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Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 31st Jul 2020, 4:30 pm   #1
Tantanometer
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Join Date: Oct 2019
Location: Virginia Water, Surrey, UK.
Posts: 13
Default Vidor 254 “All Wave AC-DC Three” (Circa 1936)

Back in February when the world was a very different place, Jeremy (Pamphonica) came round for lunch and an afternoon of varnishing and French polishing. He brought along three empty radio cabinets, two 1950s Pamphonic sets which were relatively straightforward and the Vidor 254 which turned out to be an interesting story. The Vidor was one of two cabinets that he had previously taken along to a French polishing course where time ran out and he had returned with it sanded down and stained but not polished. Around the loudspeaker aperture it has what I presume to be an Art Deco pattern made of two contrasting veneers, see Fig. 1, which became the source of many challenges. During the course, most of the cabinet had been dyed with what looked like a dark soot and water mixture. One small section of the two-tone veneer pattern which should have been light in colour had also received this dark concoction in error.

In order to rectify the error I began by rubbing down the whole cabinet with fine sandpaper but the lighter coloured areas had dark blotches that wouldn’t go away. Further sanding risked making a hole through the veneer so I applied oxalic acid wood bleach to the lighter coloured areas. The following morning nothing had changed colour and in despair I concluded that the two contrasting veneers were actually the same type of wood and must have been dyed before being glued to the cabinet. As the light coloured sections couldn’t be made any lighter, plan B was therefore to make the dark sections darker. The challenge was how to achieve a perfect line between the two colours especially as the longest joins were along the end grain which would soak up any dye like a wick. I put masking tape around the outside edges of the lighter coloured areas and then sealed them with a couple of coats of pale, almost clear, shellac. Once it was dry, I removed the masking tape and lightly sanded what was to become the darker wood in order to remove any shellac that had seeped under the masking tape. To ensure a clean edge where the two veneers met, I used a short length of aluminium angle as a sanding guide. The darker wood was then stained with the remains of an old tin of spirit based mahogany dye. I’ve never mastered water based dyes and varnishes and it was touch and go as to whether there would be enough left in the tin to complete the job bit it just managed two coats with a few drips to spare. Finally the whole cabinet, both dark and light veneers, was given several coats of medium brown French polish (button polish).

Put like that it sounds straightforward, in reality there were many errors and hold-ups along the way. Getting an acceptable line between the light and dark veneers required many attempts; the shellac reacted with the spirit based dye and blistered after a few days; some of the black banding down either side got sanded away and needed repainting. The whole job took about 12 weeks of elapsed time, typically applying something in the morning, leaving that to dry through the day, then rubbing down and washing away the dust in the evening. About half way through all of this I completed the second of Jeremy’s Pamphonic cabinets, so we arranged a socially distanced handover in the front garden and I took the opportunity to show him progress on the Vidor cabinet. He seemed impressed but then reached into the back of his car and presented me with a box containing the Vidor chassis, loudspeaker, rear panel, knobs, etc. He said that he originally bought the Vidor as a French polishing exercise and as that had been done he had no real use for it and it was probably more in keeping with my collection than his.

Thus began part two of the story and at the risk of sparking off a debate about the relative merits of sympathetic conservation versus total restoration I decided that as the cabinet had been polished to within a micron of its life the electronics deserved a similar treatment.

The chassis was dirty with a fair amount of rust but complete. I removed the valves, tuning dial and mains dropper and attacked the rest with foaming cleanser and an old brush, then immersed it all in washing-up liquid followed by a week to dry off in the airing cupboard. The under-chassis wiring was based around a long 18 SWG busbar that was tack-soldered to the metalwork in five places. After disconnecting the tuning condenser, drilling out the rivets holding the valve-holders and removing a few nuts and screws the whole lot came out intact like a birds nest, see Fig. 2. This was great because it gave unhindered access to all of the components. Surprisingly all the resistors were within specification which helps retain originality. All the paper and electrolytic capacitors were re-stuffed as a matter of course. After sitting in an oven at 120 deg. C for 20 minutes to soften the wax their innards all pulled out quite easily.

The HT smoothing capacitors were originally in a block screwed to the cabinet next to the loudspeaker. This had long since gone and been replaced by a number of blue Hunts electrolytics which had to go. Looking at the screw holes in the cabinet gave an idea of the size of the original capacitor block and I fabricated a replacement based on a design developed for a previous restoration. This is visible in Fig. 3.

Meanwhile down in the shed the chassis and a couple of RF screens were rubbed down, de-rusted, primed and sprayed steely grey. The loudspeaker was also partly dismantled and refurbished. The electromagnet assembly came off quite easily after removing four screws and the adjuster for the spider. This enabled the dirt that was rubbing on the voice coil to be removed from the gap. The cone remained glued to the frame and was not disturbed but I was able to mask it by poking several very thin polythene bags through the holes in the frame, the sort that most supermarkets give you for loose fruit and veg. are ideal for this. The frame was then cleaned up and resprayed dark brown similar to its original colour. It came up well and when reassembled it was a relatively straightforward task to adjust the voice coil centring, despite not being able to insert any shims.

Eventually the restored and re-stuffed “birds nest” of wiring was replaced into the chassis; as it was so rigid the components fell into place and fixings were reattached. (Don’t tell anyone but M2 flat head screws were used to replace the drilled out rivets.) The bus bar was re-soldered back onto the tags in the metalwork, the above chassis components were refitted, the old rubber wiring replaced with silicone insulated wire and a new cotton-covered PVC mains lead fitted.

The Vidor 254 is a TRF set covering Long, Medium and two Short wavebands, it has three signal valves for RF, Detector and Audio plus a valve rectifier. Despite all of them looking old and decrepit the signal valves actually all tested at better than 80% emission. The rectifier looked to be full of fresh air with no sign of a getter and white powder floating around inside and I located an NOS replacement for a fair price at VintageParts.com. Finally with the chassis and loudspeaker sitting on the bench I plugged it into the isolating transformer, cautiously switched on and turned up the volume control. The valve heaters started to glow, HT came up there was a feint but healthy sounding mains hum from the loudspeaker and a few crackles as the wavechange switch was wiggled but nothing else. As I switched it off in disgust the six o’clock news suddenly came through loud and clear just before the on-off volume control went click. Like many TRF sets of this vintage, the volume control actually alters the bias on the first RF Amplifier valve, it’s not immediately obvious which way round it is connected and I had wired it back to front. Once that had been attended to everything worked fine and it was time for alignment which according to the Trader Service Sheet is simply to adjust the trimmers for the three tuned circuits at 250 metres (1,200 kc/s). There are no other adjustments. Long wave seemed to work OK with stations at roughly the correct places on the dial. For the two Short wave bands the aerial is connected directly to the grid of the RF Amplifier and the only tuned circuit is in the inter-stage coupling between the RF and Detector stages. Consequently Short wave performance is poor.

Finally with a new grill cloth fitted everything was installed into the cabinet and switched on for a final test. Disaster. As the volume was increased, uncontrollable feedback broke out. There was about 2 Volts peak to peak at 700 Hz on the anode of the detector which could not be silenced with the volume control because that worked on the previous stage, the RF Amplifier. The detector is a Mullard SP13C pentode which has a gold coloured metallic paint screen as well as being fitted inside an aluminium screening can. As that sort of metallic paint often becomes disconnected with age, I tried wrapping the valve in copper foil connected to the chassis but the problem persisted. Strangely tilting the cabinet at about 10 degrees to the vertical stopped the oscillation but that didn’t seem a practical cure. It looked as though the SP13C was microphonic and responding to sounds from the loudspeaker. I tried isolating the chassis on soft rubber grommets and placing foam between the valve and its aluminium screening can all to no avail. In desperation, having run out of things to try but still wondering if everything had been assembled correctly I bought a new SP13C which solved the problem.

In conclusion, thank you Jeremy for an interesting and challenging project which has helped keep me out of mischief during lockdown. The Vidor now lives in our dining room so as soon as life gets back to normal we will have another lunch whilst listening to it.

Len
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Old 27th Jan 2021, 6:10 pm   #2
vinrads
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Default Re: Vidor 254 “All Wave AC-DC Three” (Circa 1936)

Hi Len I have just come across this post ,what a beautiful job you have made of the restoration , and a excellent write up ,well done indeed , Mick.
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Old 30th Jan 2021, 8:18 am   #3
Tantanometer
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Default Re: Vidor 254 “All Wave AC-DC Three” (Circa 1936)

Hello Mick, thank you for your kind review. It’s encouraging to have your appreciation because the friend who donated the Vidor wireless subsequently persuaded me to submit an article for the BVWS Bulletin which is a lot more daunting than posting on this forum.
Best wishes.
Len
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Old 30th Jan 2021, 6:33 pm   #4
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Default Re: Vidor 254 “All Wave AC-DC Three” (Circa 1936)

Seconded - well done!
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Old 31st Jan 2021, 1:24 pm   #5
line sync
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Default Re: Vidor 254 “All Wave AC-DC Three” (Circa 1936)

Hi Len
Just read about the restoration of your vidor radio and i have to say you have done a super job restoring this.
That vidor is a lovely looking set only due to all the effort that you put into it.
Excellent job.

Robin
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Old 31st Jan 2021, 4:10 pm   #6
Radio Wrangler
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Default Re: Vidor 254 “All Wave AC-DC Three” (Circa 1936)

A gorgeous restoration of a very stylish set.

With so much work inside and under the chassis, it would be a good idea to take some high resolution photos and have an album to accompany the set so you can show people.

David
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Old 3rd Feb 2021, 11:02 pm   #7
saddlestone-man
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Default Re: Vidor 254 “All Wave AC-DC Three” (Circa 1936)

Well done, an excellent restoration.

I restored one of these sets a few years ago and eventually sold it through a BVWS auction.

I always found that the wavechange mechanism wasn't very positive and you couldn't be sure you were in the right position without wiggling the knob to get the right pressure of the cams on the contacts. Also because there was no wiping action on the contacts, they easily became tarnished and intermittent.

Did you notice this at all?

best regards ... Stef
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Old 4th Feb 2021, 4:58 pm   #8
Tantanometer
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Default Re: Vidor 254 “All Wave AC-DC Three” (Circa 1936)

Firstly a big thank you to all who have posted such positive comments, it's a great morale boost and makes me less nervous after having been persuaded to submit a full-fat version to The Bulletin.

Yes, Stef's comments about the wavechange switch are spot on. It comprises nine springy single pole contacts operated by a set of cams. Several contacts needed considerable straightening and I had to clean almost all of them with a diamond spatula before any continuity was obtained. Probably the reason they were bent in the first place was as a result of many contact cleaning events over the years. The cams rotate through 90 degrees for each step of the switch and the detent mechanism is vague but it helps a bit when the knob is fitted because you can then see the position of the four coloured dots.

Thanks. Len
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Old 5th Feb 2021, 5:00 am   #9
FStephenMasek
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Default Re: Vidor 254 “All Wave AC-DC Three” (Circa 1936)

Beautiful work!
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