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

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.
There is no contrast control. Brightness is always at minimum. I turned down Sub Bright but the H sync still goes off.
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.
https://i.ibb.co/jZ2RtGM/IMG-6360.jpg
Actually, I've probably already replaced those. The only caps left alone were in the audio circuit or were bipolar.
None were grey?!
I suppose it doesn't hurt to try.

I found a 12k Ω resistor (R804) in the power supply with paint peeling off. My multimeter says it's actually resisting 73000Ω.
https://i.ibb.co/D4FFm0y/P4230074.jpg

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

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

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

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.

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

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

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.

Normally, only the charred ones or with extremely bad original soldering due to overheating/thermal cycling. Measure some, and if all measure ok, don't need to continue. (again, is good to remove one leg to eliminate readings from circuit).

I replaced all of those except C1603 or C1604 since they were on the channel selector board. Best to do that while we're at it.

Dude, R804 has got to go. It's clearly gone sour and is probably bringing a supply line or component up too high.
Here's my replacement parts list for the important PSU resistors: https://www.digikey.com/en/mylists/list/PTPXQHEAGB ("Notes" column contains part numbers from the schematic)
I also have cap lists. I'll share them later, although I could not find a replacement for the one bipolar 3.3µF @ 160v cap that lives in the H circuit. They just don't make bipolar caps with that kind of voltage tolerance anymore.

I think he just meant in general you don't have to test every single resistor. If you test a bunch that look okay, then usually all of them in the same area and/or of the same type will be okay. The main thing to look out for is burned or otherwise darkened areas on the PCB or the resistors themselves. Usually newer resistors (post 1960s or so) don't go bad unless they burn up.

I will add to that, resistors can have corrosion on them like rusted legs that can go inside the package and ruin them, and that's not always visually obvious from the outside. Also, resistors can burn up partially and you won't be able to see it from the outside either.

Just check anything that looks weird and anything close to a heat source like a transistor mounted to a heatsink or smaller resistors that are next to larger power resistors that are meant to get hot


It's possible to create a bipolar cap from two polar caps. Do a google search for the way to do it

A bipolar electrolytic capacitor can also be made by connecting two normal electrolytic capacitors in series, anode to anode or cathode to cathode.

What isn't mentioned is that doing it this way should cut the overall capacitance value in half. Some also say it decreases the volt tolerance.
I'm not taking a risk with such a hack.
I use DuckDuckGo and you should too, if you respect your privacy. Which is already dead, I guess.

You can over provision the voltage handling to avoid any risk, and you up the starting capacitance to reach the target bipolar value. It's also fairly common to parallel a film cap across the electrolytics in order to keep the ESR impedance low.

If you do it right, it's not risky.

Also, you can probably just use a film cap instead and be done with it. There are some places in a set that you might not want a film cap because it will cause ringing or uneven brightness, but most places it's fine

It used to be many years ago that film caps were simply not available in higher capacitances as electrolytics were, and they tended to be more expensive, so they didn't use them. Nowadays, you can get them up into normal value ranges pretty high; although the very high ones are still pretty expensive

Well, while replacing R804 today it turns out the in-circuit resistance reading was incorrect. It was always 12kΩ even with the paint bands falling off!! I replaced C1603 and C1604 but there's no difference in behavior. I have replacements for all the small value bipolar caps but something tells me that won't fix the H sync either.

The H lock fails began post-recap, picture was fine before it. First thing I did after the recap was run with a 100W or 200W lightbulb in the +B circuit. I removed the bulb when strange behavior occurred (no picture, audio still running). So either the lightbulb caused damage, or something is different after the recap.
Not to mention the other complications that appeared when reflowing solder joints for the PSU, H circuit and chroma zone.

Here are extra pages from the Sams'.
https://i.ibb.co/pQXRFXV/Panasonic-monitor-002.jpg
https://i.ibb.co/s6MdQw1/Panasonic-monitor-006.jpg
https://i.ibb.co/jWQLnXc/Panasonic-monitor-007.jpg
https://i.ibb.co/Y8QNGGt/Panasonic-monitor-008.jpg
https://i.ibb.co/FqkyX1k/Panasonic-monitor-009.jpg
https://i.ibb.co/QNvXfpg/Panasonic-monitor-010.jpg
https://i.ibb.co/VWzBxkX/Panasonic-monitor-011.jpg
https://i.ibb.co/3sKBV02/Panasonic-monitor.jpg

I replaced some small value bipolar caps, and the one near the horizontal driver transformer. Same issue. (didn't replace any resistors as I haven't found more bad ones YET) https://youtu.be/P8dgQ33JAhQ

Although it's hard to see in the video, the picture shrinks (and sides curve inwards) slightly as it warms up. So I think there's still an HV/power supply issue.

Oh, and I recapped the "channel selector" board & audio circuit (couldn't replace a few caps though). Now there is no sound, but I can still hear the amp working (so in other words it acts as if I don't have audio plugged in).

Q554 emitter is at 12v! What is triggering the H osc disable circuit?

At this point, I wouldn't be surprised if there wasn't a hard-to-see break in the PCB or something. PCBs can get brittle with age, and a drop or a jostle (like from being taking out of storage and put on the side of the road) can cause little fractures

Usually the best way to stumble upon such an issue is by following voltages. if you get the right voltage at one end of a supply, and then you follow it along the trace to components, you will often find a break in the PCB by finding it not where it is supposed to be

It's kind of like doing a Sudoku and figuring out a row or box by omission

Of course it's not for sure, but it's one thing you could do if you're feeling stuck (follow all voltages from their supplies)

The Hor lock issues could be the Hor Frequency adjustment. You usually put a small white box up, and then short a transistor in the Hor circuit and adjust the freq pot until it stands still or as close as you can get to it. Usually in older TVs I've never been able to dial it in perfect, it always drifts a little (in the adjustment phase, it always works fine after reconnecting the circuit)

Edit: actually, I just read your manual and apparently you don't need to short anything, there is an adjustment for HSYNC, R505 which can be tweaked without any other procedure

Limiting the TV power with a bulb can have weird effects on voltages inside the set. I know I've seen issues with not having enough juice to start the Hor oscillator, which can throw off voltages in that circuit. It was a tube TV though, so I don't know if the same thing can happen in a solid state set as I've never tried it

Also, probe the 3.58MHz crystal in the Hor circuit to make sure it's outputting the correct frequency. If the crystal is pooched it will mess a whole slew of things up

I don't have a scope or frequency counter :(

As I said, there's 12v on Q554's emitter which means the H osc. disabling circuit is activated (which is what's deliberately throwing H sync off as a "safety feature"). I don't know why it's activating though. Could be excess HV??

Idk for absolute certainty, but I would suspect that using the bulb or a Variac could prevent the Hor oscillator from starting, which could in turn throw off voltages inside the set, or maybe do something weird with the "disabling circuit," especially if there's still something else wrong

There are some low cost scope options for someone on a budget that will at least give you some feedback. For around $100 you can get a little handheld battery powered one that will be high enough to capture the bandwidth of a crystal. Check out this video https://www.youtube.com/watch?v=iG0-0R9qYWU
The cheapest one only goes up to 200kHz, so I would probably avoid it.

Uhhh I don't test with the bulb anymore. The disabling circuit still activates without one present.
Please, pay more attention to the thread.

Yeah, I don't exactly feel like blowing a hundie just to debunk ONE crystal, especially when a replacement crystal probably costs less than the oscilloscope itself!

I measured various PSU voltages, just to be sure:
19.77v line = 18.77v
12.10v(A) line = 12.40v
12.10v(B) line = 12.36v
12.09v(A) line = 12.39v
160v line = 155v
11.60v line = 9.80v (measured from C559 instead of L351 because I didn't bother playing this game of Where's Waldo long enough)

Looks good enough to me. As I mentioned earlier, you could also trace the voltages around the board. If there's a break in the PCB somewhere, that's usually a good way to find it because voltages are stable and predictable. Also, since you don't have a scope, you won't be able to check the various waveform that the Sam's calls out. Which, incidentally, is also a good reason to have at least a basic scope. You can look at all of those little black windows in the Sam's to make sure they look right.

If you plan on doing this kind of thing any more than this one set, a scope is a pretty core tool in electronics troubleshooting

I'd likely need a fuller picture of the Sams' for that. Right now, I only have about a dozen pages out of 30. And I seriously doubt the board is broken, as the picture was perfect pre-recap. If it were fractured, how the flinkerjub would I begin repairing such a fault?

And I sure wonder how'd you go about fixing a bad waveform. Actually, I think it might be worth it to buy the full Sams' for this TV, considering all the problems we're wading through.

This is a one-time ordeal. I hope.

About the H disable circuit - I'm seriously stumped as to why it's being activated. Hopefully our lord and savior Sams' shall yield thy answers...

You clearly had issues or you wouldn't have been recapping anything. But even so, problems can get worse or become less intermittent when you work on thing or have it on for longer. Just moving stuff around and (more importantly) heating things up has a tendency to make problems come out.

You would bridge over the traces with wire, or solder bodge wires to restore continuity to the broken trace(s).

I'm not suggesting that it's the most likely problem, but it's a possible problem that should be fairly easy to check out with a multimeter.

You would take the bad waveform as evidence that the circuit is pooched in that particular area of the board and start testing components connected to it. Some people are good enough to know what is likely wrong just from that, but I would have to just test stuff mostly. If the waveform originates from an IC and not a group of discrete components, it might be a sign of a bad IC, and it is usually possible to lift things out of the circuit and test the output of the IC removed from any possible shorts or loads and see if it's good or not.


I wouldn't know. Hopefully one of these other oldbies can't point you right. My level of troubleshooting is "okay," and I can generally figure stuff out if it's right in front of my face and I'm working on it.

I recapped because HOTs kept blowing out. Did you see this?

I read about H osc. disabling circuits in other Panasonic TVs. It pumps up H frequency to eliminate X-Ray risk if HV is found to be above spec. Which might explain why the picture is so bright & shrinks sometimes. But most other sets from other brands simply shut down if HV is too high.
I can't test the HV without a high voltage meter though.

Well I did some testing tonight and found the +B voltage floating around. It was up to 125v with a dark picture but lowers to 120v when bright. +B control resistor DOESN'T work sometimes. Sometimes it goes back to 130v and that's when the H osc. disable circuit gets triggered. I think the low voltage regulator is crapping out! https://youtu.be/OqzFIbvbYJQ

The lack of color & white horizontal dots seriously concern me. Honestly, I'm almost at my wits end with all these failures!
Considering just sending this set off to Multi Media Medic in Maryland.

If I was seeing fluctuating voltages in the B+, I'd probably suspect one of the transistors of being flaky. Sometimes they only behave poorly when under load, and they test okay when you take them out. Usually, that will come out when you use a curve tracer, but not always. And they are pretty expensive

Interesting. I live in Maryland but I didn't know about that guy. I used to always go to a dude in Silver Spring called Danco, but he's semi retired now and he won't always take stuff in if he doesn't want to. Last thing I brought to him he sat on for six months and then said he didn't want to do it lol

Does anybody know why the color is gone & how to fix? You can kind of see it but just barely.

In an attempt to cripple the H disabling circuit I left R539 open, and switched the set on. I've never seen the HOT blow out quicker!
I give up.

https://i.ibb.co/hy5fHTZ/Panasonic-monitor-013.jpg
https://i.ibb.co/x32y14X/Panasonic-monitor-012.jpg

Well I tried calling this Multi Media Medic man today and he didn't pick up. Left him a voicemail but I doubt I'll get anything back.

Please, enlighten me to any other repair shops or techs in Maryland or Virginia. I cannot bring myself to work on this set anymore. If anything, I can sell it for parts on eBay or something...

MUSTS HAVES !
Power supply must be 130 VDC under both zero beam current or max
( full normal brite ) beam current. & varying line voltage. If not suspect
Q801.

Too bright. REPLACE C559 no matter what, its very common on ALL
brands of TV's, Its in the top ten TV problems. Lots of different symptoms too !

G2 must be about @ 300 VDC too high = too bright.

CRT cathodes need to be @100 VDC. Too low too bright & visa versa.

Blows HOT. Be sure its running cool. If not it WILL give up soon.

NOTES : The FBT's in this era of Pannys / Quasars were trouble. Usually
windings shorted & it cooked, crackled, smoked then blew the HOT.
It ended the TV often. On yours it MAY be it has a bad triple / divider
section.
Last keep in mind to do things right you need: a variac / isolation transformer(S). quality meter & good 100 + Mhz scope with 1 KV probes. Anything less is pushing it. Just think of the $ in blown parts you will save
if you do more sets.

73 Zeno:smoke:
LFOD !

I've already done a near-full recap.

To have a good color pix you NEED a good B&W pix first. Ignore the
color & audio until you have a good B&W set.
The set had ONE part or PC con fail then maybe some other damage, a chain reaction. There is an order to it. Always follow it, any set.
1) power supply
2) hoz osc & drive.
3) hoz out & HV
4) vert sweep

At that point you should have a B&W raster & you can clean up any
other problems. Trust me on that, I fixed tens of thousands of TV's
in my time.

Zeno:smoke:

This is my first CRT repair and I think it's gone over my head by this point. The set has multiple, intrinsic issues. I need another tech with EXPERIENCE to look @ this.

I found another place in Maryland that specializes in Panasonic among a few other brands. https://fnpsites.net/shipley/
Sent out a message with their contact form, never got anything back. I should try calling.