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Forum 141

Cross-referencing CRT base connections for CRT tester..

In The Workshop

Last Post by Red_to_Black 10 years ago

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Katie Bush

(@katie-bush)

Posts: 4884

Famed Member Registered

Topic starter

Hi all,

I seem to have given myself a bit of headache today..

I'm trying to rig up a B12 CRT base for use with my CRT tester, and all I have to work on is the connection data for Mullard CRTs; A51-570X and MW55-80.

I realise there is a world of difference between these two, but they are all I have to go on, so I'm trying to map out the wiring so that I can "piggy-back" the B12 onto the lead adapter for the colour CRT.

So far I have the following

A51-570X
Pin Electrode

1--------g3
2--------NP ( no pin? )
3--------k (blue gun)
4--------IC ( internally connected? )
5--------NC ( not connected? )
6--------Heater
7--------Heater
8--------k (red gun)
9--------g1
10-------g2
11-------NC
12-------k (green gun)
13-------g1
14-------NP

MW55-80
Pin Electrode

1--------Heater
2--------g
3--------NP
4--------NP
5--------NP
6--------IC
7--------a2
8--------NP
9--------NP
10-------a1
11-------k
12-------Heater

Have I got it right so far?

If so, would I be correct in thinking? That;

A51-570X pins would relate to MW55-80 pins
7----------------------------------1
9----------------------------------2
?????------------------------------10
8----------------------------------11
6----------------------------------12

If so, which pin on the A55-570 base, would map to pin 10 (a1) on the MW55-80 (B12) base?

I'm getting myself awfully mired in what should be a straightforward job, or have I missed something obvious? .. I don't want to wire this up incorrectly, and fry a good CRT whilst trying to test it.

Marion

Posted : 01/02/2014 6:18 pm

Cathovisor

(@cathovisor)

Posts: 6415

Famed Member Registered

It doesn't help that some manufacturers treat the electrodes between the cathode and final anode all as grids, whilst others treat anything after the control grid as an anode!

But in your case, pin 10 maps to pin 10, as:

g = g1
a1 = g2
a2 = g3

The other abbreviations are:

NP = No Pin
NC = No Connection, as in DO NOT CONNECT TO THIS PIN.
IC = Internally Connected.

Bush shot themselves in the foot using an "NC" pin for terminating a grid stopper on the DAC90A. Nul points, Chiswick! Some valve data books do actually stress that connections must not be made to a pin marked "NC" as it can occasionally be strapped to an electrode - and that electrode may not be consistent...!

HTH...

Posted : 03/02/2014 6:55 pm

Katie Bush

(@katie-bush)

Posts: 4884

Famed Member Registered

Topic starter

Hi Mike,

Thanks for that info.. Marc has also sent me essentially the same data, so all I need to do now is to await the plug from Framer Dave, and the B8H socket from Glowing Anode, then I'm in business. :aad

Cheers,

Marion

Posted : 03/02/2014 9:41 pm

sideband

(@sideband)

Posts: 4216

Famed Member Moderator

You could get an idea of how long an engineer had been in the trade depending on the terminology used. When setting up a colour TV, some older engineers would say 'I'm going to set up the A1's' whilst younger engineers would refer to them as the G2's...

I usually referred to them as A1's which confused newbies as they spent time looking for the instructions for A1 pots. Gradually I started using G2 more but then I tended to to use both terms for the same adjustment...'don't forget to turn off the A1 switches when you adjust the G2's......! :aae

Rich

Posted : 03/02/2014 10:49 pm

Katie Bush

(@katie-bush)

Posts: 4884

Famed Member Registered

Topic starter

Hi Rich,

Now that was what I meant about something obvious.. I should ahve known that! :ccb :bbd having tweaked, purity-fied ( :aak ) converged and greyscaled a fair few colour sets - How did I miss the relationship between A1 and G2? :bba