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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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6th Feb 2020, 11:55 am | #1 |
Hexode
Join Date: Sep 2019
Location: Crystal Palace, Bromley, London, UK.
Posts: 417
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Cleaning aquadag coating on Bush TV22 tube
Hi
I would like to have your advice on cleaning the aquadag coating on my Bush TV22 tube (MW-12-16). The bottom of the tube is spotless, but the top is invariably dirty and dusty. From a small test, I noticed that solvents such as meths or isopropyl alcohol appear to dissolve the coating, so this looks like a clear no no. What are your suggestions? Dry brushing alone, for instance? Or is there something else that can safely be used? Thanks! Helder |
6th Feb 2020, 2:38 pm | #2 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
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Re: Cleaning aquadag coating on Bush TV22 tube
Just dust it off. Any attempt to clean it will result in it disintegrating completely. Keep it DRY! It is after all a dirty gray looking material even when new.
'DAG' may be available in small quantities from it's makers. Google ELECTRODAG for some useful information. John. |
6th Feb 2020, 2:57 pm | #3 |
Hexode
Join Date: Sep 2019
Location: Crystal Palace, Bromley, London, UK.
Posts: 417
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Re: Cleaning aquadag coating on Bush TV22 tube
Thanks John!
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10th Feb 2020, 2:47 pm | #4 | |
Hexode
Join Date: Sep 2019
Location: Crystal Palace, Bromley, London, UK.
Posts: 417
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Re: Cleaning aquadag coating on Bush TV22 tube
Quote:
https://www.ebay.co.uk/itm/AQUADAG-C...H/261808496366 |
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10th Feb 2020, 5:32 pm | #5 |
Dekatron
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 3,612
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Re: Cleaning aquadag coating on Bush TV22 tube
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10th Feb 2020, 6:17 pm | #6 | |
Hexode
Join Date: Sep 2019
Location: Crystal Palace, Bromley, London, UK.
Posts: 417
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Re: Cleaning aquadag coating on Bush TV22 tube
Quote:
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11th Feb 2020, 11:27 am | #7 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
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Re: Cleaning aquadag coating on Bush TV22 tube
It may not stick to glass. RS RF shielding is brilliant but it just falls off glass when dry. Maybe a primer coat will help but I'm wondering if it might have an odd effect due to the paint forming a second capacitor.
Why worry about a couple of small holes? They will have absolutely no effect on the performance. If it works, leave it alone. John. |
11th Feb 2020, 4:00 pm | #8 | |
Hexode
Join Date: Sep 2019
Location: Crystal Palace, Bromley, London, UK.
Posts: 417
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Re: Cleaning aquadag coating on Bush TV22 tube
Quote:
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11th Feb 2020, 5:18 pm | #9 |
Heptode
Join Date: Jun 2006
Location: Eindhoven, Netherlands.
Posts: 642
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Re: Cleaning aquadag coating on Bush TV22 tube
Helder,
There will be no corona effects, because the aquadag layer does not carry high voltage. I fully agree with John: a few holes in the layer or small parts of the conductive layer surface missing will not make a difference. Basically it is just the EHT smoothing capacitor (capacitor between graphite layer on the inside of the CRT and ditto on the outside). Just make sure that the layer makes good contact with ground potential (chassis). Not all CRTs have the outer conductive layer, and thus require a separate smoothing capacitor (suitable for the EHT voltage). The Ekco TMB272 is an example. Graphit 33 will adhere to the glass and works excellently. Most DAGs are waterborne products, and do adhere to the glass, but are not really "glued". It is just colloidal graphite in water. Jac |
11th Feb 2020, 8:32 pm | #10 | |
Hexode
Join Date: Sep 2019
Location: Crystal Palace, Bromley, London, UK.
Posts: 417
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Re: Cleaning aquadag coating on Bush TV22 tube
Quote:
Thanks for your detailed reply! I understand that the only way for the top "plate" of the smoothing capacitor to be at a high potential is in case of a bad connection to the "ground" (chassis), which is of course a bad thing to have regardless of any holes. I will check this on my set (already on my to-do list for the weekend). As for the holes, they are a bit unsightly, but that's all, as the resulting change in capacity is minimal (area of the holes / total area of the rest of the coating). Thanks for the tip on the Graphit 33 spray. Helder |
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