Hi all, With the help of your hints, I did some measuring today regarding the voltages. The voltages of the supply all lie in an acceptable range: 12,22V, 5,17V, 3,29V, -12,25V. I observerd recently, that when I turn on the VAX, it comes up with the languages menu und then freezes. The diagnostic displays turns from F to E and then back to F. Turning it off and on again doesn't let the menu come up anymore (and the "E" on the display") anymore. It's completey frozen then. I've got the impression, that some capacitors are playing bad games somewhere. Another thing: On the KA660-board, there are four other red LEDs, which turn on all together (and stay on) and there's a green LED. In the CPU maintenance manual, it says that this green LED stands for "DC-OK". Well, it doesn't burn when power is applied... Furthermore, I measured the DCOK and POK signals: The voltage is 3,51V. Do I have to interpret that as a "signal high" ? Tomorrow, I'm going to measure the signals and voltages with an oscilloscope. Do you guys have any further hints? Regards, Pierre _______________________________________________________________ SMS schreiben mit WEB.DE FreeMail - einfach, schnell und kostenguenstig. Jetzt gleich testen! http://f.web.de/?mc=021192