B12-262 pin mapping

Are G2 & G3, pin 1 & 10 on the A51-570X, tied to the singular pin 10 on the Leader?

There doesn't seem to be any other option, Chris. Thinking about it logically, the only reason to have them separated would be to adjust the focus - I doubt the Leader is up to that! The only thing that is lost is the ability to measure any leakage between the two ...

What about G1? The A51-570X has pin 9 & pin 13, however the leader plug has pins 2 (spec), 3(R), 4(G) & 5(B)

The manual shows only pin 9 connected for G1, so I'd go with that. The Leader is obviously designed to connect to a wide variety of tube configurations. I initially assumed that the SPEC pin was for colour tubes with common electrodes and the R, G & B were for separate connections to each gun - the early A63-11X, for example, had separate connection to three electrodes in each gun:

NB: A1 & A2 here are synonymous with the G2 & G3 in your tube. There is an oddity as far as the G1 is concerned as the Red G1 connection is also used for monochrome tubes and I would have expected it to use the same pin for colour tubes with only one G1 connection. However, perhaps this would then only give test results for the Red gun, so best to use the G1 SPEC pin to start off with. You can always transfer it to the G1 Red/B&W pin if it doesn't work

Hi Terry, Thanks for your input. I've made up the socket adapter, the socket that Mikeystep sent me was a PCB type so I used Veroboard. I extended all the pins legs from my component cut-offs tin, staggered all the pins so they are on isolated tracks. Wired all the fly-leads, I just need to hook this into the existing loom then hopefully I can have a look at the 9905 CRT to assess its state.

The finished adapter, tested and worked a treat, results can be seem here on the testing of the A51-570X