by bordonbert Tue May 24, 2016 7:13 am
Glad to hear it's sorted itself out TRB but that sure is an oddity! It is just possible that the problem is just a dirty contact in the valve base and either the TSC is affecting things when it detects something odd, or maybe a power supply is detecting something unusual about current draw for the same reason and shutting down. That really is unusual. Of course it could also be that the intermittent effect you described has just kicked out and it will drop out again soon. I'll keep my fingers crossed for you.
Thanks for coming back to us with this info. Even though we don't understand why, we now know it is something else really simple to advise others to try when they get problems of this type. It would help if we had the schematics for the GM36 but these are not out in the public domain yet. It is very hard advising accurately on issues like this when you are working blind. Logic is your best friend!
As a piece of advice, if it happens again in the near future, swap your valves back to the originals just one at a time and try it after each one is replaced. Start with the preamp valves in order V1 (with the cover), then V2 next to it, then go on to V3 and finally the output valves, one matched pair at a time. This may take a bit more time but it's easy to run it up each time without putting the cover back on as long as you are careful to keep fingers away, and it will give you a suggestion as to where the problem may lie. This could be due to a fault in particular valves (very unlikely as it does it with two valve sets), a socket, or the pcb joints around that particular valve. Though it is not unknown, the infamous "dry" or "cold soldered" joint that sends people resoldering every joint in their amps almost never happens nowadays! While lead free solder is an abomination, it takes a really poor piece of work to create that with automated flow soldering techniques. My advice is not to be convinced to go down that route!
Good luck and do keep in touch with us here. We always love to have new members putting their own ideas and experiences into the pot for us all to share.