Random Communication Faults in the Docutech Family

Probably one of the most frustrating system faults is the elusive communication fault that refuses to go away. Actually the machine is quite perceptive and just when you think you have the communications problem almost solved, it will automatically change to something new. When you enter the SCP screen to see if there are any other associated faults, you get that brief “gotcha” message before the screen displays any additional information. We have all had them at one time or another in our 5090 and Docutech family of printers. They remind me of the 19th century Gremlins waiting for you behind a tree or something with an axe handle. It’s their way of saying, “Hey there guy, I gotcha”.

About two months ago, one of my self-maintainer customers called me with an intermittent 03-243 communications system fault. Needless to say, this very bright fellow taught himself how to repair the copier just by observing the technicians and felt qualified to do his own service. Eventually he confided in me that he called his parts supplier for telephone help, and between the two of them that usually got things resolved. This usually happened after spending many hundreds of dollars for parts. After purchasing a FBN CORE PWB (part number 160K23970), PHN CORE PWB (160K23970), and two DIO PWB’s (160K23990) he decides to call me. Editors note: Keep in mind that all parts support vendors are in business to make money. Several vendors have a customer help line for self-maintainers, and I think that’s commendable. It is extremely hard to isolate a machine electrical problem when you are on the phone two thousand miles away and are not able to take accurate electrical readings from a competent electrical meter. Actually their job is quite difficult because they truly want to help the customer resolve their problem, and since telephone diagnostics are usually free, where they make their money is in replacing parts that are suspected to be defective. Unfortunately if the vendor makes a mistake and sells them an electrical component that doesn’t fix the problem, then it is assumed that an associated component could also be defective. So they sell you another PWB or two. Hey, it’s happened before where one bad PWB took another PWB (or two) out when it failed.

Personally this type of service call has me somewhat concerned because as a technician, the customer’s blunders have to be fixed first before we can tackle the real machine problem. After a small technical talk with the customer I convinced him it would be to our best interest to restore the copier to its original condition before he replaced any PWB’s. Miraculously he remembered which PWB’s were replaced; he used a magic marker to tag the PWB’s. Bless his heart.

After restoring the copier to its original state, we powered up the copier and it did display a system fault code of 03-243. Incidentally this was the original fault code the customer had before replacing the PWB’s. This system fault tells us that the PHN Core PWB cannot communicate with the PHN DIO PWB #3. The DIO failed to respond to a polling message from the PHN Core PWB. Not being a rocket scientist I followed the Initial Actions in the RAP. That seems simple, elementary and direct doesn’t it? The machine is trying to tell us there is a simple communications fault where communications between two PWB’s is not happening. I think the first question we should ask ourselves is whether the BUS connector that goes from one (any) PWB to another is making a good connection. . All too often we tend to be kind of brutal when connecting or disconnecting a BUS connector and we distort the connector at the end of the wire every time we disconnect the BUS line. It actually happens after many attempts to mate and un-mate the connector. In the case of the 03-243, the BUS line from the PHN Core PWB to the DIO PWB #3 was quite loose at the DIO J5 connector on the line itself. It was just a bad wire.

What complicated matters in this situation was the customer could not tell if the wire connector to the DIO PWB was bad or if the PWB was bad. Form a layman’s point of view, the connector on the BUS line looks ok and it seems ok; therefore it must be the DIO PWB. The customer made no electrical measurements because there was no electrical meter available. And even if there was one available, it would have checked out electrically ok. Being this was an intermittent 03-xxx-system fault, it was harder to troubleshoot and one of the troubleshooting tips the service manual actually asks you is to jiggle BUS lines to see if you can change the state of the system fault. In this situation the machine was in standby and ready to print when I started to jiggle the bus lines to the PHN DIO PWB #3. Then I noticed the 03-243-system fault. When the machine is in print there is a considerable amount of vibration in the machine and from the vibration, any loose connectors will intermittently fail. That’s why you are able to clear the system fault on the screen and return to productivity.

Let’s say for the record, if the customer was able to accurately relay the problem and the symptoms to the help desk and the vendor was correct in the choice of parts to resolve the issue, there was only one additional hurdle to consider: the correct position of the J2 Jumper on the CORE PWB’s. That would mean additional telephone time to diagnose and locate that elusive J2 Jumper and troubleshoot the fix. By the way, both of the Core PWB’s had the J2 jumper on the wrong jumper pins. At this point I was not going to swap out the PWB’s to see what system fault I had, but I did make it clear that whatever code he was getting, it was due to the wrong position the J2 Jumper was connected to. Always be super aware of what pins the Core PWB J2 connector is covering. When in doubt, check the service manual for the correct position. There is one quick way to see if they are all jumpered correctly. And that’s by checking Dc-303. If any Core PWB is not in line, this screen will show it to you in a heartbeat.

Information for the shared line termination Jumper J2 is as follows:

Document Handler Node (DHN) Core PWB J2 should connect
pins 2 and pin 3.

Marking Image Node (MIN) Core PWB J2 should connect
pins 1 and pin 2

Paper Handling Node (PHN) Core PWB J2 should connect
pins 2 and pin 3

Finisher Binder Node (FBN) Core PWB J2 should connect
pins 2 and pin 3

Notice that all the Jumpers connect pins 2 and 3 except for the MIN Core PWB and that’s because by jumping pins 1 and 2, it tells the machine logic that this is the last PWB on the BUS. But I’ll bet you already knew that and I was just thinking out loud. Hey, someone has to be last in line.

If I was able to help you out in any way with this article, please let me know. I am always open for ideas and suggestions. And if you have a specific issue with a Docutech system printer or any 5090 family copier, please feel free to contact me at: VillageCopierNY@AOL.COM