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1970 Decca CS2611 - Bradford 10 Chassis

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crustytv
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As a minor diversion from my BRC 2000 repairs, I recently took delivery of this 1970 Decca, thought I better start this thread properly rather than continue adding or trying to split off the one in the transport section.

The background to this set

This TV came to me from a nice chap ( Thanks Gary) in London. It used to be switched on from time time for his mother when hers went wrong. As far as I can tell for the last few years it just sat in a spare room. No longer wanted, rather than taking it to the tip, Gary found my website, spotted my request for old CTV's, hence it was saved from the crushers.

As usual the superb Forum courier service sprang into action, namely the two main stalwarts Mike & Graeme and also took the offer of bed and board for a few days over Xmas at Marc's gaff.

I had been after one of these and narrowly missed one last year. It will fit nicely in with my other Decca's:-

As has been mentioned on this board before by many ex trade engineers. The Decca Bradford was well liked by the trade, It was the single standard successor to the CTV25. This particular set is fitted with the superb Telefunken mechanical tuner and was considered one of the finest in the trade unlike the subsequent piano key tuner that was fitted and became a constant point of failure.

Observations

The Mahogany cabinet was generally OK with everything present and the small legs intact. The top was in quite bad condition and the rest of the cabinet dull. A small amount of refinishing brought this back to a nice gloss.

Once inside some of the past horrors were revealed these are as follows :-

The grey-scale tracking presets 2KR VR241, VR296 & VR336 have been thoroughly bodged with radio pots.
R299 has been bodged along with C211, C204, R407, R487. C604 has broken away from the board. V1 PCL82 sound output valve is missing and the sound output TX has been replaced with a huge affair bolted the the cabinet bottom.

The control panel print had worn away around the control, this was easily touched up with an black matt indelible mark pen, finally covered in lacquer to protect, .looks good as new now.

The Mullard A66 120X is low on all three guns, Red the worst followed by Green with Blue being the best. The CRT was subjected to a clean & balance and responded favourably with all guns high at around 80%

Finally the mains lead has a nasty gouge which goes through to the core.

So there we have it, another large early CTV saved from the knacker yard. I hope to get around to this one in January once I've cleared the G6, HMV 2701 and Fergy 3700 from the workshop.

Required

I have a wanted ad placed here to try and obtain some 2KR presets, if anyone can help I would be most grateful.

in the meantime some photos of the Decca.

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Posted : 29/12/2014 5:46 pm
Marc
 Marc
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Hi Chris,

The cabinet looks a darn sight better than it did whilst it was here, your elbow grease certainly looks to have paid off. :aad

Marc.

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RSGB call sign 2E0VTN

 
Posted : 29/12/2014 6:03 pm
crustytv
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Thanks to a kind forum member I will have a spare decoder by the weekend, complete with correct grey-scale pots intact. Its the same early type as mine with the larger delay line. I think I will just swap the boards over and see how it performs.

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Posted : 29/12/2014 6:55 pm
Cathovisor
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Hi Chris,

The cabinet looks a darn sight better than it did whilst it was here, your elbow grease certainly looks to have paid off. :aad

Marc.

I'll second that - it looks an awful lot better than I remember, not least the sticky black patch on the top :ccf

 
Posted : 29/12/2014 7:11 pm
Refugee
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What is the part that is mounted on an angle bracket above one of the delay lines on the left hand side of the decoder board?

 
Posted : 29/12/2014 9:13 pm
crustytv
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Aerial socket

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Posted : 29/12/2014 9:17 pm
Refugee
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That is just me with my roots in the early CCTV trade :ccb

 
Posted : 29/12/2014 9:23 pm
TVJON74
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Mine also has a cut out switch on that bracket.
Has yours been removed Chris or is the button broken off?

Jon

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Posted : 29/12/2014 10:25 pm
Cathovisor
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There's a bit of me looking at that blue and white cap on the timebase board and thinking that it should be replaced on sight - I believe that's the infamous 0.22uF boost cap!

 
Posted : 30/12/2014 12:42 am
crustytv
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Hi Mike,

Yes the cap stood out to me too, certainly will whip that out before proceeding with a power up

Meanwhile whilst waiting to start the electrics this coming Saturday, ( New decoder arriving) I continued with refinishing the cabinet a bit more flatting and then the final coats. Its now come up a treat, I've also repaired the hole that was in the back cover with a spare piece I had lying about.

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Posted : 31/12/2014 6:27 pm
Tazman1966
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Nearly all the Decca Bradfords that had any sort of mileage on them had a disintegrated back cover above the PL and PY! You've made a nice neat job of repairing it.

Tas

 
Posted : 31/12/2014 7:51 pm
crustytv
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Gary came over this morning and dropped off a new decoder and power supply.

The decoder just needed a couple of resistors sorting and that now resides in the chassis.

I then set about the power supply, if you remember mine was badly bodged with all sorts of resistor lash-ups, capacitor lash-ups and an external sound output TX due to the original having failed in the past.

Unfortunately the PSU board Gary gave me must be earlier or a next gen board as the wiring harness sockets are all too small for my loom plugs to fit, they also have less pins then my plugs have.

Not to worry I decided to use this new board as a source of parts to repopulate my board with all the right components. This was all going well until I got to the output TX. Its pin-out positioning is totally different to mine so it cannot be fitted to my PCB. Therefore I will have to leave the external TX in situ for the time being.

As a note and answer to a previous query by Jon, no my aerial bracket does not have the cut-out, this set does not have one fitted. There is a manufacturers note on the bracket stating and pointing to two anti-surge fuses fitted mains 2A and LT 500MA.

I've almost rebuilt the old power board with the better components including the output valve stand-off socket, hope to apply power to the set this evening.

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Posted : 03/01/2015 5:24 pm
sideband
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If the new transformer is the same electrically and just has a different footprint, you could mount it on Veroboard, fit flying leads to the pins so they can be neatly soldered into the correct holes in the PCB and then fit short stand-off's to the Veroboard and mount the assembly in place of the old transformer.

 
Posted : 03/01/2015 7:09 pm
Cathovisor
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They're not 30-series boards by any chance?

 
Posted : 03/01/2015 7:36 pm
crustytv
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The decoder is definitely a series 10 as I can easily recognise the differences.

I think you're right though about the PSU, it certainly looks like the new power supply board is actually Decca 30 series PSU.

Well the old series 10 PSU is rebuilt removing all the bodge components and replacing them with parts from the 30 PSU. As I said above, for now I will leave the ouput TX as is.All I need to do is fit it all back in the cabinet now switch on :aac

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Posted : 03/01/2015 8:01 pm
crustytv
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Original PSU refurbished before refitting. In case anyone is interested the replacement TX is an RS universal output transformer.

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Posted : 03/01/2015 8:29 pm
crustytv
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Powered on, degauss thump heard, followed by a nasty electrical fizzing/crackling sound coming from the area around the main transformer and smoothing block. Nothing visibly obvious made its presence to me, I didn't like the sound of it so powered down fairly swiftly. The smoothing C601/C602 2x400uF 350Vcan seems to have a bit of electrolyte puking out of the top but that looks old. It sounds like a possible transformer issue, there's definitely a distinct electrical smell too it if you know what I mean. :aai

Think I will retire for the evening, been at it all afternoon and early evening now, no picture this evening I'm afraid.

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Posted : 03/01/2015 9:15 pm
crustytv
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Didn't get a chance to get into the workshop today, spent most of it in the loft packing away the Xmas decorations. Anyway as I said yesterday the fizzing/crackling was coming from the vicinity of the three transformers and smoothing can.

All the components are crammed and stacked over on the left-hand side of the chassis, in the following order :-

Working from top down

    • 1. Frame Output TX
    • 2. C601/C602 400uF 350V
    • 3. H.T. Smoothing Choke TX
    • 4. Mains TX

Once I removed the frame output TX carefully flipping it over to the sets baseboard, I could now gain access to the Smoothing can. I removed the clamp and this allowed me to flip this over to the vertical, revealing the top.

Being optimistic I'm counting on C601/C602 being the main cause of my fizzing/crackling. The can is split open at the top, really sticky and has puked a lot of the electrolyte, some of which has gathered in the bottom of the metal chassis. I've got a NOS replacement 400/400uF in stock, so the plan is to reform that tomorrow, install it and hope that gets me going. Don't yet want to contemplate 3 or 4 being short at this stage so fingers crossed.

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Posted : 04/01/2015 8:43 pm
sideband
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That can definitely looks like it's seen better days....hopefully that's all it is.

 
Posted : 04/01/2015 9:13 pm
Cathovisor
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I have to be honest, that can would have been in the bin before I'd even powered up: there's slight venting of electrolyte and then...

 
Posted : 04/01/2015 9:29 pm
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