T1200 MFP printer/scanner question

[D Hook]

Re: T1200 MFP printer/scanner question

Been a couple weeks and no issues. Everything on the printer seems to work as it should now.

Of course, we had a power surge that toasted the power supply on the wide format scanner that is paired with this printer about a week after the printer went down. Checked for replacement PS and cheapest was around $250, with HP wanting about $385. Did some research using the model number on the power supply and found it's the same one sold as a replacement for a small form factor HP computer. Bought a brand new one for $29.00 off ebay, slightly higher wattage and installed and now the scanner is back up and running. But will need to go back into the scanner touch screen and do some adjustment on the extra wires that the new power supply came with like SATA power, etc. Need to trim those off and shrink tube the ends to make sure air flow is good.

So we're back up and running. (knock on wood)

[Kiran Otter]

Re: T1200 MFP printer/scanner question

Wow.. well I'm glad you found where the grease was coming from! I seem to remember working on a printer (5000 maybe) that had a mountain of grease added to the helical gear on the paper advance motor. Like enough grease for 100 printers. Came from HP that way.

Also got a service station once from HP that had about a quart of the oil they put into the absorbers.. and it didn't leak out until I put the box on its side on my couch. Picked it up the next day and there was a huge stain on my couch and the box was soaked.

Anyway, glad you got it sorted!

Kiran

[D Hook]

Re: T1200 MFP printer/scanner question

So I installed the new encoder disc today and did media advance testing and all the numbers came out just fine. No High Friction warning, no 81:01 errors.

Went ahead and put it all back together, tested again and it started skipping, just like it did before.

Took it back apart and found grease on the new encoder disc. WTF! I was so careful when installing the new disc!

Looked at the BACK side of the black spittoon cup that sits over the encoder and media advance drive gears and found piles of grease all over the back side/top of the cup. Also could see a track where the encoder wheel had been dragging through the grease. Not sure how the grease got there, whether from the factory or if the guys that worked on it before added it.

Cleaned all the grease off, put it all back together again and it's working fine.

That's something I should've checked when I first took it apart I guess. Just never thought to closely examine something as inocuous as the spittoon cup.

Live and learn.

So we'll use it for a few weeks and see how it behaves before declaring victory.

[Kiran Otter]

Re: T1200 MFP printer/scanner question

Good job!

Kiran

[D Hook]

Re: T1200 MFP printer/scanner question

UPDATE:

I went ahead and replaced the encoder disc with one from a T790. Before replacing, I tested the alignment on the media advance transmission and found it to be out of alignment. Tool was difficult to slide in place, indicating something wasn't sitting correctly. There are three screws that hold the transmission in place, one at the top and two at the bottom. Loosened all three and placed the alignment tool on and held it in place while tightening the three screws. When finished, the tool was bound up and wouldn't slide off easily. So I loosed all three screws again and tightened them one by one, checking that the tool was able to easily slide off between each tightening. The bottom two were fine but when I tightened the top screw, the tool got too tight. So I backed that screw off just a little bit until the tool was loose enough to easily slide off.

I no longer get the "High Friction" warning.

The "speed error" reading is now 22.75 / 14.25. That's a significant difference.

The "PWM St Dev" is now 47.72 / 42.41

The other numbers are similar to what they were earlier WITH the white gear in place.

Did some test prints and had no 81:01 error and everything worked as it should.

So I'll replace the encoder disc with a new one when it gets here and test it out for a few days and see if the problem is solved.

[D Hook]

Re: T1200 MFP printer/scanner question

Decided to just order a new encoder disc.

Tested WITH the white gear in place:

PWM AVG: 8480 / 8449
Speed Error: 159.75 / 34.25
St Dev.: 60.57 / 45.30
PWM MAX: 8460 / 8638

Tested WITHOUT the white gear in place:

PWM AVG: 7823 / 7909
Speed Error: 127.75 / 31.75
St Dev.: 61.20 /49.76
PWM MAX: 7983 / 8138

Checked the service manual and it says:
"The first PWM avg result (forward move) should be between 7700 and 10560 and the second PWM avg (backward move) between 7600 and 10450".
"The first Speed error result should be no more than 78.65 and the second no more than 112.5"
"The first PWM StDev result should be no more than 162.5 and the second no more than 187.5"
The first PWM Max result should be no more than 12250 and the second no more than 12125."

Still getting the high friction warning without the gear in place.
So it looks like there's some numbers way out of whack.
I haven't adjusted the media drive transmission yet until I get the new encoder disc.

While I was doing the testing, it started doing the skipping thing again so I cleaned the encoder wheel again because I could see a bit of a smudge on the outside of the wheel. Took care of the skipping. The smudge was there when I removed the left cover so not sure how it got on there.

Once I get the encoder wheel in, I'll do a new alignment on the media drive transmission and see if that fixes the friction warning.

Thanks for reading.

[Kiran Otter]

Re: T1200 MFP printer/scanner question

You can reuse it assuming it still sticks well.

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

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

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

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

[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

[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.

[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.

[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