Well, I made a deal to sell my Tron. After the guy left, I was getting it ready for a later pickup and found that the spinner was erratic.
Tron's hand would jump from place to place and not follow the smooth spinner movement.
Test mode showed large gaps in the count display when the spinner was moving.
Being a packrat, I pulled out another CP and it did the same thing.
Being a packrat, I pulled out another I/O board and it worked fine (but that I/O board had no sound).
Being a packrat, I pulled out a manual, which was very difficult to read I'll add.
The schematic showed a set of 74LS244's bringing the spinner inputs, button/joy inputs, and DIP switch inputs to a common bus. The processor picks the right chips when reading the various inputs.
I noticed that all the signals from the spinner were routed through a single chip at E2. Suspected this since all the button inputs worked fine.
Lo and behold, I had some 20pin sockets and more amazingly, a few 74LS244 chips. Socketed it, slipped in the chip, and returned to the storage building to test it out.
Works fine.
I'll add this- after I brought the board home, I checked some old posts, both here and on Google archived RGVAC feeds. Dozens of posts where people complained about the same thing, but were directed to suspect voltages, optics, and connections on the spinner itself. Several people had luck with that.
Had I not had the spare parts, I would have probably started there too, but taken a LONG time to get back to the PCB.
Anyway..
Tron's hand would jump from place to place and not follow the smooth spinner movement.
Test mode showed large gaps in the count display when the spinner was moving.
Being a packrat, I pulled out another CP and it did the same thing.
Being a packrat, I pulled out another I/O board and it worked fine (but that I/O board had no sound).
Being a packrat, I pulled out a manual, which was very difficult to read I'll add.
The schematic showed a set of 74LS244's bringing the spinner inputs, button/joy inputs, and DIP switch inputs to a common bus. The processor picks the right chips when reading the various inputs.
I noticed that all the signals from the spinner were routed through a single chip at E2. Suspected this since all the button inputs worked fine.
Lo and behold, I had some 20pin sockets and more amazingly, a few 74LS244 chips. Socketed it, slipped in the chip, and returned to the storage building to test it out.
Works fine.
I'll add this- after I brought the board home, I checked some old posts, both here and on Google archived RGVAC feeds. Dozens of posts where people complained about the same thing, but were directed to suspect voltages, optics, and connections on the spinner itself. Several people had luck with that.
Had I not had the spare parts, I would have probably started there too, but taken a LONG time to get back to the PCB.
Anyway..


