[rescue] IPX modern PSU (hanshuebner)

[vom513]

Hello all,

First a bit of admin/update:

Original project (now RO):

https://github.com/hanshuebner/ipx-psu-replacement

New home:

https://code.netzhansa.com/hanshuebner/ipx-psu-replacement

On that note - the new site doesn’t seem to allow creation of a user account (it’s a “private hosted” platform ?). I reached out to him via the email listed on Github and no reply yet hence posting here…

I built one of these a ways back - and originally it seemed to work.  Now it doesn’t.  The behavior is that the IPX chimes and gets a green power LED - but never any video.  I’m guessing that the system is never “turning over” (i.e. CPU at least).

On the bench - I notice that the +12 is actually 11.7.  +5 / -12 seem okay.  Real Sun PSU (recapped) gives me a hair over 12.  hanshuebner will power up and supply voltage with no load.  Original Sun won’t (I connected an old Seagate 1G SCSI to molex to get it to come up).  Technically the MeanWell 12v module in the hanshuebner is in spec I think (+/- 3% ?). Regardless a data point in comparing the new vs. old.

A few more notes on my particular IPX:

- I have a PowerUP 80mhz CPU
- I have the (officially not supported) 501-1823 32mb memory SBUS card
- I do not have an internal HDD.  I run from an external (and externally powered) ZuluSCSI

So finally I was wondering if anyone who has built this has any insight or general electronics insight to what I am seeing.

My only two stabs in the dark are that the 11.7 vs. >= 12 is an issue.  Also the SENS line (which is connected) could have an issue ?.  Beyond that I have no idea what it could be or what to test.  I have thoroughly inspected the board for bridges / bad solder / blown caps etc.

Thanks.