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-   -   Baird Garrick (https://www.vintage-radio.net/forum/showthread.php?t=145778)

peter_scott 21st Jun 2021 7:34 am

Re: Baird Garrick
 
A really neat job.

Peter :thumbsup:

Andy - G8MNM 21st Jun 2021 7:15 pm

Re: Baird Garrick
 
i have new CRM92 with mask. Amazing how it has survived. Andy

beery 23rd Jun 2021 12:40 am

Re: Baird Garrick
 
5 Attachment(s)
Hi all,
I have attached some pictures to show the changes made to the line timbase.

The first picture shows the modified circuit that the set had when I received it. Note that it has flyback EHT. The transformer was a bad match with too much output and severe distortion to the right hand side of the picture. An inductor had been placed in series with the line coils to reduce the width (relative to the EHT).

The second picture shows the corrected circuit as originally designed.

The third picture shows some of the detritus that was removed. At this point I had already replaced the 1K width control for one with the correct 2K resistance.

The fourth picture shows a 50uF capacitor of the correct type for the line scan coil coupling in this set. It has been re-stuffed.

The fifth picture shows a round cover that I made up to cover the rather unsightly hole (it was roughly cut) that was left after the extra line linearity control was removed.

Cheers
Andy

FERNSEH 23rd Jun 2021 9:19 am

Re: Baird Garrick
 
Hi Andy, regarding the second attachment, the line timebase certainly resembles the Baird T5 circuit. Component values are almost the same.
No sync injection winding on the Garrick transformer.

DFWB.

beery 2nd Jul 2021 1:38 am

Re: Baird Garrick
 
4 Attachment(s)
Hi all,
I thought I should post some pictures of the pictures as it were...

It was difficult for me to get the camera square with the screen, but I can tell you that the line linearity is pretty good, much better than it was with the transformer that was in the set when I obtained it.

The first photo shows the picture from the transformer that was in the set.

The second photo shows the picture from the line output transformer that I made up to replace the original one that the set was made with.

You may notice that the frame linearity is poor. I'm not sure why. There is no adjustment for frame linearity (the control that I thought was frame linearity is in fact frame shift). It might be because the scanning assembly is not square on the tube, but is leaning forward somewhat towards the top. It is not easy to adjust, but I will have a play with it at the weekend.

The pictures are contrast heavy. Remeber that in this set, both the cathode and the grid of the CRT have video drive applied to them in a kind of push-pull arrangement. So, lots of contrast, no problem with flyback lines, but when the contrast is reduced to what I would say is a normal level, the sync gets weak. I wonder if it is worth reducing the drive to the CRT grid, whilst keeping the cathode drive as is (which also feeds the sync separator)?

The other two photos show some people engaging in outdoor pursuits. Of course we know that they would be having much more fun indoors fixing old tellies, if only they had the chance to try it ;D

Cheers
Andy

peter_scott 2nd Jul 2021 9:01 am

Re: Baird Garrick
 
Looking at that net, that's totally unacceptable!

EMI say: "A slight amount of frame crushing at the lower end of the picture is standard."

Peter ;)

beery 1st Aug 2021 9:53 am

Re: Baird Garrick
 
5 Attachment(s)
Hi all,
Finally, the Baird Garrick is back together after 3 years!

There are still some niggling issues:-

1. The picture is rotated slightly clockwise. This is a real pain because unlike in other sets where the scan coils can easily be rotated, in this set it requires removal of the chassis to power it up on the bench. The scanning gantry is screwed to a semicircular slot accessible from the front of the chassis.

2. The CRT is not secured. I had hoped that when the chassis was pushed back into place that the rubber mask would butt up against the safety glass. In fact there is a 1/4" gap, which is probably due to the fact that these sets were made with either a Mullard CRT (as in my set) or a Mazda CRT. If you recall, the CRT was originally secured by sewing braided wire through the rubber mask and attaching it to the wooden CRT guide behind it. This was not a good idea as it caused the mask to distort. I had the idea of securing the CRT via the neck, TV24 style, but as the mask does not push up against the glass, this can hardly be considered safely secured. Also there is nothing to stop the mask sliding off the front of the CRT.
What I propose therefore is to make an aluminium securing band the clamp the mask to the rim of the CRT and then thread braided wire around the clamping band in to the wooden CRT guide in a similar way to the original arrangement. The neck clamp can then be dispensed with.

3. The control shafts for brightness and contrast are bent. The extension shafts are made from 1/4" welding rod, which are seized into the shaft couplers. I think penetrating oil and heat will be required to free them for straightening.

4. More width would be nice. There is sufficient width to fill the mask using the Hedhog test card, but the output from my PC is slightly underscanned. It is a minor issue, but another 50 turns on the secondary of the LOPT would solve it.

Other than that the set is OK and since putting it back together I have enjoyed watching Casablanca on it.

The first photo shows the front view of the completed set.

The second photo shows test card C, slightly rotated and a shadow on the right hand side, this was because the CRT had slid forward slightly.

The third photo shows a man getting a headache from the wonky picture.

By the fourth photo he had decided to fly off to find a better TV set. Can you guess what serial these shots are from?

The fifth photo shows how the Hedhog test card looks with the CRT relocated, which has removed the shadow, but reduced the width.

Nearly there...

Cheers
Andy

Panrock 1st Aug 2021 10:02 am

Re: Baird Garrick
 
An unique piece of history in action. Well done!

Steve

stevehertz 1st Aug 2021 10:17 am

Re: Baird Garrick
 
Lovely job, well done!

Panrock 1st Aug 2021 11:07 am

Re: Baird Garrick
 
How many of these are known to exist? I recall one in Michael Bennett-Levy's book... and that's all.

Steve

peter_scott 1st Aug 2021 12:43 pm

Re: Baird Garrick
 
Quote:

Originally Posted by stevehertz (Post 1394554)
Lovely job, well done!

+1

Peter :)

slidertogrid 1st Aug 2021 1:04 pm

Re: Baird Garrick
 
Fantastic job! I very rare set saved ! :clap:
Was the film the original version of the Rocketeer?
Rich

beery 1st Aug 2021 4:29 pm

Re: Baird Garrick
 
Many thanks for all your kind words Still a little way to go before I can sign it off. I at least need to secure the CRT more reliably.
Quote:

Originally Posted by Panrock (Post 1394583)
How many of these are known to exist? I recall one in Michael Bennett-Levy's book... and that's all.

Steve

Hi Steve,
During my research I located three other Garrick sets, like mine.
One has the same darker coloured cabinet as mine. That set is owned by a collector who has kept it in storage since it was purchased many years ago. It has a broken tuning scale.
The other two have the central section made out of a pale wood, possibly beech. One of them has matching ivory coloured knobs. I think that one is located in the museum of Scotland. I don't know where the other one is located.

Then there are the two Lyric sets, the same chassis but with a roller shutter over the CRT.
One of those, in Birds Eye maple is the one from Michael Bennett-Levy's books.
The other Lyric was formerly in the Thorn collection in Enfield. After Thorn closed, a private collector became the custodian of the collection. That set is in a light wood cabinet (pale oak?) and has been restored to working order. I was kindly given permission to take some measurements of the set to help with the restoration of my Garrick.

Also sharing the same chassis was the Adephi, but no one has seen one of these, I've not even seen a picture of one to know what they looked like.

Cheers
Andy


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