WG 19K4600 degauss circuit

DarrenF

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I'm finishing up remounting a 4600 chassis into a new frame with a new CRT & yoke out of a TV. All that's good (picture is fine, etc.).

The 4600 chassis appears to have several components of the degauss circuit mounted off of the main PCB. The schematic shows R647, X610, X611 & C638 on the board side of P602. On my 4600, they were mounted on a tiny terminal strip that was attached to a metal "shroud" behind the CRT.

Is this normal for a 4600?
Do I need to patch them in to the newly mounted config?
Or can I just plug the new CRT's degauss plug straight into P602?
 
One thought is; "of course they're needed, they wouldn't have put them there if not."

On the other hand, after looking at a number of early-80s color monitor schematics, it appears that WG was about the only ones with these add'l components (anti-parallel diodes, a resistor and a cap). Pretty much all the other monitors just have a PTC varistor (posistor) between one AC leg and the DGC; nothing else! For that matter, at least one model of Wells was also this way.

So this leaves me wondering if the add'l circuit is necessary. The diodes just look silly wired in that fashion-- parallel in opposite direction, AC still passes both ways just fine, with just a volt or so drop (out of 120RMS). Seems pointless. But perhaps they're to limit the residual current after the PTC resistance has risen...
 
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