Blackstar: no volume in dirty channel until long warm up

[jmcgarvey]

Hi,
I have a Blackstar HT Studio 20 head that produces no volume out of the dirty channel until a long warm up (approx. 30 minutes). And at other times, the volume seems weak. When this started and the amp was cold, I would reseat the tubes, which did work, but no longer. Before I replace all of the tubes I would like to understand the problem. Any thoughts?

Thanks!

Joe

[Stevem]

If the preamp, or any tubes are mounted right on a circuit board then one or more of the solder connections (tube pins to circuit board trace) has factured.
This will be the most likly cause, so break out the soldering iron and use a leaded type (vintage if you will) solder if you can as leaded type will stand up far better to the expansion and cool down factors that most times cause these cracks.
This will show up as a ring around the tube socket pin on the board.
The non leaded solder and wave soldering production that they use making these amps is not a long term thing in regards to amp life!

[jmcgarvey]

Thanks for the guidance. I am going to tear her open this weekend and see if this is the issue.

[jmcgarvey]

I couldn't see any fractures in the solder points, so I think it's time for a pro to take a look. Thanks for the advice. I'll follow up with the result for others that might have the same issue in the future.