I have been trying to fix a Heathkit GC-1197 digital clock (for educational and sentimental reasons). The main fault I found was that diode D101 had shorted out. I replaced that but the clock still didn't work. I figured IC 101 had become damaged. I did some research and found that the IC is a FCM3817D (F3817PC). I was unable to source a replacement but noticed that an MM5316N has a very similar pinout so I bought one of these but the clock doesn't work although the display lights up and shows some numbers.
Can anyone see if the original IC can be replaced with the MM5316? I attach three files. The circuit diagram of the clock, the pinout of the original IC and the spec of the MM5316 IC.
Can anyone see if the original IC can be replaced with the MM5316? I attach three files. The circuit diagram of the clock, the pinout of the original IC and the spec of the MM5316 IC.