Amiga Apollo 1230 MK2 - RAM not detected. :(

[Crashedfiesta]

So I have an Apollo 1230 MK2 which, when I first tried it, had 8mb of fast RAM. It's been in a (dry) box for the last few months and I pulled it out last night after I recapped one of my A1200s to try again but now no fast RAM.

Amiga Test Kit reports the 68030 at 50Mhz (but crystal is 40Mhz?) when its plugged in but only the 2 meg of chip RAM that the A1200 has. Things I've tried so far:

Cleaned every contact on SIMMs and every pin on the SIMM sockets
Cleaned the edge connector on the motherboard and the pins in the expansion connector on the 1230 board
Re-seated the GAL chip
Replaced the one SMD electrolytic (it's never the capacitors)
Tried a 32meg SIMM I had from an ancient HP PC
Tried it in a different A1200

None of the above have had any effect, the RAM is not detected.

Does anyone have any idea where to start with a fault like this? I was thinking maybe the three 74F257s under the SIMM socket on the CPU side or the ceramic caps associated with those chips but I'm clutching at straws a bit here..

 

[Timo W.]

It's a common fault on these Apollo cards that the MACH chips go bad. You may need to find another person with one and try swapping the MACH chips. (note: the chips are programmed, so you can not just buy replacement ones)

 

[Crashedfiesta]

It's a common fault on these Apollo cards that the MACH chips go bad. You may need to find another person with one and try swapping the MACH chips. (note: the chips are programmed, so you can not just buy replacement ones)

Thanks for that. I'll have to try reseating them for now as I really don't know anyone who would have one of these...