'Figaro Special'

[Yorkie]

I've made some progress with this little set. The two section 32uF smoothing cap wouldn't reform, so I stuffed that, using miniature high ripple rating caps from Farnell.(On reflection, I could have drilled through the centre of the two positive terminal rivets to put the + leads of the new caps through, rather than drilled through the plastic base, but it's neither here nor there). It's a screw fitting cap, 25mm diam x 35mm tall, and I didn't think I'd easily find a replacement, though I later discovered that 'askjanfirst' in Germany stocks them at a reasonable price, albeit plus P&P.  Useful to bear in mind for the future.

I noted the absence of an HT load resistor which should have been across the two sections of the cap - 1k2, and had a suitable 4 Watt wirewound one to hand so fitted that. The auto-transformer and output transformer windings were all intact, and the valves all lit up, though not the DM70 magic eye, which had an open circuit filament. There are no stated Voltages on the circuit, but on checking the AC output of the auto transformer is was 160V AC, and the rectified DC output of the contact cooled rectifier was 165V DC, so the rectifier seems in good shape.  Since the pic of the chassis below was taken, I've replaced all the paper caps as a matter of course, though haven't, as yet, checked the old ones to see if they were leaky. Most of the resistors were well within spec, though one - a 2M2 - had gone high and was 4m8 so I changed that.

Though the HT around the valves looked OK, there wasn't a peep out of the set and a signal injected to the audio stage produced no sound. Well it wouldn't do if the speech coil of the speaker was open circuit! Never though to check that when carry out initial tests. It's an elliptical speaker and as the set is so small a replacement would need to be the same size. I did an internet search, more in hope than expectation, and found a firm at Bognor Regis selling just the right thing at £5.89 post free. It's a general purpose speaker with several alternative mounting holes.  All I had to do was to carefully trim away the surplus metal around the rim and file the edges to shape, using the old speaker as a template. I took the precaution of taping up all the holes in the speaker frame to obviate particles of steel being drawn into the speaker through the magnetic field.

I've managed to find a N.O.S DM70 magic eye for £5.99 plus £2.90 P&P (Buy it Now) on ebay, which couldn't have been better packed had it contained the crown jewels. The circuit of the set contains an error in the it shows the filament being fed from 'point B' yet there is no such point shown.  The actual feed point for the 1V4 heater is tag 6 on the auto-transformer, which the circuit shows as going to ground.

As well as the cabinet being minus its back, it didn't have a base either, so from pictures I found on internet, I've made a replacement base for it. It was also missing a Bakelite headed M3 screw which attached the chassis to the cabinet (one of four), so I used one as a pattern to make an alginate mould, and cast a head onto an M3 stainless steel screw, using 'Super Steel' epoxy, which sets black. The cabinet itself had a few chips  and scratches in the gloss lacquer. I toyed with stripping it back to the bare wood, but didn't think it warranted that, so I gave it several coats of polyurethane spray, cutting it back with a U-Pol pad after each coat.

Still some work to do, including casting a new knob, but as time permits, this little relic of the Cold War era is coming together nicely.

Some pics attached.

Hope that's of interest.