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Old 24th Aug 2023, 7:57 pm   #1
MarkAffleck
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Default Philips TV CRT Socket

Hi everyone!

Hope this qualifies for the site and forums.

I have limited knowledge with respect to CRT televisions (I did discharge the tube - HV probe between Anode and DAG strap etc. and the high voltage caps before doing any work on it) and wonder if anybody can throw some light on what I have found inside the CRT socket of this Philips 14PT2666/05, Lo1.2e aa chassis. Please see the attached images.

The TV does start up and display the picture Ok, but shortly after a random time (usually moments or minutes) the picture sort of ‘fizzles’ out. Sometimes, if I switch it off then back on again it does it again, other times no joy. Then a few days later I’ll try it again and the same.

The CRT socket is a JEDEC B8-294 9 pin one. I can’t work out if what I am seeing is a shorted spark gap between pin 6 and pin 1 (G1 and G3 / Focus respectively as I understand) or an intentional connection. (Lack of knowledge strikes again!)

It is hard to see in the images, but the metal ring running round the bottom inside the socket does seem to be slightly bent in towards that stub on pin 6, as if it has been drawn in (Arcing?). I notice that the stub on pin 6 facing the ring is bigger than all the rest, so is that supposed to be a spark gap?

What led me to this ‘discovery’ is that I was just testing a few components on the neck board, resistors etc., and thought I had found a faulty 1.5K ohm resistor when I measured zero ohms across it. When I lifted one end it measured Ok, about 1420 ohms.

What I can’t understand is that from resistor 3348 (bottom right of image) the trace goes to pin 6 only (apart from on to the equivalent pin on the larger socket outline) and nowhere else. So, my question is, if pin 6 and pin 1 are supposed to be connected, why would that resistor be there anyway? If that’s supposed to be an intentional connection between those pins inside the socket, its not a very clever one, just one bit of metal touching the other.

Apologies for the long description, but it is quite difficult to describe. I’m sure that the more knowledgeable folk will instantly get the picture and hopefully be able to enlighten me.

I realise that I’m probably way off base here, but at least I may be able to rule out anything wrong with the socket.

Lastly, if it looks like I need to get another socket, does anybody know where I could find one. I have been looking but there doesn’t seem to be much out there.

Many thanks in advance to any help.

Regards,

Mark
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Old 25th Aug 2023, 9:01 am   #2
Welsh Anorak
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Default Re: Philips TV CRT Socket

Hello and welcome to the forum.

If you get a short on those pins it can only be the socket or a short in the CRT.
If you let us know the model / chassis number perhaps a manual will be forthcoming and we can check what's supposed to be happening. It's quite a common socket so shouldn't be too hard to find - post the CRT number too.

I have to admit that, besides corrosion and damage due to arcing, I don't think I've ever had to change a CRT socket.
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Old 25th Aug 2023, 10:51 am   #3
MarkAffleck
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Default Re: Philips TV CRT Socket

Hi Glyn,

Thanks for your reply.

The TV is a Philips 14PT2666/05 colour portable with the so called ‘Global’ L01.2e aa chassis.

I got things slightly wrong. As I said I haven’t had much (any!) experience with CRT technology but since posting I have realised that the track you can see running from the right side of resistor 3348 (looking at the board as in the image), which seems to be indicated as pin 1, connects to the metal ring running inside the socket.

I believe the ‘focus’ connection is the thicker black wire which goes into the top of the CRT socket, and this connects through within the socket to the separate triangular sort of shaped pin receptacle at the ‘6 o’clock’ position of the socket. I guess this is pin 1! See the image of the socket I have attached.

There is no continuity between this and any where else within the socket, which I assume is good.

I’ve seen things online showing pin designations with pin 1 listed as ground and or G3 / focus!! Different configurations I suppose.

Anyway, there is continuity between pin 6 and the ‘ring’ which bypasses the 1500-ohm resistor, so is this correct? Is what I’m showing in the pictures a spark gap that’s shorted?

I did do a search online with the only number I could see on the socket (03306200) and one site in the Ukraine showed it! I don’t think (If they are still able to trade even) it looks like they ship here anyway.

Again, thanks for any info you can offer, much appreciated.

Regards,

Mark
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Old 25th Aug 2023, 6:01 pm   #4
IKC2E51R8
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Default Re: Philips TV CRT Socket

Hi

I would suggest Re-Soldering the pins for the Line Output transformer and check the pins for the heater on the neck board and on the main board. if the heater goes out the picture will go with it, ive had it on older Philips sets where it lost the heater feed so the screen went dark even though everything appeared to be working fine.

I have a service manual for this set somewhere so i'll post a service diagram soon once i find it
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Old 25th Aug 2023, 6:22 pm   #5
IKC2E51R8
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Default Re: Philips TV CRT Socket

Here is a diagram of the CRT panel on L01.2E. the heater feed connection comes from a small plug on the neck board and goes to pin 4 & 5 of the socket, ensure that these connections are correct and follow the wires to the main board also and ensure they are connected properly, best to resolder to be sure.
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Old 25th Aug 2023, 7:22 pm   #6
MarkAffleck
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Default Re: Philips TV CRT Socket

Hi Luke,

Thanks for the advice. I’ll reflow the LOT as you suggest.
Also, thanks for the schematic.

If I’m reading it correctly, it shows that pin 6 only goes via that 1.5K ohm resistor on the board to the pad that is connected back to the Dag (It’s the thinner black wire in the image of the neck board in my first image, hanging down and out of shot, that was connected to the wire strapped around the tube).

So, it does look like I shouldn’t be reading continuity between pin 6 and that connection, which I do so is it a short?

I was trying to show with the microscope images that, as I said the metal ‘stub’ of pin 6 within the base of the socket is butting up against that metal ring (hence I’m getting close on zero ohms when I check it).

This is where my knowledge runs out and I got to thinking that this was supposed to be some sort of spark gap that’s shorted fuelled by things (lots of!) I read online.

Glyn ‘Welsh Anorak’ asked me to post the tube number as well. It is a ‘A34AGT13X’. I’ve attached an image of the CRT label.

I got the CRT base JEDEC specification number from these details after putting them into ‘tubular.atomized.org’

Thanks again to everyone contributing advice on this post. I’m out of my comfort zone when it comes to CRT black magic!

Regards,

Mark
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Old 25th Aug 2023, 9:34 pm   #7
IKC2E51R8
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Default Re: Philips TV CRT Socket

can you describe a bit more what you mean by the picture 'fizzles' out and how the set behaves before this happens, is the picture 100% correct before this happens? and when it fizzles out does the set remain on (with sound etc) or does it shut down/ go to standby?

When it fizzles out does it go dark straight away or does it fade out slowly? and does this happen every time you use the set or only sometimes?

any other symptoms/descriptions might be helpful in narrowing down what's happening, I've never seen a socket fail so perhaps something else is happening, the more information we have might point us in the right direction. Id start anyway by checking all the connections on the neck board and any that go from the neck board to the main board.
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Old 25th Aug 2023, 10:49 pm   #8
MarkAffleck
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Default Re: Philips TV CRT Socket

Hi,

I’ll try, it’s a bit difficult to describe in words. I nearly caught it on camera in the early days but it happens randomly. I think the longest its stayed on is about twenty minutes or so, but I’ve got it in bits now.

I got this two years ago and it was working fine but I put it away for about a year in the house (wasn’t stored in damp conditions etc.). I then dug it back out and shortly after all this started.

The picture is normal until the issue occurs then it seems to go bright with the picture still showing and sort of shrinks (I don't mean to a dot) and goes into standby. I must admit I do hear some sort of crackle when this happens, not particularly loud like that of high voltage arcing.

This could be a red herring, but when it has turned off, I generally can’t get it to come back on, it just stays in standby, but it does seem if I leave it for a couple of days it will turn on normally and then it all starts over again.

It will switch ‘off’ as in on this set the red LED gets brighter when it is off at the set but dim when you go to turn it on but of course, it doesn’t actually come on.

I have managed to bring up the SDM menu at times and the only codes in the error buffer, but not always, are 4, 6 and 10. I ignore 10 because this is something to do with the tuner and when I bought the TV the seller declared that the RF side of it did not work.

I found by research that those two other codes are apparently i2C bus errors, but no codes ever show up which may indicate X-ray, overcurrent protection etc. I just assume (probably incorrectly) that when they show up it is because of the way the set just shuts down.

So do you think that what I’m finding with regards to the fact that although that resistor is in that circuit, there’s still an apparently parallel path, because that doesn’t seem right to me.

I’m not saying that is the answer to the issue I just want to rule it out as any other potential problem, so that I can at least get the socket back in and look elsewhere for the problem.

Cheers,

Mark
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Old 27th Aug 2023, 1:41 am   #9
IKC2E51R8
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Default Re: Philips TV CRT Socket

Quote:
Originally Posted by MarkAffleck View Post
Hi,

I’ll try, it’s a bit difficult to describe in words. I nearly caught it on camera in the early days but it happens randomly. I think the longest its stayed on is about twenty minutes or so, but I’ve got it in bits now.

I got this two years ago and it was working fine but I put it away for about a year in the house (wasn’t stored in damp conditions etc.). I then dug it back out and shortly after all this started.

The picture is normal until the issue occurs then it seems to go bright with the picture still showing and sort of shrinks (I don't mean to a dot) and goes into standby. I must admit I do hear some sort of crackle when this happens, not particularly loud like that of high voltage arcing.

This could be a red herring, but when it has turned off, I generally can’t get it to come back on, it just stays in standby, but it does seem if I leave it for a couple of days it will turn on normally and then it all starts over again.

It will switch ‘off’ as in on this set the red LED gets brighter when it is off at the set but dim when you go to turn it on but of course, it doesn’t actually come on.

I have managed to bring up the SDM menu at times and the only codes in the error buffer, but not always, are 4, 6 and 10. I ignore 10 because this is something to do with the tuner and when I bought the TV the seller declared that the RF side of it did not work.

I found by research that those two other codes are apparently i2C bus errors, but no codes ever show up which may indicate X-ray, overcurrent protection etc. I just assume (probably incorrectly) that when they show up it is because of the way the set just shuts down.

So do you think that what I’m finding with regards to the fact that although that resistor is in that circuit, there’s still an apparently parallel path, because that doesn’t seem right to me.

I’m not saying that is the answer to the issue I just want to rule it out as any other potential problem, so that I can at least get the socket back in and look elsewhere for the problem.

Cheers,

Mark
OK from what you've described the Beam Current protection is kicking in for some reason, the set is shutting down in protection mode due to Excessive beam current, there could be a few causes, most likely something in the line output area and not the socket itself.

Here is a piece directly from the L01.2E Manual which describes your fault.

you'll need to look in the beam current limiting section for something gone faulty. Could also be the LOPT itself might be past its best.
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Old 27th Aug 2023, 11:53 am   #10
Maarten
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Default Re: Philips TV CRT Socket

If there's really a short in the circuitry connected to the dag. this would affect the beam current tripping circuit.

I didn't find the time to study the schematic yet, but this would be worth investigation.
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Old 27th Aug 2023, 2:03 pm   #11
MarkAffleck
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Default Re: Philips TV CRT Socket

Hi guys,

Thanks for the feedback. I’ll investigate the area of excessive beam current as you have suggested.

Can anyone suggest where I may be able to get that CRT socket from anyway, as I guess it won’t exactly cost a lot. Then at least I know I can rule out any issue with that. Cheers.

If I ever get the set working, I’ll post back here to let you all know!

Many thanks for all the input thus far.

Cheers,

Mark
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