Oki Microline 320 Turbo 9-Pin Dot Matrix Printer

	Oki Microline 320 Turbo 9-Pin Dot Matrix Printer by bjb1178 (9/6/07 8:36 PM) reply	+ / -
I have one of these that I need to figure out what's wrong with it. I'm not exactly fimiliar with these dot matrix printers. The user attempts to print labels, it prints about 6 of them and then they get these strange characters. They turn the machine off, then on again and it prints another 6 labels, then does the same thing again. The print head has been replaced. Is this a board problem? What can I do to fix this? Thanks

	Re: Oki Microline 320 Turbo 9-Pin Dot Matrix Print by Bert (edited 9/7/07 12:16 AM) reply	+ / -
Make sure there isn't a computer issue. Make sure you have a good printer-computer cable and that its solidly connected on both ends. Run the printer self test by pressing the LF button while turning on the power. If printing problems are still evident during the self test and/or through the I/O, remove the case if you haven't already and direct some cool air at the main board. (There are several latches just under the front edge of the case that can be released with a slot style screwdriver.) If extra cooling extends the print time or solves the problem, I would replace the main board. Regardless, the main board is almost certainly the problem. There are no comprehensive schematic diagrams in the service manual to facilitate repairing it. Get the service manual free here. http://www.eserviceinfo.com You can inspect the carriage trailing cable but I've never seen a problem with them unless some strange "mechanical event" has occurred. Blow the paper dust out, particularly around the paper sensor. Clean the platen. There are products made for that purpose. If the backup roller assembly roller is made of plastic, replace it. The plastic ones get a flat spot eventually and cause margin drift. Lubricate the carriage drive rack gear with a light grease. If you are bold I suggest taking it out and cleaning it. Clean the carriage rod and lubricate it with a couple of drops of very low viscosity oil. I use Tri-Flow that is available at cycle shops. To much lubrication just helps attract paper dust. You can get parts at http://www.agson.com For your amusement: I once found dog biscuits inside one of these carried there by rodents. They even gnawed the case around the I/O opening. That taught the customer the pitfalls of feeding their customer's dogs.

	Re: Oki Microline 320 Turbo 9-Pin Dot Matrix Printer by mcprinter (9/7/07 12:49 PM) reply	+ / -
I have worked on a lot of these. Bert's advice on maintenance is spot on. It sounds like it is either a computer problem or the emulation on the printer is set wrong. i.e Printer set to Epson, the Computer is sending IBM control codes. Find a user manual and put the printer in hex dump mode and you will be able to see what codes are being sent to the printer.

	Re: Oki Microline 320 Turbo 9-Pin Dot Matrix Print by Bert (9/7/07 5:47 PM) reply	+ / -
It appears that two techs are better than one. mcprinter is trying to give me a head ache by mentioning hex codes. Seriously, the input is appreciated. I didn't think of an emulation problem. Refer to page E11 in the Users Guide to determine which mode the printer is in. http://www.precision.com/manuals/Okidata_ML320_321_Manual.pdf

	Re: Oki Microline 320 Turbo 9-Pin Dot Matrix Printer by bjb1178 (9/7/07 6:16 PM) reply	+ / -
Guess I will have to check the emulation out. I took the printer apart and took the boards out. I was going to swap out the boards with a brand new one we have but of course the boards are a different size. Nothing is simple these days. Hope I can get it to print more than 6 labels without the strange characters.

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