I had not tried the test utilities but RAMTST claims my RAM is good on several runs.
I might have to expand my reflowing beyond just the RAM ICs. Haven't checked voltages or the top side of the board yet. Thanks. -Josh On Mon, Sep 25, 2017 at 12:09 PM, Fugu ME100 <[email protected]> wrote: > Hi > > The ‘bodge’ is a 30 year old ‘oops’ and should be present, if I remember > they are both ground wires :) They have been on every T102 I have looked > at but perhaps they fixed the board layout in the newer runs so I would not > like to claim it was standard. > > You may have already tried these options but…. > > Have you tried the RAMTST.BA or RAMCHK.BA utilities to check the SRAM is > OK? They are available at http://www.club100.org/library/libutl.html > > The T102 PCB is not very good quality and traces tend to develop > micro-cracks after a while, it could be that one of the lines to an SRAM is > cracked? I had that issue with a T102 where a trace to the reset capacitor > was cracked, only discovered after some continuity testing. The bad trace > meant the T102 only started after power on with a push of the reset button. > > I assume you have checked the +5V is good as are –5V and VB? None of the > Electrolytic caps have leaked? If voltage levels are not quite right some > of the chips will not operate correctly and may exhibit weird behaviors. > > One tedious option is to use a magnifying glass to inspect all the through > hole part solder joints. Again I have found areas of a board that had not > been reflowed properly causing dry joints on a board that had been > working. In this case it was the Clock IC which had the bad joints causing > the clock to produce odd results and a few other things to fail. > > From: M100 <[email protected]> on behalf of Josh Malone < > [email protected]> > Reply-To: <[email protected]> > Date: Monday, September 25, 2017 at 7:32 AM > To: Model 100 Discussion <[email protected]> > Subject: [M100] M102 weird behavior and bodge wires > > All, > > I'm trying to track down the source of odd behavior in my 102. It's had a > long history of memory problems that I thought I had resolved by replacing > the decoder IC. Some time after that, it developed an issue where trying to > load CO exes via basic loaders would cold-start the system and it would > boot reporting only 8k installed. > > Greg suggested a bad solder joint, so I reflowed all the RAM and decoder > joints on the board. THis has changed the behavior a bit. This time I was > able to load TSD.DO via telcom, but "load"ing it into BASIC cold-started > the machine to reporting ~11k free. > > Also, while soldering the RAMs I noticed what looks to be a very bad bodge > on the printer port. These 2 are clearly making contact (verified w/ > meter). The top wire goes to a cap to ground, the bottom one runs to a pin > on an IC that I didn't bother checking. Are these normal on a 102? > > https://drive.google.com/file/d/0BwcKlz5N5PLcYnR6XzZPYlpyRDNXN > Wo2THhPYURpMlQzZWc4/view?usp=sharing > > Thanks, > > -Josh > >
