Weird Baseline

[syx]

we had a baseline problem this morning in agilent 1200 series with DAD. the baseline was recorded as in the picture:



the 'wave' was not interfered by flow. though the flow was stopped, the 'wave' was still appeared. it could be eliminate after we shut down the system and then turn it on. I conclude that the source of the problem is in detector but I have no idea what it is exactly. could you please give me any reason about this phenomena as the basic to build a reasonable preventive action?
thanks in advance.

regards,
siswanto

[DR]

Two thoughts...

1) How old and how many hours are on your lamp?

2) When the detector is on, is the fan running consistently, or does it cycle on/off?

[philippem]

another thought or comment

some years ago I've experienced a comparable phenomenum:

it was caused by the airco (power supply) . the pattern in the detector signal equals the on-off of the airco. .....

but here the time between the peaks is rather short , but who knows....