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DECCA 131

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Front view [61K]
  • Released first half of 1950
  • Single channel superhet.
  • Picture size ~ 15½"x11½"
  • 28 valves (T.V.) plus 6 valves (radio)
  • A.C. Mains.
  • Original cost £198-9-0.

 

NOTES

At the time, Decca were very much in the up-market television sctor and, of course, anyone affluent enough to afford such luxury would demand something a bit bigger than the 15 and 16 inch screens available using available cathode ray tubes. The only way to get the large pictures was via projection techniques, and during the early 50's Decca marketed a large number of projection models, including this model 131.

Projection optical unit with CRT [24K]
The main projection assembly

In common with projection sets intended for lesser mortals, the projection system is based on the standard Schmidt optical system in conjunction with the mullard MW6/2 projection C.R.T.

This particular example is equipped with the optional 3-band radio unit. basically a 4 valve + rectifier superhet, complete with its own A.C.-only power supply. However an additional valve (type L63) is added with the sole purpose of acting as an amplification stage for a gramophone pickup. Such extravigance1

The valve line-up of the television is an unusual mix of Mazda and Mullard, with a sprinkling of Brimar and Osram for good measure. Decca seemed to be biased towards Mazda, which maybe explains why a 1950's set is still using antiquated Mazda T41 thyratrons as timebase generators. The optional radio is a primarily Brimar affair.

The cabinet and, indeed, electronics are similar to the Decca model 121, the main external difference being the television controls being to the right of the screen in the model 121 whereas they are to the left on the model 131. (For the uber-anoraks, the handles on the doors that cover the screen are also different).

SERVICE DATA The service manual can be downloaded from the Decca TV Manufacturers page.

Prior to getting the service manual, I hadn't come across any mention of the Decca 131 (or it's close relative the 121) prior to 1952. However many of the drawings in the 131's manual are dated February and March '50
CURRENT STATE Sound cabinet, though the top surface would benefit from some TLC. The electronics are very clean.
WHERE FOUND Bought privately for £50 and a nice example for the price.
ADDITIONAL LINKS 1. Information about the projection system
2. Servicing the projection system
Radio chassis [19k] The back of the set. TV power supply [25K]
The Radio Section For a large cabinet, the set is quite full. Power supply section, complete
with ancient replacement
smoothing caps and a Cossor
rectifier.
Main chassis [61K] Control hidden behind panel.
The main chassis; the yellow bit on the left is the aeriel connector cover,
the colour indicating that this is a London single-sideband version (would
be nice if this was mentioned in the manual for this set!). The four pin
connector above it is, I think "Connecter C" whose purpose I can only
guess was used for factory tests of seom kind - its only use seems to
be the short circuiting of both the contrast and focus controls
The side panel on the right of the set
opens up to reveal the various
adjustment controls. The hole at
the top was probably once filled
by an after-market
Band III ("I.T.V.") convertor.

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J.Evans 2009
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Last updated
9th December 2009