Please help me with me with a little diagnostic help or recommendations. I have a second board set for TRON which was sold "as is" on eBay. Here's what I've done so far and what's happening:
1. First power up with random screen items; L116 on SCPU smoked and ruptured. I replaced L116 and the 12 volt capacitors on the SSIO board. CP20 was shorted. I also replaced all of the 470 mf and 100 mf electrolytic capacitors on the boards; replaced the inter-board ribbon connectors.
2. Subsequently got a readable screen with a ROM ERROR D5; I took the D5 ROM from my working board set and replaced the defective one. Board booted to the start up screen. The game plays normally with two exceptions:
a. The left channel sound (Channels 4,5 and 6) are working, but are lower in volume than the right. I replaced the preamplifier (LM3900) without improvement. I am going to change out the sound generator chip and see if that helps.
b. All of the sprites (TRON, disc arm, tanks, MCP tower, grid bugs, cars) have horizontal lines through them in the color appropriate to each; see photo. I replaced both 2114-2 chips on the Vid Gen board along with all 8 of the 93422PC video ram chips with no change. Occasionally when I turn the game on, the sprites are OK for a couple of minutes.
3. I have intermittent loss of "UP" on the joystick with all other functions normal. That's not major for now.
4. The Vcc for both 5 volts and 12 volts at the chips are OK.
Please let me know your thoughts. Thanks again for any assistance that you can offer.
Thanks,
SLW74
1. First power up with random screen items; L116 on SCPU smoked and ruptured. I replaced L116 and the 12 volt capacitors on the SSIO board. CP20 was shorted. I also replaced all of the 470 mf and 100 mf electrolytic capacitors on the boards; replaced the inter-board ribbon connectors.
2. Subsequently got a readable screen with a ROM ERROR D5; I took the D5 ROM from my working board set and replaced the defective one. Board booted to the start up screen. The game plays normally with two exceptions:
a. The left channel sound (Channels 4,5 and 6) are working, but are lower in volume than the right. I replaced the preamplifier (LM3900) without improvement. I am going to change out the sound generator chip and see if that helps.
b. All of the sprites (TRON, disc arm, tanks, MCP tower, grid bugs, cars) have horizontal lines through them in the color appropriate to each; see photo. I replaced both 2114-2 chips on the Vid Gen board along with all 8 of the 93422PC video ram chips with no change. Occasionally when I turn the game on, the sprites are OK for a couple of minutes.
3. I have intermittent loss of "UP" on the joystick with all other functions normal. That's not major for now.
4. The Vcc for both 5 volts and 12 volts at the chips are OK.
Please let me know your thoughts. Thanks again for any assistance that you can offer.
Thanks,
SLW74


