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Old 25th Sep 2018, 1:33 pm   #1
coopzone
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Default DAC90 replacement waxies

Just started on a DAC90, usual issues;

All the rubber wires hard and cracked.
Someone had replaced the reservoir cap - badly. So needed a new one.
bulb blown
All caps replaced, see below.
dropper resistor caused damage to the rear and paxolin - all rewired.
Mains switch open-circuit - good cleaning sorted that.
V2 EF39 had broken screen wire - ended up covering with tinfoil and re-wired

Then came the slightly more anoying;

Speaker vibrating and I could not just it - tried for hours. In the end replaced it with my only spare!
Had to replace the rubber supports on the tuning cap - it's tricky.

WAXIES
Anyway I figured after all that I would have a go at replacing the wax caps with something that was a little more sympathetic than the bright yellow poly ones I have.

I started with 400v poly caps soldering new wires at 90 degrees to the body - converting them to radials.

Then I added two ends to then, consisting of rolled up foam packing, stained at one end (dark brown liquid shoe polish) and then pushed over the new wires.

Printed some reproduction art work based on T C C wax originals. wrapped the new assemble in the printed wrapper. Glue in place.

And finally "dip" in hot wax, allow to dry clean up with hot soldering iron.

And fit! (I must be mad, I did 11 in total!)

See photos


Derek
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Old 25th Sep 2018, 2:06 pm   #2
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Default Re: DAC90 replacement waxies

Wasn't the "vibrating Speaker" just the spider come away on the back?
I've successfully fixed two of these with superglue, it's nice still having the original speakers.
BTW great job on those caps.
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Old 25th Sep 2018, 6:19 pm   #3
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Default Re: DAC90 replacement waxies

Yes about ten minutes after the first post - I remembered about checking the back of the cone. And yes it's come away so my next job is refitting the original speaker !

Thanks for the advice.

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Old 25th Sep 2018, 8:15 pm   #4
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Default Re: DAC90 replacement waxies

You seem to have converted them from radials to axials. A bit confusing along with the reference to bright yellow (axial?) ones as well.

Nice looking results!
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Old 25th Sep 2018, 8:22 pm   #5
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Default Re: DAC90 replacement waxies

Excellent job.
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Old 25th Sep 2018, 8:35 pm   #6
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Default Re: DAC90 replacement waxies

Remember to put a clear note somewhere inside the radio to indicate what you've done!

Some time back I reworked a radio, instinctively ripping out the waxies and a couple of paper-cased cathode-decoupling electrolytics because they were bound to be bad.

Nice shiny new yellow 400V-working MKTs and Rubycon electrolytics went in.

Only later did I discover that the summarily-junked capacitors had been restuffed by a previous owner.

[I was happy to leave it with the MKTs and Rubycons on show: at least that gives a positive indication of the rework!]
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Old 29th Sep 2018, 1:04 am   #7
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Default Re: DAC90 replacement waxies

Quote:
Originally Posted by coopzone View Post
WAXIES
Anyway I figured after all that I would have a go at replacing the wax caps with something that was a little more sympathetic than the bright yellow poly ones I have.

I started with 400v poly caps soldering new wires at 90 degrees to the body - converting them to radials.

Then I added two ends to then, consisting of rolled up foam packing, stained at one end (dark brown liquid shoe polish) and then pushed over the new wires.

Printed some reproduction art work based on T C C wax originals. wrapped the new assemble in the printed wrapper. Glue in place.

And finally "dip" in hot wax, allow to dry clean up with hot soldering iron.
Thats exactly how i do them,in my Philips projection tv there were about 25 of them,took me a while.
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Old 29th Sep 2018, 12:50 pm   #8
David G4EBT
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Default Re: DAC90 replacement waxies

Back in 2009, Colin ('Retired'), who is no longer into radio restoration but remains a member of this forum, set up a 'mini production line' and made quite a lot of reproduction 'waxy' capacitors. The technique he used can be seen at this (closed) thread and might be of interest. As will be seen, they looked very authentic:

https://www.vintage-radio.net/forum/...ad.php?t=46963
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Old 29th Sep 2018, 1:01 pm   #9
Ian - G4JQT
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Default Re: DAC90 replacement waxies

A pity we can't do this with resistors...
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Old 29th Sep 2018, 1:14 pm   #10
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Default Re: DAC90 replacement waxies

Each to their own, and on that note so long as it's well engineered and to spec, underchassis originality holds no real interest for me. There was a time when I would restuff electrolytics that were mounted above chassis, and I do recognise the amazing work that restorers do in achieving chassis originality.
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Old 29th Sep 2018, 2:27 pm   #11
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Default Re: DAC90 replacement waxies

Some might argue that paradoxically, re-stuffing capacitors is actually taking authenticity away because during a radio's life, at some point it may break down and if it did, the service engineer would use whatever replacement component was to hand. I guess that the older, rarer and more valuable a set is, the more that conservation and preservation. rather than repair or restoration, comes into play.

Not something I feel strongly about - my priorities have always been safety, functionality, and originality in that order, but I certainly wouldn't dictate to others how they should go about repairing or restoring their own equipment.
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Old 29th Sep 2018, 4:29 pm   #12
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Default Re: DAC90 replacement waxies

I think it depends on the set, to an extent. There are some "showcase" sets for which it is well worth creating original-looking capacitors (2 watt metal film resistors already look sufficiently period), but there are many other "workaday" sets for which a repair using more modern parts than were available when it was built would be entirely authentic.

Even into the late 1970s / early 1980s, there were plenty of older people still listening to MW and LW on 1950s and 1960s-era valve sets; they would have been maintained by the last of the repair shops, who would not have thought twice about fitting a modern polyfilm capacitor in place of a waxed paper original.

I'm sure there must even be cases where someone has acquired a pre-war set that had a component replaced in the 1950s, and ended up replicating a 1950s era part to match the original repair as an integral part of the set's history.
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Old 29th Sep 2018, 4:35 pm   #13
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Default Re: DAC90 replacement waxies

I wear my 'service engineer's hat' when repairing old/vintage radios -i.e., I do as Julie & David suggest, replace faulty capacitors with the nearest available modern equivalent. Unlike the OP, I have no objection to using the axial yellow poly. types - in fact they are what I usually use. However, as ahas already been said 'each to their own choice' as long as safety and reliability are kept in mind.
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Old 29th Sep 2018, 6:16 pm   #14
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Default Re: DAC90 replacement waxies

Quote:
Originally Posted by Ian - G4JQT View Post
A pity we can't do this with resistors...
I tried - (large 560k with lots of volts across it) but was not happy with result so left the old one in situ with a parallel resistor chain hidden in some heatshrink.
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Old 30th Sep 2018, 3:11 pm   #15
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Default Re: DAC90 replacement waxies

Quote:
Originally Posted by stevehertz View Post
Each to their own, and on that note so long as it's well engineered and to spec, underchassis originality holds no real interest for me. There was a time when I would restuff electrolytics that were mounted above chassis, and I do recognise the amazing work that restorers do in achieving chassis originality.
I admire the effort put into 'invisible' sympathetic restorations too, I take middle ground. I like my radios to look as they were originally laid out with their backs off but under the chassis I see no point in going into all that trouble.
But as said "Each to their own."
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