than rely on visual.

Thanks. I've checked the fuses and everything seems to be fine.

Didn't even know that I could remove the pre-amp tube covers. How do I check if the problem is a pre-amp tube or not?

 

[JKD]

First guess would be that you dislodged something while cleaning..if you didn't remove the pre-amp tube covers (metal cylinders) then chances are it's not a pre-amp tube.

Make sure the power tubes are all seated.

Another place I'd look would be the output load (ohms) selector...make sure it's not 'inbetween' settings....other than making sure the cab is still connected to the Main output...can't think of much else externally.

You could power off and pull the tube fuses..sometimes they go and no failure light....it's best to test them with a meter rather than rely on visual.

Thanks. I've checked the fuses and everything seems to be fine.

Didn't even know that I could remove the pre-amp tube covers. How do I check if the problem is a pre-amp tube or not?

You push down on the top of the covers and twist clockwise or anti-clockwise until they pop off (they are spring loaded)....that way you'll be able to see the tubes heater at least and how well they are seated...

 

[jmgman70]

Process of elimination,take known good tube and swap one by one.There are a lot of internal fuses too.

 

[bj4rd]

you could have a bad tube (power or preamp). power tubes have a shorter lifetime, so that is more likely. sometimes you can't tell a tube is bad by just looking at it. are all of the tubes still biased correctly? after two years of use the power tubes probably need to be changed anyways. if you change them, then remember to rebias once your new tubes are in there and turn the bias controls down a little before starting.