Marc, Michael, Yuhang

It was reported in elog2627 that we have problem of OPO locking servo, which works from time to time.

To solve this problem, we contacted Pierre for suggestions. Now, it becomes clear where the problem is from.

Firstly, we need to notice that we should check the OPO locking servo circuit when 'servo output' is just an offset. The test result reported in this elog is in this situation.

We found a triangular wave at J10 Pin3 but not at J10 Pin2. According to Pierre, this is related to the 'amplitude' potentiometer. We will check the impedance between J10 pin1/pin2/pin3. According to Pierre, the total impedance should be about 2k. If not, we need to buy a new one and replace it: Bourns (3590S-2-503L). We should make sure there is no issue for this potentiometer soldering.