Replace C2 on PLM Serial Board

[johnjces]

My PLM, Version 2.2 became very flaky after about 2.5 to 3 years. Sometimes things would work and sometime things wouldn't. A new PLM, V2.5, fixed all my issues. The 2.2 PLM didn't fail due to a power supply issue but it was heading there, at least getting pretty darn flaky, even though the caps on the 2.2 version were beefed up a bit from what I can tell. Not to the recommended values in the threads, but they were getting a bit more robust.

In pouring over the threads on replacing the capacitors in the PLM, I could find no mention of replacing C2 which is a 100mfd 6.3 volt cap on the serial daughter board. I am going to replace all the main board caps but I am not sure what C2's purpose is. However, is this something that should be replaced? Figured I might as well, but sometimes it might be best to leave well enough alone if it is truly doubtful that a replacement would help. And I am seeking the experts thoughts on this one.

Thanks

[Brian H]

C2 on the serial daughter board. Is the DC filter capacitor for the 5V DC logic supply for its electronics. Probably OK as it is only the ripple of the supply. Could not hurt to change it if you want to. As an extra measure. Note as mentioned. V2.4 and above have a new serial daughter board. Its markings for that capacitor may not still be C2.

Starting with V2.3 the two main power supply capacitors C7&C13 where changed to a different series capacitor. Made for switching power supplies. Starting with V2.4 the serial daughter card was updated. With a serial interface chip with better ESD ratings and the serial I/O lines to the outside world have protective components on them.