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Old 27th Sep 2021, 2:02 pm   #1
stevehertz
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Default Ekco AD75 questions

Regarding the circular Ekco AD75, I have the following queries.

The plastic dial on mine is only mildy warped and I'd like to flatten it somehow. I'm thinking about sticking it to a stiffer piece of some kind of material? Has anyone done this? What to stick it to and what glue? I'm thinking that warped dial is going to do its best to pull away from anything it's stuck to!

Mine is in pretty good shape so apart from the warp I intend to very carefully clean it with just water on a cotton bud, I'd hate to rub off the lettering. Been there, done that..

There is no clear plastic cover over the dial. Having researched previous AD75 threads there's seems to be no consensus to this. Some say they never had one, and others 'swear' they have seen them. Does anyone know for a fact?! I do find it a bit strange that prying fingers would have access to the dial pointer, be they little ones or big ones..
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Old 27th Sep 2021, 2:16 pm   #2
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Default Re: Ekco AD75 questions

Interestingly, my AD75 also has no clear plastic cover over the dial, which I did find odd when I purchased the set a couple of years ago. I wonder if anyone out there knows for sure whether one would have originally been fitted?

The dial on mine is slightly warped, however, I decided to leave it as is, as I didn't wish to risk damaging it further! In the end, I settled for a light clean with a cotton bud, dipped in water.


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Old 27th Sep 2021, 2:50 pm   #3
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Default Re: Ekco AD75 questions

No cover on mine either, also doesn't look like there would be any way to attach one, which also supports the theory that there never was one. The pointer is also insulated from the chassis by a Paxolin mount, accessed through removal of the tuning knob, quite often it's found broken, because someone forgot to remove the screws securing the pointer before removing the chassis!

If the pointer doesn't foul the dial then I'd suggest leaving it alone, there are ways of flattening these dials, normally involving heating it before placing it between 2 flat objects with a weight on it, I've tried it once and the dial also shrinks a little, which isn't a good thing! You could try gluing a bit of aluminium to the back of it, but you would have to be totally sure that the glue you used wouldn't react with the dial material and cause it to discolour, shrink, or crack, as well as finding a glue that actually sticks to it!

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Old 27th Sep 2021, 3:09 pm   #4
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Default Re: Ekco AD75 questions

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Originally Posted by Lloyd 1985 View Post
No cover on mine either, also doesn't look like there would be any way to attach one, which also supports the theory that there never was one. The pointer is also insulated from the chassis by a Paxolin mount, accessed through removal of the tuning knob, quite often it's found broken, because someone forgot to remove the screws securing the pointer before removing the chassis!

If the pointer doesn't foul the dial then I'd suggest leaving it alone, there are ways of flattening these dials, normally involving heating it before placing it between 2 flat objects with a weight on it, I've tried it once and the dial also shrinks a little, which isn't a good thing! You could try gluing a bit of aluminium to the back of it, but you would have to be totally sure that the glue you used wouldn't react with the dial material and cause it to discolour, shrink, or crack, as well as finding a glue that actually sticks to it!

Regards,
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Thanks Lloyd. Regarding sticking the dial to something, well yes those are my thoughts too, that's why I'm asking; has anyone done it successfully? Alternatively, is there a source of repro dials or artwork for the same?
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Old 27th Sep 2021, 3:16 pm   #5
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Default Re: Ekco AD75 questions

I repaired 2 of these in the last year and neither had a cover.
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Old 27th Sep 2021, 3:33 pm   #6
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Default Re: Ekco AD75 questions

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I repaired 2 of these in the last year and neither had a cover.
Thanks Hamish. I think 'no cover' is the way that most people are thinking, but as I say, I have seen reference in past AD75 threads where some are saying that they have seen ones with covers. Maybe people have made covers for them?
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Old 28th Sep 2021, 3:53 pm   #7
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Default Re: Ekco AD75 questions

The AD75 and AD36 had similar tuning dials They never fitted a glass front to the scale. So you could actually touch the pointer and tuning scale from the front.

My AD36 had a badly rippled scale, but I was able to flatten it by removing it from from the set and placing it in a bowl of moderately hot water, which softened it. I then put it in between newspaper sheets with a moderate weight on top. I then allowed it to cool, and then I found it was perfectly flat.
The AD36 dial is made of a celluloid type material with with letters and numbers firmly bonded on the celluloid. If the AD75 set has the same, you might be able to flatten the dial in the same way I did on my set.
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Old 28th Sep 2021, 4:19 pm   #8
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Default Re: Ekco AD75 questions

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Originally Posted by mister valve View Post
The AD75 and AD36 had similar tuning dials They never fitted a glass front to the scale. So you could actually touch the pointer and tuning scale from the front.

My AD36 had a badly rippled scale, but I was able to flatten it by removing it from from the set and placing it in a bowl of moderately hot water, which softened it. I then put it in between newspaper sheets with a moderate weight on top. I then allowed it to cool, and then I found it was perfectly flat.
The AD36 dial is made of a celluloid type material with with letters and numbers firmly bonded on the celluloid. If the AD75 set has the same, you might be able to flatten the dial in the same way I did on my set.
Ah, good information, thanks. I'm just a little worried that immersion in moderately hot water may melt/lift some of the colour from the dial markings? Presumably it didn't happen in your case.
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Old 28th Sep 2021, 4:49 pm   #9
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Default Re: Ekco AD75 questions

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Originally Posted by stevehertz View Post
Quote:
Originally Posted by mister valve View Post
The AD75 and AD36 had similar tuning dials They never fitted a glass front to the scale. So you could actually touch the pointer and tuning scale from the front.

My AD36 had a badly rippled scale, but I was able to flatten it by removing it from from the set and placing it in a bowl of moderately hot water, which softened it. I then put it in between newspaper sheets with a moderate weight on top. I then allowed it to cool, and then I found it was perfectly flat.
The AD36 dial is made of a celluloid type material with with letters and numbers firmly bonded on the celluloid. If the AD75 set has the same, you might be able to flatten the dial in the same way I did on my set.
Ah, good information, thanks. I'm just a little worried that immersion in moderately hot water may melt/lift some of the colour from the dial markings? Presumably it didn't happen in your case.
No I didn't lose any dial markings on my dial, but looking at the picture of your dial, it looks to be lighter than the dial on mine, so it is possible that it may be of a different material to mine. It might be possible to warm it very slightly & gently with a hair dryer but that could be a bit 'iffy'.
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Old 10th Nov 2021, 7:53 pm   #10
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Default Re: Ekco AD75 questions

Update. I've now taken this set apart. It was working very well, but there were a few niggles including a scratchy volume pot, dodgy on/off switch and so on.

As a matter of course I cleaned the dusty area around the top caps of the HF valves and applied contact cleaner to all valve bases and pins. I cleaned the wave change switch and drilled small holes in the volume pot and combined on/off switch and applied cleaner. I then applied small pieces of gorilla tape over the small holes.

Regarding the dial scale, nothing appeared to clean the grubbiness including soapy water and IPA. I didn't try anything stronger as I didn't want to risk removing any lettering. Now, as others have found, the dial scale has warped. This is due it shrinking, exacerbated by its lower edge being held at a constant distance by the two mounting bolts. Hence the distortion. I've put the scale in warm water, gradually increasing the temperature to 'hot' to make it pliable. I've then clamped it between two pieces of flat wood. So I'll leave it a day or two to see if it has had any effect. I'll then elongate the two mounting holes to facilitate re-mounting.

The performance of the set is surprisingly good though for what it is.
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Old 11th Nov 2021, 11:54 am   #11
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Default Re: Ekco AD75 questions

Well, I haven't left the dial scale clamped for two days, more like 12 hours. But anyway it's much better and would be ok, but I'm going to repeat the hot water and clamping process again to see if I can get it a bit flatter. Pity I hadn't taken any 'before' photos, but anyway the 'after' ones are here.
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Old 11th Nov 2021, 11:03 pm   #12
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Default Re: Ekco AD75 questions

It's getting there !

As I mentioned in an earlier post, I never had any problem with losing any of the lettering on my 'AD36' radio dial when I softened it using hot water. But as it is a slightly different colour material on your set compared to mine, I couldn't be certain of the lettering adhesion. The last thing you want is all the letters/numbers to come off.
They seem to bond quite well to the acetate ? or is it cellulose ? material even if it does shrink with age. I had to elongate the mounting holes on mine because of the shrinkage.
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Old 12th Nov 2021, 10:03 am   #13
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Default Re: Ekco AD75 questions

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It's getting there !

As I mentioned in an earlier post, I never had any problem with losing any of the lettering on my 'AD36' radio dial when I softened it using hot water. But as it is a slightly different colour material on your set compared to mine, I couldn't be certain of the lettering adhesion. The last thing you want is all the letters/numbers to come off.
They seem to bond quite well to the acetate ? or is it cellulose ? material even if it does shrink with age. I had to elongate the mounting holes on mine because of the shrinkage.
Yes the lettering seems very resilient to hot water and even cleaning attempts. In terms of the latter I've tried various cleaning substances on a cotton bud but the grubby marks just refuse to budge, they seem infused into the plastic. But I'm not going try anything more aggressive, a dirty dial with intact lettering is better than one with sections of lettering rubbed off! Later today I'll release the clamps again and see if there's any improvement and report back.

Meanwhile I'm using the time (not that I have lots of that to spare!) to clean around upper chassis parts with a cotton bud. The case was already quite clean but I've toothbrushed in the corners and the grainy surfaces using foam cleanser. This has resulted in traces of a brown residue being removed, probably brown boot polish. Having worked on lots of bakelite sets I personally am not a fan of using boot polish if the surface is properly cleaned and gleaming.
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Old 12th Nov 2021, 1:01 pm   #14
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Default Re: Ekco AD75 questions

Given the age of these dials, they're most likely celluloid, (or a similar nitrocellulose product). It's an unstable material and deteriorates with age due to chemical changes which can cause it to shrink and distort. Applying even gentle heat can be a gamble. See 'deterioration' here:

https://en.wikipedia.org/wiki/Celluloid

Dials are such a prominent feature of any radio, (perhaps less so with smaller dials such as the AD75 or AD36 as compared to the A22), and there comes a point at which - depending on whether we see deterioration as 'patina' which enhances, or detracts from the overall appearance of a radio - that a replica dial needs to be considered, especially if a good scan of the artwork is available.

I don't think the AD75 dial is backlit (albeit I believe the AD36 is), so the plastic sheet doesn't need to be translucent. - maybe just a 1.5mm thick sheet of white acetate, Perspex etc. If a decal was printed on white decal paper the colour of the material wouldn't matter, but if clear decal paper was used, a close match to the original Celluloid would be needed.

There are lots of suppliers of acetate sheet in a wide range of colours, thicknesses and sizes.

I don't know where the attached AD75 dial scan came from, but it might be of help to someone.

Good luck in your efforts.
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Old 12th Nov 2021, 1:19 pm   #15
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Default Re: Ekco AD75 questions

Thanks David, great info as ever from yourself.

Now, I've just released the dial scale from between the two compression blocks and it has flattened out even more - see photos. In fact it is now quite good enough to refit. But I'll give it another treatment to hopefully make it even flatter.

So my dilemma now is, do I use the original, quite flat but grubby one, or get a new one made?
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Old 12th Nov 2021, 1:45 pm   #16
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Default Re: Ekco AD75 questions

Just a crazy thought, have you tried Brasso on the dirt? It would take quite a while with little bits of it between the print, but it might shift it! It’ll probably polish off the print so best to keep it off it as best you can. Keeping the original is always better than a replacement, unless the original is so bad as to be unusable.

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Old 12th Nov 2021, 1:54 pm   #17
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Default Re: Ekco AD75 questions

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Just a crazy thought, have you tried Brasso on the dirt? It would take quite a while with little bits of it between the print, but it might shift it! It’ll probably polish off the print so best to keep it off it as best you can. Keeping the original is always better than a replacement, unless the original is so bad as to be unusable.

Regards
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I'll give it a go Lloyd, but it could well end up patchy as I won't be able to work right up the lettering if you see what I mean. I'll have a go. But for now, another night being squashed.
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Old 12th Nov 2021, 2:43 pm   #18
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Default Re: Ekco AD75 questions

I'd leave it. It's aged 'gracefully' and doesn't detract in any way imo. It's not damaged and the lettering is intact. Normal age related deterioration of celluloid as David pointed out

In fact a replica dial may detract from the value of the set more than leaving the original in situ.

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Old 12th Nov 2021, 2:58 pm   #19
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I'd leave it. It's aged 'gracefully' and doesn't detract in any way imo. It's not damaged and the lettering is intact. Normal age related deterioration of celluloid as David pointed out

In fact a replica dial may detract from the value of the set more than leaving the original in situ.
I'm tending to agree and I'll make a final decision when the last flattening session is done and it's refitted. It being flat will make loads of difference to the overall appearance.

Here's the clamping arrangement for those interested. Note, that top piece of wood is perfectly smooth on the underside.
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Old 15th Nov 2021, 8:22 pm   #20
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Default Re: Ekco AD75 questions

I've now water heated and clamped the dial scale for four sessions now, and it's quite flat, certainly flat enough to use. I tried Lloyd's suggestion of using Brasso to clean it, and lo and behold, it worked! I used a cotton bud and worked very slowly and methodically, trying not to press too hard over lettering. The result is hardly any damage to the lettering but a much cleaner dial. I had to elongate the scale's mounting holes outwards and downwards to accommodate the position of the 6BA mounting bolts. I'll post photos of the set with the revived scale fitted in due course.
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