Mis-aligned Agilent 1100 Autosampler

[andrehbui]

Hi everyone,

I need your help in diagnosing and potentially fixing a problem with the autosampler I'm currently using with my Agilent 1100. I powered on the Agilent and noticed that the autosampler was suddenly not initializing with the ChemStation software, like normal. The thing is, it was functioning perfectly only one day previous, so this just happened out of nowhere. To me, it appears as if the autosampler is mis-aligned, as it attempts to go through its configuration routine, but ends up stopping and then I hear a grinding sound, like one of the gears on the mechanical arm is grinding to a halt. Naturally, the autosampler errors out and nothing happens. I get an error code (3822) in the ChemStation control panel, but haven't had any luck with determining what exactly that means.

I think the autosampler hardware is mis-aligned in that it's not really in the correct position that it should be in when it is doing its initialization, but I have no clue on how to fix it short of calling up an HPLC tech which would cost lots of $ that my company isn't willing to spend.

Any help would be appreciated. Thanks.

[lmh]

I'm not at work so I haven't got the manual or help-file available, but have you checked that everything is clean and able to move? The arm is driven by several little stepper-motors and lots of toothed belts if I remember correctly, and if the guide rods have become coated in a mix of dust, oil, general gunk and black icky stuff, eventually they'll reach a stage where the motor can no longer drive the arm along. If so, a careful clean may make it work again.
I don't think it should be a problem of alignment otherwise, because when you first turn the unit on, I think it sorts its alignment out by driving along to various points where the arm would hit something, and noticing!

[djacqo]

I had a day where I had to reinitialize an 1100 autosamper with the arm in all sorts of random positions after I had an issue where the power kept getting turned off while it was operating (an annoying story behind that one). It always realigned itself during initialization with no problem.

I would watch carefully and see what is trying to move when you hear the grinding sound. It could be the assembly which moves the arm/down and left/right, the motor that pivots the gripper arm, or the gripper. These move clearly independently from each other. If you have another autosampler to familiarize yourself with the exact movements that could be useful. The good news is that the entire assembly lifts right out pretty easily for cleaning if that's the issue as lmh suggests.

Sometimes hardware gets hung up on some strange behavior and the problem can be helped by power cycling the module (including unplugging for several minutes to completely discharge all capacitors). It's easy to try.

[bisnettrj2]

It's been a while since I've had to deal with this problem, but I think I used to have the 1100 lock up occasionally in an odd position and be unable to re-initialize itself. I would reach in and manually move the horizontal toothed belt so that the arm was in the middle of the transport assembly as viewed from the front, and by moving the vertical toothed belt so that the arm is about 1/2" to 3/4" from the top of the autosampler, and I would move the arm so that it was pointed to the front-left corner of the instrument, and I would take the tray out. Then when the instrument would try to power up, it wouldn't encounter any restrictions when it does its initial polling of all the stepper motors (where it does a short back and forth movement of each motor before going through the alignment process). It should be using some optical sensors to re-align itself. If it still won't start up, check the log book - if it's displaying a motor over-temp error, you may need to pull the transport assembly and clean the threaded rods that the assembly moves along to get rid of any accumulated dust and dirt that may be impeding the movement of the assembly. The manual says to use isopropanol to clean them, and they recommend a lubricant in the manual that is an 'obsolete' part number in their online store. Others on this forum have suggested silicone lubricant for the rods.

[andrehbui]

Thanks for all the replies everyone, I'll have to try them out to see if something works.

lmh, I did manually move the arm around, and it appears to be moving around fine. The grinding sound appears to happen when the arm swings around to the back, as up and down movements seem to be fine. It's hard to say if the movements are being obstructed or not, but since you guys say it's easy to remove the assembly and clean it, I think that's the first step.

Thanks again everyone, this was really helpful.

[James_Ball]

I have used the silicon oil that Hach sells to lubricate their repeating pipettes to lubricate the guide rods in the back of the instrument. They really shouldn't have very much on them at all, so I just put some on a chemwipe then wipe the rods down with it. If you get too much it will collect dust and cause problems faster. Also if you can see grease on it, wipe it off, it really shouldn't have it on there but some did leave the factory that way.