1979 GTE Sylvania GT Matic CX9164W chassis E24-3

[pac.attack76]

I can't find any numbers on that output. Maybe if we could figure out which one this chassis is designed to use.

[JohnCT]

Originally Posted by pac.attack76

I can't find any numbers on that output. Maybe if we could figure out which one this chassis is designed to use.

I scrapped all of my GTE/Philips schematics years ago along with most of my SAMS of those years.

If anyone has any SAMS still, it's in 1751 folder 2.

John

[damen]

Sams 1751-2 shows the damper diode as "SC448". It's on the circuit board between the yoke socket and the focus control area. It's between the horizontal linearity coil, L470, and a large cap labeled C448. Sorry, can't post pictures.

[pac.attack76]

And I just remembered the diagram is on the inside of the back cover showing horiz output is Q402.

[pac.attack76]

So I'm testing sc448 with the same setting? Does output need to be installed during test?

[Alex KL-1]

Probably, it will measure low like the first measurement, since this diode can be in same circuit of the HOT.
Measure using the diode scale on DMM; then, you can desolder it, and check if the low value remains on the part, or in the circuit board (at same PCB location).

[JohnCT]

Originally Posted by pac.attack76

So I'm testing sc448 with the same setting? Does output need to be installed during test?

Yes on the same DMM setting (200 ohm scale), no on does it need to be installed, but it doesn't matter either way. You've confirmed the horiz output is not shorted, so on a resistance test of the diode, it will read "open" as if it's not even there.

The damper should also read open on your meter for resistance the way the horiz output did if it's good, or at least 100K ohms in circuit which is essentially open for this discussion.

If the diode reads short (I think you had something like an 8 ohm short to ground), then unsolder one end of the diode or remove it completely and test again. If it's reading that same 8 ohms out of circuit, then the diode is shorted and you need to replace it. If the diode reads open, something else is shorting the B+ to ground. Reinstall the diode and horiz out and we'll go further (retrace cap would be next).

John

[pac.attack76]

Ok, hopefully today or tomorrow ill find out.