Intermittent picture\colour problems in Philips Z26C512-80

[Agent24]

I have an old Philips TV with a couple of intermittent picture issues. It's a Z26C512-80 with microprocessor control, an A66-540X CRT and I believe it's based on the KL9 chassis.

I have recently replaced the tripler as the old one developed a hairline crack in the side and started arcing over. At first I thought the problems might have been caused by the old tripler dying but they are still there with the new one. Then I thought the issues were in my VCR (dry joints) but that was only another problem (total picture dropout). Naturally, while all the faults disappeared after I worked on the VCR, most of them returned a couple of weeks later!

I have had some help with this already, from Glen (GLENZ32 here on the forum) who pointed out the memory backup battery and gave other good advice, and who should be sending me a copy of the schematic any day now. I also found that I have a copy of the KT3 schematic which I believe is quite similar.

There are two main problems I notice at present:

1) The colour is sometimes erratic, going from almost black and white, and sometimes everything is completely oversaturated. This has seemed to calm down somewhat since I worked on the VCR but it's also winter now so the fault may just be hibernating, I haven't figured out if it's the TV or the VCR.

2) Intermittent flickering (usually black\grey) horizontal lines through the picture. I have attached some photos trying to show this, I don't know if it's a common picture fault with CRTs or what the name is if it is, hopefully someone here recognises the problem. I have tested with a test pattern generator and verified this problem is definitely in the TV set.

I have resoldered a few suspect joints on the main board but haven't been able to get at the daughter-boards. How does one remove them? I do not want to break anything.

I also measured the voltages that I could see on the silkscreen (this was without input, just displaying snow), and most seem OK but the 300v and 180v supply seem a little off, and some of the lower voltage rails also. I don't know if that is within normal tolerances though for these old TVs.

140v (main filter capacitor) -> 141v

129v (pin6 supply control) -> 129.9v
9.5v (pin13 supply control) -> 10.65v
12v (pin12 supply control) -> 12.17v
0v/5v (pin1 supply control) -> 0.8v on / 5.38v standby

300v (R470) -> 315.6v
33v (other end R470) -> 33.6v

23v (D468 cathode) -> 24.65v

180v (D583 cathode) -> 173v

32v rail -> 32.33

Negative 23v -> Negative 25.22

There's a 13v rail which has many test points, some are 13v, some 12.8v, and one 11.8v - but I'm not sure if it's all the same rail though.

For the record, I have experience with electronics in general and I have repaired some computer SMPS and LCD Monitors and other things but have not a huge amount with TV sets.

I do have a test pattern generator, oscilloscope and isolation transformer so I think I'm good to go as long as someone here can help me in the right direction.

Attached some photos for reference. Image of the main board is before replacing the tripler and cleaning the dust off. If any extra photos are needed I can take more.

[Philips210]

Hi.

This chassis does look very similar to the European KT3 which was very reliable, the tripler being the most common weak point. The KT3 is a swing down chassis, yours looks like it swings outwards on the side like the old British BRC 1500 mono TV.

From experience, the most likely problems are going to be dry solder joints, very few other problems occur.

The daughter boards (modules) are easy to remove, just gently ease the plastic retainers outwards away from the PCB edge whilst carefully pulling the daughter board away from it's socket. You have to do this for each retainer. When replacing the module, you'll feel a positive click as the retainer locates in the module. These modules are also worth checking over with a strong magnifier for dry joints.

The early KT3 had a two chip decoder whereas the later chassis (Edition 2) had a single chip type TDA3560. If this is socketed, then it's worth checking the socket pins. These ic sockets can be dismantled and the individual sockets can be carefully cleaned.

I have had problems with the vision IF chip TDA2540 (on the KT3/K30) playing up giving intermittent vision problems. I don't know if your set uses the same ic.

The connectors on the control panel have been known to cause intermittent faults, sometimes due to poor crimping in the connector pin. It might be worth flexing them a little while the set is on. Bear in mind the chassis could be live, the KT3 has a non-isolated chassis so this could be the case with your set as well. If in doubt, use a mains isolation transformer to be safe.

The voltage readings you've taken look fine.

I have all versions of the KT3 service information if needed.

Regards
Symon.

[Philips210]

Hi.

I have just realised your set uses the A66 540X CRT so therefore is the 110 degree version.

The European KT3 and K30 were the 90 and 110 degree versions respectively.
The KT3 used a conventional line output transformer (LOPT) with a tripler for an AX tube, whereas the K30 used a diode split LOPT for 30AX tubes.

Your set is thus different in that it uses the separate LOPT/tripler for a 110 degree 30AX tube.

Regards
Symon.

[Maarten]

Timeline-wise or at least in order of development, I suspect the KL9 as a 110 degree KT3 variant, is the second development in the line KT3-KL9-K30-K35. It would be nice to have some pictures of factory labels (I spot one on the LOPT, but there might be some elsewhere on the chassis) and code numbers (on labels, but also silkscreened or in the copper layer of circuit boards), both as anecdotal evidence for year of manufacture and origin of design and for my Philips number collection.

A schematic can be found at www.elektrotanya.com by entering "KL9" (including the "") in the search box.

[steve1010uk]

Faults on this series of chassis are often due to dirty or tarnished edge connectors on the plug in modules, its worthwhile removing the modules and cleaning the edge connectors and chassis sockets,

Also as Symon has recommended remove and clean the pins of any plug in i/c's

Steve

[Sideband]

When I was at Philips, the problem of colour flickering/streaking/blinds etc could be caused by poor contact of the large chroma chip (sorry can't remember the number now) in its holder on the chroma panel. A quick fix was to simply unplug and refit. Certainly I would give this a try first. Long-term cure was to solder the chip in directly, dispensing with the holder

[Welsh Anorak]

Hi
TDA 3560, ISTR. And, yes, clean the pins or solder in as suggested above. And while the board's out clean the edge connector with a fibre pen.
Glyn

[Agent24]

Originally Posted by Philips210

This chassis does look very similar to the European KT3 which was very reliable, the tripler being the most common weak point.

Most of the voltages listed on the silkscreen have two voltages, labelled KT3 and KL9, so it definitely seems to be one or the other. Glen said it was a KL9.

Originally Posted by Philips210

I have had problems with the vision IF chip TDA2540 (on the KT3/K30) playing up giving intermittent vision problems. I don't know if your set uses the same ic.

Was that dirty contacts with the IC or was it faulty?

Originally Posted by Philips210

The connectors on the control panel have been known to cause intermittent faults, sometimes due to poor crimping in the connector pin. It might be worth flexing them a little while the set is on. Bear in mind the chassis could be live, the KT3 has a non-isolated chassis so this could be the case with your set as well. If in doubt, use a mains isolation transformer to be safe.

When I replaced the backup battery, I resoldered all the sockets for those connectors at Glen's advice. (Actually they looked OK and seemed to have been reworked previously but I did it anyway) Didn't check the plugs themselves though.

Originally Posted by Philips210

The voltage readings you've taken look fine.
I have all versions of the KT3 service information if needed.

Good to know. Thanks.

Originally Posted by Maarten

Timeline-wise or at least in order of development, I suspect the KL9 as a 110 degree KT3 variant, is the second development in the line KT3-KL9-K30-K35. It would be nice to have some pictures of factory labels (I spot one on the LOPT, but there might be some elsewhere on the chassis) and code numbers (on labels, but also silkscreened or in the copper layer of circuit boards), both as anecdotal evidence for year of manufacture and origin of design and for my Philips number collection.
A schematic can be found at www.elektrotanya.com by entering "KL9" (including the "") in the search box.

I'll take some photos of the labels and post them soon.
I tried that search and only came up with KL9-S – not sure if that's the one you mean or if it's the same one, or one that is close enough?

Originally Posted by Philips210

From experience, the most likely problems are going to be dry solder joints, very few other problems occur.
The daughter boards (modules) are easy to remove, just gently ease the plastic retainers outwards away from the PCB edge whilst carefully pulling the daughter board away from it's socket. You have to do this for each retainer. When replacing the module, you'll feel a positive click as the retainer locates in the module. These modules are also worth checking over with a strong magnifier for dry joints.
The early KT3 had a two chip decoder whereas the later chassis (Edition 2) had a single chip type TDA3560. If this is socketed, then it's worth checking the socket pins. These ic sockets can be dismantled and the individual sockets can be carefully cleaned.

Originally Posted by steve1010uk

Faults on this series of chassis are often due to dirty or tarnished edge connectors on the plug in modules, its worthwhile removing the modules and cleaning the edge connectors and chassis sockets,
Also as Symon has recommended remove and clean the pins of any plug in i/c's

Originally Posted by Sideband

When I was at Philips, the problem of colour flickering/streaking/blinds etc could be caused by poor contact of the large chroma chip (sorry can't remember the number now) in its holder on the chroma panel. A quick fix was to simply unplug and refit. Certainly I would give this a try first. Long-term cure was to solder the chip in directly, dispensing with the holder

Originally Posted by Welsh Anorak

Hi
TDA 3560, ISTR. And, yes, clean the pins or solder in as suggested above. And while the board's out clean the edge connector with a fibre pen.

Thanks everyone for the information. I'll poke around the modules etc and see if I can reproduce the problem and try to narrow it down.

Will pull all the modules and check for dry joints too, though, and let you know which IC(s) mine has and check those too.

[Philips210]

Originally Posted by Agent24

Was that dirty contacts with the IC or was it faulty?

Hi.

That was due to the ic itself, I don't recall the vision IF chip ever having a socket fitted in the KT3/K30 sets.

I had a problem with an Edition 2 KT3 decoder only last year. I had an odd Hanover blind effect which was cured by cleaning the TDA3560 and the socket pins. ISTR the socket is a QIL type rather than DIL so it was a case of cleaning it rather than trying to find a replacement. It's easy enough to clean though.

Your set may have the early decoder which had two ics TDA2525Q and TDA2560/3Q. The Q denotes quad in line so the ics themselves had a QIL layout, and I don't think sockets were used on the 2 chip decoder.
Again, it's easy to bend the ic pins to form a QIL pattern from a standard DIL ic if you have to replace the ics.

Regards
Symon.

[Maarten]

KL9S was the one I meant, and as far as I know it's close enough. The last letter most likely only indicating small design adaptation differences between different factories as was the case in the TCX-S and CTX-E chassis.

[Agent24]

Well, I finally got around to having a look at it again, the fault has returned a lot more, recently... funny how that gets you off your bum

I have found that my set uses the TDA3560 and the TDA2541, which match the ICs in the KT3 (NZ version) schematic I have. Interesting...

As for issues, I have found so far that the chroma board had tarnished contacts (the only one to have dirty contacts) - although the TDA3560 had bright, shiny pins and no evidence of dry joints on the socket - but I resoldered it anyway.

I also found that the RGB amp board has many joints with cracks, so I will resolder the whole thing. Perhaps that will fix an even more intermittent issue I have been seeing again recently (had actually forgotten about it) which is I believe a loss of green: a pinkish cast to the picture (usually goes away after a minute or two)

Originally Posted by Philips210

I have just realised your set uses the A66 540X CRT so therefore is the 110 degree version.

Out of interest - what does that angle refer to? I'm guessing something to do with deflection?

Originally Posted by Maarten

Timeline-wise or at least in order of development, I suspect the KL9 as a 110 degree KT3 variant, is the second development in the line KT3-KL9-K30-K35. It would be nice to have some pictures of factory labels (I spot one on the LOPT, but there might be some elsewhere on the chassis) and code numbers (on labels, but also silkscreened or in the copper layer of circuit boards), both as anecdotal evidence for year of manufacture and origin of design and for my Philips number collection.

Here's the photos you were interested in, hope they are of use. There are more but I can only upload 5 at once.

[Welsh Anorak]

Hi
To answer your question - yes, it's the deflection angle. Early colours were 90 degrees (in fact some oddball portables were 70 degrees) as were earlier black and white CRTs. Around ten years ago Samsung made one with a larger angle, but this needed complicated geometry correction and weighed a ton, so they soon were discontinued in favour of the then new LCD and plasmas.
Glyn

[hans]

Was there any significant difference between the KT3 and K30 except for the tripler/Lopt?

As far as I can remember at least some of the modules were the same.

As for defection angle didn't Sony have 114 degrees in the late 70's? I read that Thompson tried 140 degrees With no luck

[Agent24]

Originally Posted by Welsh Anorak

Around ten years ago Samsung made one with a larger angle, but this needed complicated geometry correction and weighed a ton, so they soon were discontinued in favour of the then new LCD and plasmas.

Thanks. It's a pity, I really like the picture quality of a good CRT, especially for films and gaming. LCDs are usually not as good. Haven't really looked at plasma but I hear they are going out of fashion too!

Out of interest, here are some close-ups of a few cracked joints on the RGB output board.