Chromatography Forum

Hi Folks,

I have a varian 3400 GC coupled to an 8200 autosampler, all controlled by computer. The instruments are quite old and have been out of use for a number of years, but despite that, are now (generally) working well.

However, my autosampler (or the communication to the autosampler) is giving me grief. When the autosampler performs an injection, the syringe carriage lowers and performs the injection, but only returns halfway up before stopping. Unfortunately it is too low to allow the next vial to come in, making it a kind of mono-sampler rather than autosampler. If I manually return the carriage to the top, it quite happily undertakes the next injection.

When the carriage stops, the instrument gives a readout of "Fault 131 - 8200 motor timeout", but the manual does not provide any assistance in determining this error, and when I run a diagnostic check, there are no faults identified. I thought it was a problem with the carriage drive or motor, so I changed the autosampler over to a spare one, but this stops in exactly the same position.

Does anyone have any suggestions as to what is going on here? I suspect some sort of communication problem, but don't know where or how.

Thanks,
Karen

Hi Karen

A way around the problem, (which you might have already tried) might be to drive the GC and autosampler from the front panel of the GC, and just have a start stop ready signal and the data going to the computer.

Good luck

Peter

Hi!
Syringe assembly is attach to autosampler body by 2 arms and often, this arm are dirty or misaligned....if autosampler have difficulty to return at home position, it will stop...check first if the arms is dirty or sticky and if yes, clean arms with hexane.

Hi again!
You can try to control autosampler by GC only....it is possible that your problem is a problem of configuration.

Hi Folks,

Thanks to everyone for your comments and suggestions. Cleaning the syringe guide rods and the drive belt, and adjusting the tension on the drive belt appears to have solved the problem.

Thanks again,
Karen