When you get an unstable beam current, please check the
three components: +80V 1.5A, +75V 7.5A, and AL-02J in the EOS unit.
+80V 1.5A and +75V 7.5A (HV and CL/OL supplies)
The first step is to check the output voltage between check terminals. If the output voltage is incorrect, adjust it by VR1. Also, if the output voltage is unstable, you need to repair the PSS module. The easiest way is to replace all electronic parts on the PCB. You need to use 1/2W or grater registers instead of the original 1/4W registers when replacing the PSS components. The simulation shows the power consumption of those registers is more than 300 mW.
AL-02J (ALIGN coils and STIGMATOR)
I guess that insufficient thermal design may damage transistors on the AL-02 module. If this module’s output is unstable, you can replace transistors mounted on the heatsink (TO-220 package). Please apply high-quality thermal grease.
