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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 15th Oct 2017, 9:06 pm   #1
'LIVEWIRE?'
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Default Roberts RT1 rejuvenated!

Some weeks ago I was handed a rather sorry looking RT1, which, as some members will know, was Roberts first transistor radio, released in 1957. Amongst other problems, the volume control was seized up (never known that happen before!), the tuning gang was shorting out at various points, and the circuit board was cracked in several places around the driver and output transformers due, obviously, to the fact that the radio, or at least, the chassis, had at some point been dropped. After extracting, with some difficulty, the chassis from the cabinet, I first replaced the volume control. Fortunately I had an almost identical 5k Log pot. in my spares stock, so it was a simple process to fit that once I'd cut the spindle of the replacement pot. to the required length. I then set about soldering suitable lengths of 18swg tinned copper wire across the points where the board was cracked. This, combined with the fact that the PCB is secured at eac end to the metal frame, helped to make the repair rigid. With some difficulty, I managed to clear the tuning gang of it's short circuits and electrically leaky spots. The radio was now working again, although the alignment was a little out on both MW & LW. With the aid of my AM signal generator I confirmed that the I.F. was correct at 470kHz, so a judicious ttweak of the Oscillator coila n MW Osc. trimmer corrected the MW settings, although Radio 4 LW is still slightly out of position. As reception on both bands is good, I have decided to leave the alignment as it is. Other electronic repairs have involved several capacitors, including the AGC line decoupler and main smootihing capacitor (Whilst writing these notes I don't have the service sheet to hand, so am unable to quote component reference).
The cabinet now needed attention. I began by removing the broken lengthts of the original handle. This involves unsoldering washers from the pims inside the cabinet. Next I reglued the (rexine?) inside the cabinet by using a hot mely glue gun, having cleaned the covering, using first a cloth with a little washing-up liquid, then applying a coating of green shoe polishing cream, and allowing that to dry overnight. The radio is now ready to reasseble, once I receive a set of replacement knobs from member Ti Pwun, who makes relacement knobs for early Roberts radios, price 18 for a set of three, or 7 each. The same knobs, incidentally, were used on the Revelation 'Silvertone' record player..
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Last edited by 'LIVEWIRE?'; 15th Oct 2017 at 9:27 pm.
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Old 16th Oct 2017, 8:11 am   #2
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Default Re: Roberts RT1 rejuvenated!

Further to the above, the capacitors I replaced are C6,12, 13, & 18(Numbers as in Trader Sheet 1557) C13, the AGC line decoupler was originally 8uf -it is wrongly shown as 0.01uf in the Trader sheet. I've replaced it with a 10uf, and have also replaced the original main smoother (100uf, 6v) with a modern 470uf 16v electrolytic.
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Old 18th Oct 2017, 9:18 am   #3
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Default Re: Roberts RT1 rejuvenated!

A nice repair. The new knobs are a bit expensive though.
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Old 18th Oct 2017, 4:36 pm   #4
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Default Re: Roberts RT1 rejuvenated!

As Member Ti Pwun (presumably) only makes them is small quantities, and has no doubt had to invest in equipent such as a 3-D Printer and lathe in order to produce them, I acxcept the prices being charged as being neccesary. The demand for such items is never, IMHO, going to be large, as it will be limited to people such as ourselves who repair and restore vintage radios, etc. THe only thing, besides Roberts RT1, R200, & R300, of which I know, which uses the same style knobs, as I mentioned in post #1, is the Revelation Silvertone Record player, and there can't be many of those around.
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Old 28th Oct 2017, 12:09 pm   #5
Phil G4SPZ
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Default Re: Roberts RT1 rejuvenated!

Well done! Interesting write-up.
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Old 8th Nov 2017, 10:30 am   #6
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Default Re: Roberts RT1 rejuvenated!

Following on from my earlier posts, here are a couple of pictures of the RT1,(apologies for the quality of the RH one!) showing all three knobs fitted. The centre one was supplied by Ii Pwum, and I think other members will agree that it's a very good match to the other two, which are original to the radio.
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Old 9th Nov 2017, 7:34 pm   #7
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Default Re: Roberts RT1 rejuvenated!

Nice work, and a classy early transistor radio indeed!
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Old 11th Nov 2017, 11:20 am   #8
'LIVEWIRE?'
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Default Re: Roberts RT1 rejuvenated!

My only comment is that it probably looks better in the pictures than it actually is! Ideally the cabinet should have been stripped and recovered, at least a new wooden strip fitted to the rear cover to take the hinge, and redundant holes left by added rear panel connectors filled in, plus a green carrying strap better fitted than the black one I used. If it were my radio, I might have undertaken all of these tasks, but it's someone else's, and they are happy to have it cleaned up, repaired and working, which is why I didn't go any further.
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