modessitt
Volunteer: Encyclopedia Submission Moderator
Ok, so I'm working on a 13" Keltron from a Star Castle. The monitor was dead, was partially worked on by someone else, and came to me non-working.
Upon power up it smoke R130. I found Q106 to be bad, and further inspection showed that Q106 was not the proper part. I replaced Q106 and R130, powered up and immediately started smoking R130 again (although Q106 did not blow this time). I found that if I unplugged the vertical amplifier plug, then R130 would not smoke. Checked and found a short on the 2N3716 for that circuit. Replaced it and R130, and now R130 does not start smoking on power up.
However, R118 smokes instead as soon as power is applied. This wasn't burning up before.
I've already replaced all the 2N5320's and 2N5322's. I've checked all the 2N3716's and 2N3792's, but they measure fine, and I've replaced the rubber insulators with new mica insulators.
I was reading the Cinematronics Monitor FAQ, and it mentions replacing all the 47-ohm resistors with 5W versions. I'm wondering whether this would resolve my issue, as the 5W would handle the load (and not burn up), or is there likely another problem elsewhere? I've checked all the diodes and transistors in the circuit, and can't find anything obvious.
Also, I've been hooking up all the connectors during testing except the ribbon cable. I'm not sure if that would have anything to do with it, either.
Anybody got any bright ideas?
Upon power up it smoke R130. I found Q106 to be bad, and further inspection showed that Q106 was not the proper part. I replaced Q106 and R130, powered up and immediately started smoking R130 again (although Q106 did not blow this time). I found that if I unplugged the vertical amplifier plug, then R130 would not smoke. Checked and found a short on the 2N3716 for that circuit. Replaced it and R130, and now R130 does not start smoking on power up.
However, R118 smokes instead as soon as power is applied. This wasn't burning up before.
I've already replaced all the 2N5320's and 2N5322's. I've checked all the 2N3716's and 2N3792's, but they measure fine, and I've replaced the rubber insulators with new mica insulators.
I was reading the Cinematronics Monitor FAQ, and it mentions replacing all the 47-ohm resistors with 5W versions. I'm wondering whether this would resolve my issue, as the 5W would handle the load (and not burn up), or is there likely another problem elsewhere? I've checked all the diodes and transistors in the circuit, and can't find anything obvious.
Also, I've been hooking up all the connectors during testing except the ribbon cable. I'm not sure if that would have anything to do with it, either.
Anybody got any bright ideas?


