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SR510 & SR530 Tech Support

If you are experiencing trouble with your SR510 or SR530 you can either send your instrument back to SRS for service, or you can try and fix the problem yourself. If you wish to send the instrument back now click here.

If you wish to try and fix the problem yourself, the following troubleshooting guide may help you.

SR510 & SR530 Troubleshooting Guide

Symptom 1 — Front-panel red overload LED is constantly lit

Most likely the front-end transistor of your lock-in amplifier is damaged. If you look in the SIGNAL AMPLIFIER page of the schematics (located in the back of the user manual) you will see that the first active components in the voltage input signal path (U101) is a 2N6485 FET. Your instrument will be populated with a 2N6485 or an LSK389B (newer units) depending on its age.

Take the top cover off your instrument and locate Q101. It should be in a socket so replacing the part should be easy.

You can order the three replacement parts you need by clicking here.

Symptom 2 — Can't send commands remotely over GPIB interface

Click here to download programming instructions using National Instruments Measurement & Automation Exporer.

Symptom 3 — Can't send commands remotely over GPIB interface

A modification to the GPIB interface of the SR510 and SR530 was implemented in June 1991. A 270 pF capacitor was added between pin 10 (ground) and pin 17 (DAC) on the GPIB bus driver (part number 75161, adjacent to the MC68488 controller). If you have an old unit, check to see if there is a capacitor installed between pins 10 and 17 of the 75161 chip (located near the GPIB connector). If a 270 pF capacitor isn't soldered between these pins, you will need to install one before GPIB communication is possible.

If you are still having trouble your SR510 or SR530, your instrument will need to come back to SRS for service. Click here to get an RMA number.

Phone:(408)744-9040 • info@thinkSRS.comwww.thinkSRS.com