Okidata ML393 issues - Page 1
Forum section: electronics / general

author: Expos4ever
author_rank: Newbie
timestamp: August 23, 2012, 06:52:42 am
content: HiI have an Okidata ML393 dot matrix printer that I got circa 1989, and darn it if I just can't part with this old war horse.The printer was in storage for a couple years due to moving and instability, now that its over with I'm trying to add it back to my home network.The printer itself has an unusual problem. Without a parallel cable the printer has a self test and everything goes green. A new cartridge is installed and the tractor feed seems to be fine.When the parallel cable is attached the printer powers down to the point where only the green power light is on. The error light doesn't display anything and its the same effect as if you turn it on without having the personality cartridge plugged in. Powering on the printer produces no self test and doesn't produce the normal buzz that this printer makes. and no other lights come on.Thus far in testing I've tried a different power outlet as I noticed the problem with everything hooked up I thought the power bar wasn't giving enough power.I've tried three different cables that I had in storage. All produce the same result. I've tried two different V1.0 PPSX1 Linksys print servers just to see if it was one of them malfunctioning, both produce the same result and I know that the Okidata and one of the PPSX1 ones happily worked together for over 10 years.Anyone have any suggestions, or insights?I joined because of this topic which is as close as I can find to anyone else reporting a similar problem with an Okidata printerhttps://www.eevblog.com/forum/general-chat/oki-dot-matrix-printer-annoying-problem/

author: SeanB
author_rank: Super Contributor
timestamp: August 23, 2012, 03:20:33 pm
content: Have you tried it with the cable plugged in and the print server not plugged into the cable?It sounds like the 5V supply to the centronics connector is being pulled down by the cable or the server.

author: amyk
author_rank: Super Contributor
timestamp: August 24, 2012, 07:29:02 am
content: Check the cable for shorts between the connectors.If attaching only the cable with nothing else results in this problem then see if there are big EMI emitters in the area that are causing it to act like an antenna and possibly glitch the CPU.Get out your multimeter (and scope) and check for abnormal voltages like SeanB suggested.

author: EEVblog
author_rank: Unknown
timestamp: August 24, 2012, 07:42:33 am
content: A bit off-topic, but I've been trying to score an old cheap dot matrix printer to use as a "teletype" for the live show.Darned if I can find one cheap though, you'd think people would be just throwing these things away like the do with the cheap inkjets....Dave.

author: amyk
author_rank: Super Contributor
timestamp: August 24, 2012, 07:56:51 am
content: Quote from: EEVblog on August 24, 2012, 07:42:33 amThey're still used a lot in retail and related, for multipart forms and the like. They're also a lot more robustly built, for continuous use. Consumables are cheap and long-lasting. Consumer-level inkjets are nowhere near them in terms of quality and TCO....and they're still being made, so it's not like they're obsolete:http://www.amazon.com/Okidata-Microline-Impact-Dot-Matrix-Printer/dp/B0002D6Q6M

author: EEVblog
author_rank: Unknown
timestamp: August 24, 2012, 07:59:28 am
content: Quote from: amyk on August 24, 2012, 07:56:51 amYeah, I was just hoping there would be plenty of them left lying in cupboards from the 80's no one wanted!Dave

author: amspire
author_rank: Super Contributor
timestamp: August 24, 2012, 08:03:26 am
content: Quote from: EEVblog on August 24, 2012, 07:42:33 amI have a Citizen GSX140 that hasn't been used for at least 20 years. Plus 3 spare ribbons I think.A 24 wire colour dot matrix printer. Friction or tractor feed - rear or bottom feed.http://www.virtualizationadmin.com/files/whitepapers/ultimate_printer_manual/printers/mczg14.htmNot a bad printer at the time. You can have it, if it is any use.Edit: Looks like it works - I got it to print "Citizen GSX140". Looks like the ribbons I have a black ribbons, not the colour ones. The ribbon in the printer still works amazingly.The feed is top feed or bottom feed - there is no back feed. The LCD panel is now faint, but readable.

author: EEVblog
author_rank: Unknown
timestamp: August 24, 2012, 08:24:47 am
content: Quote from: amspire on August 24, 2012, 08:03:26 amAwesome, thanks, if it's not too much trouble.What would postage cost?Dave.

author: amspire
author_rank: Super Contributor
timestamp: August 24, 2012, 08:30:41 am
content: Quote from: EEVblog on August 24, 2012, 08:24:47 amIf you can pay for postage, that would be great. I added a link to a user guide above.Looks like it will weigh 3 to 4kG to post - not too bad. Do you need a parallel printer cable as well?The earliest I can post it would be Monday. I think it will be about $15 regular post or $33 express post.Richard

author: amyk
author_rank: Super Contributor
timestamp: August 24, 2012, 08:38:18 am
content: Quote from: amspire on August 24, 2012, 08:03:26 amLCDs don't wear out unlike VFDs or OLEDs. Could be a bad cap or a resistor in the bias voltage divider that's drifted over time.

author: EEVblog
author_rank: Unknown
timestamp: August 24, 2012, 10:20:59 am
content: Quote from: amspire on August 24, 2012, 08:30:41 amDone deal.Just let me know the total and your PayPal address.Regular is fine, I'm in no hurry.Will probably want to make a custom cable for this, I want to control it from an Arduino.ThanksDave.

author: amspire
author_rank: Super Contributor
timestamp: August 24, 2012, 12:35:08 pm
content: Quote from: EEVblog on August 24, 2012, 10:20:59 amI have the perfect cable then. A printer cable with non-molded screw-clamped connectors. I will send it with the printer. The printer has the colour ribbon in it and it probably has some life in it. It doesn't look all that used. I am also sending 3 black ribbons still in sealed packs.There is meant to be a sheet holder for single sheet feed - I will see if I can find it. It will work without it, and the feeder is not needed for tractor feed.Looks like the printer can do Epson LQ and IBM X24 emulation.There is an optional RS232 interface card. It may be you can plug a ribbon cable and drive the printer via RS232 protocol. If they are using a uart on the processor, you may be able to use it. The printer works by looking at which interface gets the signals first, and it makes that the default interface. So nothing need to be switched to use serial protocol instead of Centronix parallel.Richard.

author: EEVblog
author_rank: Unknown
timestamp: August 24, 2012, 12:43:18 pm
content: Yep, serial might be a better option, but that cable sounds good, thanks.I used to write my own printer code to drive these printers direct back in the (DOS) day, and knew all the Epson and IBM codes etc. Know I don't remember a damn thingDave.

author: firewalker
author_rank: Super Contributor
timestamp: August 24, 2012, 01:23:13 pm
content: Every public service in Greece uses dot matrix printers (especially the tax). It is easy because they use a continuous piece of preformated, perforated paper.Alexander.

author: amspire
author_rank: Super Contributor
timestamp: August 24, 2012, 02:25:38 pm
content: Quote from: EEVblog on August 24, 2012, 12:43:18 pmMy wording wasn't to good. I meant to say there is an optional card space, but I do not have the card. Just the connector for the card.The card could have had a uart on it, or it could use a uart in the micro, and the card would have then been just the level converters and perhaps some switches going back to the micro to configure the RS232. If the uart is on the micro, then you may be able to use the micro's serial interface without the proper RS232 card.Otherwise, you will have to use the parallel interface.Richard.

author: Expos4ever
author_rank: Newbie
timestamp: August 25, 2012, 06:09:34 am
content: Hi everyoneThanks for the replies.With just the parallel cable in the printer and it connected to nothing it boots and works fine. It's when I add it to a powered print server that it powers down. I have three parallel cables in total and the behavior is the same in all of them. As well I have two print servers and they both produce the same results.As for EMI emitters, I'm living in the core of a major city so I suppose its possible. But I don't see any obvious sources like broadcasting towers or cell phone towers in my immediate vicinity.Playing with the printer today I noticed in addition to the parallel connector it has a 25 pin serial connector that was behind a metal cover with two screws attached and Its never been used all these years, in fact I never knew it was there. Digging around my box of old wires I found a 25 pin to 9 pin serial adapter and a 25 female to 25 female serial adapter but no 25 pin serial wires or serial to parallel converters :/I'm going to experiment with it and see if I can get it to work through the serial port. I just found pinouts for the printer for both ports.http://my.okidata.com/MAN393HB.NSF/WebBPXContents/7B5095A80C8207BD852565750059A4E6?OpenDocumentI will dig my multi meter out of storage and see whats up.

author: Expos4ever
author_rank: Newbie
timestamp: August 25, 2012, 06:32:21 am
content: Okay, so good newsThe printer now works great.I got it to print. It looks like it's a grounding issue. I tried one of the parallel cables again just now for the heck of it and it failed as before, but accidentally knocked the top metal tab that holds in the centronic connector with my and the printer roared to life. It looks like it just wasn't making clean contact.I just sent a test page to the print server and it came out crisp and clean.

author: amyk
author_rank: Super Contributor
timestamp: August 25, 2012, 08:25:14 am
content: Quote from: Expos4ever on August 25, 2012, 06:32:21 amThat is rather strange. You may have just masked the real problem. Ensure that the outer shell is not carrying any current, as it shouldn't be; there are ground pins in the connector. The fact that it wouldn't even power up correctly with the cable connected before suggests a more serious fault.

author: SeanB
author_rank: Super Contributor
timestamp: August 25, 2012, 10:39:56 am
content: You might want to open the centronics cable connector ( if it can be that is, and is not moulded on) and disconnect the 5V rail in there, as the print servers could be pulling it down to ground.