OK, I've been helping Robert with his problem (when I replied that I was helping my friend with a similar problem, I didn't realize he had joined the list and asked here about his problem! My friend and Robert are the same person!) We did some more debugging: * The U62 bank-select PROM _was_ bad, and having reprogrammed a new one with correct contents, are getting valid checksums for version 3A of the firmware on all the ROM contents * With the correct contents, and using Run UUT with the second 9010a, we hear a new beep every 4 seconds, but no display contents * We seem to be seeing a watchdog issue: Running the display and keyboard tests (triggered by writing non-zero values to 0x10081), we see the tests begin and then stop. In particular, the display tests should run continuously but they stop after ca. 4 seconds, which implicates the watchdog * Trying R14 to ground, which disables the watchdog, allows the display and keyboard tests to run normally: The display unit is fine * Testing out the Probe PIA, we seem to be seeing correct signals, but that testing uses the R14/watchdog-disable, so that may not prove anything. Does anyone have any ideas on how to debug the Watchdog? There really isn't that much in the Service Manual on this part of the circuit. grant.. On 2017-08-08 3:05 PM, robert via Techtoolslist wrote: my fluke 9010a rev 3a is not booting the diplay doesnt go on i think its a watch dog problem i have the service manual but it doesnt seem to cover the 3a rev fir mware for the rom signatures all my power test points are good and also i get a beep when power on but no display does anyone have any idea what could be the ca use of the shutdown _______________________________________________ Techtoolslist mailing list [1]Techtoolslist@flippers.com [2]https://pairlist7.pair.net/mailman/listinfo/techtoolslist FTP site is: [3]ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: [4]http://seven.pairlist.net/pipermail/techtoolslist/ References 1. mailto:Techtoolslist@flippers.com 2. https://pairlist7.pair.net/mailman/listinfo/techtoolslist 3. ftp://ttl.arcadetech.org/TTL/Test_Equipment 4. http://seven.pairlist.net/pipermail/techtoolslist/ _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com https://pairlist7.pair.net/mailman/listinfo/techtoolslist FTP site is: ftp://ttl.arcadetech.org/TTL/Test_Equipment Archive site: http://seven.pairlist.net/pipermail/techtoolslist/