Panasonic CT-1310M keeps blowing horizontal output transistor

[luRaichu]

Originally Posted by ARC Tech-109

Those big resistors just to the north of the B+ adjustment. Seriously if it was mine I'd go over every solder connection on the board with a touch of solder and replace all of the supply capacitors, they're 40 years old now and not getting any better.

It doesn't help that the nearly half-century old flux smells bad when heated. I already replaced all the electrolytic capacitors in the video circuit (sound circuit was left mostly untouched) - what exactly is a supply capacitor?

[ARC Tech-109]

The capacitors that are involved in the power supply itself, replacing the caps in the video circuit have nothing to do with the power supply itself. Those would be the likes of C558, C805, C502, C307, C203, C564, C1603 & 1604 for starters.
I know that flux smells bad, been burning that stuff since the late 70's myself so I know where you're coming from but when you described having to hit the set and things started working that was the first clue to intermittent connections. The gradual shift to bright then loss of H-sync points to either a thermal issue that might be taking down a power supply line or a bad capacitor that's hogging current. You found that bad one over in the horizontal and while the 80's didn't have the "capacitorgate" they're still prone to failure due to their wet internal construction. Just the nature of them.
If the smell of the flux is that offensive it can be washed off using either acetone or isopropyl alcohol however the main board should be removed as these will damage the cabinet plastics.

Learning electronics isn't easy, after 45 years I'm still learning and getting off the ground can be really tough when you're dealing with a tough dog. Test equipment is essential but sometimes the best tool is the experienced gained over the years, best advice I can offer is to take it slow, read & study the schematics and stick with it. I started swapping tubes in old B&W sets when I was in the 3rd grade when Carter was in office. You will get there, problems are only opportunities in work clothes that are designed to bring you up to the next level. You CAN do it.

[rcaman]

Originally Posted by luRaichu

<vent>First off, why in the hell are you too big of a pussy to say "hell" without censoring it? Sorry for encroaching on your Christian beliefs</vent>
Secondly, I buy only QUALITY, ORIGINAL parts. The HOTs I bought are 100% legit, old stock!! And eBay is only a marketplace, you can't just say all parts sold there are junk. That's like saying all the produce at a supermarket is rotten. Maybe at yours it is

well go ahead and buy the junk i was just telling you it is mostly junk as you have found out.

[luRaichu]

Originally Posted by ARC Tech-109

when you described having to hit the set and things started working that was the first clue to intermittent connections. The gradual shift to bright then loss of H-sync points to either a thermal issue that might be taking down a power supply line or a bad capacitor that's hogging current.

I think it may also be an issue of the tube drawing TOO much current. Because the picture looks brighter post-recap. Almost too bright. It actually gets less focused.
That's why I alluded to the Sub Bright pot. Perhaps we can see if running dimmer will stop the horizontal f*ckery. Then we will know if it's an undercurrent or overvoltage problem.
I'm tempted to think it is overvoltage, like zeno said.

Originally Posted by ARC Tech-109

Learning electronics isn't easy, after 45 years I'm still learning and getting off the ground can be really tough when you're dealing with a tough dog. Test equipment is essential but sometimes the best tool is the experienced gained over the years, best advice I can offer is to take it slow, read & study the schematics and stick with it. I started swapping tubes in old B&W sets when I was in the 3rd grade when Carter was in office. You will get there, problems are only opportunities in work clothes that are designed to bring you up to the next level. You CAN do it.

Thanks for the pep talk, although slightly unnecessary. I know I'll get the set in tip-top shape eventually.
My last and first recap was a Macintosh LC. The logic board required surface mount caps while the rottening power supply used through-holes.

[Alex KL-1]

Originally Posted by luRaichu

New HOT, cleaned CRT pins & reflowed pads on CRT socket, and the TV is still doing the same shit (no lightbulb!). The picture starts normal but then gets too bright & loses H sync. At this stage +B is 131 to 132v. The colors get VERY saturated, and soon Green disappears followed by Red and Blue. Then all you've got is a bunch of monochrome garbage lines dancing across the screen. Sometimes, a bright colorful flash appears indicating something just disconnected. +B jumps to something like 139v in this state, and what once was a fluctuating whining noise becomes a monotonous high pitch. Orange filament glow disappears I think.

Next to the flyback, there is a pot labeled "SUB BRIGHT". Should I bother?

Edit: Just did another test run. The picture lasted for a few seconds but then the magical flash appeared and +B dropped to 127v!

The #F002 will open if HOT shortens out, probably. If +B are not collapsing to zero V when image disappears*** (in fact it will rise due to R802), confirm measuring if HOT really shorted out. Perhaps only the oscillator can stopped due to some overload (try to run with brightness and contrast to minimum, normally this will suffice and not needs to adjust the sub bright).
Perhaps the screen grid (G2) are cranked up. Is interesting to reduce it to see that happens.

***if is the oscillator protecting something or faulty oscillator.

[vol.2]

Originally Posted by luRaichu

I think it may also be an issue of the tube drawing TOO much current. Because the picture looks brighter post-recap. Almost too bright. It actually gets less focused.

It will look less focused when the brightness and contrast is higher, that's normal. definitely turn it down to something that looks "normal" if it's gotten brighter after replacing caps.

I agree with the other post about the supply caps. Pull and test any electrolytics in the supply. That's 802 803 804 805 in the 130 V, 502 in the 12V, and all those other small voltages, C558 C203 C307 C564 C1603 C1604

Pay special attention to the caps shaded in grey

If you don't have an LCR meter, you can buy one of these cheapo component testers off ebay or amazon (any of them are the same not just this link)

It's not going to be super accurate, and it can't go up super high in capacitance, but it will at least give you a go-no-go reference for telling if a cap is super high ESR or open or shorted in some way

Also you might want to test the supply transistors. Q801, Q802, Q552 You can either test each leg just to confirm they are functioning as transistors still, but those cheapo component testers will quickly tell you if they are probably still working or not as well

[luRaichu]

I was attempting to test the 160v supply. I measured the positive leg of C559 to ground, it was something like 140v. But then the HOT popped again. I am so sick and tired of throwing away money at new HOTs.

Originally Posted by vol.2

It will look less focused when the brightness and contrast is higher, that's normal. definitely turn it down to something that looks "normal" if it's gotten brighter after replacing caps.

There is no contrast control. Brightness is always at minimum. I turned down Sub Bright but the H sync still goes off.

Originally Posted by ARC Tech-109

Seriously if it was mine I'd go over every solder connection on the board with a touch of solder

I've done just that, reflowing the pads for the power supply, H circuit and some of the rest. That only seems to have made things worse. Now there is no color & white horizontal dots across the screen.

Originally Posted by vol.2

I agree with the other post about the supply caps. Pull and test any electrolytics in the supply. That's 802 803 804 805 in the 130 V, 502 in the 12V, and all those other small voltages, C558 C203 C307 C564 C1603 C1604

Actually, I've probably already replaced those. The only caps left alone were in the audio circuit or were bipolar.

Originally Posted by vol.2

Pay special attention to the caps shaded in grey

None were grey?!

Originally Posted by vol.2

Also you might want to test the supply transistors. Q801, Q802, Q552 You can either test each leg just to confirm they are functioning as transistors still, but those cheapo component testers will quickly tell you if they are probably still working or not as well

I suppose it doesn't hurt to try.

[luRaichu]

I found a 12k Ω resistor (R804) in the power supply with paint peeling off. My multimeter says it's actually resisting 73000Ω.

[vol.2]

Originally Posted by luRaichu

None were grey?!

Sorry, those caps shaded in grey in the Sam's. Grey means they are important, both in terms of failure and in terms of observing correct values when replacing

There is no contrast control. Brightness is always at minimum. I turned down Sub Bright but the H sync still goes off.

that's nuts. No contrast? I've never seen a set without contrast. It's also called "picture" on some sets, usually older ones. If you have no contrast or picture control anywhere on the set, then your contrast is controlled by the drive controls for the guns, of which there ought to be all three (RGB) if you really don't have any manual picture or contrast knob. but that just seems too far fetched

[luRaichu]

I swear there's no control labeled contrast. These are all the easily accessed knobs,

On the front of the case:
Bright
Panabrite
Tint
Color
ColorPilot (on/off)

On the right side:
Sharpness
V-Hold

On the neckboard:
Screen
Low Light Red
Low Light Green
Low Light Blue
Red Drive
Blue Drive

[ARC Tech-109]

Panabrite=Contrast.

[luRaichu]

Originally Posted by ARC Tech-109

Panabrite=Contrast.

Apparently Panabrite changes both brightness and contrast.

Any clue as to why the color is gone after reflowing solder? Although, I should probably replace all resistors first. They're clearly going off-spec.

[luRaichu]

Originally Posted by luRaichu

I found a 12k Ω resistor (R804) in the power supply with paint peeling off. My multimeter says it's actually resisting 73000Ω.

My bad, I miscalculated the multimeter readout. It's actually 3550Ω, which is way short of it's original value of 12kΩ.

[luRaichu]

Should I replace just the power supply resistors, or ALL of them?

[Alex KL-1]

Originally Posted by luRaichu

My bad, I miscalculated the multimeter readout. It's actually 3550Ω, which is way short of it's original value of 12kΩ.

Remove one leg and measure again, to be sure (if you don't tried to measure this manner). Possibly some other resistors are in current measuring path.