This set had a shorted hor output and an open 2.7 ohm fusible in the
power supply. I also did alot of soldering on the board as well. The
original output transistor was an S2000. The Thompson data sheet shows
it as being a 1500V 8 A part. I used a BUH 715 as a sub which is also
a 1500V transistor and it is a 10 A part. When you hit the power the
set seems like its trying to start with a slight sound from the
speaker at about 1 second intervals. Lowering the AC line to about 70V
will make the set come on. After its on for about 3 minutes or so you
can raise the line to 120 and the set will stay on. Does it seem like
subbing a hor output could cause this? Thanks, Lenny Stein, Barlen
Electronics

Good probability but there are probably other issues causing the startup
problem. High esr caps in standby power circutry, etc. Check the horiz drive
to the horiz driver driver and at the base of the output when the set is
having startup problems, while monitoring the B+.
wrote in message
ups.com...
This set had a shorted hor output and an open 2.7 ohm fusible in the
power supply. I also did alot of soldering on the board as well. The
original output transistor was an S2000. The Thompson data sheet shows
it as being a 1500V 8 A part. I used a BUH 715 as a sub which is also
a 1500V transistor and it is a 10 A part. When you hit the power the
set seems like its trying to start with a slight sound from the
speaker at about 1 second intervals. Lowering the AC line to about 70V
will make the set come on. After its on for about 3 minutes or so you
can raise the line to 120 and the set will stay on. Does it seem like
subbing a hor output could cause this? Thanks, Lenny Stein, Barlen
Electronics

On Sep 21, 4:50 am, "Art" wrote:
Good probability but there are probably other issues causing the startup
problem. High esr caps in standby power circutry, etc. Check the horiz drive
to the horiz driver driver and at the base of the output when the set is
having startup problems, while monitoring the wrote in message

ups.com...



This set had a shorted hor output and an open 2.7 ohm fusible in the
power supply. I also did alot of soldering on the board as well. The
original output transistor was an S2000. The Thompson data sheet shows
it as being a 1500V 8 A part. I used a BUH 715 as a sub which is also
a 1500V transistor and it is a 10 A part. When you hit the power the
set seems like its trying to start with a slight sound from the
speaker at about 1 second intervals. Lowering the AC line to about 70V
will make the set come on. After its on for about 3 minutes or so you
can raise the line to 120 and the set will stay on. Does it seem like
subbing a hor output could cause this? Thanks, Lenny Stein, Barlen
Electronics- Hide quoted text -

- Show quoted text -

I'm going to take a look at the caps first. Thanks, Lenny.