Van Diesel
User
- Credits
- 99CR
Hi again folks and folkesses
My good friend X (an inhabitant of the Devil's Temple) brought me his Rampart PCB for me to fix.
The symptoms were that the board was resetting every four to five seconds, with a blank screen through-out.
The board was in excellent condition with no visible physical problems I could detect.
All ICs were seated well. A lovely little board in excellent condition as it happens.
Checking the operation of the CPU, it was clear this was not a 'watch-dog' type reset . . . instead the CPU seemed to be running for a while, clearly objecting to something and then resetting itself.
I had read another fix log somewhere and it mentioned that the EEPROM IC (28C16) was a possible problem. This IC is used to store various stats of the game operation, coins taken, high scores etc.
I checked the IC on my EPROM reader and this IC was indeed faulty (multiple reads of the chip gave back different results). It was replaced with another device (specifically a KM28C16-20) and . . . after a few resets (perhaps the board was installing defaults to the EEPROM at this point) . . . the game was up and running once again.
As a sideline which is vaugely related to this topic, I has some ICs arrive from China labelled as 'AT28C16-15PU'. I could not get these to work in this board or even be tested with my EPROM programmer. The ICs failed the pin test on all the pins, and could not be accessed in any way.
Whether I got a bad bunch of chips arrive . . . I don't know. I wouldn't recommend this type.
Van
Van Diesel2020-10-05 17:12:22
My good friend X (an inhabitant of the Devil's Temple) brought me his Rampart PCB for me to fix.
The symptoms were that the board was resetting every four to five seconds, with a blank screen through-out.
The board was in excellent condition with no visible physical problems I could detect.
All ICs were seated well. A lovely little board in excellent condition as it happens.
Checking the operation of the CPU, it was clear this was not a 'watch-dog' type reset . . . instead the CPU seemed to be running for a while, clearly objecting to something and then resetting itself.
I had read another fix log somewhere and it mentioned that the EEPROM IC (28C16) was a possible problem. This IC is used to store various stats of the game operation, coins taken, high scores etc.
I checked the IC on my EPROM reader and this IC was indeed faulty (multiple reads of the chip gave back different results). It was replaced with another device (specifically a KM28C16-20) and . . . after a few resets (perhaps the board was installing defaults to the EEPROM at this point) . . . the game was up and running once again.
As a sideline which is vaugely related to this topic, I has some ICs arrive from China labelled as 'AT28C16-15PU'. I could not get these to work in this board or even be tested with my EPROM programmer. The ICs failed the pin test on all the pins, and could not be accessed in any way.
Whether I got a bad bunch of chips arrive . . . I don't know. I wouldn't recommend this type.
Van
Van Diesel2020-10-05 17:12:22
