HP 5890 Oven Flapper Motor Question

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

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I came back from the weekend to find my HP 5890/5972 GC-MS with an oven shutdown. At my first attempt, it could not run a program ramp temperature and there is a squealing sound coming from the vicinity of the flappers. Shutting off the power leaves the flaps still open. I saw in another thread "6890 Shutdown 1 Oven Shut Off" [url]https://www.chromforum.org/viewtopic.php?f=2&t=91894&p=336164&hilit=oven+shut+off#p336164
[/url] That setting a high temperature worked.
If I set it for 200C, the flaps did close (squealing the whole while) it will reach T and hold it and I can step down in 25C increments and flappers open and it drops down and holds temperature. Got it all the way down to 50 then set at regular T of 40C. I'm now doing a run and it seems to be working.

I suspect the flapper motor is limping and will soon fail. My question is whether I will need to vent to get at the flapper motor to put in a replacement.

Because:
1) f I shut down the 5890 I must suppose capillary wiil be shut off, or not constant, or worse uncontrolled flow will be too high?

2) I'm not sure which side of the GC the power and control leads are on. I assume it would be on the right as looking at the 5890, same side as the power switch.

3) I'm not sure how much I need to maneuver the 5890 to get at the flapper motor.
No need to vent the MS, just pull out the column and cap the end.
Getting to the Flapper motor requires removing the back panel of the GC and the right side panel (the side with the power switch).
You will need plenty of room behind the GC, if it's up against the wall the entire unit will have to be pivoted quite a bit.

I have a maintenance manual around here somewhere, I'll go digging for schematics.

TomC
I've replaced flappers on both 5890 and 6890, and not too tough. I even had a flapper disc fall off once, and riveted it back on.
TCCrab wrote:
No need to vent the MS, just pull out the column and cap the end.
Getting to the Flapper motor requires removing the back panel of the GC and the right side panel (the side with the power switch).
You will need plenty of room behind the GC, if it's up against the wall the entire unit will have to be pivoted quite a bit.

I have a maintenance manual around here somewhere, I'll go digging for schematics.

TomC


That is exactly what I would do. Cool the interface, have a blank ferrule in a spare nut and quickly pull the column out and replace with the nut and blank ferrule while the rough pump keeps running. Then you can pull the GC away, you can even unplug the interface heater and move it to another bench if you want while the MS remains under vacuum.

If you have a diffusion pump, you can run the vent process to cool the pump then run pumpdown after you remove the column and cap it off but you probably don't need to.
The past is there to guide us into the future, not to dwell in.
The last one I changed wasn't the motor itself but had a weird problem where the "collar" that ties the motor to the shaft was stripped out and the motor actuated but wouldn't work the flaps.

I had a complete flapper assembly here that was a pull because one of the flaps had fallen off. A few minutes on the drill press had the old rivet out of the flap, and with a pop rivet it was good as new.

I did as others have said-I did the quick column pull-blank ferrule routine to avoid venting. Since it was against a wall, I turned the GC 90º and worked by sitting on the bench next to it. As said above, you need the back door off and the side cover on the electronics side(right side when facing the front of the GC, opposite where the transfer line comes out). Stubborn me didn't grab the repair manual when I went to do this repair, but it wasn't super difficult to figure out. The full assembly is held on by two screws, but you'll need to remove the horizontal "chimneys" around the oven vents to get to it-they come off as one piece of sheet metal that's also a few screws. I haven't looked to see if the flapper motor can be changed in-situ, but access is awfully tight back there if I did a motor only I'd probably change it on the bench. The wires for the motor snake over in the wire bundle and plug into the mainboard via a multi-pin connector that IIRC has some other things on it. You'll probably want one of the little tools designed to pull connectors from Molex-type plugs to make your life easier since you'll have to pull the old ones out of the connector and put the new ones in.

There may be a few other pieces you need to remove, and I think I may have needed to cut a zip tie or two to get the wires for the motor teased out of the wiring harness. That part should be sort of self-explanatory. The schematic would be handy just to make sure you have everything connected properly after transplanting pins, but I just did it one at a time.

I have a few new motors-email me if you need one.
Any place to get a new stepper motor?
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