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Old 24th Jul 2020, 8:37 pm   #2
Join Date: Sep 2004
Location: St. Albans, Hertfordshire, UK.
Posts: 1,099
Default Re: Marconi TF2431 Counter Service Manual / Schematic

Alas I don't have a manual for a TF2431 but I used to work on them some 40 years ago and can remember a bit. After the main gate the counting chain is much the same as the 2430 you have, except it uses an MC10231 rather than an MC10131 to help it get to 200MHz. So you can use the 2430 schematic with a reasonable degree of confidence. Further on down the count chain the circuit is modified a bit to to allow an 8-digit display rather than seven.
Although the first MC10231 is configured as as a divide by 2 it is also wrapped up with other bits and feedback to give an overall divide by 10 function. So you might not be able to make much sense of it. It might be worth trying with a 10sec. gate time.
You may be suffering from dry joints. That generation of MI stuff used through-board rivets (AKA griplets) instead of plated through holes, that after many years of thermal cycling tend to develop cracks each side of the pcb. It would be worth running over all of them with an iron to reflow the solder joints.
Lets hope somebody has a manual!

Richard, BVWS member
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