if you can remove the displays from the board, I would try holding a small high voltage high frequency AC source near them and see if the neon turns on - you do not need to touch the pins to this high voltage ( I use my trusty DermaWand )
hope this help
Phrama Phil
---------- Original Message ----------
From: N9KTW <n9ktw1...@gmail.com>
Date: April 25, 2020 at 12:19 PM
Hi All:
With the "shelter in place" going on I have a lot of time to work on the projects that have been "staring at me"
I have a Sperry "evaluation" clock which uses the sp-151 + sp-232 displays. I acquired it in 2015, and it has never lit up as long as I have had it. I went and replaced capacitors, transistors, and resistors (I think on the resistors), with no luck. I have also tried swapping the MM5314 chip with a working pull. Still nothing.
Is it possible that the displays have merely reached the end of their useful life and are just no good? I have the manuals for the clock and am at a loss as to where to go from here. Can anyone help me ? I would love to get it working, as there is a special place in my heart for old electronics (my XYL, and Accountant both HATE my Heathkit GC-1195 With the chime kit that I restored the case and converted the display to LED's)
Anyone have any ideas where I should start looking for problems?
de Howard, N9KTW
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