A Developing Shrubbery.

[ucl82]

I would like to credit whoever I got the wax on screwhead tip from but I can't remember now! Fantastic if the screw isn't magnetic and is awkward to access! I never throw out old components (being part of history and all that) so keep them in a large bag under my bench. When I need some more wax into the bag I go!

[AlanBeckett]

For many a long year I've favoured Vaseline, particularly for big nuts which you need to 'glue' into a socket to get it started. On the other hand people see a big jar of Vaseline in the garage .......
Alan

[Joe]

I could have swore I'd already said this but I must have forgotten to press 'Post' or something.

I've just been getting 'round the case with Ajax and it's come up very well. I'm hoping that bleach will reduce the appearance of the worst cracks but agree that they are part of its character and won't both myself too much over them.

I'm looking forward to hearing about your DAC90, Rob, as I wouldn't mind getting one of those myself just to see the contrast.

- Joe

[Joe]

I've heard of people buying things off e-Bay in their sleep and I must have done it as I've just had a signal congratulating me on winning a UL41for £5.20 which I have no recollection of bidding on.

I haven't done anything on this set today as I've been doing some much neglected general tidying up.

- Joe

[tiv48]

£5.20 ? if that was new old stock that was a bargin
rob t

[Joe]

My first task on this today was fitting a proper mains lead. This was going well until the MW coil started to slip off the former. I managed to get it back and then gave it a coat of heavy shellac and have had no problems since.

   

After fitting the lead I made some LED dial lights up for it and have just been investigating the low HT.

I put my trusty continuity tester across the smoothing cap and didn't like the sound of it. I de-soldered it and tacked a new one in place and with that the HT was up to 190v, which is close enough for rock 'n' roll.

I connected the old one up via a 15W lamp and diode to see just what it was up to. It leaked about 7mA and the voltage across it never exceeded 280v. I left it for a bit to see if it would reform any better but after a while the leakage started to rise. It still felt cold but there's obviously something amiss with it. I also thought the it discharged rather quickly considering it was only connected to a DMM on volts.

   

Just for comparison I repeated this test with the new one. That leaked 0.5 mA and the voltage went up to 345v (it's rated at 450v) and took far longer to discharge.

Despite the reputation of Bush ones it looks like that's where the trouble lies. I suspect the other half of the can won't be any better but don't have a 16μF capacitor to play with. Luckily I'm not in a rush and there are other things I can be doing both on this set and others and will no doubt be ordering other bits pretty soon.

It wouldn't have been nearly as interesting or educative if it had worked first try. In fact I'm coming to the conclusion that this radio is fond of me and is making sure I spend so much on it that there's no point my thinking of selling it. This had initially crossed my mind as it's the repairing that I enjoy and it would have been a way of making a few bob to fund the next one. That said it's grown on me but the problem now is that I'm fancying a black one to complete the set!

- Joe

[tiv48]

ah a chance to try restuffing the can, to be fair they are over 50 years old, just luck i have not had a duff one
rob t

[Joe]

Re-stuffing those I think is fully justified as it's the best place to put the new ones.

I've just been doing the mains filter cap along with a bit of re-wiring.

   

It's currently playing 'The Safety Dance' by Men Without Hats. Is it trying to tell me something?

- Joe

[Joe]

I got a new 15μF capacitor from Farnell's this morning and have fitted that and the voltages are now spot on. I've only done it in a temporary way as it's as hot as a welder's clog up here and a dropper, valves and/or a soldering iron are not what's wanted.

I'm not going to restuff the can yet as at some stage I may make a reformer so it will be handy to experiment with.

Farnell's were the only place I could find who sell 15μF capacitors so, just for future reference, if I hadn't been able to get one would a 10μF or 22μF have been the best to use as 16μF is bang in the middle? I know the usual advise is "next one up" but that would make a total of 54μF and the UY51's limit is 50μF.

I also got a couple of 390pF ones, another value that was hard to find, so will try these as alternative tone correctors/IF bypass.

I'll probably make a repro dial too as the old one is so filthy that even LEDs can barely pierce the murk. That will have to wait until my printer can be trusted with expensive water-slide stuff though.

Cheers
- Joe

[OldTickTock]

just for future reference, if I hadn't been able to get one would a 10μF or 22μF have been the best to use as 16μF is bang in the middle?
Cheers
- Joe

As a rule of thumb for these types of caps always the same or higher never lower.