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Old 4th Jun 2007, 7:41 pm   #21
Heatercathodeshort
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Default Re: Decca 1000 Projection TV Pre-restoration Advice Request.

Hello again Peter,
The actual EHT unit is very reliable. Due to the fact that flyback or rather in this case R.F. derived EHT was still cutting edge,the problem is one of regulation as apposed to a fault within the unit. At moderate or high brightness or contrast settings the unit would groan under the load and drop its output by at least 20% resulting in picture swelling and defocusing. These sets were always run on the absolute limit and developed a bad reputation because of this annoying fault. They were like it from new. I have an instruction book for a White Ibbotson model installed a few days before the Coronation. A mention is made of the 'unique auto focus' circuit
and the original owner has written in pencil beside it 'Ha Ha Ha!' All projection sets including the Decca 1000 use the Philips unit.
The original EY51 valves were very reliable and many vintage direct view sets still contain the original valves. I suppose on cost grounds it was not considered worthwhile to fit high grade types. The Mazda U25 was another story....
My Decca has been switched on for hours on end without a disaster and I would imagine that yours will be much the same providing you have replaced the capacitors in the sensitive areas. As if I need to tell you that....
For those Forum friends that don't know what I'm talking about I have attached a couple of shots of the EHT unit fitted to the Decca 1000. It uses an EBC33 oscillator and stabilizer [!] and a EL38 driving the 'tin box' containing the ringing choke and the 3 X EY51 voltage tripler rectifiers. [Shades of Thorn 1500 here..] The EHT output terminates in a tight fitting connector that fits into a glass 'funnel' on the side of the MW6-2 projection tube. Hope you get it working reliably. Regards John.
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Last edited by Heatercathodeshort; 4th Jun 2007 at 7:46 pm.
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Old 4th Jun 2007, 9:33 pm   #22
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Default Re: Decca 1000 Projection TV Pre-restoration Advice Request.

Thanks John, this is very informative, and yes, I have indeed changed all of the condensers, with exception of the mica ones.

Interesting about the drop in EHT, but now I understand why.

My Decca 1000 is quite an interesting one. I did a Google search for this set and found a couple of examples on-line, mine is different to all of those shown on-line though.

The lower half of the set both front and back is a solid piece of wood on all the sets I found using Google, however my set has a very decorative panel on the front and back which could almost be described as pleated. It's very much orginal. The previous owner said that it is a very early example, possibly as early as 1949. I don't know how accurate this is, but certainly it is different to all of the other examples I have seen. The drop down flap is the same and so is the circuitry. In the base of the EHT chassis the condenser which is said to only be present on the early sets was there in this set, also, some of the extra screening present in the pictures I have seen on-line around the CRT assembly and the EHT unit is not present on my set and never appears to have been either, an example is the metal box surrounding the EHT unit on your set, there is no such metal surround on my set and it doesn't appear to have ever been there. The valve line-up and chassis layout is exactly as detailed in the service data, there are just various things that make me think that this may well be an early model, especially the more elaborate cabinet panels at the front and back.

The glass funnel on th CRT is amazing, and connected by a spring as well! Interesting about many original EY51's still being in sets, I've always replaced these when restoring a set, but maybe this is not always essential?

So far all seems reliable, when I get it set up with a projector screen I'll take a couple of pictures.

Regards,

Peter.
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Old 5th Jun 2007, 11:47 am   #23
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Default Re: Decca 1000 Projection TV Pre-restoration Advice Request.

I can only suggest what the previous owner said, that this was a very early version. Anyone know otherwise? It's certainly different to any set I've seen a picture of on-line.

As you can also see it's now working perfectly, a very good picture, bright, clear and with the line structure just visible.

Any thoughts about the set welcome.

All the best,

Peter.
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Old 5th Jun 2007, 12:13 pm   #24
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Default Re: Decca 1000 Projection TV Pre-restoration Advice Request.

Thats the Decca Dual Unit. Electrically similar to the 1000 and introduced a bit later, it came with a very fancy screen unit which also housed the loudspeakers.

Something not quite right about the photo of the chassis though. Looks like a 121/131 to me.

Tony
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Old 5th Jun 2007, 1:16 pm   #25
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Default Re: Decca 1000 Projection TV Pre-restoration Advice Request.

That's interesting Tony, I have actually turned the picture of the chassis 90 degrees to make it readable, the controls sit along the bottom of the cabinet. The speaker is housed inside the cabinet, not externally. The chassis inside are indentical to the Decca 1000, the absolute only difference I can see, from the pictures on-line of various sets, are these external panels on the cabinet.

I'd be very interested if anyone does know any further information. Certainly a very interesting set. The turrent tuner has obviously been added later, but everything else looks original.
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Old 26th May 2015, 12:51 pm   #26
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Default Re: Decca 1000 Projection TV Pre-restoration Advice Request.

One post moved to a new thread here:-

https://www.vintage-radio.net/forum/...d.php?t=116845
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