Hi, Everyone, seeking a few general pointers as I am out of my depth on this one, a customer has sent a Redifudion cable tv in for repair, now here in Buxton we never had cable so I have never seen one of these before, to make it worse there is no interconnecting cable from the box to the TV and no model number on the TV or the box, where should I start, I have not taken the back off the TV so no idea what chassis it is either.
And I didn't attach the photos
The set is a Rediffusion MK1 CH2210 cable set. The convertor is designed for the cable set to operate via an aerial in areas where the cable network is unavailable.
@malcscott Oh, I remember those boxes being offered for sale via the various electronic surplus shops in the 80s. Didn't they also form the basis of a cheap and cheerful System A modulator? I certainly remember one sitting with the two standards converters at Dulwich.
Hi Michael, I've uploaded some data manuals for you to the Technical library, link above.
- Redifusion Frequency translator Installation manual
- Rediffusion Frequency translator Operating guide
- Rediffusion M1 service manual
Link to my Cable Wired System TD70 5.9MHz CCH213 https://www.radios-tv.co.uk/1976-rediffusion-mk1-ch2213/
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Many thanks for that, right so I should be able to power up the TV without the box connected, interesting enough when I look at the inside of your box and the diagram it looks very much like something that came out of the Decca factory, and I notice there's only 2 wires connected to that multi pin socket on the back.
Another interesting thing I have a Redifudion Mk1 and only last week I was thinking of selling it due to having a damaged rear cover but now it could be useful for spares.
The A56-120X crt should be ok. They were never worked hard in cable sets compared to aerial sets.
@cathovisor some were also repurposed as tuners for RGB monitors, but the one my school had, labelled Telebox 2, didn't work very well.
You'll need two pairs to connect the TV to the box, one pair have the 8.9Mhz vision and the other for the audio, those female McMurdo octal cable mount sockets are hard to find. Those boxes were designed for the version of the cable system which has an FM carrier for audio, the TV would have been used with the system that had high level AF audio distribution. Those boxes were widely available in the nineties as they were useful as TV sound tuners with little modification, getting a 1V CVBS signal needed a buffer amplifier.
Many thanks for everyones replies at least I can now make a start when I get time.
Hi everyone, finally got round to looking at the redifudion MK 1 cable TV, set powers up, the line output valves are working, the CRT cathode about 125v,500v on the G2 but no rasta, I'm suspecting a frame fault as I can't hear the scan coils, so my question is, should this set produce a raster without the tuner box connected.
Moderator Note:
Merged today's newly created thread with your original thread started in December. There's no point in having multiple threads running about your same TV under repair. Many thanks.
Hi, Chris, how do I access the technical library to have a look at the service manual?Hi Michael, I've uploaded some data manuals for you to the Technical library, link above.
- Redifusion Frequency translator Installation manual
- Rediffusion Frequency translator Operating guide
- Rediffusion M1 service manual
Link to my Cable Wired System TD70 5.9MHz CCH213 https://www.radios-tv.co.uk/1976-rediffusion-mk1-ch2213/
Below the cct diagram for the translator
Hi, Chris, how do I access the technical library to have a look at the service manual?
It really couldn't be simpler:
Michael, click on this link, it will take you directly to the library
https://www.radios-tv.co.uk/technical-data-library/
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Hi Chris, many thanks for that, I had to download the service manual on a pc as my phone wants me to sign up for something before I can view it, I will download the translator box in the morning.Michael, click on this link, it will take you directly to the library
I had to download the service manual on a pc as my phone wants me to sign up for something before I can view it
That is likely due to your phone not having a PDF viewer installed and active and trying to assist you with obtaining one. Probably for the best, trying to read service data on a relatively tiny phone screen is not fun, bad enough on a large PC screen. At least you can print it out, assuming you have a printer.
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@crustytv Yes got a printer, I bought it last year in the black Friday sale £188 delivered, the only downside is a set of cartridges cost over £400,however it packed up before Christmas so I rang the manifactures as it has a 3 year warranty and they determined it was the black cartridge causing the fault so the sent out a new one, it arrived 3 weeks later direct from Switzerland and in the package was a bill saying net value £15.31 so you can see this whole printer cartridge thing is nothing but a rip off, to buy a black one in the UK cost about £100.
@michael-dranfield Raster should still be visible without signal input. There is a pre-set brill pot on the t/base board and beam current limiter pot on rgb board which you could adjust.
@malcscott Going to have a look in the morning now I have the manual but I think I have already found the problem beforehand, had a quick measure round and found a 25 volt cap on the decoder pcb with only 0.7 volts on it, however when I took a quick look at the diagram the cap is connected to the base of a transistor for beam limiting, so the transistor is hard on, I did suspect frame collapse at first but taking the RGB collectors to ground with a 1k resistor lights up the screen.
