Pye Continental CTM17T (1956)

There were many chassis types installed in the Pye Continental cabinet. The example I have has the very basic 17S chassis. Fringe area versions have the high specification 17-21F chassis.

A model CTM17T appears in the list of hi-spec models covered in the 1956/57 radio and Television book.
Two versions of the CTM17T were made. Information for both can be found in pages 557 thru to 566.

Till Eulenspiegel.

I must say, that mains lead plug arrangement looks somewhat like a DIY modification, though the 'cut out' looks very neat for a DIY.

I wonder if anyone would like shed any light on that? Was it production modification at all?

Marion

Hi Marion,
That's the correct factory fitted plug. All the Pye TVs employing the hand wired chassis and the later printed circuit versions have that chassis mounted mains connector plug. After 1958 with the introduction of the CTL58F development of the 17F chassis the mains lead was wired direct into the set.

Till Eulenspiegel.

Well I left it cooking on the lamp limiter for 3 hours, then decided to plug into my isolation TX for the full beans with the Aurora plugged in.

Nothing particularly eventful (although an electrolytic did begin fizzing) - tone came up on Channel 10, as did the line whistle, but not a dickybird on the screen. Adjusted brightness and contrast - nope. Nothing. Zilch. That's where I left it last night.

Does the EY86 light up? If it does it's most likely you've got EHT. Check the voltages around the CRT base, the boost HT voltage at pin 10 should be over 350 volts, 400 is better. If low or absent the boost smoothing capacitor could be leaky. Also, the CRT grid volts should be equal to or close the cathode volts. For example, if the cathode is 40 volts higher than the grid it can be assumed the tube is at visual cut-off. A quick test is to short the grid pin 2 to the cathode pin 11 together, the screen should light up brightly. Check the position of the ion trap magnet. It should be lined up with pin 3. If it is the type with an arrow marked on it then it should point towards the screen.

Till Eulenspiegel.

Well I've made buckets of progress within a few weeks, but have now (as usual) hit a brick wall.

The symptoms can be seen in the following video as it's not easy to capture on photo.

To describe them is random lines all pulling to the right, with no noticeable pattern. I've re-capped around the line osc and o/p stages, which has improved line lock, but not this actual fault. So I checked C69 to make sure it was correctly tuned. I set that up with the user control line lock at the centre of its travel, and set the preset so that the user control doesn't actually fall out of lock at either end. No joy.

Now, when the set is switched off, either for moments or a while, switching back on usually results in an out of speed line lock, even though it was bang on the money when switched off. It might eventually correct itself after a minute or two of operation. But you can correct it yourself by only slightly tweaking the line lock user control. I know the frame is cramped, I'll be working on that one this line sync problem is sorted out.

So went to the AGC line in case there was noise on here that was modulating the line stage - replaced some Hunts caps and still no difference. So I checked the IF stages in case of noise modulation of the line stage here - nothing wrong found there but changed two Hunts while I was at it.

Next was the flywheel sync stage. That was recapped and R131 (470K) to be way out of tolerance at 640K. After replacing, there I was, all confident that changing this out of spec resistor would made all the difference and... no difference, still the same.

All the meanwhile I have been replacing all three multi-section cans, as these are in nothing resembling a fit state! One of these could have been rippling or leaky, and the line TMB may have been locking to that?

I could try the tuner valves themselves in case one has an issue but the tuner unit is a bit of a pig to get to on this model.

What do other members here think is the potential cause of this? Any help is greatly appreciated.

I'm sure I've seen that before, I have a dodgy coaxial aerial lead somewhere that does this to the picture, maybe look at the RF feed into the set? Could even be something like a dirty contrast control.

Picture is looking pretty good now though, despite the interference!

Regards,
Lloyd.

Are the verticals doubled i.e. || or is that the camera or my eyes? If it is overshoot on the video signal it could also mess up the sync pulse.
Frank

Video is here. Apologies for the flickering ...

Aidan, are you saying that the flickering is a recording artefact and not present in reality?

Can you not get a 'full frontal' view of the screen - I'm sure it would make it much easier to analyse the problems.

The doubled verticals might indicate that the set is off tune but, assuming this is not the case, an oscilloscope could prove useful, if you have one, as that reflection will also affect the sync pulse shape.

Assuming that you are using an Aurora, what attenuation are you using between it and the TV? Bearing in mind that you believe this to be fringe model it will be important to ensure that no problems are being caused by overloading.

If you don't have a suitable fixed attenuator and as the absolute signal level won't be important to you (or anybody using only one TV at a time) one of these could be useful and, most important, is easily available:

£3.76 from Toolstation

Now that Toolstation seems to opened up in every branch of Wickes (and selling many identical items at a fraction of Wickes prices!) they are much more accessible to many folk than they used to be.

To use it, reduce the signal level until the picture start to get noisy, then turn it back up again until the noise disappears. 

Well, I diagnosed the fault - it was twofold.

The easy part was why some lines were displaced so far to the right. This set has been serviced before. There must have been a problem with R64, and the repair technician soldered in a 1K rather than 10K by accident.

The main cause, though, was a low emission PCF80 sync separator and many resistors in the vision IF and line oscillator going just out of tolerance.

Speaking of low valves, at one switch-on, mains hum that wouldn't disappear with the volume came through loud and clear, almost deafeningly so! The PCL83 audio output bottle had given up the ghost!

Before this, it was pretty much textbook stuff, including frame collapse and an EY86 EHT rectifier with an o/c heater. I replaced with a used Ey86/87 and this improved matters. I then replaced it with a brand new EY86 and adjusted the focus to as best I could get it. This improved matters further but as the improvement was only marginal, I put the EY86/87 back.

Then the left speaker (assuming you are facing the front of the set) displayed evidence of "scratching" on bass that sounded all too familiar to me - my Ultra V14-53 has the same issue. The speakers are R&A 865P Mk2s, 6.5" in diameter. I opened the suspect one up, cleaned out a few bits and pieces, reassembled and now the speaker is fully functioning.

Still to clear up:

A linearity fault at the top of the picture.
Tidying up the mess of mains smoothing electrolytics underneath (aka re-stuff or replace the cans above the chassis).
Give a good hoovering inside and out.
Clean the valve pins
and spray the valve socket holders and user pots with Servisol.

And then assemble it all back together and I'll have a (heavy!) solid mid-fifties Pye!

As this set is another former Crystal Palace and Croydon set (C1 & C9 - I earlier said it's Channel 10, it's not), I thought I'd take the chance to take the set back to the late 1950s:

And in 1966, "Rediffusion... LONDON!" starting up the evening's transmissions.

Another good result Aidan, well done. Nice to see the Rediffusion idents too

So what's the Christmas project going to be? I used to love having a set on the bench over the festive period, makes a nice break from all the scoffing and lethargy.

Associated Rediffusion's start-up sequence switched from the Croydon 'Picasso' card to ARTV's clock about two thirds of the way through and, if I was just finishing off and packing my kit away when this came on, would instinctively glance first at my watch then at the screen at the precise moment of switch over.

On numerous occasions the customer would ask "How did you know that that was going to happen ...?"

Pye made export versions of the Continental. A vintage TV enthusiast from Germany visited me in 1996 and he commented about my Pye Continental saying that he had seen the 625 version. It had the same appearance as the UK set except there was a much larger Pye emblem on the front of the cabinet.

Till Eulenspiegel.

Well the set certainly is a good performer. Or rather... was.

While on soak test the frame began to shrink about an inch, so fast I actually saw it shrink a little and a problem with the top linearity get worse (as mentioned previously). There was me hoping it wasn't the FOP valve (PL83) as I don't have any more in stock, so I dived back under the chassis and took some more measurements. Like Till, I was hoping to set myself a deadline on this set's restoration.

Before this, full height could be achieved, but with the pot advanced to maximum output. The resistors in this areas had been checked - most out of tolerance so were replaced, but not much of a difference.

R150 (31.9K - actually a 1M and 33K in parallel) was up to about 50K, both resistors had gone high. Replacing these made not much difference, so I switched off again to take more measurements. In this section of the circuit, the components can get several layers deep, so to measure the FOP valve's cathode bias resistor (no capacitor in parallel) this necessitated removing all components from a few tags on the tagstrip immediately above the bias resistor (150Ohm). When one end was disconnected, it measured at 165Ohm - a little high but shouldn't have any real impact on the circuit.

So I switched back on - almost complete frame collapse except about an inch in height at maximum output setting on the frame height pot. Checked, double-checked, triple-checked and quadruple-checked all of today's work in that area (I've been down that track one too many times), nothing wrong there at all, everything wired up correctly. Checked with the set on - the oscillator is working fine, as a (squashed) testcard can be resolved and there is good strong vertical hold over much of the vertical hold pot's travel. And the height can be adjusted within the low height parameters set by this fault.

So everything seems to be pointing towards the valve being soft or low emission. It's probably lost emission over a matter of some hours in a way where the rest of the set could cope with low emission from this valve until the point where emission from the valve was so low it couldn't cope. It needed the height control at maximum to just about fill the screen, then it began shrinking, and all voltages, even on the valve itself, seem to be OK.

So I've ordered a pair of PL83s from Bardwell's. The current one came with the TV and is a replacement for a previous one (the set had extensive repairs in the frame sections before being assessed by myself), as this PL83 is a Brimar and being a Pye TV, IIRC it would have shipped with Mullard valves. The Brimar is much cleaner than most of the other valves, but the mercury splodge inside is beginning to go a little milky, so I'm suspecting this valve wasn't used much and is already beginning to die.

That does sound like an output valve slowly going to air. I have had one or two output valves go like that.

Hi Aidan, Brimar never made the PL83 so the one in your set will be a Mullard or Philips rebrand. Some Brimar valves were sourced from Lorenz in Germany but I don't think that company ever made the PL83. The PL83 was originally designed as a video output valve but like many others it got pressed into other duties.
Wasn't the PL83 developed for 819 line TV at the behest of French TV manufactures?

Till Eulenspiegel.

Any Philips manufactured valve can be easily identified from the batch and date codes etched into the glass. Being etched they are permanent and can be used to positively identify a valve even when its number has been completely removed.

On a B9A valve like the PL83, look just above the valve base for the markings.

The top row identify the valve - look-up lists are available on line -  whilst the bottom row give the factory of manufacture, year, month and, added early in the 1960s, the week of the month in which it was made. The only thing it doesn't tell you is the name of the girl who assembled it ...

A typical date code might be B3C4  which decodes as follows:

B Mullard, Blackburn (Note that some factories are represented by symbols rather than a letter)

3 Last digit of year - in this case 1963 denoted by the four-digit code)

C Month, where A = January, etc. so, in this case, March

4 Fourth week of the month

So the valve was manufactured at Blackburn in the 4th week of March 1963.

Wasn't the PL83 developed for 819 line TV at the behest of French TV manufactures?

My understanding was that it was developed to drive the MW6/2 projection CRT - BICBW.