Chromatography Forum

Hi all,

We have a couple 6850s and one of them has always been a bit noisy, lately its been intermittently very noisy. Very loud buzzing. My guess is the bearings on the oven fan are shot or something is hitting it, although I checked rotation and it seems ok.

Are there other internal fans or motors that could be a likely culprit?

Thanks,

If the 6850 is like the 6890, there is also a small fan near the injection port that helps cool it. It is behind the port near the split vent trap. Normally it is just a standard computer cooling fan, but they can get noisy and especially if something has move against the blades.

The oven motor is pretty common to break down on a 6850, I've replaced multiple.

To confirm that it's the oven motor set the oven to off in the CDS software (probably Chemstation). Check if there's no sound.
Turn the oven to on and set the temperature to 25 deg.C in the CDS software.
Check if the sound is back.

If there's excessive sound when the oven is cooling it could be that the motor needs to be replaced.
To do this you need to remove the entire back panel from the GC.

If the 6850 is like the 6890, there is also a small fan near the injection port that helps cool it. It is behind the port near the split vent trap. Normally it is just a standard computer cooling fan, but they can get noisy and especially if something has move against the blades.

The 6850 doesn't have a big inlet cooling fan like the 6890, 7890 or 8890. There's a smaller inlet fan to the right hand side. This often breaks down but because it's so small it's unlikely to make any sound.

Thanks I'll troublehsoot that and the other fans... I'm not seeing any other options other than direct from agilent and its a $1200 fan motor

Not really surprised...

Thanks I'll troublehsoot that and the other fans... I'm not seeing any other options other than direct from agilent and its a $1200 fan motor

Not really surprised...

I have bought quite a few items like that much cheaper on ebay.
It is best to make sure it is a reputable seller with a return policy.

If the 6850 is like the 6890, there is also a small fan near the injection port that helps cool it. It is behind the port near the split vent trap. Normally it is just a standard computer cooling fan, but they can get noisy and especially if something has move against the blades.

Every time our 6850's have got noisy it's been down to the inlet fan.
If you unscrew the top plate it should be easy to spot right at the front, try touching the fan (keeping away from the blades) & see if the noise changes. if it does that's your problem & it's much easier to change than an oven fan!

There is also another fan that draws air into the oven on cooldown. I've not heard noise from these but I have had several seize. They're also quite easy to change & much easier to source parts for.