Randall RG100 ES XP, volume drop??

[bullbarrel]

Hey guys, this will be my first post. Have the XP version of the RG100ES and everything works fine with the head until you switch on the sustain/boost switch. The volume will begin loud and after awhile it will become much quieter and then get louder again, if you push or tap on the switch while it's quiet it will get louder.Has anyone ever run into a problem like this with this type head? Thanks for any help in advance!! Brad

[J M Fahey]

The sustain switch in old Randalls *does* lower volume, it´s even mentioned in their user manual.
If yours does it randomly, probably the switch is dirty/rusty.
Unfortunately, lower distorted volume is "normal".

[bullbarrel]

Thank you very much for responding. I am familiar with the volume drop you speak of, I also own a '87 model RG100ES with the treble pull knob and the volume definately drops on that when I pull it out, but this XP models volume doesn't drop for the first 10-15 minutes of play, then it will become much quieter but with the same gain structure and while playing will jump back and forth ( loud and quieter ) about every 2 or 3 minutes. It happens with or without the footswitch plugged in and with or without a patch cable in the effests loop. THANKS AGAIN, Brad

[J M Fahey]

OK. Then it´s very probably not an "electronics" problem (parts just don´t go bad and then repair themselves) but a "mechanical" one, meaning poor connections along the sound path, whether a dirty connector, switch or jack, cracked solder, etc.
Download a 1KHz tone MP3 to have a constant tireless audio signal, send it to the input jack (a regular cheap MP3 player will provide around 100mV at its headphome jack, make the proper stereo mini plug to regular mono guitar plug cable), and follow the signal level along the preamp; i´m sure you will soon find a point before which it´s strong and steady, after which it dies.
Between those circuit points you´ll find the culprit.
Beware that very cheap digital multimeters, those which typically have only have 2 AC ranges (200V and 700V or so) have poor AC circuits and mistakenly read DC as AC, providing baffling results.(such as 15VAC in a 9V powered pedal).
They are only useful to measure AC at a transformer taps or wall outlets  and such.
You need one which typically has , say, 200mV/2V/20V ... etc. AC scales which lets you measure audio signals.
Still cheap and worth every penny.
Lightly tap different points in the board , move wiring around, tap pots, jacks and switches, etc. with a chopstick or plastic ball point pen; ypu´ll probably find the "weak" spot.
Good luck.

[bullbarrel]

Thank you very much for taking time to help, Brad.