HPLC pump issue

[wschatz]

I have a Varian HPLC Prostar pump that works for about 2 minutes and then completely ceases to function. No errors appear on the screen. Ideas and advice?

[tom jupille]

How long does the pump have to sit before you can restart and have it run for another two minutes?

If you're not seeing any diagnostics, the odds are it's a board-level electronic problem, and as such probably not a user-serivceable item.

[thohry]

My experience with 1090 pump of this type of fault is either check valve's malfunction or over pressure.

[wschatz]

The pump has to sit about a half hour to an hour before a restart will get it working for another 2 minutes.

[tom jupille]

I'd still bet on an electronic failure, either on one of the boards or a power supply. Sometimes a marginal component / contact / solder joint will work OK when cold, but fail as the unit warms up.

I don't have any hands-on experience with that particular pump, so all I can make are general suggestions:

Start by checking the simple things first:
- loosen the fitting at the outlet of the outlet check valve, then re-tighten it and see if the pump will start up again immediately. If it does, then you either have a blockage with overpressure, or a pressure transducer that is reading incorrectly (too sensitive).
- go in and disconnect / reconnect every electrical/electronic cable you can find. Hopefully, that will be enough to rub away any corrosion.

If neither of those solve the problem, it's time to get a service technician in to look at it. If you have more time than money, and if you have another system of the same model, you might want to try swapping circuit boards to pin down the source of the problem in more detail.