d9200 wobble

[grantspain]

I have a d9200 that has a slight wobble,its being caused by the degauss circuit-almost like some residual current making its way to the coil.Disconnect the degauss coil and its gone
has anyone seen this problem before and know a fix
I am wondering whether that current inrush limiter is a little leaky?

[MonMotha]

I'm pretty sure that on the D9200, the degauss is controlled by the microcontroller.  A PTC is provided only to limit things in the event it gets "stuck on" for whatever reason so that the coil doesn't overheat.  As such, it may be quite a bit more "leaky" than the PTC on a monitor with the degauss controlled by a big ol' power pushbutton or that just chucks it straight across the AC input with the PTC to cut it out (providing for "degauss on startup").

In this setup, the coil is usually driven by a relay which is in turn driven by a transistor.  Chances are that relay is being held "on", which isn't proper.  Check for that condition.  If that's the case, check the drive transistor and freewheeling diode (which, if failed, may have killed the drive transistor).  If the transistor is constantly being told to hold the degauss "on" (check base/gate), then something's gone amok in the MCU, since the transistor is usually driven straight off an MCU IO line.  If that's the case, your best (cheapest and most effective) bet is probably to just lift the base/gate of the transistor and ground it to force the degauss off since replacing the MCU is probably out of the question.

[grantspain]

its only a slight wobble around the edges,like you see when a ballast is a little too close to a crt
i will check out that relay and transistor
if the mcu is constantly giving a signal to the base of the transistor then i can make a manual degauss switch i reckon

[qrz]

could also be stuck relay contacts/or debris.
a .001uF/400v cap across the sw can dampen the arcing that leads to sticking 

[grantspain]

bit of strange one this,i checked out everything and could find no problems-i ran up the other need for speed i had that has a d9400 and it has the same issue although slightly less

i am gonna take a look at wiring and earths,well first thing i will do is remove the monitor and try away from the cab

[MonMotha]

So you confirmed that the DG coil is not energized while the problem is evident?

Does the D9200 have a double pole or single pole relay for the DG coil?  If it's single pole, the neutral would still be connected, which could create some interesting problems if the local earth ground line differs substantially from the neutral (occurs semi-often in large commercial buildings).

Oh, of course if you've got Hot and Neutral flipped, you'd leave hot connected which might cause exactly this.