CompuServe Thread

The scene you described is what I often came across the last few weeks as I debugged my A1000 upgrade project. If you get nothing, no video (check composite port as well as RGB), no blinking LED, and no clicking 3.5" disk drive then you have problems. What I'd do: 1) Check Power supply for +5V and +12 V. Check for AC voltage as well. If either is off, Do not turn on as that can damage your computer. 2) If power checked out, then remove all expansion bus cards and cables to your parallel & serial ports. Power up and see if the machine comes up. Since you were telecoming, you might have had a cable short out one of the clock signals present. 3) At this point if steps 1) and 2) do not fix it you probably need to take the machine to the nearest authorized service center. This should be step 1) if the machine is under warrenty. The lack of any video or a blinking LED indicated that the CPU is probably dead or halting due to illegal opcodes or lacks the necessary clock phases used to enable and disable the expansion bus and bus drivers. The clock phases can easily be checked (generated by a crystal oscillator and the Fat Agnus) with a logic probe. If they are OK then proceed to check the address strobe of the 68000. If it oscillates continually, you are in fair shape. If only once after power or reset, then something on the address or data bus is bad and that can be any number of chips. At this point, unless you have spare ROMs, 8520s, 68000s, and Agnuses, and GARY and Buster to swap, you should go to the service center. -Greg