I have a RAMWorks III card I am trying to get running in a Platinum IIe, and am running into stability problems. The board is a REV E.
When this card is inserted, there is a faint but noticeable high-pitched sqeal from the power supply. Despite the noise, the card itself works --all memory passes diags (using AE's RAMWorks tester) and is recognized in Appleworks, etc. The IIe itself will pass diags as well using Apple's IIe diagnotics, and the system will in fact run normally for about 15 minutes or so.
The first sign of something going wrong (other than the PS noise) is a bizarre "echo"/ringing sound from the power supply when the speaker beeps. This happens after the system has been running for several minutes. Very shortly thereafter the system will start crashing with symptoms that resemble bad RAM (random characters showing up on an otherwise normal text screen, hangs). There are no abnormally warm components on the RAMWorks board when this happens.
I have tried the following:
* Depopulating the board (1MB->256K) -- reduces, but does not eliminate, the power supply noise. The system will still eventually fail as noted above.
* Replacing the RAM chips on the card -- no effect.
* Swapping in a spare power supply -- no effect.
* Tried the card a completely different IIe -- same behavior.
Based on the symptoms and my testing it seems the card is overloading the power supply, but the issue is cearly on the the card itelf and not the power supply. The Platimum IIe I want to use this in is loaded down with cards (SSC, PCPI Applicard, Trawswarp, Mouse, slinky card, Disk 5.25 controller, CFFA), and it is quite stable with all of these cards and the normal Extended 80-column card. I tried removing all cards except the RamWorks and Disk 5.25 controller and it made no difference. The other system I tried is an enhanced //e with no cards other than the disk controller.
Any ideas of where to begin? I do have a DVM, but no scope.