T1200 MFP printer/scanner question

[Kiran Otter]

Re: T1200 MFP printer/scanner question

... They see the 86:01 and it's described as a "paper jam." So they think in terms of driving the paper, and get the transmission & the encoder disk. They also clean or replace the encoder strip... maybe because they realized THAT's what would cause the 86:01. But they have to install this transmission, because the customer paid for it and the tool.

This wouldn't surprise me. So many techs don't go for the 'least expensive item first' method. 86:01 is almost always caused by a encoder strip or encoder strip sensor problem. Unless the carriage is actually crashing into the media. Then if it's not that, you go for the roller encoder disc and sensor. THEN maybe its a carriage PCA problem with the encoder strip sensor? Or trailing cable, or EMOD... But like I said before, of all of the printers I've laid hands on, I've only replaced maybe 1 or 2 paper advance motors. Running the diagnostic tests should almost always lead you to the failing part. Though this is obviously a paper advancement issue, so that narrows it down pretty well.

And like the suggestion this tech has of replacing the carriage. Why replace the entire carriage? Unless it's physically broken, you just replace the parts.. like the carriage PCA. But there's no way the carriage is the issue here.

Also the paper advance calibration will not fix this gap in the paper advance; it's only for correcting fine gaps in carriage passes during draft mode. If there's a choice to restore the factory advance setting, I would do that and leave it alone.

I find it highly suspicious that they replaced the media encoder disc given the issue still remains. I would replace it again, and inspect it with a magnifying glass or scan it like I did.. look for defects in those tiny lines. I'm certain that's where the problem is at this point.

Kiran

[D Hook]

Re: T1200 MFP printer/scanner question

UPDATE:

Got the Designjet 800PS 42 working with the scanner and all the computers that need to print to it are set up with the proper driver and everything is working as it should.

We're beginning to talk to the company whose techs worked (are working) on the T1200 to see about what we're going to pay for and what we're not going to pay for. Since the media advance transmission wasn't the solution we're going to see about having them come and reinstall the old part and take the new part (and the tool) back. Then have them put on another encoder disc. Our supervisor doesn't feel it's right to pay for a part that didn't fix the problem. I passed on the comments from this thread and he's starting to understand that maybe those techs aren't doing the job.

So that's where we are right now. Still looking for another T1200 to replace this one.

Thanks everyone! Your advice and support has been outstanding! At least we can print again!

[D Hook]

Re: T1200 MFP printer/scanner question

Update #2:

Brought the T1200 home to work on. I have a T790 here that has ink station issues so I'm going to try swapping the encoder wheel and maybe the transmission from that into the T1200 and see if that fixes the problem. We're still using the 800 to print on and it's working very well but I'd like to find out the problem with this one just for my own knowledge base. I'm betting it's either the encoder wheel or the gear set that the transmission connects to to move the paper.

[D Hook]

Re: T1200 MFP printer/scanner question

I was going to replace the Media Drive and Encoder wheel/sensor with parts from the 790 but noticed this in the Service Manual:

"NOTE: Never install a previously used Endoer Sensor PCA. This can cause serious problems and may make the printer unusable."

Anyone have an idea why this is?

I see used ones on LPS and on ebay but don't want to brick the formatter or something else.

I've removed the right hand cover and the sound made when the printer skips is defintely coming from the left hand side.

I removed one of the gears that drives the Print Zone roller and it makes the skip disappear when printing line drawings but it's still there when printing renderings.

My next move is to take the Media Drive transmission out of the T790 and install it into the T1200. Was going to do the same with the encoder wheel and sensor but ran into that note in the service manual. I STILL think it's a mechanical issue, not software, because of the consistency in spacing of the skips.

[Kiran Otter]

Re: T1200 MFP printer/scanner question

I think you're safe using the encoder from another printer. These printers do store things like the model and serial number in odd places, but the roller encoder isn't one of them.

I'm glad you're getting to the bottom of this issue! I'm curious to see what the problem ultimately is.

Kiran

[D Hook]

Re: T1200 MFP printer/scanner question

Went back to the KISS method (Keep It Simple Stupid).

The original tech who worked on the printer told us he replaced the encoder wheel so I've not been looking at that as the problem.

Figured there wasn't anything to lose at this point. Took a moist paper towel and held it on the encoder wheel as it rotated to clean it.

Problem solved. No skips, no unusual ink placement on the rendering when printed in solid color. Everything is working as it should.

There is much rejoicing!

Learned a TON on this little project. Just wish it wasn't such an expensive lesson!

Thanks to all who chimed in and hopefully this will help others down the road.

[Kiran Otter]

Re: T1200 MFP printer/scanner question

I thought it was the encoder and/or disc all along. I'm glad you tried cleaning it first! Thanks for the update.

The fact they replaced the motor.... when all it that was wrong was the encoder disc was dirty...

Kiran

[D Hook]

Re: T1200 MFP printer/scanner question

Yep, you were absolutely correct on your diagnosis. NICE JOB! And thanks for the support. Really helped. I was ready to give up on this thing yesterday but just couldn't let it go. So I reread the thread and saw your response about suspecting the encoder disc and kept thinking "But they replaced that". But they didn't clean it after replacing (assuming they replaced it) so kept dismissing that as a problem. But there you go. Always the simple (cheap) stuff to try first.

*EDIT* Heard from another gentleman who said he had the same problem once. He accidently got grease from the gears smeared on the encoder disc. The grease is clear so it's not easy to see.

Now I just have to source a lower roll cover to replace one that has a broken hinge. Looking for used but not too common so might take some time.

Thanks again Kiran.

[D Hook]

Re: T1200 MFP printer/scanner question

New wrinkle in this repair saga.

Boss went to print a drawing today and got an 81:01 error. After rebooting the printer and selecting the same print from the list of drawings on the printer, we reprinted and it came out just fine. He said it's been throwing that error code almost daily.

So I did a Paper Drive test. Not sure how to interpret the results though. Also got a "WARNING: HIGH FRICTION" message on the display just before it gave a readout for the PWM. Here's the results:

PWM AVG: 8475.66 / 8477.13
Speed Error: 159.75 / 31.75
PWM ST DEV: 56.61 / 42.62
PWM MAX: 8632.00 / 8680.00

Looked in the service manual but not much info there as to what the results should look like.

The high friction warning was concerning but not sure what that applies to. I assume it means something is dragging. Paper feed maybe?

What does the PWM mean?
What does PWM ST DEV refer to?

Is this a sign the motor needs replacing?

After rebooting the printer, the next print comes out just as it should.

Thanks for any light you might shed on this.

[Kiran Otter]

Re: T1200 MFP printer/scanner question

Maybe it's your copy of the service manual, but mine has what the results should be like:

The PWM avg results must be between 16000 and 14000.
The Speed error results must be less than 50.
The PWM StDev results must be between 0 and 500.
The PWM max results must be between 15000 and 20000.

Was this the printer where the motor was replaced? If so they might not have installed it correctly. There's a specific tool for positioning the assembly during installtion and it's rather critical that it be in the right position otherwise the gears bind and you end up with too much friction. If the motor has not been replaced, I would make sure it's not something else in the path; labels wrapped around the friction roller or something jammed up underneath. It's very rare to have to replace the paper axis motor, but if this printer has excessive use, that maybe what needs to happen.

PWM stands for pulse-width modulation. The 'StDev' is the standard deviation.

Kiran

[Kiran Otter]

Re: T1200 MFP printer/scanner question

Something you might try, is eliminate the overdrive from the paper advance; remove one of the two larger white gears between the paper advance the the overdrive/starwheel area. Run the test again and see if anything changes. I'm attaching a picture with one of the gears removed.

2018-05-22 10.47.17.jpg

You have to remove the electronics module and spittoon.

Kiran

[D Hook]

Re: T1200 MFP printer/scanner question

When I was working on it earlier, I removed one of the white gears just to eliminate it as a possible cause of the skipping problem. It didn't have an effect on the skipping but I'll remove it again and make sure it's not a contributing factor to this problem.

Yes, the motor was included as part of the media advance transmission so all that is new. They did have the alignment tool when they installed the new part. Whether or not they used it I don't know.

Cleaning the encoder wheel solved the skipping problem but now I'm wondering if I should clean the sensors the encoder wheel travels between, in case there's some grease or something smeared on the sensor.

Thanks for all the info on the PWM readings. I'll take another look at the service manual. If the numbers I'm getting from the test are too low or too high, what does that mean?

As usual, thanks for the help!

[Kiran Otter]

Re: T1200 MFP printer/scanner question

Based on the warning and the numbers, I'd say there's something causing the roller/motor to turn with excess friction/stress. If you have the tool, I would repeat the process for installing the motor, make sure it's done correctly.

If it's printing correctly otherwise, I wouldn't bother trying to clean the encoder sensor. If it was fouled, you'd have errors galore.

Kiran

[D Hook]

Re: T1200 MFP printer/scanner question

Quick question: After I remove the encoder disk, do I need to replace with a new one or can I reuse the old?

[Kiran Otter]

Re: T1200 MFP printer/scanner question

You can reuse it assuming it still sticks well.

Kiran