HP FB500 FB750 Getting a-pr-1 incorrect number of carriage encoder pulses error even after replacing encoder strip

[jmasten]

Hello. I am getting a-pr-1 incorrect number of carriage encoder pulses error even after replacing encoder strip.

1 I replaced the encoder strip and cleaned the reader.
2. The problem only occurs when I am putting down a lot of ink (see pic below). So I would think then that it is related to ink and not something else (pulleys, belts etc), but I don't know what else to do.
3. It seems to stop when trying to print more ink and on larger 4x8 sheets. If I print lighter prints I can print a lot more before the error, but I can't even print one with more ink coverage. I am printing on porous felt so probably more ink going down than on paper, but shouldn't the printer be able to at least print one full sheet? I used to be able to print quite a few before I needed to clean the encoder and this is a new encoder strip.
4. I added more fan suction to pull the mist and odor out from under the cover, but that didn't seem to help this problem.
5. Today I tried reseating the LVDC dad cable connection. I found a memo online you have to unplug this cable sometimes to reset it. That didn't help either.

Does anyone have any recommendations of other things to try or check? Thanks in advance.

 

[flyplainsdrifta]

I've had issues in the past with that on our old 750. Id take a look at that on the back of the carriage and see if theres any fuzz/dust/other nonsense in there and swab it out. If that doesnt help, that reader may need to be replaced.

 

[jmasten]

Thanks. I have blown it with air and tried to get a swab back there, but doesn't really get to the opposite side of it since the slot is so small. I just inquired about purchasing a new one and found a video on replacing. Have you ever replaced one? Seems like a pain to get behind the carriage. This is a link to a video I found on replacing it. Seems pretty thorough.

 

[flyplainsdrifta]

I did with help from a tech who came in on our service contract. Definitely a pain. If i recall, i believe we took the whole carriage off the rail and replaced it like that but it was like 3 years ago so i cant be sure. Been digging thru emails to try to find the service manual pages they sent on it. Will post if i can find it.

 

[jmasten]

Thanks. I will see what I can find online as well. I also have the service manual, but it can be vague sometimes. Do you still have the printer or did you upgrade?

 

[flyplainsdrifta]

We upgraded to a digitech trufire ltx2 for the volume we were doing. Basically 4x the speed of the fb 700 and 750 we were using in tandem. Still keep the 750 onsite in case of emergency but the digitech carries the work of like 3 of those things. Can run 100 double sided yardsigns in under 40mins. The speed and ease of use is pretty absurd. Id say the only thing worth mentioning is no auto detect on sheet size so you end up having to input that on runs but once you get used to the workflow, its amazing.