Notifications
Clear all

1975 PYE CT-219 “Chelsea” 717 Chassis

Page 1 / 5
 
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10843

I think I might be taking Tas' advice and having a look at the little Chelsea next. Never worked on one of these before, in fact the only colour PYE I've worked on was a PYE CT203/1 with a hybrid 697 chassis. That was 9 years ago, it'll make a change from my usual excursions through Thorns' product catalogue

For the most part it seems to be in reasonable condition. I was shocked to see on the chroma panel a similar thick film unit for the RGB, as used on the 3000 video module. However unlike the 3000 thick film unit of which I have many, the PYE unit 428A/F does not consist of 3 x 11K/56K, it has 3 x 27K/4.7K. I hope it's OK as unlike the 3000 the PYE chroma board does not have through any hole provision to revert to discrete components.

On the line/field timebase and PSU panel, there's also a creative lash-up for R531 consisting of 3 series resistors. As I say, overall it looks to be in fairly good condition.

I'm not throwing caution to the wind so no hairy arsed shoving it onto the mains. First I'm going to service the PSU, remove and if possible reform the reservoir caps 535/536 600uF/250uf. Remove and replace the green grenade C501 which is across the line. And replace another green grenade C656, the flyback tuning cap. Oh, and replace the series resistor lash-up. I'll likely check the line output transistor which is a BU205. I've already tested the CRT, and it's a cracker. So no time wasted in doing the preparatory work.

It depends on interest, but I may or may not live-stream the work. If I do, advanced notice will be announced in our social media section.

The 717 chassis is identical to the 715, it's just cabinet presentation that differs.

1
2
3
4
5
6
7
8
10
ReplyQuote
Topic starter Posted : 02/02/2021 4:03 pm
Katie Bush
(@katie-bush)
Famed V-Ratter Moderator
Posts: 4884

This should be interesting! I had a bit of a soft spot for PYEs, back in the day when my granddad had a few coming through. Some were good, some seemed very good, but others could be downright awful!

ReplyQuote
Posted : 02/02/2021 5:23 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10843

Typical, just when I thought I had a fairly well stocked component store I appear to not have any 2n7 @ 1.5kV or above for the flyback tuning. The Nearest I had was 800V, so I've just ordered 200 x 2n7 1.6kV Philips film flyback caps from Poland. I needed to get stock so have more than enough now and can help folk out as and when.

I've also just learned this little scamp really is a "Built to a budget" TV, no EHT regulation. I thought it had poor regulation but not "No" regulation. Furthermore, I have been told no watching any Top of The Pops unless I like the picture jumping about a bit on high brightness scenes.

Now there's an interesting little project, figure out a circuit to provide EHT regulation for this PYE chassis. Right up Mr Boynes alley that one, a little daughter board that could be mounted on the right-hand side of the cabinet.

ccteht
ReplyQuote
Topic starter Posted : 02/02/2021 5:50 pm
Nuvistor
(@nuvistor)
Famed V-Ratter Registered
Posts: 4158

Where was the CRT made, lots of small screen ones were made in Japan.

The 717 chassis may have been ok, the awful  713 chassis put us off Pye small screen sets.

 

ReplyQuote
Posted : 02/02/2021 5:55 pm
1100man
(@1100man)
Busy V-Ratter Registered
Posts: 27

No EHT regulation was also a main feature of the CT205 hybrid, so obviously Pye designers had never watched Top of the Pops! I think the brightness control was labelled 'picture size'!

I'm sure my CT205 is from 1974, in which case there is a huge difference in these two chassis' from a design point of view.

I see the tube is upside down! Always looks odd not seeing the blue static control at the top.

It could be rather fun to bring it back to life in a 'live stream', or in my case a 'watch it later on Youtube stream'!

Cheers

Nick

ReplyQuote
Posted : 02/02/2021 9:49 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10843
Posted by: @1100man

It could be rather fun to bring it back to life in a 'live stream', or in my case a 'watch it later on Youtube stream'!

I mentioned in the other thread Nick, I live-stream to YouTube not FaceBook so If you're around for the next one. 👍 I'll try not to make them so long, trouble is I don't work fast and get engrossed in side-chat and as I also mentioned I'm finding my way with the broadcast software. Last Friday some folk hung around for the entire stream many others dipped in and out. It did fry my head and as I said in the video comments the following day after rest I could see where the fault was instantly, so keeping the live streams to2 hours or less, splitting them into part 1,2,3 etc if I get stuck is probably better than plugging away for four+ hours.

I'm waffling again 🤓 

ReplyQuote
Topic starter Posted : 02/02/2021 10:43 pm
1100man
(@1100man)
Busy V-Ratter Registered
Posts: 27

Oh, if it's Youtube, then I'll give it a go. I'll keep my eyes open for the announcement! I guess you'll need to recover from the last one for a week or so before you do another 😊 

ReplyQuote
Posted : 02/02/2021 10:59 pm
crustytv liked
irob2345
(@irob2345)
Reputable V-Ratter Registered
Posts: 289

In SS TVs with doublers or triplers, EHT regulation is achieved by using a regulated HT to the line OP stage. Are you saying that isn't done here?

Oz Pye CTVs at the time used Toshiba in-line 110 degree CRTs. They were sharp, bright and very long lasting. PSU was a simple series pass type with over-current foldback. Heatsinks on these sets were oversize to allow for safe operation at high ambients in excess of 50 degrees C. with a blanket draped over the back of the TV!

The following T30 chassis replaced the T29's selenium tripler with a silicon one and raised the EHT from 25 to 30kV. There was an EHT regulation issue that was fixed by adding a big green 22 megohm resistor from the focus tap on the tripler to gnd. I wonder if that is what is happening here?

ReplyQuote
Posted : 03/02/2021 1:08 am
Nuvistor
(@nuvistor)
Famed V-Ratter Registered
Posts: 4158

@irob2345

This was a Philips/Pye attempt at a inexpensive small colour TV to be sold at £199 or less, trying to compete with the Japanese small screen sets. The Japanese  sets were about £40 more expensive but when the customers we had saw the sets side by side they invariably chose the more expensive  set. It wasn’t a bait and switch, we just showed them the sets and they chose. 

The first Chassis was the 713, later sets used 715 and like this 717 although I never saw those two variants. The 713 was that poor we sent our consignment back and didn’t sell any.

Poor focus, which I understand was improved in the 715 by a high voltage focus CRT. Extremely poor EHT regulation which saw the picture vary in large amounts with brightness changes. Other faults but I forget, the later 715/7 may have improved the performance but for our shop it was a step too far.

I don’t know if it was a collaboration or a Philips design but for me it was a failure, after saying that it was widely used by rental companies so there were probably lots in use.

It will be good to see it working again, after all it was a milestone in UK CTV to be able to get the price down below £200.

We were Ekco Pye dealers for many years but the sets Pye produced after the 693 chassis were not my favourites, the 725 chassis was ok but others were not as good as the competition. We took on the ITT agency sets and they were so much better sets.

This is all a personal recollection so others may have had different experiences with them.

 

ReplyQuote
Posted : 03/02/2021 9:40 am
crustytv liked
irob2345
(@irob2345)
Reputable V-Ratter Registered
Posts: 289

I've often wondered why UK Pye TVs were so bad, taken overall.

I do know that Pye Australia sent some engineers to the UK in the early 70s to see what the parent co. had in the pipeline. I believe they got back on the plane determined to do much better, which they did. But then they also visited Toshiba in Japan. The Toshiba CRT allowed them to design a simpler TV that just blew away most delta gun based designs at the time.

ReplyQuote
Posted : 03/02/2021 10:39 am
Nuvistor
(@nuvistor)
Famed V-Ratter Registered
Posts: 4158

@irob2345
Pye with a misstep in their first hybrid mono set made quite good sets in the 1960’s. The 11u and variants were fine, the 368, 169, 173, 569 and 573 chassis’s were fine, all mono. Their first dual standard CTV and the two SS variants 691 and 693 were fine. These CTV’s were designed around Mullard circuits of that time.
The 697 chassis a variant of the 693 etc was not as good, component quality problems, PCB material problems on the CDA board, the PCB line/PSU assembly.

The 725 chassis was not too bad, it had its problems but none that usually couldn’t quickly be repaired in the house. The 731 chassis 110 degree set based on the 725 chassis was not as reliable, the extra power required for the CRT caused problems although the circuit had been designed to provide the extra.

I think it was after that the Philips G11 chassis was used, I have little experience with that due to leaving the trade but I understand it was a decent product.

The hybrid mono set I referred to as a misstep was I think the 40F chassis, the tuner was a dual uhf/vhf type with the IF strip bolted onto the back of the tuner. It didn’t work well, it’s Achilles heel was the tuner/IF strip, other parts of the set were ok, in fact they were the base for the next much improved 368 chassis. The tuner/IF strip was unreliable, mainly the IF strip although the push buttons in the first tranche would fly off across the room. Poor picture and in some areas patterning that was not easy or possible to remove, I think that was the London Ch 1 area.

These are my thoughts on Pye, on the whole decent through 1963 to about 1972 then perhaps it’s money problems caught up with the company. Philips took a stake early in the 1960’s and I think completed it in the late 60’s. Leaving to themselves for a number of years before slowing integrating Pye badged Philips products. At first it was radios, then the audio and finally with the G11 CTV’s.

If anyone can correct my memories that’s ok, but that’s how I remember it.

ReplyQuote
Posted : 03/02/2021 1:36 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered
Posts: 5477
Posted by: @nuvistor

@irob2345
Pye with a misstep in their first hybrid mono set made quite good sets in the 1960’s. The 11u and variants were fine, the 368, 169, 173, 569 and 573 chassis’s were fine, all mono. Their first dual standard CTV and the two SS variants 691 and 693 were fine. These CTV’s were designed around Mullard circuits of that time.

[...]

The hybrid mono set I referred to as a misstep was I think the 40F chassis, the tuner was a dual uhf/vhf type with the IF strip bolted onto the back of the tuner. It didn’t work well, it’s Achilles heel was the tuner/IF strip, other parts of the set were ok, in fact they were the base for the next much improved 368 chassis. The tuner/IF strip was unreliable, mainly the IF strip although the push buttons in the first tranche would fly off across the room. Poor picture and in some areas patterning that was not easy or possible to remove, I think that was the London Ch 1 area.

I agree with the sentiments about the 368 - although mine was prone to over-heating and as a seventeen year old I didn't have access to suitable equipment to diagnose it but I did write to Television magazine to ask for pointers - I think I still have the letter in reply somewhere. I also remember the 40F chassis - a transistor IF panel, wasn't it?

It's a view held by a few people that had it not been for the "Pye IF Strip" that was used to such success in WW2 that Pye would have gone under; before the war their sets got progressively cheaper and nastier - C. O. Stanley was very much of the mindset that "a penny spent is a ha'penny wasted". Sets with unscreened IF transformers that couldn't be adjusted, anyone?

ReplyQuote
Posted : 03/02/2021 4:55 pm
malcscott
(@malcscott)
Noble V-Ratter Registered
Posts: 1493

These sets were produced to compete with the BRC 8000 sets, which were the first ctv under £200. Never seen a good picture on one. Early sets used low focus crt. 

ReplyQuote
Posted : 03/02/2021 5:05 pm
crustytv
(@crustytv)
Vrat Founder Admin
Posts: 10843
Posted by: @malcscott

Never seen a good picture on one.

Well there's always a first time Malc, this one looks great to me, If I can get mine looking as good as Chris Field's (The_teleman) I'll be well pleased. Unless it only looks good when viewing a static test-card, and dire with anything else.

ct200
ReplyQuote
Topic starter Posted : 03/02/2021 6:33 pm
malcscott
(@malcscott)
Noble V-Ratter Registered
Posts: 1493

@crustytv If it has a high voltage focus crt you have a good chance. I should have spare RGB thick film units for these if you need one, Malc.

ReplyQuote
Posted : 03/02/2021 6:53 pm
Nuvistor
(@nuvistor)
Famed V-Ratter Registered
Posts: 4158

@cathovisor

They were ok between 1963 to around 1972, perhaps there was some influence from the Ekco design team. I am convinced that the 40F was down to Stanley wanting to get the first hybrid mono TV to market, another 6-12 months would probably have come up with the 368 design. The hybrid RBM Bush TV135 came out a few months later and showed how it should be done.

The rush to get an all solid state CTV first to market it has been said was  Jules Thorns goal, the rumour was that each one sold lost the company money. It certainly was a fantastic engineering fete, pity the performance didn’t match some of the hybrid chassis that had  a more conventional circuit. Still it gave them lots of experience for the 3000 chassis.

Penny pinching could not have helped the industry but if items are too expensive they don’t sell and cause the firms demise, Hacker Radio produced excellent products but were expensive, they couldn’t compete with the less expensive products. Roberts Radio went down market in build quality but were able to keep a decent if not “Hacker” level, they survived. Appreciate that they have now changed hands since Roberts family owned it.

ReplyQuote
Posted : 03/02/2021 8:20 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered
Posts: 5477
Posted by: @nuvistor

@cathovisor

They were ok between 1963 to around 1972, perhaps there was some influence from the Ekco design team. I am convinced that the 40F was down to Stanley wanting to get the first hybrid mono TV to market, another 6-12 months would probably have come up with the 368 design. The hybrid RBM Bush TV135 came out a few months later and showed how it should be done.

The rush to get an all solid state CTV first to market it has been said was  Jules Thorns goal, the rumour was that each one sold lost the company money. It certainly was a fantastic engineering fete, pity the performance didn’t match some of the hybrid chassis that had  a more conventional circuit. Still it gave them lots of experience for the 3000 chassis.

Penny pinching could not have helped the industry but if items are too expensive they don’t sell and cause the firms demise, Hacker Radio produced excellent products but were expensive, they couldn’t compete with the less expensive products. Roberts Radio went down market in build quality but were able to keep a decent if not “Hacker” level, they survived. Appreciate that they have now changed hands since Roberts family owned it.

I think the best hybrid for picture quality was the RBM A640 chassis; just a pity they had an appetite for line transformers.

It amused me that after the Hacker Brothers sold Dynatron to Ekco, they seemed to be so dismayed at what was being put out with a Dynatron badge on it that they started up Hacker to compete with their old brand - and later Dynatron stuff (once under the Philips/Pye badge) is just rubbish. Funnily enough, I was rebuilding a switch assembly for a Hacker 'Centurion' Unit Audio yesterday.

Roberts is now owned by GlenDimplex, as is Belling.

ReplyQuote
Posted : 03/02/2021 8:34 pm
Nuvistor
(@nuvistor)
Famed V-Ratter Registered
Posts: 4158

@cathovisor
RBM produced some good hybrid monos, yes the A640 was excellent, but I used to carry a LOPTX on the van.

The TV135 I don’t know it’s chassis number was their first hybrid and it was extremely reliable and had an excellent performance, we sold them and forgot about them. The TV135R was mainly valve apart from the UHF tuner, made for the rental market and around £10 cheaper to buy. Not a patch on the hybrid for performance or reliability.

ReplyQuote
Posted : 03/02/2021 8:40 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered
Posts: 5477

@nuvistor

I was given a Bush TV183D (A640) at the same time as I was given my Pye fitted with the 368 chassis: whilst the Pye occasionally overheated, the TV183D was dead from the start - one half of the dropper was o/c, the line tranny was dead and upon test the tube was as flat as a pancake. Sadly that went down the tip, but this was at a time (1981?) when you could still buy the LOPT and the dropper for them.

ReplyQuote
Posted : 03/02/2021 9:03 pm
sideband
(@sideband)
Famed V-Ratter Moderator
Posts: 3971

The lack of stabilising made for some interesting picture effects.....Imagine watching skiing....bright white snow scenes and darker backgrounds or barriers down the ski slope. Certain scenes, the skies would change shape as the skier went past a darker barrier and in fact the barrier would move.....! As for Top-Of-The-Pops and flashing disco lights.......

ReplyQuote
Posted : 04/02/2021 9:33 am
Page 1 / 5