Dammit !, anywat, NAP 31X3 chassis
- From: ZZactly@xxxxxxx
- Date: 3 Aug 2005 22:31:11 -0700
Sorry, the last post was a test. Friggin Google will sit there and let
me type for an hour and THEN ask for login, which loses it all.
Anyway, I'd like to know the mechanism by which the CRT blows the
chroma, or more aptly the -Y outputs of IC200. I can't see how this
cannot be protected against, and I'm still having trouble even
believing this is the cause.
I have had wierd stuff in the past, V height for greyscale, open
speaker causing no HV, I am not a babe in the woods. What I'm having a
hard time understanding is how any phenomenon connected with the CRT
could do this again and again without blowing any other components in
the path.
I have solved a similar problem in a CTC169, I just found a transistor
that was fairly linear in gain, but had a 400 volt Vce to replace that
ECG123 (or was it a 159 ?) equvalent. It never blew the chip, but maybe
RCA's chip of the day had better protection. What's more IIRC that
transistor is the last stop in the Y driver chain.
Is possibly the collector to base capacitance saving these transistors
by delivering the jolt to the chip ?
Seems to me a way could be figured out to protect it from that, that is
if I knew the failure mode. I have never witnessed it and as yall know,
even if I had I might still know nothing. I might know something but I
might not. I would have seen it, but I have not.
Ideas ?
JURB
TIA
.
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