1502 YT recorder final repair note

Peter Gottlieb

After all my other repairs, the YT chart recorder was still hard over to the left. Since I could desolder the CA3130 without disassembling the thing I tried that first, substituting a socket (the round metal can leads had been formed into a 8 pin DIP pattern anyway). Looked up the CA3130, wow, special super high input impedance, what the heck? Why did they choose that for this application? Don't need that at all, freq response is uncritical, same with voltage swing. Dropped in an OP07 as I had a pile of them nearby and it worked perfectly. Now the chart recorder is doing what it should. Pretty standard 8 pin DIP pinout, I bet most any modern op-amp would work there.

Next I'll adjust it properly then get the connector to mate fully then I can put the 1502 back together.


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