1970 Decca CS2611 - Bradford 10 Chassis

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.

Marc.

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.

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.

Marc.

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

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?

Aerial socket

That is just me with my roots in the early CCTV trade

Mine also has a cut out switch on that bracket.
Has yours been removed Chris or is the button broken off?

Jon

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!

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.

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

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.

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.

They're not 30-series boards by any chance?

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

Original PSU refurbished before refitting. In case anyone is interested the replacement TX is an RS universal output transformer.

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.

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

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.

 

That can definitely looks like it's seen better days....hopefully that's all it is.

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...