Argh PROBLEMS WITH RM100 Skipping sound + with PLEXI MODULE

[Kudogg]

1. The RM 100 on Channel 2 makes a noise, almost like a computer skipping sound it does this while I'm playing, or just sitting there not strumming. So I don't think it's a tube issue. Any advice? It sounds like something that would come out of the computer.

2. The Plexi I bought off ebay is dying. The volume on it has decreased dramatically. At times it sounds like a vibrato with volume coming in and out. Volume is about 1/2 of what it once was. I tried different tubes but it has not helped. Advice?

Thanks guys... starting to get bummed!

 

[rhequiem]

1. Not sure. If it's only on channel 2, that'd be a good place to start the process of elimination. Does it do it with other modules in slot 2? Maybe try cleaning the interface slot in that channel?

2. I'd send it to one of the modders to have it looked at. If you're in the US, I think Rob at Jaded Faith has pretty reasonable repair rates. He could probably mod it for you for not much more, too

 

[kc2eeb]

You might be getting high voltage arcing on the output tube (power amp) board.
Not a good thing.
DISCLAIMER: There are lethal voltages present in these amps.
If you don't have experience in high voltage circuits DO NOT attempt ANY repairs.
OK
Noises like your are hearing may be caused by high voltage shorting.
If you are competent in working on high voltage you can take the chassis out of the head box and look for any black sooty looking marks or traces
around the output tube sockets or the HV connectors to the board.
Had the problem with my RM50 and at first I thought it was picking up digital
artifacts from the studio computer or a cell phone.

 

[Kudogg]

as I just got this amp I did notice one of the ppower tubes burning much hotter than the other... also noticed the guy only has 2 power tubes plugged in when there are 4 slots.

Not sure what to do/ Get new tubes? bias?

 

[kc2eeb]

First,
If there are only 2 tubes they should be in either position 1&4 or 2&3.
What do you mean by 'one tube is burning much hotter?'
Are the plates (the part of the tube that looks like a gray metal box)
glowing red?
If it's glowing red shut it off immediately.
I would try a set of 4 new tubes but first check the the 4 fast-blo fuses
by the bias adjust pots.
If any of them are blown (check them with a meter even if they look good)
hopefully they saved the amp from internal damage. Also check that they haven't been replaced by a much too high amp value. You can use .312 amp or .400 amp fuses instead of the .250 amp fuses, but nothing over those values. They are 5x20mm fuses.

 

[Jaded Faith]

Your amp issue sounds like it could be tube related, particularly when you mention the 2 tubes in there. I suggest either getting a properly biased quad in there ASAP ot making sure the two tubes are in the correct spots (1&4 or 2&3) and that you remember to set your impedance switch to half of what your cab is rated for. Since you mentioned one tube "burning much hotter", I suspect something is wrong with the tubes/configuration you have in there and you should probably start with a fresh set to err on the safe side and prevent further damage to your amp.

Your Plexi sounds like one of 3 issues:

1: Bad tube(s) in the module
2: Bad Optoisolator on the module (likely from hot-swapping modules with your amp turned on).
3: Broken volume or gain pot.

If you are interested in a repair or mod (repairs are free with mods) contact me via email directly.

Hope that helps,
Rob