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Normally a cap won't blow unless it was in backwards or the wrong value...
C902 should be a 35V not 5V.....maybe that's the reason![]()
Well, the HV board isn't too complicated. That's the input line for the -25 volts from the low-voltage supply on the deflection board. Make sure that voltage isn't lower than about -32vdc.
If you're blowing C902 every time you power up, then the first part I would check would be R907 (2.2-ohm 2-watt). If that looks okay (and there are no solder bridges underneath from any of you rebuild work), then move on down the traces to XD901, Q902, Q901, Q903, and Q900. Also, look for any resistors that look dark in the middle and check them for shorts or opens. If all those look fine, start testing all the other transistors and diodes.
If there is an open down the line, then that could shunt more voltage through that cap then is expected, blowing that cap...

Okay, that is a problem.
That "white box" is a fireproof resistor. However, it shouldn't be there. That is supposed to be C905 - a 33uF 150v axial cap (You can use radial if you don't have an axial).
Since that cap is in a parallel circuit to the C902 your are blowing, the resistor that is in there now is changing the circuit, and is probably why the cap is blowing.
BTW - that 2.2-ohm 5-watt resistor (white box) that is in that location should actually be placed in R907 (that blue resistor seen to the right just above the connector) as an upgrade....
Check all your fuses.
i remember why i put it there cause the 33uf caps i got from bob roberts the leads werent long enough but the old one that was there looks like its still good so im going to solder it back on and im going to put in my last 100uf cap i hope this works and thanks for all your help mod
EDIT: update, i recaped with right parts and c902 is no longer going out however there is no picture at all, when the cap first went there was a loud pop and then smoke coming out of the top of the cab through the vents, could i have completely messed up the tube to where it no longer works?
What is your B+ reading right now? Measure it where the orange wire connects to the neckboard from the HV connector. it should be +180vdc. If it's not there, or is the wrong (or right) value, that will tell us what to look at next...
also i have a digital volt meter but what setting would i use?