AVO All Wave Oscillator restoration

[hilitevr]

I have two AVO all wave oscillators, both working perfectly but looking scruffy.

Both have chips out of the paint on top panel and would presumably need to be re-sprayed. what worries me is the lettering around the various control knobs which will require re-whiting.

How would I prevent the engraved lettering becoming filled with paint when re-spaying?.

Any ideas, tips or suggestions greatly appreciated

Thanks
Trevor

[Brian R Pateman]

Hi Trevor,

Take a look at this thread

https://www.vintage-radio.net/forum/...read.php?t=781

which might help.

Regards,

[hilitevr]

Thanks Brian

The suggested thread dosn't answer my question.

AVO mulimeters have a non metalic black top panel.

The All Wave Oscillator has a cast aluminium top panel which is painted black.

If this panel is re-sprayed the engravings which will eventually require re-filling with white paint/wax or whatever will be covered.

What I need advice on is how to prevent the engravings being filled with black paint when re-spraying.

Thanks
Trevor

[Leon Crampin]

I have an AWO but I'm not desparately fussed about its appearance. If you manage to restore the front panel I might change my mind and follow suit.

How about preparing the panel carefully for painting, degreasing thoroughly and then filling the engravings carefully with white wax. When you spray the panel, the paint won't stick to the wax - if you're lucky.

Leon.

[Mike Phelan]

Trevor
I think if you spray it with acrylic or cellulose, then fill the letters as per Brian's thread, the same method applies. The thickness of the engraved lettering should be deep enough not to affect filling it.
I have done this on a vintage car instrument panel, which was brass; painted it black with cellulose then used white oil paint, wiping it off when tacky and finally using T-Cut after a week. Perfect.

[Radio_Dave]

I stripped and re-sprayed my AWO with black enamel paint. The lettering was then painted in with a fine brush and water based white paint. The excess was wiped off with a damp cloth, pulled tightly over my finger

The lettering isn't as sharp as the Bakelite AVO's and it took several attempts and a lot of trial and error to get the white paint to stay in the recesses, but it was worth it in the end as it now looks great!

David

[Colin]

Pictures please Dave!

[Radio_Dave]

Originally Posted by Colin

Pictures please Dave!

Here's a before and after

David

[Leon Crampin]

Nice job David. My AWO is actually looks a lot better than yours did, so I may well leave it as it is. Is yours the mains or battery version? If it's a mains AWO, could you possibly measure the HT voltage?

During restoration of my mains AWO, as well as the usual capacitor replacements (not very many) I wired a 1N4007 diode in series with the selenium stick. This does not affect operation at all, but avoids damage (and a nasty smell) if the Se diode were to fail. It also protects it against the full applied transformer voltage when it is reverse biased.

These oscillators seem to work remarkably well for such a simple circuit using a couple of 6J5 triodes.

Leon.

[Radio_Dave]

Hi Leon,

You'll find the answer to your question and a lot of other useful info in this tread https://www.vintage-radio.net/forum/...&highlight=awo

Regards
David

[Leon Crampin]

Thanks for the link, David. The HT voltage on my AWO is roughly the same as the units measured and I also wondered about the "soft" regulation assisting with the output amplitude stability, which is largely why I left the Se stick in place. I'm not fond of the wholesale removal of important components in such well made old equipment.

It's good to see that somebody else also had the idea of putting a Si diode in series with it. Great minds....

Leon.

[Colin]

Thanks for posting the pictures Dave. Great job, the lettering looks first class and considering what you started with it's even more impressive. Very well done. I have two of these, both mains operated and they're in good nick compared to your starting point. They work very well too following the usual cap replacements etc, I may well add a 1N4007 as suggested though ... seems like a very sensible idea!

rgds
Colin

[David Simpson]

Hello Trevor & other AWO owners. Just received my Mains powered AWO in the post after purchase on the internet. Seems to be in excellent condition.Checked against scope & stable LW - SW Marine Rx - pretty good. If the serial no follows the AVO convention on dating, then mine was built in '47. Has been converted to a bnc lead o/p,& one of the dummy aerials is missing, but otherwise - in good nick for it's age.
Is one osc a "Hartley", and one a "Collpitts ? My memory is too dim to recollect the circuit configuration. Regards, David

[PL259RDB]

Originally Posted by hilitevr

Thanks Brian

The suggested thread dosn't answer my question.

AVO mulimeters have a non metalic black top panel.

The All Wave Oscillator has a cast aluminium top panel which is painted black.

If this panel is re-sprayed the engravings which will eventually require re-filling with white paint/wax or whatever will be covered.

What I need advice on is how to prevent the engravings being filled with black paint when re-spraying.

Thanks
Trevor

You might try cleaning out the grove with a round tooth pick then rubbing with a wax crayon or small candle making sure only the grove is filled(wipe with a thinner) then after painting remove the wax with the round tooth pick and refill the grove with office white out. PL259