ATX PC will not start when printer is powered on

Edited text of question

Have you checked the laser printer recently on another machine?  Maybe something shorted out during the move.  Will the laser print a test-page when it is not connected to the computer?  Have you checked the BIOS settings for the LPT1 port and considered altering them?

Sounds like a power issue, a PC needs a huge surge of current on boot, if the printer is sinking any power at all from the port this could be enough to flip out the PSU, solution is either to turn the rpinter off every time, or, put it in a case with a bigger PSU. sounds like the PSU is a bit critical anyhow, so extra drives might cause a problem for it in the future. Though it could be the motherboard's "power good" detection being foiled by the printer sinking some, rather than a weak PSU. A way to check if it might be something other than PSU, might be to see if it does the same with an add in parallel port in that particular system, if you have a spare i/o card.
Sound odd, but a longshot is to try plugging the printer into a different socket, across the room from the one your PC is powered from. Oh, surge protected extension sockets can be a problem for that, anything else running on them when a PC is switched on, causing boot failures due to the surge protector acting and making the power the PC can draw brown out. *smile*

hope that is some help,

Road Warrior.

Have connected laser to add on LPT2 port, same problem. There is nothing wrong with the laser, it works perfectly Ok when powered on after the PC and also works perfectly well on a Pentium 133, none ATX machine. I agree that the printer connection is possibly draging the power down on the bus somewhere, could it be a BIOS setting?

I assume from the location of this question, that you are running either Win 3.1 or Win 3.11,why? (if I'm wrong ignore the comment)

Experience has taught me that the ATX form factor boards require a *minimum* power supply unit (PSU) of 230watts, personnally I would use a 250 or 300watt PSU.

In CMOS you might try disabling Power Management and try setting the printer port to SPP - if that is an option, otherwise EPP.

To Anray,
No I am not using Win 3.1. First time question ended up in the wrong area, but the question is not operating system related.
Will try out your recommendations in the New Year, thank you.

I have been building numerous ATX systems over the last fortnight and have found all have various jumpersettings on the m/board allowing the system to be powered on from such devices as the keyboard, network, mouse, modem, try looking up in you motherboard manual.. If you don't have one .. someone stuffed up. and look for a jumper that controld printer poweron. change it to the opposite of whatever it is currently at.
just a thought.

Have just returned from vacation, will evaluate all proposed resolutions tomorrow  5 Jan 99, thanks to all.
Happy New Year

No jumper on the motherboard associated with printer power on.
Have changed the settings in the bios from spp to epp and ecp, neither have any effect. Thank you.
Regards.

Try unhook the LPT cable and then Turn on the printer and the computer. i need to know if your problem is electricity or the LPT transmission. Try it and tell me what you got.

Your problem is a 'ground loop' through the parallel port,which triggers a 'soft crowbar' condition in the power supply.The hardware to replace here is the port.If you can find one with ground loop protection,it will cure this - but they're rare.I have a small supply of no-longer-manufactured cards that I use myself when this problem crops up,so I'm sure that will do it.Outside of trying various parallel port cards until you find one that works,you could plug everything into an outlet strip and use its switch to turn all on at once.

Eviltekk,
When LPT cable disconnected the PC and Printer both power up perfectly, the problem isn't power. The suggestion by MATTCE seems logical enough although, the ATX motherboard comes with the LPT1 port as an intergral part. I have already installed a separate LPT2 port (ISA PCB) but this has exactly the same effect.

Try Connecting the Printer to the power without using the ground cable (with a special plug which avaliavle in any hardware store) and see if its work. or you can try to cover with paper the 0 pin in the lpt plug plugged into LPT1. this will coverup the ground pin incase MATTCE suggestion is true.

eviltekk,
Thanks for you comments, I will try out you suggestion early next week.
Regards

You could try a printer cable intended for Amiga computers, only the essentials are connected and the grounds are not joined as I recall, due to similar wierdness being common with auto power on printers etc on that platform.

regards,

Road Warrior.

If that doesn't work, you could try resetting the CMOS - it's conceivable that you could have some wacky setting enabled that causes the powerup to fail.

Also, when you say your computer fails to start, exactly what happens?  Can you hear the power supply fan?  Do you hear any beeps?  Do you see anything (even a flash or some garbled characters) on the screen?  Tell us what happens and we might be able to figure out where exactly the computer is failing.

-JPC

Eviltekk,
Ground loop it was, used mains lead with earth disconnected and parallel cable with pin 0 blanked off, thanks for your help. How do I give you the points and close the question?