[labnetwork] SPTS (STS) Advanced Silicon Etcher

[Roy Cork]

Hi Richard,

I'm not sure if this is the right way to reply to your message in the forum but I'll try (for some reason your message isn't appearing in my thread).

I have attached the drawings for the AMC modules (sorry they are not totally clear but they are photocopies of photocopies). There is a block overview along with the capacitor adjust PCB (located on the side of the coil MU) and 4 drawings of the module, the important one is Page 3 module_main. In my experience that is where things go wrong.

You wrote "I watched the voltage going to the motor and it is in fact getting a pulse as opposed to a constant voltage.  That being said, Tune Cap 2 looks like it is stepping more than just adjusting slowly.  I watched the resistive pot and it "steps" past where it needs to be and then tries to adjust back to the resistive value it was looking for.  The problem here is that it always overshoots the needed resistive value so it never actually adjust correctly. "

It could be the gain for the motor control is set too high. That is it accelerates too fast and overshoots the setpoint, turns back goes past again and so on, this kind of looks like its pulsing. Check on the AMC analogue board that jumpers LK1 and 2 are set correctly (also try the opposite to what they are and see what effect it has)

Setting LINK's
                                    LINK1 TUNE CAPACITOR       IN for VACUUM TYPE
                                    LINK2 LOAD CAPACITOR       OUT for AIR SPACED or SF6 Types

Also take a look at the small POT PCB on the side of the coil MU (drawing attached), this can also be limiting the range of the movement (try comparing both load and tune POT values).

Finally if the motor is always slowly creeping I have also seen a problem with a leaking OP amp. Try changing the components (IC's) in the load circuit for ones in the tune circuit and see if the problem swaps over.

Let me know how you get on. I have some more docs I can dig out if you need more help.

Roy
DTU Danchip
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