Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!mcsun!ukc!axion!masalla.fulcrum.bt.co.uk!igb From: sie@fulcrum.bt.co.uk (Simon Raybould) Newsgroups: comp.sys.atari.st Subject: DEAD ST Keywords: OHH DEAR Message-ID: Date: 8 Jan 90 14:29:27 GMT Sender: Simon Raybould Organization: BT Fulcrum, Birmingham, England Lines: 36 I have been trying to fit an expansion into my atari ST 520STFM. I de-soldered all of the holes, soldered in the sockets, soledered in the 16 capacitors, and added the three resistors. I then checked the ST only to find that it won't boot. I have since removed the sockets and the capacitors and the three resistors, but still no boot. I have had a hunt around with a logic probe and all seems to be functioning. The only thing that I did notice is that the 2 of the 3 extra lines from the MMU are being held high, whilst the third is pulsing in much the same fasion as the original 9 lines. Does anyone know if these two lines from the MMU should be held high or if they should be pulsing. I have been advised that this is probably a solder wisker between two address lines or two data lines or between an address line and a data line. I have searched for this but have had no luck. The processor will sometimes stop altogether, with its HALT line low. When reset, it will go again for a while and then HALT. Could this be caused by a sloder whisker ?? If this is wrong then is my MMU blown ?? I am talking abaout the MMU side of the resistors that go to the DRAMs. The resistors are not in place as they are not in the standard 520STFM, so these connections go the the MMU and nowhere else !!. I beleive that only one of these three lines are needed to access the second 512K of RAM. Any help here would be much appreciated. S.J.R +-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-+-=-=-=-=-=-=-=-+-=-=-=-=-=-=-=-=-=-=-=-=-=-+ | Simon Raybould | BT Fulcrum | Are all your pets called | | path : sie@fulcrum.bt.co.uk | Birmingham | Eric ??? - Python | +-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-+-=-=-=-=-=-=-=-+-=-=-=-=-=-=-=-=-=-=-=-=-=-+