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Old 16th Nov 2022, 10:43 am   #1
nigelr2000
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Location: North Walsham, Norfolk, UK.
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Default Bush DAC90 Rebuild

I have just done a re-build on a DAC90 and fitted Ed Dinning's brilliant autotransformer mod.
Once completed I tried it out and it worked well but was heterodyning really badly especially on Long wave.

A quick search here bought up this thread https://vintage-radio.net/forum/showthread.php?t=59495

This was the same trouble with mine, metallizing not connected so I dug out some conductive paint I bought several years ago thinking it would be useful
well now it has been, I put a blob on the rear side of the valve after a quick scrape to show the conductive surface and buried a thin wire in it clamped in place by a couple of turns of stiff wire and a small square of insulation tape to hold it down till the paint went off. I then ran the wire round the front of the valve and soldered it onto the earth pin and removed the stiff wires.

The result is that it works perfectly now and is stable. The mod is hardly noticeable unlike wrapping in foil.

A few pics of the unit and the transformer mod. The live is not shrink wrapped yet as I am awaiting the fuse holder to turn up. I can then box it up and send it back to the customer.

Another success and it now runs pretty cool as a bonus.
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Old 16th Nov 2022, 1:17 pm   #2
60 oldjohn
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Default Re: Bush DAC90 Rebuild

Quote:
Originally Posted by nigelr2000 View Post
I have just done a re-build on a DAC90 and fitted Ed Dinning's brilliant autotransformer mod.


Another success and it now runs pretty cool as a bonus.
I have done the mod on my DAC90, In effect turning it into the AC90 the circuit is at the bottom of the DAC90 manufactures sheet.

John.
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Old 23rd Dec 2022, 4:11 pm   #3
telstar
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Default Re: Bush DAC90 Rebuild

I have yet to do the modification on my Bush DAC90 radio. Where can I obtain a fuse and holder from for the work, please?
Mike
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Old 23rd Dec 2022, 4:16 pm   #4
telstar
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Default Re: Bush DAC90 Rebuild

Quote:
Originally Posted by nigelr2000 View Post
I have just done a re-build on a DAC90 and fitted Ed Dinning's brilliant autotransformer mod.
Once completed I tried it out and it worked well but was heterodyning really badly especially on Long wave.

A quick search here bought up this thread https://vintage-radio.net/forum/showthread.php?t=59495

This was the same trouble with mine, metallizing not connected so I dug out some conductive paint I bought several years ago thinking it would be useful
well now it has been, I put a blob on the rear side of the valve after a quick scrape to show the conductive surface and buried a thin wire in it clamped in place by a couple of turns of stiff wire and a small square of insulation tape to hold it down till the paint went off. I then ran the wire round the front of the valve and soldered it onto the earth pin and removed the stiff wires.

The result is that it works perfectly now and is stable. The mod is hardly noticeable unlike wrapping in foil.

A few pics of the unit and the transformer mod. The live is not shrink wrapped yet as I am awaiting the fuse holder to turn up. I can then box it up and send it back to the customer.

Another success and it now runs pretty cool as a bonus.
Hi. I have found some conductive paint that I bought from Halfords for rear window heating repairs. Hope that this will be suitable for my EF39 valve screening.
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