i cannot edit my posts so i add it here:
i got another VLB based 486/386 hybrid system (opti based) where this problem does not exist

2VLB that dont power on (one with onboard IO, one with VLB IO controller card)
1 PCI + 1 VLB that works (ISA IO controller card)

If the Zip drive is connected but not powered on does it still create the issue?

no, it works fine if the zipdrive is off.

Hi!

I came across posting or booting issues on many motherboards.

Now, I never had power on issues. I press the button and it just works, maybe hangs but I can hear fans spinning.
I'd try a different PSU and check if there are grounding issues, as it looks like some short (not sure, just a guess).
If you have a different Zip power brick, try another one. Could be the issue...

You could try with another controller card just for lpt, having HDD + FDD + COM on another.

A real iomega expert is needed here 😀

Edit: check if lpt from zip has all pins correctly issuing their signals. Change lpt cable if you are using the one supplied by iomega.
Also check signals at the Zip's unit port. Could be the short be there?
This is a huge hunch.

thanks for your suggestions i will consider them...
i already found another zipdrive in my stash: zip100plus... the plus feature seems to be: "autodetect if LPT or scsi"
stuff i tried:
switch PSU (the plus has a much smaller, near baby psu ... its only 5V 1A like the brick thats on the problematic lpt only zip drive)
try using the zip100plus with the problematic VLB 486: it works as in powers up and boots. but running guest.exe does not detect anything.
i know the zip100plus works but just to be sure i grabbed my L486E pci machine et voila, it properly detects the zipdrive.

so i guess i can rule out the zipdrives psu... i have to check if the autodetect cable is different from the LPT cable. then i will switch those for further tests.
i also have a 16bit isa controller card i could test but i guess i have to disable all onboard features like com/lpt via jumpers on the FIC vlb board... this will take some time 😀

will report back as soon as my time allows... thankful for any further suggestions/help

cucgod wrote on 2026-03-03, 13:27:

thanks for your suggestions i will consider them... i already found another zipdrive in my stash: zip100plus... the plus feature […]
Show full quote

thanks for your suggestions i will consider them...
i already found another zipdrive in my stash: zip100plus... the plus feature seems to be: "autodetect if LPT or scsi"
stuff i tried:
switch PSU (the plus has a much smaller, near baby psu ... its only 5V 1A like the brick thats on the problematic lpt only zip drive)
try using the zip100plus with the problematic VLB 486: it works as in powers up and boots. but running guest.exe does not detect anything.
i know the zip100plus works but just to be sure i grabbed my L486E pci machine et voila, it properly detects the zipdrive.

so i guess i can rule out the zipdrives psu... i have to check if the autodetect cable is different from the LPT cable. then i will switch those for further tests.
i also have a 16bit isa controller card i could test but i guess i have to disable all onboard features like com/lpt via jumpers on the FIC vlb board... this will take some time 😀

will report back as soon as my time allows... thankful for any further suggestions/help

If the problem were on the motherboard? If you can, post a pic of the mobo. Check area around the LPT for some blown component...
Maybe the Zip is working correctly after all.

You would get this kind of thing with printers back in the day when you had them plugged into a different socket/circuit than the PC. Ground loop issues. So that's my gut feel at the moment.

quick update:
i did try the all plugs into the same socket: no dice. still no power on
i also did check the zip100 parallel port installation manual in the web, which states the following:
"Always
turn on power to your computer before or at the same time as
you supply power to your parallel port Zip drive. "

and thats what i did: first the pc, then the zip drive. et voila everything up & running including guest.exe detecting the drive.

i will investigate further but at least i can use it now on this machine 😀
thanks everyone - problem has a workaorund 😀

cucgod wrote on 2026-03-06, 16:56:

quick update: i did try the all plugs into the same socket: no dice. still no power on i also did check the zip100 parallel por […]
Show full quote

quick update:
i did try the all plugs into the same socket: no dice. still no power on
i also did check the zip100 parallel port installation manual in the web, which states the following:
"Always
turn on power to your computer before or at the same time as
you supply power to your parallel port Zip drive. "

and thats what i did: first the pc, then the zip drive. et voila everything up & running including guest.exe detecting the drive.

i will investigate further but at least i can use it now on this machine 😀
thanks everyone - problem has a workaorund 😀

Very good!

I wonder if the LPT circuit has some kind of protection or similar in action.