lowen
Veteran Member
well the village idiot struck again...Yes me while I was attempting to isolate the HD problem with the controller I accidently plugged in the Static RAM chip in backwards. ...
Why do I do these things! I know get in a hurry and don't double check.
Looking at the schematic, you may have done more damage than just the PAL. The SRAM is directly connected to the WD1100-11 (U27), a 74LS244 (U21) is connected, among other chips. You need to look at the schematic, pages 226 through 228 in the PDF of the 6000 SM in the archives (237, 239, and 241 in the hardcopy), and suspect every single chip that touches the SRAM chip. Oddly enough, the PAL at U18 shares no lines in common; just because the system will boot with it out does not mean that it is bad and everything else is good. You really really need to not try to troubleshoot this with just a DVM.
The good news is that these controllers show up more often for sale than the type 2.
For the type of damage that this sort of reversal can cause, look at the thread on this forum:Free to a Good Home (with conditions) (I know it wasn't a chip reversal that caused that, but rather an improper cable, but the type of damage you can see is very similar, and could be difficult to diagnose.) The other bad news here is that the equations for these PALs are not in this manual.
On the bright side, it may only have fried the SRAM chip. But if it won't boot with the SRAM out, that's probably not the case.