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Parallel Ports: PC doesn't start with scanner or drive plugged in.

I've got a clone PC, Win95b, LPT1 is an add-on parallel card and LPT2 is the one on the motherboard: it was a right royal pain getting the IRQs right for these, so I hope I won't have to fiddle with them.
I've got a Syquest Sparq drive (LPT1), HP5100 scanner and HP LaserJet 6L (daisychained on LPT2).  They all work together pretty well, but: the computer will not power on if the scanner or the Sparq drive are plugged in.  I need to unplug them, start the PC, then plug them in as it boots.
I suspect it's a power supply issue: any hints?
1 Solution
Hi myoyce , I think you have hit it on the head. I have had the same problem using the hp6l.  It seems to be somthing with the smart turnon used by the HP it does however relate back to your power supply and the load place on it when you first turn it on having the scanner and printer plugged in.  As you stated everything works fine as long as you power on first.  I found the simpliest and cheapest option was to simply replace the power supply this was done after changing everything else in the system to try and isolate the problem including the motherboard.  Changed over power supply and no more problems.
I know this doesn't really give you the reason but hopefully you won't waste as much time as I did trying to find the fault.


This can be caused by a power supply OR parallel port design defect.In the case of the latter,a 'ground loop' exists with the device(s) plugged into the port.Try to narrow it down to one device,then move it to the other port.If it turns out to be ANYTHING plugged into one port,then it is a port problem - replace it with another brand.If it's the onboard port,disable it and add another plug-in port.

Alternatively,some cheaper solutions:

If you have an AT power supply,the simple solution is to use an outlet strip to power on everything at once.

If it's an ATX supply with 'soft' power on/off (most Pentium II systems use this),plug all devices EXCEPT the system into it,turn it on AFTER the system is powered on.
mjoyceAuthor Commented:
I haven't had time to chase this up, but this seems to explain it: I do get other errors if the PC shuts down without warning, so I think that irelandone's solution of replacing the power supply will be the simplest option.
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