1967 Decca CTV25 - Colour Dual Standard ( GranadaColour)

All very clean and tidy .

Cheers,Neil.

Hello Chris,
Pleased that it has arrived safely and is in first class order.
Regards,
Chris

Hi Chris,

Very nice indeed....err now what were you saying about getting it in the new year !
Bet your like a big kid in a sweet shop

Marc.

Wow! Very impressive. Looks to be in mint condition.
Cheers,
Brian

Aah lovely, Chris! My first colour set, bought ex-rental from a back-street dealer for £75 in 1971. I was less in love with it after the third EHT overwind replacement, and eventually left it to its fate when I moved out of my flat.

Regards,

Lucky you Chris, that is a superb example of a very rare beast! You must be feeling at least some of the thrill it's original owners felt when the Granada van drew up outside their house in 1967. I bet that had the neighbours' net curtains twitching! You should see if you can track down a Christmas '67 edition of Radio Times to see what BBC2 had to offer that year.

It's worth mentioning that whilst Christmas '67 and '68 had BBC2 in colour, with all three channels colour in time for the end of 1969, Christmas 1970 was a non-event for ITV colour viewers due to a technicians strike which saw many popular shows (On The Buses, Please Sir! Upstairs Downstairs etc) taped and shown in monochrome. More on that here including a list of affected series: http://en.wikipedia.org/wiki/Colour_Strike .

Does your set have the dreaded Philips-based 'Prestomatic' tuner that causes so much grief? The 25" crt looks quite small in the cabinet in the rear views, giving some idea of the scale of the thing.

Whatever it cost you, it was worth it. Hope it behaves!

Steve

Full of your favourite lockfit 3 legged fuses!
Does is it the shunt regulator setup or has it had a tripler fitted?
The one I had back in the mid 70's came with a duff tube (green gun kaput) and a S/C decoupling cap on the 'Green' PCL84 colour driver valve.
It was quite frightening removing the duff tube, just imagining the bang and glass shrapnel if the tube let go.

Andy

Does is it the shunt regulator setup or has it had a tripler fitted?
Andy

It has the original set up of Shunt regulator and a TV6.5 for the Focus ( 5kV) see here

I was also give a complete second LOPT which has had the over-wind removed and a tripler fitted. It was fitted to the set and ran on it, but when a new LOPT was sourced it was returned to original configuration. Should the worst ever happen and the over-wind goes on the new one, I can at least fall back and fit the tripler lopt.

Yes and the Bush CTV25, CTV167, Murphy CTV2510, CTV2511 used a DY87

Did some first generation UK colour sets use an EY51 to rectify the focus voltage?

Philips G6 did, though I do belive it was eventually replaced by EY57 in the later sets (very late).. I've never seen a G6 with anything other than EY51.

Marion

That's a very nice telly you have there, Chris... What a pity it's not a TARDIS.. I'd love to go back to those days.

I reckon there can't be many of these left now, and with its horizontal chassis, it looks rather more modern, and less intimidating, than many of its contemporaries.

Enjoy,

Marion

The set came with the complete Decca service manual. Its a fantastic fat manual packed with superb info. I was reading up on the precautions to take when working on the cage, basically they say don't. However if you have to you must put a lead glass over the valves.

Makes me think the polystyrene cups I saw David use on Lucy's set, about as useful as a chocolate teaspoon

I hope I never have to go in there, that chimney holds as much fear for me as mains derived does. I wonder if E-bay sell NBC Suits?

This will be me working on the set

Back in 1968 I remember an imaginative television rental shop displaying a Decca CTV25 with the back removed in their shop window, so passersby could marvel at the latest technology. I used to make a point of passing by this shop, on the way home from school, and being intrigued with the PD500 chimney and its X Ray warning.

Mike

... The EHT itself can bite and bite quite hard but it's not in the same lethal league as mains derived EHT. I'd rather have a shock from the EHT than from a high boost rail where lots of current is available ...

25kV @ 1mA (or more) from a colour TV?

You must be very thick skinned, Jeffrey, if you can survive that!

It is more to do with the frequency Terry, 15kHz EHT is not a dangerous as 50/100 Hz EHT, and it hurts less if that is any consolation

Ps. I did not think it was as high as 1mA on line output derived supplies , I thought it was more in the micro-Amp range, although will stand to be corrected., RE: mains derived EHT I was always under the impression was lethal.

Stabilised at 1mA.
I remember reading in Television magazine years ago a warning not to use the 25KV EHT to try and clear an inter electrode short in the tube.
The wording was along the lines that if the TV engineer tried it then his widow would be cashing in his life insurance policy.
25KV at 1mA = 25 watts.
I know it is the current that kills but 25KV at 1mA sounds pretty nasty to me.

Andy

It is more to do with the frequency Terry, 15kHz EHT is not a dangerous as 50/100 Hz EHT, and it hurts less if that is any consolation ...

Funny - all the colour tubes I've ever worked with used DC EHT supplies ...

by Spot-Wobble » Thu Dec 05, 2013 3:01 pm

Stabilised at 1mA.
I remember reading in Television magazine years ago a warning not to use the 25KV EHT to try and clear an inter electrode short in the tube.
The wording was along the lines that if the TV engineer tried it then his widow would be cashing in his life insurance policy.
25KV at 1mA = 25 watts.
I know it is the current that kills but 25KV at 1mA sounds pretty nasty to me.

Thanks for that,
I did not have much to do with very early CTVs, and knew they were more dangerous than later sets, just 1mA sounds a lot by later sets standards.

edit: just looked at a 1978 Thorn 9600 manual, EHT 26kV +/- 1kV at zero beam current, 1.5mA at maximum beam current , ouch!

If I get a chance I will have a look at some more modern sets specs if it is given at all.

Well I live and learn, to be fair I had no real reason to look at this before, as any fault finding in this area is derived at by measuring at a much more practical point in the circuit (across a resistor etc. at the bottom end of the overwind) and at a much lower level.

Ps. I have been bitten from the EHT a few times, and yes it still bloody hurts.

It is more to do with the frequency Terry, 15kHz EHT is not a dangerous as 50/100 Hz EHT, and it hurts less if that is any consolation ...

Funny - all the colour tubes I've ever worked with used DC EHT supplies ...

Well yes it is, but it is pulsed at line rate with a fairly short duty cycle (flyback), it is usually only smoothed by the aquadag at the crt itself, plus it is amazing how fast you move when it cracks across to you.

Mains derived is a different beast entirely.