06-01-2025, 06:02 PM
(05-01-2025, 09:02 PM)Mike Watterson Wrote: The Thorn / Ferguson TX9 was live chassis (mad thyristor based PSU?) and mid 1970s, but the TX10 was isolated, thus could have video / audio. Late 1970s.
Bit later. The TX9 was 1979, and the TX10 was 1981.
An uncle worked for them at the time - initially as a field engineer but subsequently moved into R&D in Enfield until GE took the site over in 1991 IIRC. I spent a week there on work experience during A levels, which would have been 1990 or '91, so right at the end, and it was quite a depressing experience to see the vast empty spaces - entire floors - that had previously been occupied by scores of R&D engineers. My uncle was on the RF side, and was setting up a new EMC testing facility at the time. He had a lot of expensive gear to play with - all rather intimidating to a young audio enthusiast!
At the time, the TX10 was really unusual in having a natively isolated chassis. Probably not unique, but I can't immediately recall any from that era (not that I'm any sort of expert here). Of course, by the 1990s it was much more common, but not universal - I was still seeing sets lacking AV connections when I worked in an electrical shop (1989-1991). The competing Philips K30 and K35 had a live chassis, and sported a large isolation transformer when AV inputs were offered. I've got an old transformer from a TX9 hidden away somewhere.
During that particular visit he gave me a TX10 to play with, and a blank PCB of a prototype Scart interface which I was able to populate and build into the TX10, along with a Fastext/PLL tuning PCB from a TX100 (and a NICAM PCB that I eventually got results from a bit later). The final set was quite sophisticated for the time, and I learned a lot about Scart and TVs generally. The final step was to swap the flat CRT with the much more lively one from the K30 we had at the time, but despite my best efforts at setting it up, I was never happy with the picture. The Philips set was much better to my young eyes. The TX10 was probably more "accurate", but less enjoyable. I ended up returning the CRT to the Philips set, and making the Fastext/PLL board fit that instead. That was a lot of work, not least finding a way to transfer the Fergusson pre-scaler to the U321 tuner for the PLL tuning, but I was pleased with the results. Even added a little circuit to make the picture go to a dark blue blank screen when not tuned in, as was a common feature at the time. Eventually I "won" a TX9 from work, and transferred the Fasttext PCB to that, returning the K30 to its original form. That TV saw me through university and several other places before I eventually gave it away on the UKVRRR forum. Wonder where it is now?
Of course, the thyristor-based PSU in the TX9 was replaced with a TDA4600 in the mark 3 PC-1044 chassis (mark 2 changed to the TDA3560 decoder). I think that was around 1984. That allowed the PSU to have a standby mode. At least the original was fed via a bridge, so wasn't putting DC on the mains, and was fairly efficient.
Happy memories. I guess the above partially explains why my A level results weren't brilliant
