I've recently acquired a 200B-1 head and cab, and on the normal channel, everything works great. The bright channel, however, doesn't work at all. The only way to get any noise is by turning the volume to max, which results in a barely audible distorted sound coming through. The bright switch on the bright channel also pops quite loudly when turned. I've opened up the head and can't see anything jarringly wrong such as bulging capacitors or anything like that. Any help on fixing this would be appreciated!
stevem Messages: 4736 Registered: June 2004 Location: NY
Senior Member
The problem is that the first and maybe second gain stage transistor has gone bad when this problem is seen..
If you go to this sites technical page and open up the schematic for a PC105 board you will see the input jack feeding transistor Q100 and then that transistor feeding Q101.
I would replace both of these since they are less a dallor each these days.
You can order them from NTE parts direct.
Q100 crosses to a NTE123AP
Q101 crosses to a NTE129
I would get a few of each just in case you might need then down the road.