HMV 2712 (Thorn 8000A chassis)

[Tazman1966]

I posted this up on Dave Newman's Facebook site but as many aren't on FB, I thought I'd post here too, if that's ok.

Finally, I got my hands on one of these. Don't laugh but I've always wanted one of these cheapo little 17" Thorn 8000's in a posh frock so here it is courtesy of Finn Tait up in Scotland. Me and Mrs S made a long weekend of it as the set was all the way up near Edinburgh! On our return, and with some time on my hands the following day, I couldn't resist getting it on the bench and giving it the once over.

First thing to note was one of the BF256 video output transistors was rattling around at the bottom of the cabinet, the legs having rusted off! In fact, there was a fair bit of rust on the signals panel but there didn't seem to be too much corrosion anywhere else. I slapped a new one in and checked for any short across the mains. All good. The smoothing electrolytics looked in good nick so with a little bit of bravado, I hit it with the full goodness of the mains. To my surprise, the set burst into life and very shortly, a raster full of snow appeared. With a signal applied and a bit of a tune around I got a snowy, smeary, cyan, rainbow striped test card F! A touch on the reference oscillator pot locked the chroma but it was yucky. As stated earlier, the panel was rusty and I knew I had a good working one so I transplanted it and now had a clean picture although still lacking any red. I checked the A1 voltages and all three were OK and roughly equal. What next?
Out came the CRT tester/rejuvenator and the news wasn't great. Blue very good, green good, red rubbish. With nothing to lose, I set the machine to work.

To my amazement, the red gun responded beautifully to rejuvenation and with a quick tickle on the A1 controls and the drives, the greyscale was great as was the chroma. I also changed R615, the 180k resistor in the beam limiter circuit as this always goes high and drags down the CRT grid bias which also makes it look like a low emission CRT. Sure enough, it was up at 250k and with a new replacement, the picture looked even punchier.

I next turned to the surprisingly already reasonable convergence. All was well other than the blue lateral adjustment. The magnet on the neck of the tube was not doing what it was supposed to be doing. I then realised that it had been put on the neck the wrong way round so I loosened the clamp, slid it off and put it on the right way. Now the blue verticals lined up correctly.
While I was admiring my work and appreciating my luck so far, there was some arcing down near the LOPT and disturbance on the screen. Just as I was about to hit the off switch, I noticed that the picture had shrunk all round and the brightness had increased. I just knew what it would be! The line output stage tuning capacitor across the line output transistor was bubbling away and too hot to touch! Yes, it was one of those green cylindrical ones on its way to open circuitness! Years ago, John Wakely gave me a bag of Thorn approved capacitor replacements for various critical parts of the circuitry in the 3000 and 8000 series sets. In amongst these was the approved (and not green!) replacement. In it went and the line output stage was tamed again.

I still have to attend to the degaussing which is inoperative - I had to use my external wand type degaussing tool to cure patchy purity.
There is a fair bit to do to the cabinet but so far, so good at this point.

I'm over the moon with it having hankered after this exact model for so long.
Sorry it's such a long essay but in my excitement, I got a bit carried away!

[Tazman1966]

Some more photos...

[greg_simons]

Excellent picture there, not a bad set the 8k, did loads, surprised all those blue tants in the decoder are still ok!.
Greg.

[Restoration73]

Amazing picture for the original crt. Using the manual and a Labgear colour pattern
generator I taught myself how the decoder worked many years ago.
The cheaper cabinet version was sold at Comet for £159 and sold well.
The Class A audio output with transformer was a novelty.

[Andrew2]

An excellent story, and lots of memories re-awakened! I must have serviced/repaired hundreds of these alongside 3000's, 3500's and of course the 8500. We were Thorn/BRC agents so we became very familiar with their sets. The only one of theirs that I didn't like was the 'budget special' 9800, which seemed to be made from leftovers and sweepings-up shovelled into a creaky plastic cabinet!

[slidertogrid]

A lovely set and a great write up Tas. I also worked on a lot of Thorn sets I have a 8500 Marconi that was bought by my parents new. Your HMV really is posh for an 8000 I wonder how much more it sold for above the Ferguson versions?
I saw a few HMV versions of the 3500 and maybe a couple of 8500s but I can't remember ever seeing an 8000 version.

Rich.

[Welsh Anorak]

That does look a bit strange with its wooden cabinet and rounded CRT - the 3500 and 1500s you usually saw wearing the HMV badge were much squarer. Glad it was worth the journey - didn't the A suffix signify a less rubbish tube?
Agreed the class A audio stage was unusual, though I think the Decca MS2000 just pipped them at the post.
Here's a little reading for you...sorry it's upside down!

[Heatercathodeshort]

Yes the reliable little 8000. I remember reading in the Ferguson Feedback that the service call rate for the 8000 was much less than the 3000/3500.
A customer buying say a Philips 17" TG100 in 1960 for around £75 just 11 years later could have purchased an 8000 colour receiver for £160. How technology raced ahead.
Customers were very happy with them. The half wave EHT tray was a rare failure. Nice one Tas! John.

[slidertogrid]

Interesting to compare those prices in 'Today's Money'. £75 in 1960 equates to £1213. Today. £160 in 1971 equates to £1633 today. Given that you were probably going to get about 8/10 years useful life with a few repairs along the way it's no wonder people rented!

[Hybrid tellies]

A good and worthwhile project Tas. These small screen 8000’s did give a good account of themselves and gave a much better picture and were more reliable than their larger screened, 8500, 8800, cousins.

[its ur aerial]

I think I only ever saw one HMV version of the 19" 8000, they must have been pretty rare.
I liked all the 8000 and 8500`s, overall a reliable set that had very few obscure faults.
TTR, even rented a huge 26 inch version with doors and speakers at the bottom, I think the model number was a 8769.
These were only rented by people who lived on the top floor, in blocks of flats with no Lift !
As Andrew2, stated better than the 9800 that was all the old bits with a diode split LOPT.
Ken G6HZG.

[Tazman1966]

Hello folks!

Sorry about the delay in replying but thanks for all the comments. Beware the blue tants that Greg mentioned reminded me of the article from the legendary Les Lawry-Johns relating the tale of the later 9000 that had a decoder fault caused by one of the blue tantalum caps. Incidentally, the 8004, the final 17" incarnation of the chassis used the same decoder as the 9000 with all the mods and improvements. I have one - a Ferguson 3727.

That Comet price sounds a bargain although I didn't like the styling of the bog standard Ferguson 3712 cabinet.

Never had my hands on a 9800 Andrew. I did have a very nice looking 22" HMV 8800 with this style of wooden cabinet. Varicap tuner and slider controls though and (gasp!) raster correction!

I would imagine that the HMV version was a tad more expensive Rich in its real wood cabinet. No Fablon covered chipboard here!

The A suffix was to do with the PSU and the CRT was no different unfortunately, Glyn. Thanks for the scan, by the way. Thorn were certainly blowing their own trumpets in it

Yes John, absolutely spot on with your comment about the natural successor to a 17" mono set. Incidentally, I have a new old stock RS replacement for the EHT rectifier should I ever need it.

The small screen sets quite often seem to give a nicer picture as you say Simon although I used to have a 19" Alba badged 8500 and that was lovely. Should've kept it really but space dictated its new ownership.

That 26" monster sounds a bit of a brute Ken. It's hard to imagine this chassis driving a 26" tube. What was the performance like?

There is an update to my story coming up soon...

[Tazman1966]

I had another free day not long after the original one so I thought I'd plough on with the remaining faults on this lovely HMV 2712.
Firstly, I had to attend to the Thorn mechanical tuner disease. The plastic grommets had all but disintegrated causing buttons sticking, springs getting tangled up etc. I used the Mike Bennett method of repair using cup washers which works perfectly.
Next, I attended to the non working degaussing circuit. This was an easy fix. A dry joint like a volcano on the posistor.
Next was the cabinet which was a bit on the rough side which is to be expected after spending years and years in a barn on a farm! A thorough clean up followed by sanding down several times with rub downs with white spirit. I cheated a bit with a few of the "dings" and used a touch up pen. For the finish, several applications of Lord Sheraton's beeswax followed by a thorough buffing. It gave a result that isn't showroom new but very nice indeed and got the seal of approval from Mrs S and it's made the grade as the week's dining room telly.

[Tazman1966]

Some more photos...

[Welsh Anorak]

Looking really good Tas! As usual, you've got the convergence spot on. You'd have been in great demand if you were around in the Seventies!
Much nicer cabinet than the American looking Ferguson 17" - much more traditional, and no plastic in sight.
I'd keep clear of the 9800 - it never gave good pictures and was a sort of 'what can we do with these odd bits before we have a 22" TX available?' - bit like Philips and the G9.

[its ur aerial]

Originally Posted by Tazman1966

Hello folks!


That 26" monster sounds a bit of a brute Ken. It's hard to imagine this chassis driving a 26" tube. What was the performance like?

There is an update to my story coming up soon...

All the ones I came across the picture quality was poor! In fairness I don't think the original CRT`s were very good quality.
But they were a reliable set, the only fault peculiar to them was the bridge rectifier in the remote rx power supply used to go O/C.
Ken G6HZG.

[Tazman1966]

Thanks for the info about the "big" 8800 Ken, and thanks for the praise about my convergence efforts, Glyn. I hope it doesn't make me a "one trick pony" though!

There is a post script to this however. After a couple of days service on the sideboard, Mrs S remarked that the picture was starting to look kind of greenish. I hadn't been watching it as I had been on lates at work finishing at stupid o'clock in the morning! She'd only been using it for a hour or so whilst preparing her dinner etc so it wasn't getting a beating.

In the morning I ran the set up and sure enough, the picture was a rather nasty shade of cyan with pretty weak reds. I was pretty sure that the Mazda tube that had bopped so nicely wasn't playing fair. I grabbed the tester from the workshop and connected it up to the ailing CRT and indeed the red reading had slipped back. Not as bad as it was originally but still in the poor section. I resisted the temptation to give it another bop but decided that it wasn't good enough for general use

It was shamefacedly humped back to the workshop for future attention and its place taken by another set from the Thorn stable, my Ultra 6703 (3000 chassis).

A few days later, I decided to sacrifice my Ferguson 3727 (8004 chassis) and grab the tube out of that to stick into the HMV. It's quite a straightforward job a tube change in these as once you remove the plugs from the timebase board and the earth lead from the CRT base panel, you can swing the chassis to the side and out of the way.

The old tube went into the Fergie as I just couldn't leave it in pieces and the nice one went into the HMV. I just took a couple of pics of the two sets running side by side. The HMV is lovely again but the poor Ferguson is looking decidedly sick! The photographs make it look better than it is unfortunately.

Needless to say, I'm now on the lookout for a good A44 271X