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