G1362A RID Diode Balance. -1 or 1

Hello, while trying to balance the diodes in our RID we discovered that no matter how small of an adjustment is made the signal will only vary from -1 to 1.  The detector has been purged for hours with water and mobile phases and appears to be free of any air bubbles.  My thoughts are that one of the light receiving diodes has become faulty thus making balance impossible.  Any help would be greatly appreciated.  

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  • I just wanted to make sure you understood how to use the purge valve to flush the system and use the set screw. Some people don't understand the working principle.

     

    Your guess one diode is faulty could be right, but also the main board could be defective, but less likely. I would ask for an Instrument Exchange module at a fixed price or, alternatively have the repair done with an exchange optical unit (-69 part), which is less expensive.

  • I appreciate your help, and we are discussing repair options now.  Would there be any type of diagnostic test that I could perform on the module to narrow down the root cause?  As of now, nothing can be run on our system before the error message clears on the RI module.

     

    Thanks again.

  • No, there are no additional tests for the diodes or the optical unit itself. If the diode balance cannot be achieved with a well flushed system, something is broken. As mentioned, repair level would be either the optical unit or the main board. Usually they don´t break, but it depends on the age of the RID. More often the purge valve goes bad (mainly by leaving it sitting in water or buffer) and then you would also have issues with the diode balance, but at least you could see moving readings, not just 1 and -1.

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  • No, there are no additional tests for the diodes or the optical unit itself. If the diode balance cannot be achieved with a well flushed system, something is broken. As mentioned, repair level would be either the optical unit or the main board. Usually they don´t break, but it depends on the age of the RID. More often the purge valve goes bad (mainly by leaving it sitting in water or buffer) and then you would also have issues with the diode balance, but at least you could see moving readings, not just 1 and -1.

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