CTV [Sticky] 1974 HMV 2726 Coloumaster; Thorn 4000

Congrats! I really hope you don't live to regret it!

Boy that does bring back some memories! Back in '74 - 75 I worked for a company that did warranty service on new CTVs. More than half my time was spent fixing (and modifying) new 4KAs, AWA's version of the 4000.

The back on yours is the same as our 4KA! Even down to the plastic screw clips. Only differences I can see are the power supply board and the cover over the HV.

Bummer about the missing vertical module. As I recall there wasn't much to it in terms of components, maybe I could make you a functional equivalent if all else fails.

If my experience is anything to go by, that TV, even once it is running, will keep you busy fixing it for as long as you care to keep on doing it. Keeping those things running for more than a month or so kept us busy, back in the day. It's one of the reasons why there's none of them still around. Despite a good number being produced, they found their way to landfill earlier than most TVs.

I've heard the thick film components were the achilleas heel of the 4000 series.

Some other colour sets of the same era seemed to unreliable, the French made EMO sets were troublesome & hard to source, & at least one workshop ended up with a pile of them with the same faults.  Eventually the management decided to scrap them all as their were too troublesome & the Colour Boom was probably easing by that point.

Just by way of an update to this thread and keep it in sync with my other 4K thread. The missing board problem for this HMV is sort of resolved, by purchasing the 3C03. Both sets bought from the same source, it is believed the HMV deflection board was used to keep the 3C03 in service. It shall be returned to the HMV, which still leaves me with the difficulty of needing another deflection board for the 3C03, as ideally I would like both to work.

Wow, you've actually managed to get one of these sets at last. Very similar to the only 4000 set I ever handled, controls-wise, but the one I handled was probably a 22" model, and on a stand, rather than a console. I think it had seven slide pots - I recall this as I had to reset them once after they received the attention of a toddler. It did develop a bizarre fault that made programme 3 difficult to engage, but fortunately it was tuned to the same channel on 6 at the time. It was a MultiBroadcast rental set.

Not a set I have any great interest in, other than the nostalgia, but a worthy set for any Thorn colour fan. My Thorn interests are mainly in TX9, 10 and 90 sets, but also the 2000 due to it being so innovative for its time.

Posted by: @emleymoor

Wow, you've actually managed to get one of these sets at last

Indeed, and not one but two, the other being a 3C03.

Posted by: @emleymoor

Very similar to the only 4000 set I ever handled, controls-wise, but the one I handled was probably a 22" model, and on a stand, rather than a console

That'll be the 3C05, Jim (jcdaze) has one, see here.

Posted by: @emleymoor

It did develop a bizarre fault that made programme 3 difficult to engage

A known fault, with the touch change control set I read about in PT, apparently brought on by the overuse of household polish shorting the contacts. A good clean often restored function.

Posted by: @emleymoor

My Thorn interests are mainly in TX9, 10 and 90 sets,

In that case, you'll be interested in my other two recent acquisitions.

37063

6038M

@crustytv The 3C03 looks an interesting set, shape-wise. I can imagine what our cats would have made of it.

The set I handled had a somewhat more odd fault with programme 3, I seem to remember... it was producing the "untuned" effect when selected - though it seemed you could get it to work if you made it the last of a long sequence of quick selections. It does indeed look similar to a 3C05 and I may have been wrong about the 7 slide pots - though if I was right, the third along was bass!

Nice stereo TXs you've got there.

Testing the 4K CRTs today. The HMV A67 150X was, and excuse the pun, a picture of good health. Phew what a relief!

@crustytv That’s a big relief that the crt is good as I bet it would be like trying to find hens teeth to locate another A67-150X let’s hope the 20” one is as good 👍

chris 

Posted by: @the_teleman

let’s hope the 20” one is as good 👍

It is now, see here.

Think the HMV might date to 9th September 1975. There is a date stamp on the inside, also Vic Hallam. After a bit of research it would appear this would be the cabinetmaker, they did all sorts of word working, for all manner of things. Vic Hallam were based in Langley Mill, Nottingham, and I got this TV from Nottingham, coincidence. As an aside, some photos at the foot of this post.

Also wanted to investigate why the wires to VT308 on the line board, were disconnected. This is the EHT regulator transistor. Tested it, and it appears to be OK, so the mystery as to why it is disconnected, remains for now.

A look under the hood at the top of the tower

Vic Hallam Ltd - Langley Mill, Nottingham

I like them Vic hallam pictures with the Thames Trader lorry. The tripler looks like a Remo replacement as the origainal ones were all Mullard black ones I think. The Remo tripler is thicker than the Mullard one and therefore reduced the spacing beetween it and the focus unit. I think the mod to restore the gap and increase airflow was to add a couple of washers between the focus unit and the chassis.

Posted by: @jcdaze

I think the mod to restore the gap and increase airflow was to add a couple of washers between the focus unit and the chassis.

Wonderful Jim, it's tips like that from you old Thorn boys, that makes all the difference to those of us finding these sets for the very first time. 👍 

Hi Chris, I’m guessing you have already spotted, but there appears to be some bits missing in the top corner of your line board, in picture 3, no idea what though.

Regards,

Lloyd

Hi Lloyd, yes it's TF303, I've been trying to fathom what components are in it and its function. I can see TF303 on the cct, however, unlike the vertical deflection TF's which are detailed, there does not appear to be anything in the service manual for TF303.

Looking at the cct TF303 would appear to consist of 3 transistors, 3 diodes, 2 zeners and 12 resistors. It looks like TF303 drives VT308 to obtain automatic width stabilisation, with varying EHT. This will be related to why the wires are off the EHT regulator transistor VT308. I suspect a width fault, the last person tested VT308 found it to be OK and then traced the fault to TF303, and never replaced it. Maybe why the set was then laid up.

Oh how I wish you could just order up some thick films. Jim, don't suppose you have a spare TF303?

Posted by: @jcdaze

I think the mod to restore the gap and increase airflow was to add a couple of washers between the focus unit and the chassis.

I removed the focus and the singular washers were there, Jim. The gap between the tripler and focus is only about 1mm. I'll add another couple to increase the gap further.

Added enough to provide 5mm clearance.

You've got good eyes Lloyd! Pages 7 and 8 of the circuit description book, that I uploaded, has a bit more details about TF303. The good news is that the 3 spare boards that I've got do have the thick films in place. The only problem is that I don't have much luck sending things. I think a homing pigeon is probably the way to go.

Need to use UPS Jim, I'm happy to pay whatever they charge. RM are not fit for purpose and have not been for quite some time. If they've lost the vertical deflection cradle, coil and plug and it's not looking good for a next day delivery taking over 3-days. I may just have to not give my posty his tin of Quality Street this year in protest.

@crustytv Those pictures of Hallam's remind me of a joinery company that was in Yaxley (the one near Peterborough) for many a year - Bee-Rite Boxes. You used to see stuff like that going on in there: the offcuts, splinters and broken bits were often cut up and if you brought a sack, you could have a sackful for a quid as firewood/kindling. I can remember my great-aunt, my mother and myself going up there and filling my Datsun Sunny estate up with sackfuls for my great-aunt - she only had a coal fire, none of this central heating nonsense.

As discovered above, not only was the vertical deflection board missing from the HMV, It was also missing TF303 on the Line board.

Thanks, to the wonderful kindness from Jim @jcdaze, I not only have a replacement TF303 but a complete line timebase/switched PSU. This is so what I desperately need for the two 4K projects, spares, so I'm over the moon.

Thanks Jim, you're a star and a credit to the community at VRAT.