RM20 schematic needed

[drunton]

I have an RM20 head that seems to have a high voltage supply issue. It blew the high voltage fuse and even after replacing, doesn't seem to be working. The preamp side works fine, I get signal from the effect send, but I can't adjust the bias (it reads 0mV all the time) and I don't see any heater glow from the EL84's or the 12AX7 phase split/invert tube, though at least two of the 12AX7 preamp tubes and module connections are fine since the pre-side is working.

If someone has a schematic, it will help me pinpoint potential failure points. I don't see any burned resistors, so it's probably a rectifier or something silicon based, but still having the diagram will surely help.

I've seen where Randall won't give them out any more, but there are some posts saying people have received them in the past.

 

[Heritage]

Hi!
Have you got the schematic - i would be interessted too!
To help you with your issues: first off all : warning! In a tube amp are lethal voltages and you do any repair on your own risk and i don't take any responsibility for damage or other harms!
1. pull out the power tubes, replace the fuse and turn the amp on. If the fuse doesn't blow, you should read some voltage on the two leads from the output tranny going to the EL 84's - if you can read ca. 300volt ore a little more, put a new pair of EL 84 in it and your done ( you have to bias the EL84's first!)!
2. if the fuse remains to blow: it could be the rectifier or the filter caps on the rectifier and filterboard or the tranny itsself.
If the fuse blows after the engaging of the stand by switch (to position "live"), tranny and rectifier and the filter capacitors before the stand by switch should be ok- in this case the filter caps after the standby switch should be defective.
3.I am surprised that you have heat voltage on V 1 and v 2 - are you're shure about that? Test all the voltages and report them on the board - those on the EL 84's too and help will be on its way
It,s not so hard to fix your issues if you are familiar with a multimeter
Best regards
Bernhard