J7 / P7

J14 / P14

Peter wrote:
One reason why it might appear as dead is, when for example a monitor is placed on top of the unit and the mechanical pressure through the monitor on the top cover presses down the vertical riser-card, so that the pins at the underside of the systemboard get shorted against GND on the case. This was pretty familiar mistake one some series of Mod. 55SX.

I would recommend to remove the top cover, all MCA-adaptercards and detach the harddrive cable from the riser-card and try if the system comes up again.

On some few occasions the 55SX suffers on a defective power supply, which did not send the "Power Good" signal to the board and this therefore does not come out of the pre-POST status (no reset, no Power On Self Test, all subsystems deactivated).

> A problem devloped with the 55SX Power Supply. If I flip the switch the system is dead, but if I leave it that way with the power on in about 5 to 10 minutes the system will boot normily. One time starting up I got a 1XX error with a few question marks underneath. and the syetm crased with a stak error System Halted, and after filliping the switch and waiting fifteen seconds the system refused to power on, but after sitting ten minutesw the power came on and the fan started moving.

Stephan Goll
Hello Mike. I believe, you are right with the power supply. But there is voltage up to 1.5 kv insight, and it´s not funny to get shocked by this.  But if you try, there must be a resistor (near the high-power capacitors) inside loading a small capacitor, that supports voltage for the low-voltage powered control-electronic. May be the resistor or the cap´ (or someing else) is wrong (and that is simplified). The 55 PSU contains only one board, not that complex, but be warned. Really only
for people, they know, what they do. Learned by experience. ;-|