Agilent 6890 on/off power switch rod

Discussions about GC and other "gas phase" separation techniques.

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6890 will sometimes be hard to power on with the button up front and occasionally even fully shut down during a run (and we can only restart after a while; I'm assuming once the temps have gone down). Looking at how the power switch/rod seems to complete the circuit on the AC board in the back, it looks like perhaps the actual plastic rod needs to be replaced? Anyone has any experience in replacing those? I'm not quite sure how to go about it without breaking the rod or the switch on the board, and starting to wonder if it might be easier to have the electronics shop rewire it to something simpler...

Many thanks!
The replacement switch is fairly expensive according to my service rep. My GC-FID has a related problem that the rod has come loose. I have to fish for the microswitch with the rod every time I turn it on or off. But its cheaper than replacing the switch.

If your machine is cutting out during a run, that sounds like not just the switch.

Somebody correct me if I'm wrong but I have turned off GC's in the middle of a run and if I recall correctly, turned it back on and set conditions to bake off the rest of the run without having a problem. It should not need to have initial conditions to turn on. It will of course set about returning to the set initial conditions unless you intervene.
Just to be clarify, when I say "shut down", I mean the GC lost all power. When I tried to depress/repress the power button up front, the screen flashed briefly but then nothing. And then I could not power it up again until I tried after about 45 minutes of it being off (at the time it powered off, oven was probably at around 275 degC). I remember we had issues with the button staying in the right place about three years ago, which is why I thought it might be related, but I'm definitely open to exploring other options. I had also found this thread http://www.labwrench.com/?community.pos ... er-switch/ where Wilhelm mentions a similar issue.
I had the instance on a 6890 where the power switch long plastic rod was OK, but the little nub on the big circuit board was bad, wouldn't stay engaged with the rod, would slip off.

Rather than just unplugging from the wall when needing the GC off each time, I drilled a small hole in the plastic nub on the circuit board and used a bread bag twist tie to simply hold the rod in place, and then it worked fine.

Agilent service engineers have to fix stuff "by the book", their fix is to replace the entire circuit board, costly.
Consumer Products Guy wrote:
I had the instance on a 6890 where the power switch long plastic rod was OK, but the little nub on the big circuit board was bad, wouldn't stay engaged with the rod, would slip off.

Rather than just unplugging from the wall when needing the GC off each time, I drilled a small hole in the plastic nub on the circuit board and used a bread bag twist tie to simply hold the rod in place, and then it worked fine.


I like this!

We had our first 5890 (non-computerized) before the 7673 autosamplers were available, but boss said budget meant "buy now", so we got the existing autosampler. Everything was fine for a few months on our routine assays - all isothermal. Then we tried some temperature programmed assays and found that nothing was triggering the GC to start heating. So I took a small momentary switch and had our shop make a little mount for the tower, so every time an injection was made it would trigger contacts on the panel on upper right side to start the GC program; before this GC would have no signal to start its program.
5 posts Page 1 of 1

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