I inherited a Tek T912 storage scope. When I first tried it out, it
did not work and soon began smoking. I opened it up and found that
there was a shorted cap and a resistor had burned up. I replaced the
cap with one of the same value ( .033uf). But the resistor was so
badly burned that I could not read the value. I took a guess,
installed a resistor and found that it now works (without smoke).

The board around the resistor is so burned up that I cant read the
component number. So, the problem is figuring out the correct value
for the resistor. Here is what I do know:
- the unknown resistor connects to C478, .033uf
- there is a zener diode, VR476 nearby that I'm pretty sure is
related
- there is another resistor R476 that may be related.

I'm hoping that someone has a copy of the scematic for this scope and
would be willing to help me out.
What I need to know is what resistors connect to C478 and their
values. I think there wont be more than 1 or 2, since this part of the
circuit is very simple.

I did obtain a scematic for a similar scope (T921/922, non-storage
version) that does not use the VR476 zener. It says that "R475 and
R476 provide the proper voltage for the vertical plate shield and R478
and C478 decouple the first accelerator electrode frome the +33V
supply." It is on the CRT & Vertical Amplifier section of the
manual.

TIA
John Basel
remove 00 from address to reply

Try asking on the Tekscopes group on Yahoo ...

Dave
"John Basel" wrote in message
news:PsdQ7kk3DhN8-pn2-PNkiz5c5d1zd@localhost...
I inherited a Tek T912 storage scope. When I first tried it out, it
did not work and soon began smoking. I opened it up and found that
there was a shorted cap and a resistor had burned up. I replaced the
cap with one of the same value ( .033uf). But the resistor was so
badly burned that I could not read the value. I took a guess,
installed a resistor and found that it now works (without smoke).

The board around the resistor is so burned up that I cant read the
component number. So, the problem is figuring out the correct value
for the resistor. Here is what I do know:
- the unknown resistor connects to C478, .033uf
- there is a zener diode, VR476 nearby that I'm pretty sure is
related
- there is another resistor R476 that may be related.

I'm hoping that someone has a copy of the scematic for this scope and
would be willing to help me out.
What I need to know is what resistors connect to C478 and their
values. I think there wont be more than 1 or 2, since this part of the
circuit is very simple.

I did obtain a scematic for a similar scope (T921/922, non-storage
version) that does not use the VR476 zener. It says that "R475 and
R476 provide the proper voltage for the vertical plate shield and R478
and C478 decouple the first accelerator electrode frome the +33V
supply." It is on the CRT & Vertical Amplifier section of the
manual.

TIA
John Basel
remove 00 from address to reply