all my dedicated followers
(ok, PA0PBZ gets credit) should be pleased to hear that instead of going on witchhunts I followed the signal and I found a sweep generator that is not working.
There is a overheating HEF4040BP (42C+ with no outputs changing) connected to a circuit with ADC's and DAC.s that are stuck dead in the water.
Considering that many of these parts are legacy and would require ordering from odd vendors at exorbant prices (10 bit ADC for 45$!!!), ad573jn, I began to desolder the parts in the non working circuit block and test them on breadboard.
Hopefully the damage is confined to the HEF4040BP ripple counter, but I need to check near by circuits for operation.
There is also a MK4501N that may be causing trouble.
Thankfully the Mp7531 DAC and the expensive ADC work fine.
Parallel devices are a pleasure to test as you can do it with a simple pulse generator and oscilloscope with no need for any kind of SPI communication or micro controllers.
Maybe some of you have those fancy serial decoders..... hooray old equipment