Amiga 4000 Dark Grey Screen
Posted: 23 Dec 2025 10:05
Hi all,
I recently acquired a Rev D (so no dreaded battery leakage) Amiga 4000 board that produces a dark grey screen on startup. The first thing I did was replace the capacitors and cleaned the board. Still a dark grey screen. I am using a know working set of Diagroms.
I have since discovered the following in no particular order:
1. 25MHz clock is present on the CPU.
2. No serial output from Diagrom.
3. U141 appears to be working (Pins 2, 4, 6 & 8 > low to high Pins 10 & 12 > high)
4. AS (pin 125 on the CPU) - no pulsing or waves when checking with my scope.
5. HLT and BGACK both are high. They seem to be high as soon as I power the motherboard
Can anyone provide further direction?
I recently acquired a Rev D (so no dreaded battery leakage) Amiga 4000 board that produces a dark grey screen on startup. The first thing I did was replace the capacitors and cleaned the board. Still a dark grey screen. I am using a know working set of Diagroms.
I have since discovered the following in no particular order:
1. 25MHz clock is present on the CPU.
2. No serial output from Diagrom.
3. U141 appears to be working (Pins 2, 4, 6 & 8 > low to high Pins 10 & 12 > high)
4. AS (pin 125 on the CPU) - no pulsing or waves when checking with my scope.
5. HLT and BGACK both are high. They seem to be high as soon as I power the motherboard
Can anyone provide further direction?