BALANCE - Cahn Microbalance
- jr_suhonen
- Former user (Deleted)
- jr_liu
Feb 6, 2024 Cahn #90193 hang-down wire got bent again, and it caused for the balance not to weigh right. The balance was disassembled and the wire was straightened. During the repair the spare #51470 was used.
#90193 weighs a little low after the repair. A 10 mg weight weighs approx. 9.9 mg. A calibration procedure will be attempted in port.
#51470 is again occasionally exhibiting its old "stabilization delay" symptom. It does work very well, but if Tare is pressed "too soon", it sometimes ends up with a graph as shown in the Apr 7, 2020 note below. The balance was left onboard as a "still functional spare" but should be sent for repair at the end of X402 and then returned for X403.
Jan 26, 2024 The Cahn #90193 hang-down wire got bent badly and caused for the balance not to weigh right. The wire was straightened and resoldered. During the repair the spare #51470 was used. Both balances are in great working order.
Sep 12, 2023 Cahn #90193 hang-down wire broke and was repaired. During the repair the spare #51470 was used. Both balances are in great working order.
Jan 26, 2023 A scientist had weighed samples for the coulometer but the samples were not showing up in coulometer software. It turned out this was because the scientist had logged in to Cahn and only had “SCIENTIST” privileges. “CHEM SCIENTIST” privileges allow writing to coulometer; “SCIENTIST” privileges do not. The scientists were given CHEM SCIENTIST privileges for the remainder of the expedition, but for future reference it is recommended that the technicians always log in to the IODP applications in the lab. The issue was rectified by manually entering the weights from the Cahn history file into Coulometer software.
Jan 16, 2022
#52427 - broken hang down wire. Took good communication board and port from this unit and is now being used in #90193
#90221 on shelf at the weigh station - electronics repaired by Chris. unit powers up and weights display. have not tested communication with computer and cahn balance software yet because the working one is in use and didn't want to disconnect it. This will hopefully stay as our one working spare unit.
#51470 In College Station.
#90193 In use. Working. Swapped good communication board and port from #52427.
#51359 Need to be recalibrated.
Jan 14, 2022Broken hangdown wire on the cahn balance. Replaced with the spare that used to be in a box under the IC. That one had a bad communication board though so we took the communication board and connector from the one with the broken hangdown wire and it works. No calibration procedure was necessary, as we were at sea when it happened anyway. Tested with the small known weights. The 20mg weight showed 20.0007mg after 200 counts in very calm seas. If you are ever connecting a different one make sure the little white switches on the communication board are in the same configuration as the one currently hooked up. There appears no way to access comm settings in the new cahn balance software, they are apparently settings that are hard coded in. Will see if we can piece together #90221 and #52427 into one working spare if time allows.
#52427 - broken hang down wire, bad communication board
#90221 on shelf at the weigh station - tried to use this but when powered on the display just shows E
#51470 going home for repair ?? Is this still in College Station?? Feb 4, 2023 Yes, still in College Station.
#90193 Working. Swapped good communication board and port from #52427
#51359 in rad van
Nov 6, 2020 A work light was installed at the Cahn balance station. A retractable arm was built for it to enable the light to be pushed completely out of the way if desired. More lighting was desperately needed, as the Cahn balance corner is very dark, and the light in question happened to be available onboard. It had recently been removed from the paleo lab. We have no spare bulbs for the light onboard. Spare bulbs can also not be purchased, as they do not seem to exist, so a replacement light fixture will eventually become necessary. The replacement light can be installed on the same retractable arm that the current light is on.
Apr 9, 2020 Onboard Cahn balance inventory:
#52427 in use
#90221 on shelf at the weigh station
#51470 going home for repair
#90193 in box under the IC
#51359 in rad van
Apr 8, 2020 When it becomes necessary to ship a Cahn Balance, utmost care should be taken to secure the hangdowns "just right". See image.
Apr 7, 2020 Cahn balance tag#51470 was experiencing a delay in stabilization after a weight was placed onto the scale. There were no issues if you placed a weight and waited 60 seconds and then... clicked "Tare", but if you clicked sooner than 60 seconds, the graph would come out looking similar to the image below. The balance was opened up, and the shaft was very carefully lubricated with CRC ELECTRICAL GRADE 2-26 Plastic Safe Multi-Purpose Precision Lubricant while simultaneously moving the scales by gently blowing onto them. This made the occurrence of the issue less frequent, but as it was still present after the lubrication and several test weighings, a decision was made to send the balance back for calibration and service. A tag on the balance indicates that it was last calibrated in 2005. The balance was temporarily replaced with the tag#52427 unit, which is not exhibiting any of the aforementioned issues.
Apr 7, 2020 NOTE: When turning on a Cahn balance: If the balance is displaying 8888888, press the TARE button on the balance to activate it. Otherwise, do not ever press TARE on the balance. Use the tare feature in the software.