1975 MultiBroadcast 7773

Thorn 9000 Chassis

Model: Multibroadcast 7773


System:625 Line

Valves: None


Integrated Circuits: Yes


In 1975 Thorn once again startled the TV industry with the introduction of the 9000 series chassis with its Syclops combined chopper regulator/line output stage.

The 9000 used a parallel switched-mode power supply running synchronously with line. A conventional transistor line output stage except that it uses the power supply switching transistor to conduct the latter portion of scan with an efficiency diode conducting the first part. This was known as SYCLOPS (SYnchronous Converter and Line OutPut Stage)

Here we have a 20″ Thorn Television Rentals Model 773 badged for the Multi-broadcast chain. Ultrasonic remote control (sequential channel change & sound mute only)Nice touch is the nixie tube channel indication.

This one came from the same storage source as the Ferguson 3713 and therefore the electronics have suffered with the same humidity/rust issues.

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14 thoughts on “1975 MultiBroadcast 7773

  1. Worked on a few of these as an engineer for Multibroadcast Woking and Maidenhead during the 70s and 80s. Triplers were regular failures on them, especially in dampish homes near the river Thames.

    Happy days.

    • I worked as an engineer at the Staines branch of Multibroadcast from 1967 to 1976 and was often seconded to Maidenhead. Don’t remember much about the TV’s now but I do remember the names of some of the Managers – Mr Sprague, Mr Chitty, Mr Strowger etc.

      • Hello Chris, Funny how you can come across people from the past. I worked with you at Staines 🙂 Do you remember Peter Layton? I was looking for stuff on Multibroadcast and came across you. Funny hey. We did good work together in those days I thought. My memory is a bit vague. Bob Locke was rep & my best man at my wedding. Dave ? was manager. John ? also a rep I think. He bought my old morris car. I live in Melbourne Australia since 1974. Would be good to swap a few stories with you. 6 Curlew Cres rings a bell.

        • Hi Peter,
          Sorry for not getting back to you. My computer threw a wobbly and I have lost all the emails in my address book. If you can reply to me directly, I will resume our conversation.

      • Hi Chris, Just sitting thinking about our time together at Multibroadcast. I remember the Staines shop manager’s name. David Jenkins & the rep John Hall. Funny how we all like to reminisce.



        • Hi Peter, how lovely to hear from you! I was thinking about you when I wrote my last post. Yes we had some fun at MB and would love to catch up. I retired last November.

          Kind regards

  2. looks like the thorn 9000 series, the semikron diode mounted next to the line opt transistor used to go and like the tripler the set pulsed as it tried to start. Usually the tubes were low with a milky picture. Hard to find now, the 3K’s seem to crop up more than the later sets..

    Oh and the joys of jangling your keys making the ultrasonic remote ones change channel !

  3. I worked for Multibroadcast from 1965 for thirty two years. I started as a representative and by 1968 was promoted to manager of their Beckenham shop. I remember we were the first company in the UK to rent remote control TVs. I went on to run Croydon and Mitcham before Multibroadcast merged with DER And finally Radio Rentals. I also ran shops in Dagenham, Ilford, Canning Town, finally ending up at Colchester. It was great team work having the engineers working direct from the shops.

  4. Well I was just showing my son 21, the old days of tv’s. I worked for Visionhire then when they took over British relay, lots of fun and many a time I got a belt from the 3000 chassis,and those big old resisters on the PSU’s , they were fun times I worked mostly in south London, those convergence pots used to cook.

  5. Strange to find this. Multi Broadcast came into my mind and I Googled it and found my way here. I worked at Guildford from 1976 to 1978 before moving onto IBM. We went into the workshop in Weyside Road in the morning, picked up approx 10 call tickets for our specific area and then disappeared for the day. No mobile phones to call in etc. When you finished your calls you were done for the day. Everyone had to work Saturdays and I generally had Thursdays off. I usually managed to complete my calls and make last orders in the pub on a Saturday lunchtime. Good times. A bit rusty now on names from the past … (engineers) Mel, Bob Bewsey (from Knaphill), Dave Dinham, Rob xx (from Ellens Green), Colin xx (left to join Fire Service I think), Clive Chart & Kevin Carol. Reps were Brian Jackson (from West End) & John Dolphin. Even though I was only there a short time I really enjoyed working there and fixing TV’s. Everything seemed far less complicated then.

  6. I worked on this chassis whilst I was at Radio Rentals. Even though we got to know the stock faults there were not many engineers who fully understood how the Syclops psu worked. It was way ahead of its time but dreaded by many.

  7. Hi Simon,

    Nice to see you here again. I had no idea you used to work for Radio Rentals, you lucky so-N-so. What a great company to have worked for, I’m huge fan of their early 700 & 710 series chassis’.

    Also as you can probably tell from my collection above, very much a fan of Thorn, my favourite chassis being the 3000/3500. The 9000 repair as detailed above was certainly a challenge, made more so by the poor storage it had encountered. Facing SYCLOPS was a formidable learning curve but happy to say the set gives a fantastic picture as can been seem above.


  8. Hi
    I worked for Multi Broadcast in the early 1960’s when they were part of A.E.I. our newly opened branch was at Tonbridge in Kent. Because we started from scratch I did relief from time to time at Bexley, Ashford, Beckenham and Hornchurch.

    At one time we stored the old relay equipment from Bexley until its disposal. Our area manager was a Mr Trayner. I remember the Chief Engineer at the time(whose name I cannot recall) lived near Lewes in Sussex and we had the unenviable task of trying to install a standard Multi Broadcast T.V. with a box 6 element aerial on a 15 foot mast (the best available from stock) in the lowest possible signal area. Not the best of jobs to impress, bearing in mind this was when only Crystal Palace was available. Interesting and testing times!!!!!

  9. I worked for Multi Broadcast in the early 1960’s when they were part of A.E.I. We were a newly opened branch at Tonbridge in Kent and started from scratch. As the branch service engineer and only a few sets to service initially my work load was very low so I was called upon from time to time to do relief at other branches. These included Bexley, Ashford, Beckenham and Hornchurch. The area manager was based at Bexley and I recall his name was Mr Trayner. Although I was only with the company for around 3 years or so I can recall many stories from the time up until DE R became involved and the T.Vs were supplied by Thorn i.e Ferguson rather than A.E.I i.e Ultra.

    Good times

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