1972 Ultra 6713 1

Thorn 8500 Chassis

Model: Ultra 6713

Year:1972

System:625 Line

Original List Price : £222.64 (exact price in 1971 unknown, this is the 1975 price )

Valves: None

Transistors: Yes

Integrated Circuits: Yes

General Information:

June 1971 saw the production of the first British colour chassis aimed at breaking through the £200 barrier – The Thorn 8000 series chassis. With a 17″ A44-271X shadow mask tube and all solid state circuit. Along with its successors, the 8000A, 8500 and 8800, proved to be very popular with the viewing public and more reliable than many engineers at first predicted.

Here we have the Ultra 6713 with the 8500 chassis, which was released in July 1972. It differs from the 8000 using a 19″ tube: the higher scan drive requirements led to a redesigned line output stage and focus circuit and the use of a choke instead of a dropper resistor in series with the live mains input line. This latter modification provides an HT rail of about 190V in place of the 170V used in the 8000 series. Line output is via a 1700V transistor the BDX32

1972 Ultra 6713 2

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lyons.den@ntlworld.com
Member
1 year ago

My Mum and Dad rented the Marconiphone 4713 version of this set back in 1974 . Overall, the picture quality was satisfactory. However, BBC1 transmissions only, suffered from loss of Sync ( Rolling Pictures ) when on screen captions were being transmitted. Numerous visits by Engineers from our local rental company were unable to resolve the problem. A few years later , Our local rental company was taken over by Rediffusion who replaced the set with a Brand new 22 inch Mark 3 with a PIL Tube . Excellent performance and reliability.

Last edited 1 year ago by lyons.den@ntlworld.com
slidertogrid
Member
7 months ago

I still have the 8500 (Marconi) my parents bought new in I think 1973. We rented a Decca 2230 from Granada for a year and then they decided to buy. The little 19″ Marconi seemed a bit small when we first got it but I soon adjusted to the smaller screen. It now resides in my dining room and is used occasionally. It has been remarkably reliable. When it was my parents main set it only needed adjustment to the ref osc and a new Tripler to cure poor focus. Other than that it was faultless. In it’s old age it has needed a few jobs doing, power switch, tuner cams a couple of capacitors, nothing major.

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