asked Nov 20, 2008 at 4:15pm
Hp HP CopyJet Color

DesignJet 1050C belt replacement

Recently replaced a belt in an HP DesignJet 1050C. Instructions said to check continuity at points under right rear cover BEFORE connecting power and turning printer on. (I did not check this before disassembly.) This is due to disconnecting the Trailing Cable from the printhead so it can be removed to install the belt. I have continuity here, so I checked the Trailing Cable, twice. Still have continuity. So I disconnected the Trailing Cable from the electronic control module completely. I STILL have continuity. Color me puzzled.

Is there an issue with this or something that needs to be discharged? Are the instructions backwards? (I've checked the latest version of the manual.) Anyone ever run into this before? Instructions state that if there IS continuity, then the Trailing Cable is installed incorrectly and damage to the EM fuse can result. I REALLY don't want to fry the EM but I'm stopped until I can clear this up. The only thing I can think to do is remove the EM and closely inspect the sockets on the mainboard for any debris.

Any thoughts would be appreciated. Thanks.
Just went thru this!! no fun, wound up ruining the cable ends re-installing so many times trying to get the fuse to read open on the meter.

bought a new cable and installed same thing re-installed a couple more times before meter read open-not sure what the deal is here
but customer is running...

Good luck with yours
by Anonymous on Nov 20, 2008 at 4:46pm Add comment
At least I'm not alone! That's why I quit trying to 'correctly' install the cables- They were getting frayed on the ends. I guess I'll see what a new set costs tomorrow.

Sure would be nice to know what causes this condition.

by RoverLRC on Nov 20, 2008 at 7:02pm Add comment
I have done about 100 belt replacments on this model over the years and after the first two I have never done the test as it is misleading and sometimes you can loosen and damage the connection at the emod site just trying to gain access to the test points. From what I remember and my memory is a bit fuzzy now you got a reading the would start at lets say 300 ohms and then it would start to go down gradually so I do not know what hp meant by continuity. As long as you are careful when putting the trailing ribbon cables back into the carriage assembly, no need for testing. On the non plus models you have to be very careful as you can indeed blow the emod. On the plus models just make sure you have a spare fuse on hand. The biggest problem I know encounter is the white plastic ledges on the ribbon cable at the carriage end start to fall off. I just make sure I carry a container of crazy glue so I can reattach them. They are the most important part to be able to insert those ends in the sockets and firmly pressed down with a small flat tip screwdriver. Always check the contacts to make sure they are straight and not separating from the ribbon cable. Crazy glue also helps if one or two are coming loose.
by dmzcompute on Nov 20, 2008 at 8:15pm Add comment
I am testing the contact points at the carriage with cables detached. If I test positive negative it says open , but if I test negative positive it says 10 ohms. I think I have a carriage problem with this same error code. Is this what the ohm value should be? But HP says less than a 100 ohms at the emod. Is there a diode there? Thanks. - tiredfingers
Thanks for the tip. This is just a plain ol' 1050C, no plus and I don't know if the fuse is replaceable or not or if it's soldered to the mainboard.
by RoverLRC on Nov 21, 2008 at 5:17am Add comment
You need to check fuses F7 and F8 on the main board. They are surface mounted fuses.
by Anonymous on Nov 21, 2008 at 5:34am Add comment
I have seen the fuse replaced on the mainboard. Its been years and I went back and checked my documentation and couldnt find the fuse electronic specs. in there but when I went to training in Chicago when we disassembled the machine like 3 of 7 came up with the error and the instructor had the fuse and soldered it over the fuse in the machine. and was like see I told you how important it is to check. It is a very tiny fuse. About the size of a small resistor and doesnt look like a standard fuse. Anyway I always check continuity before replacing and after so I know what I need to look for. Some belts like HP OEMS come with instructions. I havent done as many as DMZ but Im always very very carefull the first time and the 20 twenty ive done I only had to replace one trail cable. The main thing is the connectors are so small and so many that if you get it in there at the slightest of angles it shorts out a design flaw that I guess HP's only solution was to add a replacable fuse which I think they should have done alot earlier in the products production life.
by nivek on Nov 21, 2008 at 5:42am Add comment
Again, thanks for the info. But my main problem is that, after I got the error (continuity at the test points) I disconnected the trailing cable entirely. And I STILL get continuity at the test points. Other than inspecting the sockets on the mainboard for debris, I don't have any other ideas.

by RoverLRC on Nov 21, 2008 at 5:59am Add comment
Checked this AM and got NO continuity, reconnected trailing cable and still got NO continuity, so powered up and got an error-- 0B0006, which is cables connected incorrectly or fuse blown, I think.

So I've ordered cables 'cause these won't stand being removed and installed again.

Any other thoughts? Everyone has been most helpful and I appreciate it.
by RoverLRC on Nov 21, 2008 at 10:20am Add comment
Thank you very much DMZ Nivek and the others who have posted tips
without this help I would have surely blown the emod on my install

Being the first one I have had to do I went by the posts here and the manual and did NOT power the machine until there was no continuity on the meter. I did ruin the trailing cable and ordered another one. Plotter was purchased in 1999 and has had one other trailing cable installed by HP.

I noticed in my instructions for installing that you can still recieve the code 0B0006 which means you have blown the fuse or the cable is installed incorrectly. re- install according to the directions.

I think this "kit" should come with aspirin and a six pack

So we dont have to be concerned about continuity readings with
a proper cable install? I am also fuzzy on this as this was my first install on this model.

Thanks again for the help guys...
by Scytex on Nov 21, 2008 at 11:23am Add comment
Yeah that sucks. I will say that Ive seen one machine do that and if you pressed the enter key it would continue plotting. But not a very good solution. They did very little plotting on the machine and used it that way. I havent called this company for years but you might call Hytec in florida they do board repair once again I quit using them becuase I wasnt always satisfied with the product I got back but you can try them. If not maybe you can get ahold of a good tech at HP who knows his stuff and can get you the proper fuse and the schematic for the repair. Im doubting the cable will fix your problem. Sorry to hear about your situation just understand your not the first and probably wont be the last to be faced with this bad situation.
by nivek on Nov 21, 2008 at 12:58pm Add comment
Everytime I have seen that error it is always the emod that has blown. Some of the later A models came with a fuse just like the B models and only requires the replacment of the fuse. If no fuse but a square looking block at that location then you need to send the emod out for repair as it is toast. My understanding is there are some very tiny fuses more than 1 that blow on the board not protected by a fuse in a holder and in that case the board has to be repaired.
by dmzcompute on Nov 21, 2008 at 4:21pm Add comment
Got new cables on Wed before Thanksgiving. Installed them today and all is well. Plotter works like a charm. Now that I've been through one, I have a better idea what to mess with and what to leave alone.

Thanks for everyone's support and advice. I'll now adjust my pricing and time to reflect my new experience with this belt replacement.

Thanks again.

by RoverLRC on Dec 1, 2008 at 3:26pm Add comment
Does anyone know what the exact ohmic values should be at the test points at the emod and carriage with the cables removed? Or can they describe what happens? I am reading only 10 ohms at the carriage. Thanks.
by tiredfingers on Nov 6, 2009 at 12:47am Add comment
I really do not take a reading as I said above. You just have to be very careful when putting the cables back in the carriage side. There is never and I mean never a reason to remove the cables at the emod side unless the cables are being replaced or the emod being removed. I seem to recall with the cables removed at the emod the test point will be open with no resistance.
by dmzcompute on Nov 6, 2009 at 5:29am Add comment
Tiredfingers. I noticed you posted the same question to the HP forums. if you've got an 0b0006 error and your mainboard type doesn't have the glass fuse installed then check fuse F7 (upper right hand side of the electronics module). You can solder a 10A (or 7.5A) axial lead fuse over the existing surface mount fuse quite easily - just tack it onto the sides of the surface mount fuse. This is what i've done in the past. Then with the cables inserted correctly you should get a high resistance reading (over 100 ohms) at the electronics module test point. Personally, as dmzcompute said above, i don't bother with the readings and just be extra careful with the cables.
by huckle on Nov 6, 2009 at 5:04pm Add comment

There is a good article about the resistance check for the HP Designjet 1050C after replacing or reconnecting the trailing cable. The article has a picture showing all 3 types of test points that were used with this plotter. Note: The very early Designjet 1050C main logic boards had no test points at all. If the dread 0B0006 comes up on this board, all you can do is put a 2A fuse in around F7 or get a new board (non-Plus) The 1050C Plus board is also available but the Error 0B0006 can usually be cured by simply replacing the glass fuse.

by Bob Wert on Mar 17, 2016 at 2:29pm Add comment