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ever: Restore and Repair C/A

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Forum » Radios and other type of sets (Physics) etc. » RADIO MODELS DISPLAYED » ever: Restore and Repair C/A
           
Michael Watterson
 
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03.Aug.12 23:28

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Well, I knew from the advert it was a C/A or a C/E, (not Octal) but only subsequently realised how to tell a C/E (I updated the pages with what I found out!.

No one else bid so I got the radio at the very minimal asking price. The seller was honest.


One of the quite honest eBay photographs!

 

If you are of a nervous disposition hit the back button now!

Is it permissible to send so much livestock via courier from UK to Ireland?

The paint was holding that side together! 


The corner came away in my hand! Honest!

 

More...  Really leave now!


The base of the set came off!


Can you see them waving?

 

 

Curiously I could find no holes on the wood of the frame aerial. Well the Chassis and loop aerial is nice. Paint flaked and also purple from glue on the perspex.

Michael Watterson
 
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03.Aug.12 23:54

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How hard can it be?

I made paper templates of each part as I dumped it in the bin. All the cross members only very lightly "worm" infected, in comparison to the plywood panels so I really really cooked them with blow torch and then soaked in Ronseal "total wood preservative"


Well toasted.

 

I decided to make the sides out of a thin piece and thicker piece of plywood glued together. The original may be one sheet with a rebate made by router. I have a router, but not much space to use it, nor the thicker plywood. I happened to have a sizeable  piece I bought as it was 1/2 price. The thinner piece was the lid of a broken games box.

But I only had enough thin ply for ONE side. Is the right side so bad? I retrieved it from the bin and blow torched it severely as it was at least not crumbling!

 

With the electric jig saw I quickly cut out the speaker baffle board, large part of base, small part of base and the two sizes of rounded panel to bond together to make a new side.

I marked out the dowel holes for the two top cross members and drilled the side without going right through!

With the aid of the photos of the original the basic frame takes shape quickly!

 

Then I soaked it ALL in Ronseal "Total Wood Preservative"

Quick "reality" check with chassis and a folded laser printed front and bottom of a B103 battery scan

 

So what else?

  • Filler, sand and paint cabnet (the hard work!)
  • Touch up the perspex paint work
  • Clean the front and back cloths
  • Repair the Electronics. You don't imagine a 65 year old chassis is perfectly "OK" do you?
Michael Watterson
 
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08.Aug.12 22:59

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The obvious fault is the DL92 is open filament. Probably due to the faulty coupling capacitor from DAF91 anode to DL92 grid.

The DAF91 anode to DL91 coupling capacitor replaced, as is V2 DF91 screen grid decoupling and V3 DAF91 screen grid decoupling (feed resistor from HT is 4M7 Ohms!). Audio Transformer "Tone Correction" capacitor at least goes to HT and not 0V/LT-, but is very high leakage. So is C1 the AGC capacitor (but it only has a few volts so shouldn't be a problem). These four are the only Wax /Paper types. The main HT+ to LT- Electrolytic seems OK!

On going to replace the DAF91 screen grid capacitor the tag on the rear of the socket snaps. Fortunately these are quite deep sockets and a wire is easily soldered to the rest of the socket for that pin.

But even after replacing there is no IF. On this set the IFTs don't use cores, they are tuned with compression type mica washer variable capacitors.

The DK91 seems to be oscillating, but strangely at 1500KHz to 1600Khz end of the dial. No visible IF with 600KHz or 1000KHz. Time for more extreme measures!

So I remove DK91 and feed the generator direct via capacitor to anode socket at 452kHz. The IF is badly out. Someone has twiddled!. But only IF on DF91 grid. nothing much on the Anode. The filament tests OK, the valve must be really worn. Replacing the DF91 I now can tune up the IFT on DF91 anode and DAF91 diode. But only a very faint feeble tone on speaker. I replace the DAF91! Loud tone now on speaker.

Back to the beginning and re-fit the DK91. No 600KHz! The Filament is OK, so I try a different DK91. Success, now the MW is OK, but only up to about 1300KHz on the dial, after that the set "squeals". But the L.O. padding Cap is very open and the frequency is nearly 1600kHz, not 1300kHz.

Alignment. Always do the low frequency end of MW first. On Trader sheet this is 2nd preset, C12 and 600kHz. The third (C3) is HF end MW "RF padding" and fourth (C9) is HF end MW "LO padding". Actually when these are adjusted so that 1400kHz on the dial really is 1400KHz, the instability vanishes. We can see why on C/E R2 is added to damp L.O. drive and R4 added to damp 1st IF as well as R12 "Grid Stopper" on DL92 (V4). This is a later half of C/A serial numbers so has the C/E V4 screen grid to HT and no R14 + C23 as in earlier C/A..

So amazingly three tubes with "OK" filaments and getter need replaced and DL92 o/p filament dead. So though I thought this had a nice full complement of tubes, I need to order at least a DF91 and definately the DL92 ("borrowed" from another set).

Now we have the MW working and check the LW. UK BBC R4 (198KHz) is fine after LW alignment. But no Irish (localish) RTE1 LW! (1190KHz). I double check frequency generator. Eventually I try another radio. RTE1 LW is off the air! (It was back later, then gone again the next day, then back again).

Final checking of alignment needs the "proper" battery sitting in the loop as it affects the tuning. The DK91 socket is a bit dodgy, but seems OK after clean. Original DK91, DF91 and DAF91 still don't "work".

Finishing

The case is now "refurbished"

The rebuilt case (visible side panel is new)

The handle was disintegrating, but I had a matching one. The flaked off "gold" on rear of perspex was replaced by using an "Edding" bullet point gold marker. The flaked cream with Dulux 50ml "tester" bathroom wall paint "Warm glow" on the inside. The plywood painted by brush using a slightly different  (not as peach tinted) pale cream "tester", rubbed down with 180 sandpaper and sprayed with acrylic varnish before remounting perspex.

The cloth was cleaned with a toothbrush and household "cream cleaner" then rinsed.

Battery

The B103 is a layer cell. So an exact replica is difficult. An AD3 was about 240 hours and can be implemented exactly 8 x F  + 60 x U10/B, and a B103 might have been 150 to 180 hours. I'm not sure. Anyway, either 4 x Zinc Carbon F cells (or 4 x Alkaline D Cells) in parallel for LT (same date code) 

Each holder is double-sided so holds 10 cells

Z- folds into the space.  There are four F cells in original 996 case, but in parallel.

 

Since there is only Four F cells, not Eight, and LT is 250mA, HT about 9mA to 10mA, the AA only need be cheap Zinc Carbon (probably about 1100mAH, rather than 1300mAH due to cheap batteries having two large plastic "bungs" at top and fake Alkaline style cap on bottom. This gives an approximately balanced pack of over 110 Hours. Five packs of 14 cells is €7.45 and leaves 10 spare cells.  A set of 10 x cheap Zinc Carbon PP3 would be under 45 hours and cost the same!

 

 Plastic foam under connector to support it when plug inserted.

 

 
Battery upside down!

Now fine adjustment of the RF padding on MW & LW can be done!

Older Battery boxes have no plastic plug outline. Later Battery boxes have "Radio Battery" instead of "BATRYMAX". The illustrated design is based on a cover that may have been uploaded from Bill Morris  but edited. The box is two part from cereal packet with each "ink jet on 90gm paper" face glued on and then a couple of light coats of Acrylic varnish spray to give a slight waxy and/or litho-printed look.

See about Ever Ready Combination Batteries

 

This is the original condition

This article was edited 08.Aug.12 23:27 by Michael Watterson .

Michael Watterson
 
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17.Jan.13 02:37

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Talking to collectors of Model C, C/A and C/E it is evident that the paint didn't crack or flake with age on the side panels, it's a special crackle paint, a two or three part process similar to that used on the Ever Ready All Dry Portable 5214 and still available today. It can be single or two tone and to an extent the gap and depth can be varied.

  
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