UK Vintage Radio Repair and Restoration Discussion Forum - Ultra U930, from basket case to working.

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Ultra U930, from basket case to working.

This set was purchased from a well known auction site and, originally, was in near pristine condition. It arrived in a somewhat broken state, not through any fault of the sender but more through the poor handling it had received en route.
The case was in 6-7 large-ish pieces, the wavechange switch had been badly damaged, both mounting brackets on the chassis were bent & one of the wafers was at a very odd angle with it's associated contacts bent out of shape.
The waveband switch knob had been broken into several pieces.
With the plethora of information regarding the repair of bakelite cases on this forum it is now back in one piece, some filler in places but one piece nonetheless.
At least the ferrite aerial survived.
Sorting out the wafer switch was quite a task, it had to be removed from the chassis & with the aid of a couple of dozen photos this was achieved. Some of the contacts & contact plates had also been damaged but with about 8-9 hours of fettling it all came back together & operates as it should. Putting it back in was a mission!
The manufacturers datasheet was invaluable in this as it shows the orientation of both wafers in relation to each other when assembled, very handy.
Going through the components on the chassis I found all the Hunts capacitors were crumbling, the remaining waxies were way out of tolerance. All but 4 resistors were within tolerance, the majority were the higher values, those above 100K. C43 (50+50Uf) formed up very well indeed, less than 0.5mA leakage after a couple of hours. R31 (A - E) mains dropper looked brand new, even the values were still visible.
Internally there were the usual dust bunnies & dead spiders but no signs of damp or corrosion.
A new 10W SBC bulb was a tad difficult to track down but they are out there at a reasonable price.
All the valves checked ok for continuity of the filament which was a relief!
After changing the mains lead & adding a chassis mounted fuseholder it was time to put some power to it.
All filaments glowing nicely, HT came up well & stabilised at 205VDC from the rectifier & 190VDC after R29, these figures are comparable to the manufacturers data.
Happy with that but nothing on any waveband, from one end of the tuning scale to the other. At that point I was beginning to think that perhaps more damage had been done that was hidden away, perhaps in one of the tuning coils. I decided to leave it until the following weekend.
I was telling a colleague at work about it & he, sensibly, suggested I go back over the chassis checking all the joints that had been disturbed/re-made as a starting point. Taking his sage advice I sat myself down & after about an hour I found that I had missed soldering C15 back onto the wafer switch, it feeds the grid of the mixer valve, no wonder it was quiet!
Re-soldered & with power applied it gradually came to life on all wavebands, it really shows off on VHF though, the sound is brilliant, quite bassy but not overly so & not too bright.
Only a small re-adjustment of tuning is required from cold after perhaps 10-15 minutes, after that it holds station very well.
All in all I've learned a lot, even things that appear to be smashed beyond all possible hope can be made good with enough time & effort. The case & front grill have cleaned up well, with scale illuminated green it looks very smart & most definitely of it's time.