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Forum 141

CTV 1978 Pye CT450 - Philips G11 Chassis

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WayneD
(@wayned)
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I've been looking for one of these for years, it's the first TV I remember my parents having. One of my earliest memories is lying on the sofa watching Tomorrow's World on one of these when I was around 3 years old!

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 In fact this TV started my interest in fixing things as I remember watching the repair guy fixing it (many times!) I recall one time he replaced the tuner to the "Studio Colour" type as seen on this one. Prior to that it was a clear plastic one and you could see the tuning pegs inside. For a long time I believed that televisions had light bulbs inside as I remember the guy bringing in a basket of light bulbs from the van!

So inside and straight away I can see one of these is not like the others: 

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I'd already anticipated the dreaded red capacitor needing to be changed so I'd already asked Chris @crustytv if he had a replacement prior to picking this up. I was pleasantly surprised that the whole board seems to have been replaced!

 

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 And we have a date:

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It's older than me but only just!

 
Posted : 13/03/2022 2:51 pm
PYE625, Mikey66, ntscuser and 6 people reacted
crustytv
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Wayne, I can't be 100% sure, but I seem to remember it being mentioned it was not only the Red 470uF cap that had the small rivets, but also the light blue. It looks like you have a light blue installed, It might be worth installing the dark Blue one I gave you yesterday as a precaution.

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Posted : 13/03/2022 3:03 pm
crustytv
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Ignore me, light blue is fine, it's the middle shade of blue that has the small rivets, though I think they were better than the red. All very confusing.

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Edit:

I'm confused now, I've just rummaged through my G11 spares and pulled out a load of NOS 470uF caps, even a red one. They all appear to have various size rivets, though the ones on the red cap look feeble compared to all the others. As I say, all very confusing.

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Posted : 13/03/2022 3:08 pm
WayneD
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@crustytv I'll have a look at the one that's fitted and compare it with the one you gave me. I'll refit whichever one looks the most robust.

 
Posted : 13/03/2022 3:22 pm
Cathovisor
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@wayned I know we had one of these as our first colour television, but I'm pretty sure the front on ours was black - it was rented from Visionhire.

 
Posted : 13/03/2022 3:24 pm
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slidertogrid
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Posted by: @crustytv

Ignore me, light blue is fine, it's the middle shade of blue that has the small rivets, though I think they were better than the red. All very confusing.

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Edit:

I'm confused now, I've just rummaged through my G11 spares and pulled out a load of NOS 470uF caps, even a red one. They all appear to have various size rivets, though the ones on the red cap look feeble compared to all the others. As I say, all very confusing.

Hi Chris

            I worked for a Pye dealer when the G11 was launched. They had a huge amount of hybrid Pye sets on rental the thought was that if they were changed over for new G11s the call rate would fall and money could be spent on the renewal programme instead of wages and spares. A couple of engineers were let go and the new sets flooded in.

Unfortunately the early G11s suffered a lot of faults, they were very fussy about clean mains. A dodgy mains adapter or a sparky set of contacts on the slot meter and bye bye bridge rec diodes! Later sets were modified with a resistor in place of the neutral fuse. Then by about two years old the red smoother started playing up. The rivets on the early ones were the smallest and were very problematic then the first replacements came out with better slightly bigger rivets I can't remember any of those failing. the last generation had the really big rivets like the first blue one in your pictures. 

Our service manager managed to get Pye to pay for replacements so we were told to replace the red ones on sight. 

I went on the Len Briggs lecture when the set was released. There was a lot of talk as to how much effort and research had been put into reliability. and to be fair a lot of the problems were down to component failure rather than design. Once the dry joints had been dealt with and the switch bank changed for the Tip switch unit on Philips versions they were pretty good and had a long life. I have a Philips version as a bedroom set. I have had to do a few repairs but at least it is repairable. Unlike the "Ambilight" that was there before! 

 
Posted : 14/03/2022 8:06 am
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crustytv
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Posted by: @slidertogrid

The rivets on the early ones were the smallest and were very problematic then the first replacements came out with better slightly bigger rivets I can't remember any of those failing. the last generation had the really big rivets like the first blue one in your pictures. 

Thanks, for clarifying and putting my mind at rest, that it was really only the Red that was the most troublesome. 👍 

I gave Wayne a 'Dark Blue' version on Saturday. By way of example, these are my remaining stock, other in addition to what I have already installed on spare G11 PCBs.

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Posted : 14/03/2022 9:12 am
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slidertogrid
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@crustytv 

I often found when replacing a red smoother that someone had put a screwdriver on the edge of the rivets and given it a clout to stop the connection arcing. This may have been a field engineer who hadn't got a can on board but often it was on an ex rental set that had been sold off, so much for the "been through the workshop"! Another nasty dodge was that they would remove the glow switch and turn up the HT to make the tube look better! This usually resulted in arcing anode caps and the like! 

 
Posted : 14/03/2022 10:13 am
WayneD
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Right, I think five months is long enough for this Pye to wait, time to do some work.

I've just noticed these orange stickers around. Were these to indicate that work has been carried out I wonder?

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 That soldering on the main smoothing capacitor (red PCB) is particularly bad!

I'm going to take it out anyway and inspect it, likely replacing it with the one @crustytv gave me.

 
Posted : 27/07/2022 6:59 pm
WayneD
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The rivets seem to be identical on both the one that was installed and the replacement:

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 Someone really had problems soldering it in by the looks of it!

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Tests pretty low too:

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Replacement in, I've also checked the diodes, electrolytic capacitors, large resistors and resoldered any joints that looked even vaguely dodgy:

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As this is a very modular set I think I'll inspect each panel like this and investigate known problem areas before power goes anywhere near it.

 
Posted : 28/07/2022 7:22 am
Jayceebee
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While you are doing your board inspections it would be a good idea to remove the field chip IC2520 and check for any heat discolouration on it’s socket. It was a known trouble spot on the G11.

John.

 
Posted : 28/07/2022 12:09 pm
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crustytv
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I removed and fitted a new socket, also applied fresh compound on my Roberts G11. To save on space, these are photos already upload in 2017.

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Posted : 28/07/2022 12:42 pm
WayneD, Jayceebee, WayneD and 3 people reacted
WayneD
(@wayned)
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Timebase panel out, I immediately notice that two resistors, 056 and 102 the outer coating seems to be crumbling:

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  • However I can see that the resistor 056 on @crustytv 's Roberts above seems to be the same.
 
Posted : 28/07/2022 4:17 pm
WayneD
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Blimey! You guys weren't kidding about the socket, were you?! 😲 

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I've got a probe which I normally use for testing chip sockets on old computers which I tried on this. Four pin holes had very intermittent contact and pin hole 1 had zero continuity. I suspect this may be why this TV was retired in the first place.

 
Posted : 29/07/2022 11:57 am
Doz
 Doz
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Bend pin 16 on the IC out, and solder it straight to that wire link with the ferrites on it. This is the pin that has the most current drawn through it. Solves the issue. 

 
Posted : 29/07/2022 1:07 pm
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WayneD
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@doz aha! Cheers, although I've already unsoldered the socked. Might do that with the new one.

 
Posted : 29/07/2022 1:34 pm
Doz
 Doz
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@wayned I meant after you'd fitted a new socket. 

 
Posted : 29/07/2022 1:50 pm
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malcscott
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NOS sockets in stock here.

 
Posted : 29/07/2022 2:34 pm
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WayneD
(@wayned)
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@malcscott fab! I've sent you a message on Facebook.

 
Posted : 29/07/2022 7:27 pm
WayneD
(@wayned)
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Massive thanks to @malcscott who sent me two new old stock sockets!

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 I've done the "Doz-mod" too as suggested by @Doz wouldn't you know it the wire link itself had a dry joint.

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Some fresh heat sink compound, refit everything and then I think it's time to apply some power.

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Posted : 01/08/2022 4:41 pm
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