Hi all,
I have a Macintosh SE (M5011) with battery leak damage that stopped booting. Does anyone know what this is and how to fix it?
HISTORY
- Bought used. It worked normally for about a week, then one day it simply wouldn't start anymore. It had been left plugged in with the power switch off.
- I recapped the logic board and the PSU after it died, so the recap isn't the cause.
- The PRAM battery had leaked. The pad around the battery's + contact is completely eaten away: there is just a hole through the board there. So far I've only cleaned with isopropyl.
SYMPTOM
- The screen shows a raster with chaotic lines. No chime, no beep at all.
- 68000 pins 17 (HALT) and 18 (RESET) sit at about 0.01 V right from power-on.
- When I applied +5 V through a 1 kOhm resistor directly to the RESET pin of the 68000, it still stayed at 0.
WHAT I'VE CHECKED (multimeter)
- +5 V and GND at the CPU are fine.
- No short to ground on the RESET net with power off.
- R13 (1k pull-up) is good and properly connected.
- SND (343-0045-B): pins 5 and 6 are not shorted. Pin 6 reads about 45 Ohm to +5 V, which matches R4 = R3 (47 Ohm) on the Bomarc schematic. The reset button itself works.
- VIA pin 34, /BERR and BBU pin 38: no shorts.
- Address and data bus continuity between the CPU and both ROM sockets is good. /DTACK, /AS, /UDS, /LDS, r/W and /CE are good too.
Has anyone seen this before? Any idea what it is and how to fix it?
Thanks! Photos of the screen pattern attached (sorry for the quality)