HELP!! Raster-induced scanner blowout...

[dave]

Hey man, PM comming thru after I write this.

One thing that you could try is to disconnect the power limiter. Remove the jumper I have circled in the attached pic

[Stuka]

Hey man, PM comming thru after I write this.

One thing that you could try is to disconnect the power limiter. Remove the jumper I have circled in the attached pic

I'll give that a try a little later today -

I pulled the 40K set out and temporarily put my original 30K set back in, but quickly realized that once you get use to 40K performance for graphics, it's hard to go back...

[Stuka]

Well that stinks, not terrible though. Looking at the previous pic, the problem does appear to be with the amp, which is good, much easier to fix an amp than to fix a scanner. Would be much easier if the thing was sitting on my bench though. See if you can get the inner circle to increase in size by adjusting servo gain.

Latest update -

Removing the power limiter jumper does not appear to have any impact.
However, the servo gain does appear to affect the inner circle, at least enough to turn it into a smooth oval shape.

Is it worth trying to retune, or should I quit while I'm ahead/behind?

[chad]

Disregaurd below. I didn't realize that it was just the one axis.


have you looked at your +- and ground coming in from the power supply? If you have a scope take a look at the supply rails under load.

just a thought.

chad

[drlava]

Looks like the x-galvo is torched. with the power off, when you rotate the axis, is it smooth? Also you might want to check out the feedback section under the cap to see if there are any chips/loose parts.

[Stuka]

Torched, it appears.

Ahh, the money pit........

[-bart-]

Could be that one of the turns is shorted (due to high temp) causing loads of damping of the magnetic field. Retuning then looks like to solve the problem, but the shorted turn remains and produces lots of heat, spreading the problem even further (especially with power limit off)

90% chance that a replacement of the x galvo (and a retune of its driver) will fix this.

edit: powerlimit and the polyswitch should have prevented this from happening. Good reason to investigate if they're still functional.

[Stuka]

Could be that one of the turns is shorted (due to high temp) causing loads of damping of the magnetic field. Retuning then looks like to solve the problem, but the shorted turn remains and produces lots of heat, spreading the problem even further (especially with power limit off)

90% chance that a replacement of the x galvo (and a retune of its driver) will fix this.

edit: powerlimit and the polyswitch should have prevented this from happening. Good reason to investigate if they're still functional.

Looks like I'm going to cut my losses on this one, and replace them with a set of DT-40's.
I plan to get these repaired and use for a future project (there's ALWAYS a future project, isn't there? )

Thanks to everyone who chimed in with troubleshooting tips & ideas!

[DZ]

Ah, I stand corrected, looking at the pic again, the problem did stay with the galvo and not with the amp. Bummer. My apologies for the confusion.

Looks like I'm going to cut my losses on this one, and replace them with a set of DT-40's.
I plan to get these repaired and use for a future project (there's ALWAYS a future project, isn't there? )

Thanks to everyone who chimed in with troubleshooting tips & ideas!

[Stuka]

Ah, I stand corrected, looking at the pic again, the problem did stay with the galvo and not with the amp. Bummer. My apologies for the confusion.

No problem - I appreciate the assist!

Randy