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Old 7th Sep 2018, 8:39 am   #41
red16v
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Default Re: Baird Garrick

Enjoying your updates, well done so far.
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Old 9th Sep 2018, 12:24 am   #42
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Default Re: Baird Garrick

Hi all,
Thanks again for people's encouraging comments.

I've attached the diagram for the vision TRF section. Do have a look, it is very unusual. If I had not drawn it out then I would have put the detector valve in the wrong socket for sure.
I've never seen push-pull video drive before. However I assume that vision output 1 is for the CRT (as it has a peaking coil) and vision output 2 is for the sync separator. I've not traced out the CRT connections, so I can't say for sure.

Cold checks have revealed that R8 has increased in value by 10 times and is looking decidedly brown. R14 is also high an a little bit discoloured.
The really odd fault is that VR1 is open circuit at both end connections, in that there is no reading between them and no reading between either terminal and the wiper irrespective of the wiper position; that's a new one on me.

I'm not sure how much more work I will do on it for the time being as I am gearing up for a trip to Malaysia in a couple of weeks, so I really do need to take time out to pack...

Cheers
Andy
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Last edited by beery; 9th Sep 2018 at 12:29 am. Reason: Grammar
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Old 9th Sep 2018, 9:54 am   #43
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Default Re: Baird Garrick

Very neatly drawn circuit diagram of the vision RF stages andy , must have tock you a while to do that.
I`m enjoying reading about your progress with this set .

Robin
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Old 9th Sep 2018, 11:29 pm   #44
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Default Re: Baird Garrick

Nice to see your updates on this restoration - hope you get it fully working in the end!
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Old 16th Sep 2018, 8:11 pm   #45
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Hi All,
I'm sure this really is my last update before Malaysia.

Quote:
Originally Posted by line sync View Post
Very neatly drawn circuit diagram of the vision RF stages andy , must have tock you a while to do that.
Robin
Thanks Robin.
Drawing circuits is part of my day job, though there are no valves used at work! When I started drawing out the sound circuit I started off using rectangular resistor symbols which looked out of place, so I changed them for the zig-zag style symbol. I also made a mistake in the vision circuit in that the sensitivity control should actually be labled contrast.

Anyway. I unsoldered the contrast control (VR1) and found a dry joint at one end, so now I had end to end continuity, but nothing on the wiper. I took the control apart by squeezing its metal body slightly with pipe grips so that the metal end cover came off. I did bend the wipers in the process, so I couldn't say what was causing the problem. After bending the wipers to shape and greasing the wirewound track it seemed to work ok.

I replaced R14 (10K) with a vintage type. R8 (5K1) I had to replace with a vintage 4K7 type. Interestingly if I heated up R8 very hot with a soldering iron it would read ok until it cooled and flicked back to around 50K, very odd.

I fitted EF91 pentodes and an EB91. I connected the vision reciever to the HT of the radio and connected the heaters to the DC bench supply set to 6.3V. I hooked up the scope to vision output 1 and fed in test card C from the Aurora and hey presto it worked

So the photos show the contrast control, R8 before and after replacement, the RF unit connected to the radio chassis and the output on the scope.

Cheers
Andy
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Old 16th Sep 2018, 11:12 pm   #46
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Default Re: Baird Garrick

Hi Andy,
everything is looking good. Your set is going to be the best of the surviving Baird "Theatreland" sets.
I notice that there is two vision demodulators feeding separate video amplifiers. I presume the amplifier with the anode peaking coil supplies positive going video the CRT modulator grid and the other negative going video to the sync separator.

DFWB.

Last edited by FERNSEH; 16th Sep 2018 at 11:18 pm.
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Old 24th Oct 2018, 8:05 am   #47
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Hi all,
Whilst the rest of my family stay on a few more weeks in Malaysia, I am back home and so have the house to myself to do some of the bigger jobs.

The first photo shows the neck box being constructed for the back panel. The box is 7" x 7" x 3 1/2" which is ridiculous really.

The second photo shows the neck box being clamped to the back. After this the back was flipped over and the pilot holes were drilled through for the neck box mounting screws.

The third photo shows the start of painting the back. Towards the top of the photo you can just see the painted neck box. The main back panel has just had the inside of all the holes painted at this time.

The fourth photo shows the vision chassis as it was when I obtained it.

The fifth photo shows how shiny the chassis is after cleaning. The vision receiver has been removed from the left hand side, and on the right hand side the rogue line output transformer and a choke have been removed to facilitate the chassis cleaning.

Cheers
Andy
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Old 31st Oct 2018, 3:12 pm   #48
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Hi all,
An update on the Baird.

The back cover is now finished, it just needs some replica labels to be made for it.

I've replaced the CRT socket with a Duodecal type to fit the new tube and replaced the rubber wiring on the socket. I've kept the rather messy look of the wiring.

I've also replaced the rubber wires running from the PSU plug to the timebase chassis.

I've has a quick go at cleaning up the cabinet and have put the radio chassis inside.

The last photo shows the view looking down through the CRT protection glass to the glowing valves of the radio chassis.

I've started to draw up the timebase chassis, but I'm now taking a little break from the Baird whilst I go back to the HMV 905 for a bit.

Cheers
Andy
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Old 9th Dec 2018, 9:54 pm   #49
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Hi all,
just a very quick update on the Baird.
Progress seems slow at the moment as I am also working on the HMV 905.

Another transformer clamp and the focus coil have been cleaned up and painted. No photos of these yet.

The PSU chassis now has an EHT transformer thanks to Mike Barker. This is from and HMV 1805. It fits the mounting holes, but is a bit taller than the original transformer, so I will have to re-make the bracket for the EHT rectifier to be a little taller.

I'm also making up a tube clamp. This is based on the early type of TV22 (non-ion trap CRT) of which I have included a photo. It is made of 1mm thick brass.

That's all for now.

Cheers
Andy
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Old 9th Dec 2018, 11:39 pm   #50
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Keep up the good work andy.

Robin
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Old 10th Dec 2018, 1:55 am   #51
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Default Re: Baird Garrick

The HMV 1805 EHT transformer will provide 6 to 6.5KV which is possibly higher than that was delivered by the original Baird transformer.
The 0.1microfarad EHT smoothing capacitors in the HMV 1805/6 are rated at 7KV.

DFWB.
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Old 14th Dec 2018, 3:55 am   #52
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Quote:
Originally Posted by beery View Post
Hi all,
The PSU chassis now has an EHT transformer thanks to Mike Barker. This is from and HMV 1805. It fits the mounting holes, but is a bit taller than the original transformer, so I will have to re-make the bracket for the EHT rectifier to be a little taller.
Just out of curiosity, did you supply the HMV 1805 transformer to Mike to be rewound? Or did Mike supply the EHT transformer? (i.e. you didn't have one?)

Edit: in hindsight that sounded a bit impolite. What I meant to say is does Mike also supply transformers, rather than just rewind ones you send. My brother Draenog doesn't have an EHT transformer for his HMV 900 which makes the difference interesting.

Thanks Phillip

Last edited by Catkins; 14th Dec 2018 at 4:02 am. Reason: My original post may have come accross as a bit impolite
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Old 14th Dec 2018, 6:20 am   #53
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Quote:
Originally Posted by beery View Post
Hi all,

The really odd fault is that VR1 is open circuit at both end connections, in that there is no reading between them and no reading between either terminal and the wiper irrespective of the wiper position; that's a new one on me.
Andy
That's a new one on me too, in the same pot.

I experienced that in combination on two pots when I was restoring the HMV 904. On one the carbon track had visibly broken about 10% from one terminal hence no connection end to end. On the other one bad handling meant the wiper had broken from the shaft, which was rotating freely, and the wiper wasn't connecting to the carbon track.

To have both those faults in the same pot is probably fairly unique

Please say what you discover is the cause ... Bad connections on all connections would be the mundane answer

As far as what I did to fix things, I superglued the wiper back onto the shaft (the original mounting had been shattered), and used silver paint to reconnect the carbon track.
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Old 14th Dec 2018, 2:25 pm   #54
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Hi Phillip,
sadly I doubt that Mike has a supply of original EHT transformers.
He can certainly make one from scratch as he did for my HMV 905 from which it was missing entirely.
For the Garrick, what was needed was a potted transformer and it was fortunate that Mike happened to find one.
From what I can tell, the Garrick had a choice of the T5 EHT transformer or another type which might be made to the Bush T91 design (I can't verify the T91 theory). Either way, both choices were potted, though the T5 transformer is much smaller and possibly has lower EHT than the other option.

About the contrast pot. I was never very clear about what the trouble was, so I am prepared that it may become intermittent in future. The carbon and the wirewound pots seem to be based on american designs (reliance branded), indeed the pot that gave you trouble in your 904 would have been american I think.

Cheers
Andy
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Old 22nd Dec 2018, 9:55 pm   #55
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Hi All,
I've now made the CRT clamp that will enable the new tube to be held in place without a wrap around mask.

The first photo shows the dimensions (based on a TV22 CRT clamp).

The second photo shows a cardboard prototype.

The third photo shows a piece of 1mm thick brass cut to shape.

The fourth photo shows it folded into shape.

The last photo shows the clamp fitted in place on the old broken CRT (the focus coil is not fitted at present).

I need to find a brass (non-magnetic) screw and nut to finish it off.
That will be all for a while. First there is Christmas and then when we get back we have to deal with an unexpected house move.

Merry Christmas
Andy
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Last edited by beery; 22nd Dec 2018 at 9:57 pm. Reason: Fordot about brass screw
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Old 25th Dec 2018, 2:22 pm   #56
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Hi Andy,
another very nice metal fabrication job. Good idea to use a down to air CRM121 CRT for test purposes. I'm doing the same for my Decca 101 recreation project.

DFWB.
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Old 14th May 2019, 8:53 pm   #57
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Hi all,
well it has been a very long time since my last post.

Now settled down in our new home, so ready to tinker...

I obtained a 0.1uF 7KV Visconal which I chain drilled on the base to open it up.
I then emptied it out (with precautions) and re-stuffed it with a new 8KV capacitor obtained from China.
I filled the base of the Visconal can with cut up lengths of hot melt glue sticks and then stuck the base on with a glue gun. The gaps from the chain drilling were filled with more hot melt. To keep the base straight whilst cooling. I bolted it to an empty baked been tin which I had drilled a hole in.

I re-made the EHT valve's mounting bracket. This time I made it 1 1/4" taller to clear the large EHT transformer. I also fitted the correct type bulgin style valve socket this time.

I then temporarily wired up the heaters to the EHT rectifier, attached my meter with a X10 probe and powered it up...

Hey presto, 5.83KV! I must admit that I was myself whilst doing this test, bearing in mind that the whole bracket is at EHT potential and also there being no bleader chain (there never was!).

That's all for now.

Cheers
Andy
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Old 15th May 2019, 7:06 pm   #58
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Sterling work there Andy! Has anyone ever tackled another Garrick?


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Old 24th Jul 2019, 9:36 pm   #59
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Hi all,
finally back to mouse turd central.
After removing the scanning gantry (I'm not sure yoke is the right term for this design), I was able to clean behind it. This as the last part of the chassis that had to be cleaned and yes, turds galore, but hopefully that is the last of them.

Now I have started to put it back together. I still have to fit the lopty and then it is time to rebuild the caps in the timbases.

Oh yes, in answer to Panrock's question back in May...

I know of two surviving Lyrics, one of which has been restored to working order. These use the same chassis and I have been able to take electrical measurements from the restored set thanks to the kind owner.
I have not found any surviving Adelphi sets (same chassis again) or even a photo of one.
Including my set, I have found three Garricks. One (with a different coloured cabinet) is in a museum and the other is privately owned, but, in storage and unlikely to be restored anytime soon.
So as far a Garricks go, no, I don't know of any working examples...

Cheers
Andy
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Old 25th Jul 2019, 9:11 am   #60
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Great work Andy! Yes I know of another guy that has tackled with success, another Garrick.

Can you believe that EHT capacitor mounted at the back of the chassis...Yes it is correct even to the overhang. It's the first thing your cat would ponce on when you took the back off! Lethal, no wonder very few of these receivers survived. Regards, John.
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