HRDx starts to fry an egg as soon as the stdby switch is flipped

[Big Alex]

Then If let him warm up for let´s say 10 min this seems to fix the issue... Who is the culprit here? bad solder joints?

It is strange that you can actually play the guitar. It seems the guitar and the noise are in in different channels.
This amp has been kept sitted for a long time since I use my Blues Jr 95% of the time. I remember somebody here saying that these amps don´t like to be kept turned off for a long time....

Another possibility could be a intermitent component but I was told that this doen´t exist. Anyway thanks for the input. Maybe it is time for a complete revision on sockets, solder joints etc...

[wingnut1]

Sounds like a bad solder connection, problem is with this type of board it could be just about anywhere. I would check around the tube sockets and the connections near the cement resistors.

[Mesotech]

It does sound like a bad solder joint, but isolating it could be problematic. You can try a few things in an attempt to narrow down where the problem may be, such as attempting to determine if the problem is in the preamp section or the power amp section. Because this amp has an effects loop, you can use that to try and split the amp circuit in half. Try running the effects loop output into the power section of another amp (this should be a line level signal, so running it into a moddeling amp, home stereo system line in, powered computer speakers, ect... for short durations of time for troubleshooting purposes shouldn't harm anything).

Likewise, if you were to pull the preamp tubes and then inject a seperate preamp signal from an effects pedal into the effects loop return should let you hear if the problem is on the power amp side or not.

There two tests will make finding the problem a lot easier. You can even isolate the issue further with more troubleshooting techniques. Such as, if the issue is in the preamp section, is it affected by the tone controls, reverb control, volume or gain controls, or even in the case of this amp in the different channel modes? Look for the common circuit points that best reflect the symptoms, and you'll trace it down a lot faster than just looking around with a flashlight and a magnifying glass.

[mageerc]

If what you mean by "frying eggs" is that you hear a bunch of noise that sounds like frying, you might want to check the plate load resistors on the phase inverter (V3) R57 (82K ohm) and R58 (100K ohm)... replace with 1/2 watt or better...

[steve25]

Your problem is solder connections from the tube sockets ( more than likly output tubes) to the board and maybe the ones on the output tube screen resistors.

If you take some 22 ga soild core wire and run it down into the tubesocket pins while the solder is hot you can than let that cool, fold it over and than solder that back to the board trace.
Sometimes it helps to scrape back the board trace more to gain more soldering area.
Be sure to have the tubes out of the sockets when soldering and to discharge the power supply first by letting the amp sit with the standy by switch in play mode for 3 minutes while unpluged from the wall outlet.

[limbe]

I usually use a heat gun and a bottle of freeze spray to try to find the
area where the bad solder joint is located.I suppose you could use a
small hairdryer instead of a heat gun if you are careful.It must have a small nozzle though.

[steve25]

Dont waste time, just shot gun it and resolder all the board to pin connections on all the tube sockets, and the connections at each end of any of the big white rectangular block resistor and you will more than likly be fine after that.
You can have the amp back up and running in 3/4`s the time it will take you with a hair dryer to find one bad connection!