" bravely wrote to "All" (03 Aug 05 22:31:11)
--- on the heady topic of "Dammit !, anywat, NAP 31X3 chassis"


A Ne2 bulb or a Zener diode at the CRT pin to ground, your pick?
Could be the glitch is indirectly injected through a large junction
into the IC's supply lines. In which case paralleling a 0.1uF bypass
disc cap across the IC's supply might catch it better than the electro
sitting there. Sneaky little problem there...

A*s*i*m*o*v


ZZ From:
ZZ Xref: aeinews sci.electronics.repair:54920

ZZ Sorry, the last post was a test. Friggin Google will sit there and let
ZZ me type for an hour and THEN ask for login, which loses it all.

ZZ Anyway, I'd like to know the mechanism by which the CRT blows the
ZZ chroma, or more aptly the -Y outputs of IC200. I can't see how this
ZZ cannot be protected against, and I'm still having trouble even
ZZ believing this is the cause.

ZZ I have had wierd stuff in the past, V height for greyscale, open
ZZ speaker causing no HV, I am not a babe in the woods. What I'm having a
ZZ hard time understanding is how any phenomenon connected with the CRT
ZZ could do this again and again without blowing any other components in
ZZ the path.

ZZ I have solved a similar problem in a CTC169, I just found a transistor
ZZ that was fairly linear in gain, but had a 400 volt Vce to replace that
ZZ ECG123 (or was it a 159 ?) equvalent. It never blew the chip, but
ZZ maybe RCA's chip of the day had better protection. What's more IIRC
ZZ that transistor is the last stop in the Y driver chain.

ZZ Is possibly the collector to base capacitance saving these transistors
ZZ by delivering the jolt to the chip ?

ZZ Seems to me a way could be figured out to protect it from that, that
ZZ is if I knew the failure mode. I have never witnessed it and as yall
ZZ know, even if I had I might still know nothing. I might know something
ZZ but I might not. I would have seen it, but I have not.

ZZ Ideas ?

ZZ JURB

ZZ TIA


.... Which sparks some mnemonic circuitry.