X68000 Power On Behavior

[mattsoft]

Greetings all...new X68000 owner here.

So I picked up a nice looking CZ-601 (ACE) that is basically a paperweight.

After researching this forum and other boards, I have re-capped the PSU completely and the CZ-601 is still dead.

What I'm wondering, since I'm new to the X68000, is what is the expected behavior of a working system on power on?

I'm guessing with the hard power switch on (on the back), the POWER LED on the front of the case should turn red, and the fan stays off.

When you press the soft power, I'm guessing the POWER LED on the front of the case turns green and the PSU fan comes on.

Can anyone confirm this is true?

As for troubleshooting the PSU, I'm also guessing that one of the +5v wires (orange?) to the bottom board (where the soft power switch is) should always be around +5v even if the PSU is hard powered on, but not connected to anything as the board needs +5v for the soft power.

Thanks!

[kamiboy]

You are correct on all accounts. The symptoms you describe are pretty typical for "dead" units. As for cause of death, well, the list is long. It could be the soft power on circuit on your PSU isn't working, most likely due owing to dead or out of spec resistors or diodes. There are a few known weakest links that you could try testing. Slightly worse could be things like dead crystals, IC's or worst case scenario dead custom chips.

[mattsoft]

Thank you kamiboy for the confirmation -- much appreciated! I'm going to replace the zeners on the PSU this weekend as I have some of those laying around. If that doesn't do it, I'm ditching the stock PSU and going Pico.

[mattsoft]

Welp, replaced all caps and zeners on the PSU and still no life (yes I checked the fuse). So screw this old thing, just ordered a PicoPSU and AC-DC adapter. Any good guides on building an X68000 PicoPSU?

[kamiboy]

I think there is one on the wiki, try doing a først um search. This subject comes up often enough.