Chromatography Forum

I recently got a HP1050 (79853A) which came up with 'Filter error, Low illumination, Data underflow'. (in that oder).

After tinkering (improved aligning) with the lamp I could fix these errors but the lamp shows signs of degradation (traces of metal on the bulb).

My only remaining problem is that I can't take measurements (which is bad...).
The problem is that the reference photocurrent is about 1.6 at 230 nm whereas the sample photocurrent is a steady zero at that wavelength with mounted flowcell. The noise is around 0,03 AU.

At around 350nm I get a reference photocurrent of about 0,23 with 0,029 for source and mounted flowcell. No noise is observed here.

Without the flowcell the sample current is around 0,9 for all wavelengths.

I flushed the flowcell with EtOH:H20 1:1 and later 100% MEK which didn't change anything.

Therefore I have several questions:
- Are these symptoms are sign of a worn lamp? (esp. the low S. current)?
- Does anybody here have a service manual for the 79853A with an 'early' optics compartment (seems like Rev. B)?
- What kind of material is applied to the mirrors of the detector? As I have access to a high vacuum sputtering apparatus I could regenerate these mirrors if only I knew what is applied (in what order) to them

Thanks for helping me out!

I was able to fix the error myself. The following defects were responsible:
- Flowcell windows dirty
- Flowcell contaminated with unknown residue

After cleaning the cell windows with water, MEK and ethanol as well as flushing the sample cell with water and then isopropanole the sample photocurrent is now about 0.8 with water (distilled water) at 220nm.

Not too bad

One of the improvements with the 1050 "C" detector was integral alignment pins on the UV lamp, made lamp changing much easier.