1967 Decca CTV25

The “Battersea” Chassis

Model: Decca CTV25

Year:1967

System: 405/625 Line Colour

Original List Price : £377 gns

Valves:
V200 PL802 Luminance output
V301 ECC82 Frame Oscillator
V302 PL508 Frame output
V303 PCF802 Line Oscillator & Reactor
V400 PY500 Efficiency diode
V401 PL509 Line output
V402 PD500 EHT Stabiliser
V403 GY501 25kV Rectifier
V600 PLC84 R-Y Amp & clamp
V601 PCL84 B-Y Amp & clamp
V602 PCL84 G-Y Amp & clamp

Transistors: 35

Diodes: 40

CRT: A63 11X

General Info:

Dual standard television incorporating 11 valves, 35 transistors, 40 diodes and providing the following:-
Colour and Monochrome on the 625-line system on U.H.F channels 21 – 68 inclusive and V.H.F. Channels C – H inclusive and suitable for colour modulation to the PAL system. In addition monochrome on V.H.F. channels 1 – 13 inclusive in bands 1 and 3 operating on the 405-line system. The set is provided with a multi-band tuner controlled by a six push button channel selector mechanism which also selects the transmission standard appropriate to the desired channel. The tuner however, has the attribute, ” any button, any channel, any system”.

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Powered on, I cannot get a good locked colour. When fine tuning to the testcard I can get a good B&W picture, but tuning to tune it for colour sync and colour lock go out is impossible. Looks like it might have decoder issues/ref osc.

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To get to the bottom of colour issue I need to disable the colour killer to shed some light on the fault condition. Checking the manual I found the colour killer can be overridden by shorting D600. I fed in colour bars from the Philips 5515T, powered on and the truth be confirmed, the reference oscillator is off hence unlocked colour.

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Now what’s needed is to follow the oscillator tuning procedure, this entails scoping pin 1 of the decoder and checking the waveform present matches the one in the manual. The amplitude needs to be 2V p-p. Then I need to connect the scope to the left hand of R658, then adjust L604 for maximum output which should be 6V. Again a sine waveform is given as an example. Fingers crossed this sorts it. Checked the waveform at pin 1 of the decoder, it looks correct and reads about 1.8V p-p, it should be 2V but I guess that’s close enough.

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Next up is setting the tuning of the oscillator and peaking it to the stated 6V p-p unfortunately the colours are still unlocked need to put my thinking head on now, I wonder if I need to now perform Burst tuning followed by setting up the phase discriminator.

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Checked the burst, it should be 30V p-p +/- 5V I have roughly 23V p-p again pretty much within spec. I will check the phase discriminator next.

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Success, adjusting the phase via VR602 has given colour lock. I think I need to sort the delay as I have blinds. Still much improved on what I had.

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PYE625
PYE625 (@pye625)
Member
5 years ago

An interesting set there. Does it still have the original PD500/GY501 arrangement or a tripler conversion Chris?

Guest
5 years ago

Hi,
Its totally original with the shunt and x-rays. The LOPT fitted is a brand new old stock. A very rare set these days.

PYE625
Andrew Saunders (@pye625)
Member
Reply to 
4 years ago

This would make a lovely set to mark the 50th anniversary of colour with.

David Leiper
David Leiper
Guest
Reply to  Andrew Saunders
4 years ago

Thanks for the interest. I think I am the last of the 3 main engineers who designed all the Battersea chassis’s.

Guest
Reply to  David Leiper
4 years ago

Hello David,

I’m speechless!

What an absolute pleasure to hear from you, very honoured to actually have one of the original Decca Battersea design engineers take the time to comment on this website. As you can see this CTV25 although requiring a little more work, still gives excellent service 50 years later. A true testament to the quality of the circuit and chassis you designed.

You might also be interested to see that I have the later version of the Battersea chassis in a very rare Decca CTV22C. That one as I’m sure you know uses a solid state tripler, you can see it if you click here It needs a fair bit of work as its been got at, however its certainly on the list to tackle and should make a lovely example of a rare 22″ dual standard.

Once again thank you for taking the time to say hi.

David
David
Guest
Reply to 
4 years ago

It was my pleasure Chris. I was interested in the bit on vectorscopes. I made one in the early days. Very easy as it’s only an NTSC decoder with the U & V outputs going to the X and Y amplifier inputs on your scope. If you want a test circle for line up you can just inject an unlocked amplitude of 4.43618 Mhz.
Have sent you an email.
Best wishes

Peter Dolman
Peter Dolman
Guest
Reply to  David Leiper
9 months ago

I’d really like the opportunity to speak to David, I worked as a development engineer at Decca Oldbury Grange Laboratory in the late 70’s. Previous to joining Decca I’d worked in Television servicing and the finest set I saw was the Decca 60 which we sold a few of. When I began working at Decca I was surprised no one in the Lab could tell me much about it! Over the years I came to realise that once the Battersea Lab had been at the heart of Decca design and wondered (still do) how the Bradford team, led by Alan Bamford, came to become central to Decca design. I began to see the Decca 60 as a metaphor for the calibre of te Battersea Lab. I’d really like to understand more about this, and even if Mr Leiper prefers not to comment I would like to wish him and any others from Decca Battersea the very best – and thank you!

Scott
Scott
Guest
4 years ago

Would love to speak to David, if he’s still lurking.

I believe my grandfather worked at the battersea factory and I remember him having loads of tv’s and parts at home and in the garage. My mother remembers going to visit him at the factory when she was young. I wonder if you knew him and could tell me anything about his role there?

Raymond Hedger was his name, regards Scott

Kinsley Birch
Kinsley Birch
Guest
2 years ago

Hi my name is Kinsley is there any workers of decca tv that worked at strawberry lane at 1976 still around you can contact me at my gmail below.
kinbirch@gmail.com

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