7673A "Plunger Error"

[osp001]

Trying to get an old mass spec on line, and I get a plunger error on the 7673A. The syringe carriage moves just fine, and it'll draw up solution just fine, but when it tries to eject the liquid in the syringe, it'll stop and give the plunger error along with the red light flashing four times.

I find it odd that a stepper motor is burned out in one direction (pushing) but not the other (pulling) when the difference in force seems to be so small.

Are there any other aspects I should test? I see cleaning the sensor is one option, but how is that done?

And if anyone has a working, used 07673-60620 motor for a bargain price, hit me up.

Thanks!

[dblux_]

Remove the syringe and check whether plunger moves easily in the barrel.

[osp001]

Remove the syringe and check whether plunger moves easily in the barrel.

Mea culpa- I forgot to mention it's a brand-new needle, it moves smoothly both in the barrel (by hand) and after installed- put in place and secured with the thumbscrew on the plunger.

[KM-USA]

Can you try an injection with no plunger installed?

[osp001]

Well, it appears to work, based on a couple of injections I did last night. BTW- if anyone needs motors for these, better hurry up because Portescap stopped making them and there's no replacement, although I think someone found a third-party solution. There's also a vendor that refurbs them for $125 (search for the HP p/n 07673-60620, it's a company in Minnesota) but there's a 2-3 week turnaround.

I disassembled the entire tower last night, wanting to clean it out but didn't really get any dirt off anything. I tried to clean the sensors, but they're just Hall effect sensors or some other magnetic sensor, so there's really not much to clean. I tried to do some fault-finding with a multimeter, but didn't really find any differences in the sensors there, either.

What I think may have helped was to move the carriages around on the belts, since they'd sat on the belt for so long and the belts had conformed to the sprockets. So, those got moved around on their respective belt a little (and the carriage belt is pretty worn- looks like p/n 531-3M-06 is about $4 online, rather less than the $27 that Restek asks for the same part), and I put it back together with little hope it would do anything. Powered it up, and WHAMMO, that sucker moves like new.

The other thing that may have helped is the wedge that holds the motor in place; I adjusted it all the way out, and one click in, figuring I could always push it further in. So, less tension on the belt.

Maybe this will come in useful for someone later.

[Yama001]

That wedge is a tricky beast. Nice job getting it running.

We send ours to GenTech if I cannot coax them in to working.