GAM tests

Date/Time

20230112-T1630-20230112-T2230

People

Connor, Nathan, Gabriel, Jackson, Roy 

Spaces Occupied

PHYS 401, 433C, In-between, Dome

Goals

1. Develop plan for testing GAM operations

2. Execute said plan

3. Take good notes of said execution

4. Tidy Control Room (433C)

Log

1. We connected to the GAM with the three cables that connect to it
   
   

   1. There is a 3 prong power input jack but it is not connected to anything on either side

2. Tried sending commands to the GAM without doing anything else but that didn't work. We also couldn't get a GAM status update through DFMTCS.

   1. We turned off DFMTCS, turned off switch on GAM control module (The bigger black box connecting to the gam).

   2. Turned DFMTCS on again and then turned the switch back on, and now we could get GAM updates on DFMTCS.

3. Tried moving translating stage, but we noticed that one of the wires on the translating stage motor was disconnected. We will need to revisit this later.

1. Next we tested rotating mirror direction.
   
   

   1. After trying to rotate mirror to north and pressing apply nothing happens. After pressing "Update GAM Status" the south filter wheel starts rotating endlessly in ascending order. (Clockwise when viewed from the instrument mounting side)

   2. We are unable to stop it. Nothing that could be done in DFMTCS stops it. Shutting down DFMTCS doesn't stop this either.

      1. Removing the serial cable on the side did nothing.

      2. This means that the GAM motor control (probably) happens inside the black box and that just receives a command from the computer.(This is confirmed on the man721 manual on page 20)

      3. The endless rotation of the south filter wheel could be a result of a bad filter wheel position encoder or a bug

   3. One possible reason for this "miscommunication" between the TCS intended output and the actual output at the GAM (in this case the output is which motors are being driven) might be caused due to the wires being attached incorrectly to the GAM controller. There are 3 ports on the GAM controller that have cables connect to the GAM (P1, P2, P3). These wires all use the same type and size of jack so they could be connected to wrong ports. All of the motors used are similar, so if there is a signal intended to be sent to the translating stage movement but because of bad wiring it is sent to the south filter wheel, it could mean that the filter wheel rotates instead. This could also explain the south filter wheel not stopping its rotation, since the controller is trying to get output from the translating stage encoder.

      1. First way of diagnosing this would be to remove each of these cables at their port and see if all of the pins on the connector are filled. If they are not, we can check to see if there are unused pins on the jack as well. If the above is true and the pin layout on the connector and jack are different, then we can easily confirm that this is the issue by connecting each connector to the jack that matches their pin layout and then test the GAM. If none of this is the case or all of the pins are populated, then we have to do other tests.

      2. Another test for this hypothesis would be to try to replicate the endless rotation of the south filter wheel and then try to engage the encoder for the translating stage position. If this stops the rotation, then the possibility of the incorrect connection being the culprit is far more likely.

      3. Another test would be to fix the loose cable of the translating stage motor and try to issue the movement command again. If this makes the translating stage move, then we can assume that at least one of the connectors are connected to the correct jack.

1. Reconnecting the translating stage motor cable changed nothing.

2. P1 and P3 connector pins match the jacks. P2 connector matches its jack mostly. Pin 17 on jack exists, but it does not exist on the connector. We could not determine if it is broken or if it came like that from the factory.

3. Engaging the limit switch of the translating stage didn't stop the south filter wheel from going on and on endlessly.

All of these tests are done assuming that the culprit is not inside the GAM. This is because:

• The endless rotation of the south filter wheel could be caused by a faulty encoder circuit. This includes, but is not limited to:

  • Faulty relay

  • faulty wiring

  • faulty encoder

  • a combination of the above

Possible testing for the missing connector pin to see if it is an issue is to do a continuity test. This would require us to test every single combination of pins on both ends of the cable. This will take a long time and is very error prone due to the amount of pins...

After connecting everything again the DFMTCS software correctly reads the on-axis and south filter wheels positions. Trying to rotate the on-axis filter wheel rotates the motor but not the filter wheel

ToDo

Notes