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Old 6th Mar 2018, 4:32 pm   #1
space_charged
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Default Philips G23T210A

I have acquired a Philips G23T210A dual standard b/w set dating back to about 1967. Its a bit more recent than I like to go for restoration projects but I couldn't resist because this was the same type of TV that we had as our first ever family TV . As a family we came to TV rather late. I was about 14 when we got it.

Has anybody any experience of this chassis. The CRT will be an A59-23W (or maybe -11W) I expect. I still have the original service sheet that came with our set. It is somewhat minimal so I have bought the full service manual from one of the outlets that we all know and love.

Any "do and don't" tips peculiar to this set would be appreciated. My main concern is whether the CRT will be OK. This set had DC restoration, and I have heard it said that that drove the CRT into more beam current thus reducing cathode life.
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Old 6th Mar 2018, 5:17 pm   #2
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Default Re: Philips G23T210A

Hello,

Your set uses the first hybrid Philips UK designed dual standard TV chassis, usually referred to as "the 210 chassis".

It has an unreliable line output transformer (LOPT), that often failed when these sets were in everyday service.

Other common faults:

Short circuit boost HT reservoir capacitor (the original type was usually a blue or blue/white cased "Dubilier" mixed dielectric type). If my memory is correct, it is a 0.1uF 1000Vdc rated cylindrical component and vertically mounted.

Boost HT stabilisation circuit feedback resistors: 2 x 8.2MOhm 1Watt, "Erie"brand ceramic cased carbon composition types, which go high or open circuit (check these and the boost capacitor before condemning the LOPT!).

Open circuit mains dropper sections.

Your CRT, if the original, will almost certainly be a Mullard and is quite likely to be OK.

When you get the set working well, I'd be tempted to reduce the Boost HT setting to a value that just gives enough width, which may help to prolong the life of the LOPT.

Last edited by dazzlevision; 6th Mar 2018 at 5:22 pm. Reason: Added text.
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Old 6th Mar 2018, 5:54 pm   #3
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Default Re: Philips G23T210A

Thanks dazzlevision for your tips.

I remember being surprised that it was partly transistorised, which I could see from the circuit diagram that was provided with the set. Our set was branded "Alba".

Yes you are SO right about the LOPT. We rented our set and when it died the local TV shop (based in Morningside) sent a service man. I could hear 15.626Kcs in those days so I knew the line stage wasn't running. There was an all too familiar smell of something getting hotter than it should. The service engineer poked about and as he did I could hear the familiar high frequency of the line stage reappearing. He (correctly) diagnosed a dry on the line hold pot, because the oscillator came and went as he moved the pot spindle.

We chatted about the fault and he became rapidly surprised that this little boy (14) knew lots about TVs and line stages in particular; always my favourite bit of a telly.

He seemed in no great hurry to switch the set off, though the oscillator wasn't running. I made some casual remark about it not really being such a good idea leaving a large pentode with no grid drive for any length of time.

At length he got round to switching it off and re-soldering the dry joint. The set worked fine after that, but NOT for long. It failed that evening and the service engineer had to called again. This time the diagnosis was an o/c LOPT primary - he he. Possibly (I love to think so) due to the over current caused by the LOV with no grid drive.

A new LOPT was fitted, but the TV had to go back to repair shop and was away for a week or two. The set was returned but very badly set up. The width and height were wrong. The family decided to go for a colour set, the Bush/Rank/Murphy one so the G23T210 went back to the rental shop. The BRM colour set was all transistor, except for the CRT.

I'll take care to dry the LOPT before I try to run it. In the past, I've done that by removing the LOPT and putting it on a central heating radiator for a month! In fact, I have one from a 17TG100U on a radiator right now. Another approach is to pass a (current limited) current through the primary to help drive off any moisture.

LOPTs can be re-wound. As they run at high frequency, the number of turns is relatively low (compared to 50Hz transformers) and the wire thick enough to handle more easily.

The overwind is a different matter, but that could be done on a winding machine, or an overwind from a donor set used. Alternatively a tripler connected to the LOV anode...

Chas
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Old 6th Mar 2018, 6:22 pm   #4
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Default Re: Philips G23T210A

I wouldn't worry too much about drying out the LOPT (unless it has been stored in a damp environment), as it is of modern construction, using a moulded plastic EHT winding encapsulation and Polyester varnish sealant for the primary winding.

I think they failed due to either a design fault with the LOPT or incorrect working conditions due to the circuit design. Exactly the same LOPT was also fitted in the hybrid Pye "368" dual standard monochrome chassis, but in my experience, seemed to last better in that.

The preceding all valve Philips "Style 70" chassis had a similar LOPT which was also unreliable.


Other things to look out for in a set this age, is upwards drift in the values of the many carbon composition resistors fitted in the chassis. In particular, check the values of all anode carbon composition load resistors.
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Old 6th Mar 2018, 6:54 pm   #5
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Default Re: Philips G23T210A

Thanks again dazzlevision,

Well I always assume the worst and that an old telly will have been stored in a damp place!

I always was surprised that a lopt could fail o/c. I wouldn't have thought a valve could pass enough current to melt the copper wire of the primary. I assumed that failure mode was more likely to be arching because adjacent strands of wire have a high voltage between them.

Thanks for the tip about high value resistors. When I was a student at Uni (reading biochemistry) I did a holiday job n a radio and tv repair shop. I picked up lots of tips from experienced service engineers about what sort of components are likely to give trouble. High value resistors were on the list.

Valves were of course on the list but nothing like as unreliable as their popular reputation was my experience.

Great you think the CRT will probably be OK. Not many of these around now and we've lost the last of the re-gunners. I've several 110 degree Mullard CRTs in Philips sets and they are all top of the form emission.

Rumour has it that the system switch is troublesome on these sets. I have an Aurora so I'd quite like to be able to run it 405 AND 625, so I don't want to do a "soldering iron" job on it, if possible.

Charles
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Old 6th Mar 2018, 7:16 pm   #6
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Default Re: Philips G23T210A

The systems switch fitted wasn’t the most robust type, but the careful application of contact cleaner/lubricant (only if necessary) should sort it out. Don’t apply too much and make sure you leave the set switched off when applying it and for at least ten minutes afterwards, to allow the solvent to evaporate. I use Servisol “Super 10”.
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Old 6th Mar 2018, 7:41 pm   #7
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Default Re: Philips G23T210A

I have switch cleaning lubricant, think its the one you mentioned. It was bought from a well known high street shop beginning with "M" and, sadly, in trouble.

Just recently I bought an AVO 8 MK-II. I've managed not to buy an AVO up till now, but secretely always did want one. The 8 MK-II was the one we had in the school radio club, so that's what I went for.

But back to switch cleaning lubricants; I used said spray on my AVO's selector switch. To my horror, as as I applied it the switch became more and more difficult to turn! Bad move.

I did some research on switch contacts to see what might be the problem. I had always thought that any sort of grease on a switch contact was the enemy - big time! Actually, it seems not. The bits of the metal that actually make electrical contact are by far the minority of the surface area of it and are composed of sharp spikes that interact. These are well able to pierce any oil or grease. The grease will in fact prevent the metal oxidising and thus increase conductivity.

Back to the system switch. I'll do the minimum I have to of course but might use a special grease I've bought on the switch. I'll try the cleaning spray first.

The Grease worked wonders on the AVO!

I've put a few photos of my 17TG100U running on my profile.

Charles
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Old 7th Mar 2018, 11:10 am   #8
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Default Re: Philips G23T210A

As well as the LOPT failures the S correction capacitor would go short circuit. Giving the impression of lack of width. If the width control was wound OUT to compensate for this fault the boost line would be running in excess of 1000v which reduces the life of the LOPT somewhat.
If these sets were run in a dampish environment you could get tracking on the main PCB between the 2x 8.2M ohm width resistors which again would reduce the lifespan of the LOPT.
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Old 7th Mar 2018, 2:24 pm   #9
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Default Re: Philips G23T210A

Thanks Simon for your tip on the S correction capacitor, I will be sure to monitor the boost voltage. I've had advice to keep the width as low as possible commensurate with a good picture.
As to the pcb tracking, I always dry, my tellies well before attempting a power up. I do basic checks for shorts, wrong valves in the sockets and a thorough visual check. First power is a cautious affair; slow ramp up on a variac to allow capacitors to reform. Sometimes if its easy, I remove the main HT smoothing caps for reforming on the bench. In this set, they may be on the PCB so I may go for the in situ reform.

I have been going through all the family slides that my mother lovingly scanned over the years. I have found one with a picture of our G23T210A (attached). The date is Christmas 1967.
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Old 7th Mar 2018, 2:39 pm   #10
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Default Re: Philips G23T210A

Attached is a photo of the family's first TV, a G23T210. It was rented from a small telly shop in Morningside, Edinburgh. The picture was taken at Christmas 1967.
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Old 10th Mar 2018, 8:09 pm   #11
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Default Re: Philips G23T210A

I am collecting the G23T210 on Wednesday so I will soon know what state it is in. You can only tell so much from the photographs provided. The worst fear is that it has been "got at". We all know what that means.
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Old 11th Mar 2018, 4:41 pm   #12
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Default Re: Philips G23T210A

I've got a later 23" version which was working but as i've not tried it for a while it might not want to cooperate now. but there is a slight problem where the previous owner/s have removed the vhf socket and part of the tuner so now it will only operate on 625. but i'm not too bothered really as I already have a 19" version which is all intact and was displaying a lovely picture.


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Old 11th Mar 2018, 4:54 pm   #13
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Default Re: Philips G23T210A

Hi
Philips also brought out a version of that TV in an almost identical cabinet to the 25" G6. Possibly this was for the Jones's brigade to make people think they had a colour TV! I nearly made the mistake of bidding for one at an auction years ago - luckily I saw the lack of knobs just in time.
It's good advice about leaving any switch cleaner to evaporate before use. A friend almost lost his workshop when a Thorn 1400 caught fire after he'd sprayed the switch.
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Old 13th Mar 2018, 12:18 am   #14
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Default Re: Philips G23T210A

Interesting about the "G6 like" version of it. As it happens, I have a G6 that I was given as a leaving present from a holiday job at a TV and radio repair workshop in Knutsford.
The CRT was low on the blue gun and I couldn't get the grey scale correct. Once I was earning as a research assistant at Leeds Uni, I bought a re-gunned CRT. The new CRT transformed the set. It worked the last time I used it, but that was a long time ago now...

As to the system switch in the G23, I'll be sure to let any solvents evaporate!
I have 405 standards converter and I'd like the set to work dual standard. I can see from the photos of the set that the VHF coax socket is still there. If the system switch is a problem I could always remove it completely and fit relays instead. Oh and talking of standards, my G6 was the 625 only version.
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Old 13th Mar 2018, 12:25 am   #15
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Default Re: Philips G23T210A

Hi Neil,

Well if my set has a major setback, such as CRT or LOPT then I might get back to you begging for help! I did send a private message to the guy here who used to rewind LOPTS for people. He hasn't replied so maybe he's given up doing it. I will have a go at a rewind myself, but failing that...

Chas
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Old 13th Mar 2018, 12:39 am   #16
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Default Re: Philips G23T210A

Hi Chas, I've got a couple of sets of panels that I removed from scrap chassis that I bought a fair few years ago so if you need a system switch etc for your set then your welcome to them. and if I remember right I have a lopt from an earlier style 70 set but I don't think it would be much use to your set unless a more informed member can enlighten me..


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Old 13th Mar 2018, 12:49 am   #17
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Default Re: Philips G23T210A

Hi Neil,

Thanks very much for the offer and I hope I won't need a LOPT. I don't know how much, if at all, the LOPT was changed during the production life of the set. Your LOPT could be of help despite changes. Depends which of the coils has a fault. Overwinds are probably the most stressed given the high voltages between layers of the windings.

Chas
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Old 14th Mar 2018, 9:53 pm   #18
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Default Re: Philips G23T210A

Collected the set today, nice run from Birmingham to South Wales.
Done a quick inspection now and first impressions are good. Complete, and not been "got at". Looks like maybe one of the resistors in the dropper has been bridged by a resistor.
Its fairly clean, only a bit of dust on the component side of the main horizontal PCB.

From the rust on the lower down screws on the back it looks like it may have been in a damp place, on a floor. No rust inside. From what the seller said, it was a house clearance from a house close to that of the seller. Quite probably one owner only. The CRT is an A59-11W. Not checked it yet but will do that first thing.
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Old 15th Mar 2018, 12:35 am   #19
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Default Re: Philips G23T210A

Quote:
Originally Posted by space_charged View Post
From the rust on the lower down screws on the back it looks like it may have been in a damp place, on a floor. No rust inside.
That's not uncommon, as the back cover of your set is made of a compressed fibre (made by firms like Fibre Form Ltd). The material is hydroscopic and absorbs moisture, especially when the TV is no longer switched on every day to get nice and warm and dry the back cover out. The moisture then causes the back fixing screws to corrode.

I'd certainly keep your TV in a warm room for several days to help it dry out, before trying to power it up. That will also reduce the risk of EHT flashover and high voltage tracking.

Concerning the open circuit mains dropper resistor section with a resistor connected across it, I'd check it's the correct value and not scorching any other components, including the back cover.
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Old 15th Mar 2018, 1:11 am   #20
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Default Re: Philips G23T210A

Yes, I'll let it dry for a day or two. The smoothing caps each have sort of blister (safety valve) with some crusted electrolyte round it. I think I'll have to replace them.

I tested the CRT and the heater is OK and the cathode is emissive. I don't have a proper tester, but at least there is emission. From what I've heard these tubes are usually OK.

Sadly I have just noticed a bit of damage in the phosphor right in the centre of the screen. Its a short (looks black) vertical line about 2-3mm long. Could have been caused by un-suppressed switch off burn, or debris falling of the electron gun during storage/transport in the face down position.

So I'm in the market for a good A59-11W or A59-23W. What do you all think my chances of finding one are? I'll post a request in the "items wanted" here of course.

Last edited by space_charged; 15th Mar 2018 at 1:20 am. Reason: spelling
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