1969 Baird 8724 - Single Standard CTV (A Rebuild)

I must admit I made an assumption the delta was pointing down, the final anode is at the bottom centre. I will go check A63-200X data

Blue gun down.

Tas and a few others mentioned I should set the Beam limiter up and the Grid bias for the A1. That's going to be interesting seeing as the A1 switches are missing.

Why not fit some temporary switches? Remove the links from the board and fit pins. Connect temporary switches across the pins. Set the board up as per instructions. Afterwards remove switches and replace links. Alternatively make the links pluggable so you don't even need to worry about the switches. You can then use the links in place of the switches.

Rich

If memory serves me, I suggested rigging up a "jumper" arrangement as far back as page four, which would obviate the missing switches.

Hi Chris,

In lieu of the beam switches, you could use those pins from your redundant convergence socket (two pins for each switch) and the plug leads as fly-leads to make/break the circuits as required.. All in all, you would need six pins and three fly-leads.. I've seen this method being used before, and I do believe it was the method of choice for at least one manufacturer.

That would at least get you started, until Malc sorts out his switches for you.

Marion

Marion

Blue gun down.

That's OK then Chris. No need to check....just need to get it all set up.

Rich

A little bench time....

I've just noticed I have zero contrast control

anyway I just wanted to check that the new Mullard scan coil/yoke/purity assembly was working ok, which it is. I then just went around and did a very quick and dirty grey scale. I sorted the width out too.

I will now set about setting the video drives to midpoint, sort the A1 levels, Grid bias ( if I remember right from Malcs instructions about green cathode zero volts) and EHT regulation. Then look into the colour or lack of.

Hello Chris
The BRC 3500 chassis “Installation Instructions” are in the Library and cover all the set up instructions.
Regards Stan

Excellent thanks very much Stan

Hi Chris.

It's getting better and better

...I've just noticed I have zero contrast control...

Have you made sure that the green (I think) two pin plug from the contrast control is plugged in properly to the video board? I've forgotten a few times...

Tas

The Video board on a 3000 was not the most reliable and there are a number of Electroltyics which I would change on sight.

C204, C205 and while we're at it C206 for the contrast.

Cheers,

Steve P.

Hi Tas,

Yes the green plug was in but upon investigation when I removed the rear control panel, the inner core of the coax has come away from the pot. At least that's a nice simple fix.

A-ha! I was nearly right then! A similar thing happens (but with the brightness control of course) if you leave the little edge connector off the beam limiter sub-panel too.

Tas

You were indeed correct Tas, just other end of the cable

Re-soldered and now I have excellent contrast control. OK I'm off to swot on the set-up (grid Bias, A1 & EHT)as discussed earlier.

Oh and the tube is a cracker

Hi Chris,

Considering what you started with, I think your efforts deserve a well earned pat on the back.

I'll bet those panels never expected to see power again.

After your previous experience with decoders, you should have this one up and working in a flash.. Oops accidental pun bearing in mind your last decoder repair.

Marion

Marion! Shhhhhh!

Don't forget the extra control when you set up the linearity - as well as main lin and top lin there's a control labelled "sit-up". All good fun

Tas

Lost for words Chris.

Even us seasoned TV guys probably wouldn't have taken on this task. Soon others will be asking you for advice.....

Fantastic work. You'll soon be enjoying full colour

Rich

I think I'm going to have to effect the Mikey405 tuner repair at some point https://www.radios-tv.co.uk/dmanager/php ... 0&file=556

I foolishly decided to change channel and spent the next 3 hours with snow. The tuner would not lock, when it did nothing would tune in. One of those moments when you say to yourself, " Why the **** did I just not leave it well alone" Eventually I managed to get it to work so could go to bed with a content mind otherwise I would have had a restless night.

This is a known problem with aged Thorn tuners, the main fault being the plastic parts that lock each tuner button when pushed, they perish and fall apart. Luckily others have blazed a trail and Mike documented it, the link above gives instruction on how.

The tuner i gave you should be working ok, Malc.

sadly not Malc, the same thing happened to the one you gave me. I operated the push buttons to check operation and two of the plastic washers disintegrated right before me. I will upload a photo in a mo, the plastic washer/stop seems to develop a white powder coating and they are very brittle.

Ah yes Malc but the satisfaction of the repair is much more fun

I have plenty of the RBM tuner cams, never needed any for 30 years