Hi,
I have been working on a stargate cpu board and need some help. The board goes all the way to all systems go and I get a zero on the ROM board and then it resets. The signals at 7G pins 8 and 9 are weak compared to my working board set. If I switch my logic probe to CMOS I can see the pulses but on TTL the probe makes a very waek noise and I can see the change in logic. I replaced 7G to see if it was being loaded down by the chip. I also noticed that the address bus A7, A*, A12 and A14 latch low when the MPU resets.
This started when I replaced IC1 to correct a issue with CMOS. I have remeoved and replaced the chip and with the old or new it has the same issues.
I looked at the theory of operation for defender and it talks about cutting the watchdog circuit and grounding the input of the or gate. Do you also need to ground the input if you do this on the stargate board?
Thanks
Dan
I have been working on a stargate cpu board and need some help. The board goes all the way to all systems go and I get a zero on the ROM board and then it resets. The signals at 7G pins 8 and 9 are weak compared to my working board set. If I switch my logic probe to CMOS I can see the pulses but on TTL the probe makes a very waek noise and I can see the change in logic. I replaced 7G to see if it was being loaded down by the chip. I also noticed that the address bus A7, A*, A12 and A14 latch low when the MPU resets.
This started when I replaced IC1 to correct a issue with CMOS. I have remeoved and replaced the chip and with the old or new it has the same issues.
I looked at the theory of operation for defender and it talks about cutting the watchdog circuit and grounding the input of the or gate. Do you also need to ground the input if you do this on the stargate board?
Thanks
Dan