In this episodes Shahriar repairs a Keithley 2500 Dual Photodiode Meter which does not power up. Teardown of the unit reveals two transformers coupled with two fully independent channels. The unit is able to source voltage in two quadrants as well as measure current down to 1-fA resolution. There is also a separate 5V switching power supply responsible for all digital circuits. This power supply is the reason why the unit does not power up. The fault is quickly traced to a bad switching power supply startup capacitor which is easily corrected.
The unit's voltage source & current measurement performance and operation is verified using a LakeShore M81 SSM system coupled with an SMU-10 module:
The Keithley 2500 is also calibrated using the same LakeShore system. An example of active fiber alignment (primary application for the Keithley 2500) is also demonstrated using a pair of infrared LEDs & detectors.
Please consider supporting The Signal Path:
https://www.TheSignalPath.com/Donate
https://www.Patreon.com/TheSignalPath
Other links:
https://www.TheSignalPath.com
https://www.Twitter.com/TheSignalPath
Leave a Reply