NeXT Cube - powers on briefly then off again

On Oct 25, 2015, at 17:42, Ian Finder <ian.finder at gmail.com> wrote: No- if it works with the standard display, the supply is fine. Now that that's clear, I recall some cube supplies would do this without a load for a display- I used to test them by triggering the power-on pin, and seem to remember this behavior occurring if I didn't have a big-ass resistor attached across the pins that normally supplied power to the CRT. Try getting a dummy load on there, the circuitry you have may not be putting enough load on the lines that usually run the CRT to keep the supply in a steady state. Cheers, - Ian Sent from my iPhone >> On Oct 25, 2015, at 16:37, Toby Thain <toby at telegraphics.com.au> wrote: >> >> On 2015-10-25 7:21 PM, Ian Finder wrote: >> I would replace the electrolytic capacitors in the power supply before going further. > > Well, the problem disappears with the standard setup. You still think caps could be at issue with the splitter setup? What's your detailed thinking? > > --Toby > >> Sent from my iPhone >> >>>> On Oct 25, 2015, at 15:38, Toby Thain <toby at telegraphics.com.au> wrote: >>>> >>>> On 2015-10-25 5:28 PM, Toby Thain wrote: >>>> Hi, >>>> >>>> After a few years I wanted to try my Cube with the soundbox/VGA splitter >>>> configuration for the first time. (I have the fading phosphor N4000A so >>>> have been keen to have an alternate video solution.) >>>> >>>> However, all is not well. Using the keyboard power button, the machine >>>> powers on for a couple of seconds, just long enough to see a NeXT logo >>>> and grey desktop on the VGA (yay!) but then powers itself off again. >>> >>> >>> I did the obvious thing and tested it with a standard monitor and cable and everything is okay. So the problem must exist with the splitter/soundbox setup. Soft power signals? >>> >>> Any suggestions welcome. >>> >>> --Toby >>> >>>> Any clues? >>>> >>>> Thanks in advance >>>> >>>> --Toby >>>> (not having a good classic computing week) >