1979 GTE Sylvania GT Matic CX9164W chassis E24-3

[pac.attack76]

Ok, I set my meter to 200k and tried the one on the right by the trip and I get nothing. 00.0 and I took the one on the left out and nothing on that one either. Hope I did it right. I have a pic of the one from the left.

[Electronic M]

One thing I learned on an SCR sweep RCA is if the breaker is tripping and you want to know if it's the trippler or not just unhook the flyback output from the trippler input and stick the lead in a jar so it won't arc. If the breaker won't trip like that the trippler is bad, if still trips you have other problems....
You can do the same test to check the trippler if the set isn't tripping the break, but isn't making HV... Only you want to monitor Boost voltage. If it's very low with the trippler and normal or high without the trippler loading it then the trippler is bad.

[pac.attack76]

Originally Posted by Electronic M

One thing I learned on an SCR sweep RCA is if the breaker is tripping and you want to know if it's the trippler or not just unhook the flyback output from the trippler input and stick the lead in a jar so it won't arc. If the breaker won't trip like that the trippler is bad, if still trips you have other problems....
You can do the same test to check the trippler if the set isn't tripping the break, but isn't making HV... Only you want to monitor Boost voltage. If it's very low with the trippler and normal or high without the trippler loading it then the trippler is bad.

This tripler is new from DigiKey

[JohnCT]

Originally Posted by pac.attack76

Ok, I set my meter to 200k and tried the one on the right by the trip and I get nothing. 00.0 and I took the one on the left out and nothing on that one either. Hope I did it right. I have a pic of the one from the left.

Let's be a bit clearer here - a reading of 00.0 on most DMMs means a dead short (you can replicate that same reading by shorting your leads together).

I've seen more than a thousand shorted horiz outputs in my life, and they all will short "hard", so if your meter isn't an autoranging type, put it on 200 ohms or 2K if that's all your meter has.

If the transistor is not shorted, then it will read the same at 200 (or 2K) as if you didn't connect the leads at all, figure something like OL on the display (means overload).

So if your meter is reading OL with the leads off and 00.0 with the leads on the horiz out, the output is shorted.

If your meter reads 00.0 with the leads open, the meter is bad.

John

[pac.attack76]

Ok I set at 200 and I show with leads not touching, then leads touching, and then leads on output and chassis.

[Alex KL-1]

Very low, for sure a damage on HO transistor (more probably) or something very close (damper diode, capacitor, PSU)

[JohnCT]

Originally Posted by pac.attack76

Ok I set at 200 and I show with leads not touching, then leads touching, and then leads on output and chassis.

Something is shorted, although 11 ohms is an odd reading (most horiz outputs short to ground at an ohm or under), but the transistor remains the most likely cause, particularly with a punctured splitter spitting high voltage around.

Remove the transistor's 1/4" screws and remove the transistor by wiggling and pulling upward. Careful if you have to pry because there's a thin mica insulator between the transistor and the frame that can be damaged.

With the transistor out, check the resistance from the metal case of the transistor body to either of the two leads. If you're getting that 11 ohm or under reading, the transistor is bad. If the transistor reads the same as open leads, the problem is elsewhere.

In any case, an 11 ohm reading from the collector case of that transistor to the ground frame means the breaker will trip immediately.

John

EDIT: your DMM doesn't use the Fluke style "OL" to indicate an infinitely high (open) value but uses a "1" two places away from the decimal to indicate an "open" condition. Same thing, different display method.

[pac.attack76]

Ah, ok, I'll check and update.

[pac.attack76]

I'm not getting anything with it out. Just the #1 at far left.

[zeno]

Your meter has a diode / transistor test, the diode symbol.
Look up that function in the manual, too long to type out.
OR look for some tubes teaching it. You will be using it !

Zeno

[JohnCT]

Originally Posted by pac.attack76

I'm not getting anything with it out. Just the #1 at far left.

If the transistor is reading open with it out of circuit, then something else is wrong. If this has a separate damper diode, the diode would be the next suspect because of the punctured tripler. Note that some transistors had the damper diode built in. Yours being an earlier SS design probably has a separate damper behind the horiz output socket (most) or on the main board close to the horiz output.

Is there a schematic on-line? (I scrapped all my paper schematics and most of my SAMS about 15 years ago)

John

[pac.attack76]

I'll see what I can find.

[pac.attack76]

I can't find a schematic and I have no idea where the damper is on this 😞

[Alex KL-1]

The diode damper probably will be the largest cased diode near the flyback, connected at least to some pin of it, sometimes in parallel with HO transistor, and other side (cathode) generally is ground on simple TV's (if is separate, like John said).
Of course, for some TV's, other or others diodes can be associated to primary winding, but is more common on newer TV's (like supply for RGB video output). So is good to check diodes nearby the flyback to be sure.
Another potential part suspect can be the pulse capacitor, the one that tune the flyback pulse, and is rated at least with 1600V (some nF), also near the flyback, and probably at same line with HO transistor. Polypropilene on newer TV''s, and perhaps something-with-oil on older TV's. Normally this fails open, but to be sure, is good to check.

[JohnCT]

Originally Posted by pac.attack76

I can't find a schematic and I have no idea where the damper is on this 😞

It might be right on the back side of the socket of the horiz output. It can either be a black barrel body or a grey round ball - either will have fairly thick leads.

Electrically, the cathode of the diode will be connected to the collector (metal case) of the horiz output and the anode connected to the emitter of the transistor (ground). If you look behind the socket, it should be there.

If it's not, trace the wire from the collector (screws are collector) to the main board to locate the diode.

Clip or unsolder one end, reinstall the horiz output, and see if the short to the case is gone. If it is, the diode is shorted but do NOT run the TV without the damper connected or you will immediately destroy your horiz output which right now is still good.

John