Amiga 4000 Fast RAM problems

[spaceman88]

I've seen a few A4000 motherboards on Ebay that won't recognize Fast ram, then about 2 months ago my A4000 started to lose memory, sometimes it would boot with 16meg, sometimes 12 or 0. So I replaced the motherboard and everything worked fine until tonight an hour after I installed the software for my TBC, I had 0 fast ram. What the heck is going on with these boards? This is a standard desktop board inside a Toaster Oven tower case. It has a Toaster 4000 board, a Time Base corrector and a 40mHz Warp engine (with no fast ram, ram is on the motherboard)
Any ideas?

[tone007]

I thought it was battery damage that generally caused that sort of problem.

Either way, stick the RAM on the Warp Engine. It'd be way faster than motherboard memory.

[Tumbleweed]

A leaking battery can cause all sorts of problems. Even if the battery has been removed, if the board hasn't been cleaned properly the alkali can sit and eat through the board slowly over time and then show up. Try removing all the memory from the mother board and then fill one memory slot at a time. Start with the slot furthest from the battery.

Putting the memory on the Warp engine as Tone suggests is a good idea as it will give you a speed boost.

Weed

[spaceman88]

Hi,
I should have mentioned in my first post that the Warp Engine has a problem, it won't boot if you install ram, played with jumpers, different ram etc., no luck. Both of my boards had a leaky battery and I did the vinegar-baking soda thing. One of the boards was mounted vertically with the battery on the bottom so most of the leakage ran off the board. I tried to an A2000 memory board in the first A4000 but it didn't show up. Would a properly working Warp Engine (or similar) solve my problem or does the damage prevent all fast RAM from being accessed?
Len

A leaking battery can cause all sorts of problems. Even if the battery has been removed, if the board hasn't been cleaned properly the alkali can sit and eat through the board slowly over time and then show up. Try removing all the memory from the mother board and then fill one memory slot at a time. Start with the slot furthest from the battery.

Putting the memory on the Warp engine as Tone suggests is a good idea as it will give you a speed boost.

Weed

[Tumbleweed]

Do you have another processor card you could try? That will help you determine if the warp engine has a fault. Does the Warp engine work with ram on the other M/B? have yout ried making sure all the chips on the baord are socketed properly etc.

[terminator4]

And this is why whenever I sold good A4000, I asked some high money not comparable to some junk on ebay, where battery was not mainted properly...  if battery leaked and ate through the pcb, then the person just cleaned the surface its kinda of too late - looks ok to the eye but board will fail.   In your case, don't sweat on it, just populate the Warp Engine as its way faster and can get more memory on it.

A leaking battery can cause all sorts of problems. Even if the battery has been removed, if the board hasn't been cleaned properly the alkali can sit and eat through the board slowly over time and then show up. Try removing all the memory from the mother board and then fill one memory slot at a time. Start with the slot furthest from the battery.

Putting the memory on the Warp engine as Tone suggests is a good idea as it will give you a speed boost.

Weed

[Castellen]

@spaceman88
I'd agree that battery corrosion is the likely cause of damage.  This typically affects PCB tracks, vias and U891; part of the fast memory bidirectional bridge.  In bad cases, the SIMM sockets themselves can be corroded to the point that they require replacement.

I can repair these fast memory problems for you, including repairs to the RTC circuit.

Email me for an estimate:  http://amiga.serveftp.net

[spaceman88]

Yes, I have a 68030 board. I have not taken the tower apart yet, but I'll try it on the first motherboard to see if I get lucky. The Warp engine won't work with RAM on either M/B.

Do you have another processor card you could try? That will help you determine if the warp engine has a fault. Does the Warp engine work with ram on the other M/B? have yout ried making sure all the chips on the baord are socketed properly etc.