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Old 3rd Dec 2018, 6:48 pm   #1
Ian - G4JQT
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Default Ekco A22 transformer and chassis

I'm restoring an A22 and wondering what folks do to tidy up transformers.

I know it's in the chassis, no one will see it, it doesn't matter, but so many restorations look lovely and painstakingly completed, I'd like to know how the appearance of chokes, mains and output transformers is improved by members, without doing any long-term damage.

The last A22 I restored soon developed a short in the mains transformer and Mike Barker rewound it, so it wasn't a problem. Initial resistance checks on this one suggest it's OK, but that's what happened last time...

The A22 chassis is steel. Is there a preferred treatment? It's not badly rusted, but not great. I suspect it's plated so I'm reluctant to attack it with a wire brush!

Thanks.

Ian
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Old 4th Dec 2018, 6:15 am   #2
Argus25
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Default Re: Ekco A22 transformer and chassis

The treatment for the transformer is to place it in a bath of mineral turpentine for a week (or UK chemical equivalent) Once the pitch has dissolved (it looks like pitch remnants in the photo) you will be left with the rusty laminations. Clean as much rust off as possible, off all the visible lamination surfaces with 600 grade paper. Then, with a small brush, paint the laminations with organic rust converter (I use Fertan brand). This will also creep to some extent between the laminations. Once that has dried which turns the remaining rust a dark blue-black color, then dip the transformer 3 or 4 times in marine spar varnish (or transformer varnish). This gives a very good result and will make the transformer look nearly new.

As for the chassis, the only way to get that good in the long term would be to remove all the sockets & components (drill out the rivets on the sockets) and have it re-electroplated, passivated zinc works well and then coat that with clear automotive spray lacquer (except mask over the earth points with 1/4 " dia sticky dots/discs) to make sure it keeps its new finish as zinc is quite reactive and will turn grey after a while otherwise.

Or you could attempt to conceal the chassis rust. If you go down that route it pays to treat the rust spots with the organic rust converter first. Then a fine silver lacquer spray like Holts automotive touch up spray will look good. But in the end, the rust is more likely to return, which is why it is probably better to completely eliminate it. Painting over rust is at best a temporary cosmetic shortcut.
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Old 4th Dec 2018, 6:58 am   #3
Boater Sam
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Default Re: Ekco A22 transformer and chassis

I have found Vactan to be the best rust converter and primer for rusted steel. The coating is permanent and it does not need to be washed off.
If dipping transformers in varnish, warm them first to about 80 degrees, as they cool the varnish is drawn into the insulation and stops any lamination hum as well as improving the damp resistance and insulation. I use polyurethane varnish, it does what it says on the tin.
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Old 4th Dec 2018, 8:13 am   #4
Argus25
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Default Re: Ekco A22 transformer and chassis

I have attached some images of previously rusted pitch coated transformers (from my 904) which were improved with the above methods. I have posted these before on another thread.
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Old 4th Dec 2018, 10:05 am   #5
Ian - G4JQT
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Default Re: Ekco A22 transformer and chassis

Excellent. Thank you very much.

@Argus: How did you get the lamination covers looking so good? Was that just careful rubbing with 600 grade? Is there any damage likely if the organic rust converter gets into the windings when painting the laminations? Is it also used on the lamination covers?

Regarding the chassis, yes, I'll be taking everything right off. So looks like a re-plating is likely, although I realise there's always the possibility of over-restoring parts that will never be seen!

This may well turn out to be my most ambitious/compete restoration to date. It's a black and chrome A22...
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Old 4th Dec 2018, 10:54 am   #6
Argus25
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Default Re: Ekco A22 transformer and chassis

By lamination covers, the transformer and choke brackets ?

If so these were fine glass bead blasted to remove all rust and electroplated with a process called electro-less nickel, which does not use electric fields. So it plates into holes and into corners. However I do not think this process is readily available in the UK, so I would suggest standard Zinc plating.

Unfortunately the people who believe you will drop dead after going near a blob of mercury or a Lead head nail have seen fit to ban Cadmium plating, which is superior to zinc.
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Old 4th Dec 2018, 11:00 am   #7
Ian - G4JQT
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Default Re: Ekco A22 transformer and chassis

Quote:
Originally Posted by Argus25 View Post
By lamination covers, the transformer and choke brackets ?
Yes. Thanks. It would be quite a job to remove them. I'll need a Plan B...
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