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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 1st Jan 2020, 2:09 pm   #1
Niechcial,Steve
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Default Gerry Wells 625 Telly

Gerry Wells made and sold a small production run of these in the early 70s using surplus IF strips and LOPTS. Does anyone recognise the attached photo of the IF strip? It is a dual standard one with the system switch under the chassis. I think that is a sound output trans top left.

I have charge of the Dulwich Museum's example of this set to repair for display. I doubt a circuit diagram exists. I think Gerry would have made it up as he went along! There are lots of Rs in parallel and Cs in parallel in the construction. No doubt 'fine tuning' to optimise performance. Does anyone else have one of these sets?

I'll do some more pics as I go along. The beast currently works with a good tube and cracking sensitivity but with a strange line sync fault.
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Old 1st Jan 2020, 2:12 pm   #2
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Default Re: Gerry Wells 625 Telly

Possibly just out of spec resistor or caps around the Sync separator,or the cap feeding the Video o/put stage.
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Old 1st Jan 2020, 2:18 pm   #3
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Default Re: Gerry Wells 625 Telly

The I.F. panel looks Bush to me, TV125, etc.
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Old 1st Jan 2020, 2:22 pm   #4
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Default Re: Gerry Wells 625 Telly

I’d say the hand wired IF chassis is the type fitted in early Sobell 405-625 convertible sets.
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Old 1st Jan 2020, 2:52 pm   #5
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Default Re: Gerry Wells 625 Telly

It's the IF unit used in the conversion kits for the GEC BT448 and Sobell ST282.
You could buy them from Manor Supplies.

DFWB.
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Old 1st Jan 2020, 2:55 pm   #6
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Default Re: Gerry Wells 625 Telly

Quote:
Originally Posted by dazzlevision View Post
I’d say the hand wired IF chassis is the type fitted in early Sobell 405-625 convertible sets.
The one in the photo is the Sobell/McMichael version, as it has an EF80 sync separator, which the GEC version did not.
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Old 2nd Jan 2020, 12:59 pm   #7
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Default Re: Gerry Wells 625 Telly

Thanks guys. I'll keep posting on how it goes. I'll start with some mass re-capping then scope the sync output if no improvement.
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Old 2nd Jan 2020, 1:36 pm   #8
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Default Re: Gerry Wells 625 Telly

I remember reading about Gerry making his own TV sets in his book 'Obsession'.
Could you post some pictures of the set, external and internal? I would be very interested in seeing the chassis and what the set looked like.
Are there any records as to how many were made and around what date?
Good luck with the restoration!
Rich.
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Old 2nd Jan 2020, 2:11 pm   #9
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Default Re: Gerry Wells 625 Telly

I was way out of whack there (as usual).

I too would be very interested to see a few pics of the set, best of luck getting it sorted.
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Old 2nd Jan 2020, 2:35 pm   #10
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Default Re: Gerry Wells 625 Telly

Quote:
Originally Posted by linescan87 View Post
I was way out of whack there (as usual).
It could have been worse Joe. You might have suggested it belonged to a TV22.

Gerry's TV sets were well constructed but I think the problems he encountered were simply the units he utilized from various manufacturers, obtained from Manor Supplies, simply did not 'marry up' very well. Gerry was the first to admit this. The chassis were quality, sprayed blue and well laid out. John.
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Old 2nd Jan 2020, 2:44 pm   #11
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Default Re: Gerry Wells 625 Telly

Very interesting John. Did he make these to sell commercially or were they made to order for friends, family, etc.?

Any idea of how many he made?
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Old 2nd Jan 2020, 3:32 pm   #12
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Default Re: Gerry Wells 625 Telly

The production run was small. It was more a case of 'can you make one of those for me?'
The problem was that Manor Supplies ran out of a particular make of IF unit and Gerry had to use alternative units with all the problems that involved.
A great deal of work went into the production. Gerry made the cabinets and the chassis from scratch. It was not a money making exercise!
Gerry always had a hankering for manufacture and I think it was more of an exercise to see if he could actually do it and he did, John.
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Old 2nd Jan 2020, 4:40 pm   #13
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Default Re: Gerry Wells 625 Telly

How's about a photo of a set?
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Old 2nd Jan 2020, 5:53 pm   #14
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Default Re: Gerry Wells 625 Telly

Pictures of the Sobell conversion unit Gerry used in the set. When supplies ran out I'd imagine he would have used the Ferguson 625 conversion IF amplifier unit that was to be fitted in Phase 2 700 series and 800 series convertible models.

DFWB.
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Old 2nd Jan 2020, 6:20 pm   #15
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Default Re: Gerry Wells 625 Telly

Quote:
Originally Posted by FERNSEH View Post
Pictures of the Sobell conversion unit Gerry used in the set. When supplies ran out I'd imagine he would have used the Ferguson 625 conversion IF amplifier unit that was to be fitted in Phase 2 700 series and 800 series convertible models.

DFWB.
The unit pictured has no sync separator valve, so only suitable for GEC branded convertible sets. The unit in the Gerry Wells set photo has a sync sep stage, so suitable for Sobell and McMichael sets. Presumably, Gerry’s design utilised this.
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Old 2nd Jan 2020, 7:29 pm   #16
Niechcial,Steve
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Default Re: Gerry Wells 625 Telly

I have not been able to find out how many of these Gerry made. This one has no label on it other than one on the back which says '86'. I suppose this could mean 86th in the production run, but it is hard to believe he would have built that many. Judging from when those Manor Supplies bits would have been around and when three channels became available, we are probably talking construction around 1968/9? It is built as John describes on a swing out metal chassis with very good access for service. When I get it up on the bench I will post some photos.
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Old 2nd Jan 2020, 9:14 pm   #17
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Default Re: Gerry Wells 625 Telly

Any photos of sets?
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Old 3rd Jan 2020, 1:56 am   #18
FERNSEH
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Default Re: Gerry Wells 625 Telly

Looking at the circuit diagrams of the Sobell and GEC convertible and dual standard sets in the Radio and Television servicing books we find out that in the Sobell ST196 and the GEC BT448 series the sync separator valve is present on the timebase board. The GEC BT455 is similar to the Sobell ST196.
So the conversion unit in my possession was made for those models.

In Sobell ST282 series the sync separator is on the IF unit. It's an EF80 and designated as V6
It's most likely Gerry would bought either version of the GEC-Sobell conversion unit from Manor Supplies.

In McMichael models MT762 and MT763 the sync separator V6 is on the IF unit.

DFWB.

Last edited by FERNSEH; 3rd Jan 2020 at 2:09 am.
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Old 4th Jan 2020, 4:42 pm   #19
dazzlevision
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Default Re: Gerry Wells 625 Telly

Quote:
Originally Posted by FERNSEH View Post
Looking at the circuit diagrams of the Sobell and GEC convertible and dual standard sets in the Radio and Television servicing books we find out that in the Sobell ST196 and the GEC BT448 series the sync separator valve is present on the timebase board. The GEC BT455 is similar to the Sobell ST196. So the conversion unit in my possession was made for those models.

In Sobell ST282 series the sync separator is on the IF unit. It's an EF80 and designated as V6
It's most likely Gerry would bought either version of the GEC-Sobell conversion unit from Manor Supplies.

In McMichael models MT762 and MT763 the sync separator V6 is on the IF unit.

DFWB.
Looking at the manufacturer's service manual, for the Sobell ST196 and GEC BT455, although they are convertible to 405-625 operation, they only have a 405-625 switched line timebase. As dispatched from the factory, they only have a 405 IF unit. The (dual standard (DS) versions of these models would have a 405-625 IF unit and (possibly) a UHF tuner (DS-T)).
However, this chassis is later than the Sobell ST195/GEC BT448/McMichael MT762 series one, which used a hand wired 405-625 IF chassis. The IF unit used in the Sobell ST196 and GEC BT455 (be it 405 only or 405/625) is a PCB.
So, the hand wired dual standard IF unit employed in Gerry Well’s set cannot be used in this chassis.
This later chassis closely resembles the subsequent chassis, used in GEC 2000 and Sobell 1000 series models, which has one large and one small PCB mounted on a metal frame at the bottom of the chassis, with a small line scan PCB mounted underneath the LOPT "cage".

I attach a scan (from the service manual) of the model/chassis feature list for the first GEC/Sobell "common" chassis range of sets (the Sobell ST195/GEC BT448/McMichael MT762 series). The same manual shows that all Sobell and McMichael models use an ECC82 line oscillator, situated on the timebase PCB, which either has, or can be fitted with, a flywheel sync sub board. The sync separator is always on the IF unit, which is either a PCB on 405 only models, or a hand wired chassis unit on dual standard ones.
The GEC models BT448, BT449, BT450 and BT451 use an EF80/6F23 line blocking oscillator on the timebase PCB, which has no provision for adding flywheel sync, and the EF80/6F23 sync separator is also on the timebase PCB. So, there is no need for a sync separator stage on either the 405 only IF PCB or the 405/625 hand wired IF unit.

This leaves the GEC model BT452 which, unlike all the other GEC models has a (triode section) PCL84 sync separator valve on the 405 IF PCB, or an EF80 sync separator on the 405/625 hand wired chassis IF unit. Perhaps this was because the sets/chassis were made in a Sobell factory, rather than in the GEC Coventry one. The attached photo is of the GEC BT452 chassis (with a 405 only IF PCB fitted).

Another interesting point is that on the GEC branded sets (except model BT452) made in Coventry, the PCBs used were only single-sided, presumably because they couldn’t make the classic double sided Sobell ones there (or not enough could be shipped from the Sobell factory to meet the additional demand that came with the merger).
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Old 4th Jan 2020, 10:25 pm   #20
FERNSEH
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Default Re: Gerry Wells 625 Telly

"The GEC BT455 is similar to the Sobell ST196.
So the conversion unit in my possession was made for those models."

I certainly got that wrong.
That's right I should have remembered that the ST196 was a completely new design which employed the new PL500 line output valve. The design of that set morphed into the much better 1000 series models of 1964.
One thing is sure the construction quality of Gerry's 625 set was of a high standard, he was brilliant at metal working. Got some examples of his work here in the shop.

DFWB.

Last edited by FERNSEH; 4th Jan 2020 at 10:30 pm.
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