This error typically happens when the cam driver of the pump has to apply too much power to drive the pistons. Something must be offering lot of resistance to the motor. Remove all connections and run the pump, check the pressure, if the problem persists call the service.

Thx

Usually, I monitor the back pressure of the system. If you have the records, you can go back to see the back pressure at 1, 100, 200, ...800 injections. 1000 samples are really a lot. If your samples are urine or something similar, precipitation might occur in your column and thus contribute the back pressure.   

Check to make sure that the line between the two pump heads is not clogged.

Try to lubricate the mechanical parts of the pump motor, especially the bearings. 

Hello there,

We have dual pump ICS 3000

I ran into a problem that Pump1 is not uptaking the eluent. On the audit details it shows:

"Pressure fallen below lower limit."

When prime the Pump 1, it does not intake eluent, which means no fluid in the tubing. I can hear the pump motor is running the same as pump 2( which is running properly)

I would appreciate any suggestions or solutions to help out

I'm not totally clear on your description. Where, specifically, does fluid leak from the pump

There are several possible causes of the symptoms you describe depending upon the leakage point. It is possible that the problem is due to the pump seal but in this case the pressure will usually not drop below the pressure limit. If the liquid is leaking around the base of the outlet check valve or the top of the inlet check valve, try tightening the check valve 1/16 of a turn. If the leakage is from the top of the outlet check valve, the ferrule may have slipped off the PEEK tubing. In this case, remove the bolt, tubing and ferrule. Then reinstall the bolt, reinsert the ferrule on the tube and reinstall the assembly into the check valve. If the problem reoccurs, try cutting off 1 cm of tubing and then reassemble as above. If the leak is coming from the back of the pump head, you need to change the pump seal. The instructions for doing this are in the pump manual.

Thanks a lot Chris Pohl for your kind help.

I re-post the question and try to explain it more clearly.

I just tested the pump 1 again. The motor seems running, but it can not pump the eluent. Is there vacuum leakage?

How to check and confirm the vacuum leakage?

You can whether there is a vacuum leak using the following process:

1. Right click on the gear icon in the upper right corner of the instruments view

2. Cluck on Pump 1 from the drop-down menu

3. Right click and select the expert setting

4. Scroll through the list and find "degasser". It should be listed as  "on".

5. Check the line below and find "DegasserVacuum". If the vacuum is okay it should say "OK". Otherwise it will say "NotOK".

Thanks Chris. I have checked it following your instructions. Degasser is on and Degasser vacuum is ok.

Dose it mean the pump has problem? I can hear the motor's running noise.

It's possible that the problem is due to detachment of the piston from the coupling magnet. This sometimes occurs if the interference grip of the pump seal is excessive. To check this, loosen the screws holding the pump in its enclosure and pull the pump far enough out to see whether or not the piston is coupled to the magnet. If you see a gap between the metal cylinder at the end of the piston and the magnet, you will need to  reattached the magnet by pulling it backward and change the pump seal. The problem could be with either piston but it's most likely the piston on the right-hand side that is detached from the magnet.

Hello Chris, thanks a lot for your suggestions. I'll check it and let you know.

Hello Chris, I found previous tech's notes: Found defective degasser on pump assembly. Pump can still work without the degasser so I disconnected power to it ."

Is this the cause of the pump not working? There is air in the tubings right now.

The fact that there is air in the tubing is probably not related to the degasser being disconnected. Generally, even without the degasser operational there won't be large gas bubbles in the feed line to the pump unless there is a lot of dissolved gas in the eluent. I think it's more likely, assuming the gas is in the feed line, that there is some obstruction to flow. For example, if you've selected eluent A but the valve for eluent A isn't opening this would cause the symptoms you describe. You can check for this situation by switching to a valve not currently in use to see if you get flow without bubbles. Alternatively, you could use a syringe with a suitable adapter to see if you can get flow in the opposite direction for your eluent feed line. To do this test you'll  need to have the pump running. If you feel a major obstruction to backflow this is an indication of obstruction of flow in the flow path. In this case you'll need to replace the eluent switching valve.

Hello Chris, Thanks so much for your help. I followed your suggestions to manually prime the pump. It worked.

Now I have another questions for you. I will appreciate your suggestions.

1. the peristaltic pump of piston seal wash system is not working. In this case, is the instrument operational?

2. I received the error message for pump-2: Drive current too large, camshaft xxx,

Excessive drive current, camshaftxxx. The pump-2 will stop working.

Do you have ideas how to solve this issue?

It happened randomly.

Thanks again for your great help.

Grace,

I'm glad to hear my suggestion help solve your problem a few months back.

With regard to the peristaltic pump, the seal wash pump is not a requirement for successful operation of the pump. The seal wash pump extends the life of the piston seals so in the long run it's beneficial to have The seal wash operational but in the short run it won't affect your results. If you are pumping deionized water and using an eluent generator to prepare the eluent, you don't need the pump seal wash. Its function is to prevent accumulation of salts on the piston which can result in abrasion of the pump seal. If there are no salts in the fluid passing through the pump, there is no benefit to using the seal wash.

With regard to the other error message on pump 2, it's possible you will need to call the service team to address this issue. However, before you call service, I recommend you check to see whether the error message is due to a clog in the line between the right and the left pump head. A clog of this line will give you that error message although it's not the only possible cause. Disconnect the line on the outlet of the right pump head and try starting the pump. You will want to place a paper towel over the outlet port to avoid a massive flow of liquid when you turn the pump on. If you fail to see the error message with this line disconnected, this is strong evidence that the line between the two pump heads is clogged. Replace the line and you should be back in business. Otherwise you will need to call service.

Thanks so much for your detailed explanation, Chris.

I'll try it and have feedback to you soon.

Grace, the problem you initially reported has nothing to do with the degasser or priming (proper priming procedure should always be carried out as should using fully degassed mobile phase all of the time). The initial error you reported, "Drive current too large", refers to the drive unit of the pump. It is consuming too much power and that is why the message appears. It is a warning, that you need to verify that the pump module is working properly (without any damage to the drive unit it. Over time, these units do wear out and require replacement). Have it checked. If you still receive the error message, than you will need to have the pump drive unit replaced (as it has failed). Please contact a professional service provider.

"There is air in the tubings right now". - Air observed in the low pressure tubing is often due to: (1) a loose connection fitting (very common. check the low pressure inlet and outlet lines from the bottles to the pump inlet); (2) A restricted solvent pickup or a dirty inlet filter or (3) you stopped degassing your mobile phase. Always use a degasser and make sure all lines (even the ones you are not using) are fully primed with fresh mobile phase.

Regarding the pump piston seal wash system. " If your HPLC system has a piston seal wash feature installed, then failure to utilize it (leaving it "dry"), may result in decreased lifetime of the wash seals and piston(s) due to the added friction they exert. If you have a seal wash system, but do not need it (i.e. running only NP solvents), then replace it with a non-seal wash system or utilize the seal wash feature to prevent damage.

"HPLC PUMP SEAL WASH & FLUSHING THE HPLC"; https://hplctips.blogspot.com/2012/08/hplc-pump-seal-wash-flushing-hplc.html

Hi Chris Pohl,

I have the same problem with the error message:"Drive current too large Camshaft 153" so I turn off the machine, prime a few times and it's now working.

What is Camshaft? Are you the same Chris Pohl that worked for Dionex many years ago? ( 25 years?)

Thank you so much William for your very decent explanation. One pump was not working because of the failure of the drive unit. We had switched the system to one pump.

Hanh,

Yes, I am the Chris Pohl that started working for Dionex in 1979! I'm still at it but thinking about retirement.

Well hello old friend Chris,

I am so glad that you are still working with the HPLC system, thank you for all the help back then. The message that I have about "Drive current too large, Camshaft 153" still won't go away after 2 runs. I have cleaned all the tubes plus piston but it's not working, any other suggestions?

If you haven't already, try disconnecting the tube from the first pump head to the second pump head. You might want to set the eluent to 100% water and place a couple of paper towels under the primary pump head to capture any water exiting the outlet check valve. Then check to see if you still get an error message when you turn on the pump. If not, this is an indication that the tube is blocked and should be replaced. If you still get the same error message you need to contact service.

Thank you Chris, I will try again!

Dear Mr. Chris Pohl! I am working with a DIONEX ICS-3000 HPLC system. I have the problem with the error message: «Excessive Drive Current. Chamshaft 74 º» too. I have cleaned all the tubes but it's not working. I still get the same error message. Can you suggest any other options besides contacting the service.

Liudmila Golobokova

For our DIONEX ICS-3000 instrument, the first pump had stopped working after the " Excessive Drive Current. Chamshaft 74 º " error message repeatably appeared.

After that I switched the system to single pump mode and it is working fine.

Hi Xia Liu!

Thank you, I will try to switched the system to single pump too.