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SOBELL T121 "Stargazer"

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Rear view [47K]   Front View [32K]

  • Released circa April 1951
  • 5 channel superhet
  • 12" Mullard MW31-16 with 6.2KV E.H.T.
  • 13 Valves
  • A.C. / D.C. mains
  • Original cost £48-17s-7d plus £10-19s-5d tax.
NOTES
Carefully shielded RF coils - NOT!
A pile of 'orrible 'unts capacitors and no screening. Great.
An interesting set for many reasons. The first is that this set used what was probably the largest bakelite cabinet made at the time (made by British Moulded Plastics Ltd), which played a big part in making this set cheap not just for a console but also for a large (!) 12" screen.

But achieving such a low price involved not just the cabinet. Looking at the chassis they saved a lot more money by paying no regard to screening either the RF coils or indeed the line output stage. The RF section, although superhet, does seem to be lacking at least one IF stage so I guess the set was a little RF deaf - and just maybe this lack of R.F. gain helped in avoiding instability.

But if saving money, why is the volume control not a simple variable resistor instead of s stupid switch selector placed in a rather odd electrical position (see 'S2' at left of diagram below).
Circuit of audio section [17K]

Its not all bad though; Sobell had finally seen the error of their ways, ditching the Mazda CRT's of their previous models in favour of Mullard CRT's.

Another sign of the cost cutting - a total absence of any screening of any of the R.F. coils. How the circuitry remains stable is a mystery, though having said that the set has less I.F. stages than a "normal" set so perhaps the lack of R.F. gain is the key to stability ?
SERVICE DATA You can download the manufacturers service instructions from the Sobell TV page, along with relevant pages from the Molloy and Poole book which has a far more readable circuit diagram. Mind you, the manufacturer's data is absolutely essential if you wish to repair this set, as the following extract illustrates:-
Essential service info [4K]
Well, no sh*t Sherlock!
CURRENT STATE Good cabinet, but missing its back. The cover that should go over the "occasional" controls at the front of the set is a replacement but missing whatever was used to hold it in place and is hence missing from the photo at the top of this page.
WHERE FOUND Fleabuy for a modest £51.

Chassis View [84K]

What a mess! Note the rather unusual boxy looking line output transformer on the right; also
note the exposed EY51 EHT rectifier perched on top ... and how well Sobell managed to drag
just about every wire right over the smeggin' thing ! Not a good idea, even if the E.H.T. voltage
is only a puny six-and-a-bit kilovolts. And no, the "S.C." label does not stand for "Shear Crap",
it stands for "Sutton Coldfield", the site of Britain's second television transmitter.

Stargazers on the production line [17K]
The T121 being tested as the final part of the production process.
Wonder if the woman realises that chassis is connected to the mains !


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Last updated
28th October 2009