> Am 09.05.2017 um 18:10 schrieb Jon Elson <el...@pico-systems.com>: > > On 05/09/2017 08:26 AM, Philipp Pap via cctalk wrote: >> Anyhow, now I have 41 and 83 Volts at the 42 and 85V test points, >> but always 0 Volts at the +5,-12,+12,+15V test points. >> The fuses are good and the secondary transformer seems good as well. >> > Does this have a switching power supply for the logic (5, 12, 15V) or is it a > rectifier/filter/regulator off the transformer? > If rectifier/filter/regulator, it seems odd that FOUR voltages would quit at > once. So, I'm guessing it might have a switching supply for those voltages. > It sounds like the regulation circuit failed (display got brighter) and then > a crowbar circuit tripped to shut it down. Unless you are pretty skilled, > switchers can be a bit hard to troubleshoot. It might be easier to get a > supply with the needed voltages and just patch it in. > > Jon OK, I just read in the service manual „The power supple is a switching type dc supply incorporating a pulse-width modulator (PWM).“ but I don’t know the meaning on the drawing „+5V ref“ „vcc“ — POWER ON —„~RESET , HALT, RESET“ Could that mean that the problem could be in this „POWER ON“ block logic???
Thanks again!
