> At 12:24 AM 6/09/2006, Phillip San Miguel wrote:
>> [Just to widen the pool of 3730 users, this is a cross post to
>> ABRF forum and bionet.genome.autosequencing]
>> There has been some prior discussion of a particular error that
>> has bedeviled our facility more and more of late:
>>
>>http://www.bio.net/bionet/mm/autoseq/2006-August/thread.html
>>
>> The error is "Tray on deck does not match tray type in run
>> setup". For us, this generally occurs between the A1 and B1 quads
>> of a 384 sequencing reaction plate. Generally, once it occurs, we
>> are shut down until and engineer fixes it. We have two 3730XL's and
>> have actually seen this on both instruments during the last month.
>> The fix is generally for the ABI Field Service Engineer to replace
>> all the sensors in the gripper assembly.
>> Usually this seems to do the trick--for a time.
>> The FSE will almost universally warn us that sensors can be
>> damaged by liquids being spilled on them. But then just as
>> universally note that there was no evidence that this had occurred
>> with our sensors. (The sensors are dry and have no buffer residue on
them.)
>> The situation is somewhat more complex than I'm describing
>> here--frequently this error seems to presage the failure of some
>> major system of a 3730. But not always.
>> Has anyone else been seeing sensor issues in their 3730's?
>>
>>--
>>Phillip SanMiguel
>>Purdue Genomics Core Facility
> Date: Wed, 06 Sep 2006 10:24:32 +0800
> From: Frances Brigg <F.Brigg at murdoch.edu.au>
> To: ABRF Discussion List <ABRF at list.abrf.org>
> Subject: Re: DNA SEQ: 3730 Tray on Deck errors
>> We have had a 3730 since 2003 and have had to have most or all of the
> gripper sensors replaced on 3 occasions since installation. The AB
> engineers are always surprised and say that they don't see this kind
> of thing at other sites. The sensors are always dry with no buffer
> residue, and the replacement sensors are wrapped in plumbers' tape to
> keep moisture out. After the most recent replacement the engineer
> suggested that it could be due to power failures or brown-outs that
> affect the sensors first, and this would probably explain why your
> sensor failures sometimes precede major systems failures. What we
> tend to see is intermittent failures with the sensors, so that they
> will run fine for a while and then start to fail with increasing
> frequency. If the sequencer is shut down for a while, it will again
> start off OK but then fail once it has been running for a while (ie
> after 1 or 2 runs). The engineer said that this occurs because the
> sensors run better when cold and are more likely to fail as they heat
> up, which could explain why they tend to go at a particular quad on a
> 384 well plate. It is a good idea to run the sequencer beforehand if
> an engineer is coming out to look at the sensors to make them fail on
> cue, as it often takes an hour after switching on with active runs
> for them to start failing.
>> The error message will depend on which particular sensor goes and at
> which point in the process it fails, so you could also see messages
> such as "autosampler cannot hold tray" from the same problem, and
> find the autosampler holding two plates at the same time. I have on
> some occasions left the sequencer on and gone back to find the
> capillaries sitting in air as the periodic automatic re-homing of the
> autosampler has started and a sensor has failed in the process. It is
> possible using the 3730 service tools/service/diagnostic/autosampler
> test to do a dry run (ie it does all of the plate movements in a run
> without the polymer fill and electrophoresis) to work out which
> sensor is failing when not all of them are affected, but if they all
> go there is not much you can do, and it only really helps if you can
> persuade your FSE to leave you a spare sensor or 2 for emergencies.
>> The engineer also said he had seen errors at other sites where the
> sensors were fine but the bottom of the plate holders were filthy and
> so encrusted with buffer that it formed a wall where there should
> have been a cut-out and made the plate appear to be a different type
> than it was. (It is a good idea to examine the base of the trays to
> see if there is anything unusual about them, particularly in the area
> that the sensor is having trouble with if it is the same plate holder
> and sector each time).
>> Finally, I have also seen software problems cause apparent sensor
> errors, but only in a very unstable system. (Our FSE did the upgrade
> from V2.0 to V3.0 for Windows 2000 and couldn't get it to work, we
> opted to wait until the XP version came out rather than trying to get
> the Windows version reinstalled properly from scratch, and hobbled
> along with a partially restored V2.0 but with bits and pieces of V3.0
> installed. The overnight runs were fine, but during the day we kept
> getting sensor errors. After a while we noticed that they occurred
> whenever the in-stack door was opened during any part of a run,
> apparently triggered by the StackerMsgBean "%% an instrument door is
> open" error message, and whatever stage the run was at it would fail
> the next time the autosampler tried to pick up a plate. Normally it
> isn't a problem to add to the in-stack with runs in progress,
> although the %% error message still appears. We would find that the
> error would also keep recurring if we tried to repeat the run using
> the same plate record, but if a new plate record was made up with a
> different name and the door was left alone it would run perfectly
> well. This took a long time to diagnose, because there was sometimes
> quite a long gap between opening the door and the error that it
> triggered, eg while the oven was getting up to temperature during a
> run, but once discovered the error could be generated on cue every time.)
>> But sensor damage due to power fluctuations is the most likely cause
> of ongoing problems.
>
Thanks for the detailed response, Frances. I'm also starting to hear
that the reoccurring problems I'm having are likely the result of power
fluctuations or spikes. (With suggestions that I should purchase a
UPS/power filter.) Of course it is very difficult to rule this
possibility out, or it would be. I think I *can* rule this out because
one of my 3730XLs *is* on a UPS/power filter. Actually it is the one I
have had the most trouble with sensor-wise.
Anyway, the Field Service Engineers no doubt have a hard job here. The
3730 is a complex instrument. But I have to admit that after a while I
get a little tired of hearing the standard list of culprits for
instrument failures:
(1) I'm sloshing buffer or other liquids on the plate type sensors.
(2) Someone/something is accessing my console computer through the
internet in a way that causes mysterious failures.
(3) The power to the instrument is bad.
--
Phillip
