Hi all, I’m working on bringing up an Apple Lisa 2/10 with CPU board 820-4009-B. The machine appears partially alive but does not produce any usable video output besides a raster and has the clicking speaker. I’ve removed the floppy and widget drive for testing.
I have already did a recap on the CPU and I/O board and have had no change in behavior. No damage to the boards as this does not have the battery pack.
Also plugged in an Apple /// monitor and it behaves basically the same as the internal one.
Looking for some advice as I’m wondering if this is video RAM related, I did reseat them but no difference.
Current symptoms
• CRT powers up and produces a stable raster
• Screen shows horizontal bands/interference but no text or graphics
• No startup message or errors on the screen
• Constant click when powered on
• Behavior is unchanged even with RAM removed, clicking stops when I/O board removed
Troubleshooting done so far
CPU
ROM
I have already did a recap on the CPU and I/O board and have had no change in behavior. No damage to the boards as this does not have the battery pack.
Also plugged in an Apple /// monitor and it behaves basically the same as the internal one.
Looking for some advice as I’m wondering if this is video RAM related, I did reseat them but no difference.
Current symptoms
• CRT powers up and produces a stable raster
• Screen shows horizontal bands/interference but no text or graphics
• No startup message or errors on the screen
• Constant click when powered on
• Behavior is unchanged even with RAM removed, clicking stops when I/O board removed
Troubleshooting done so far
CPU
- Reset line tested with oscilloscope:
- Goes high at power-up and remains stable
- Drops correctly when reset button is pressed
- Clock signals appear present and active
ROM
- Both ROM chips removed and verified using programmer
- ROMs match known good Lisa ROM
