Laserpic scanner failure

[DZ]

Does CDBeam's problem sound familiar? Because it should... My scanners were doing EXACTLY the same thing back in 2008, and we traced the problem to a 5 volt short to the ground plane, remember?

Are you sure about that? I seem to remember the problem going away after replaceing the two 24V power supplies you had with a single bi-polar supply. I remember the poorly insulated part in the Lasever supply causing a problem, but for some reason I thought it was causing a problem elsewhere, not on the scanner side.

When a switching supply starts to tick like that, it's either dead, shorted or trying to drive a load greater than it's capable of driving. With a set of these DT-40W's, if you try to scan something complex, such as the ilda test pattern, at a crazy angle, it ends up trying to drawing more current than the supply can handle and starts ticking, switch to another frame and it recovers on the fly. If you're not scanning anything and the supply is ticking, then you're either shorting the output of the supply or it's failed.

[CDBEAM]

MMMM.....I will be pulling the scanners out this weekend......really sounds like the root problem is/was a swarf !!!! The scanner amplifier boards were well protected when I did my hole modification.....BUT.....It IS possible that when I removed the protective shop cloths used....a sliver of Aluminum did escape and become lodged in the Y amplifier board ????? I have brushed and blown canned air on that board....with NO luck.
Will post my results....Thanx again for all the help !!! CDBEAM and Terrawatt

[buffo]

Are you sure about that? I seem to remember the problem going away after replaceing the two 24V power supplies you had with a single bi-polar supply.

Nah, that was later, when you were doing the complete re-build of the projector. One of the 24V PSU's went bang during the re-wire, remember? (Had an exposed wire, and when the harness was moved to one side it shorted to ground.) That was over the winter of 2008-2009 though. The problem with the 5 volts to ground from the Lasever driver was discovered at SELEM 2008. You had some mica in your toolbox that solved the problem.

When a switching supply starts to tick like that, it's either dead, shorted or trying to drive a load greater than it's capable of driving.

I don't think CDBeam has checked the output voltage of his scanner PSU yet, but that would be a good thing to test. Still, in my case, it wasn't the scanner PSU that was ticking, but the galvos themselves. (The +24v and -24v rails were stable.) The amps were picking up the 5V on ground and interpreting it as a signal. (This was back when I had the signal ground on the input to the amps connected to the chassis ground.) Since it was intermittent, they would tick back and fourth like that, but only sometimes.

Adam

[allthatwhichis]

Nah, that was later, when you were doing the complete re-build of the projector. One of the 24V PSU's went bang during the re-wire, remember? (Had an exposed wire, and when the harness was moved to one side it shorted to ground.) That was over the winter of 2008-2009 though. The problem with the 5 volts to ground from the Lasever driver was discovered at SELEM 2008. You had some mica in your toolbox that solved the problem.
I don't think CDBeam has checked the output voltage of his scanner PSU yet, but that would be a good thing to test. Still, in my case, it wasn't the scanner PSU that was ticking, but the galvos themselves. (The +24v and -24v rails were stable.) The amps were picking up the 5V on ground and interpreting it as a signal. (This was back when I had the signal ground on the input to the amps connected to the chassis ground.) Since it was intermittent, they would tick back and fourth like that, but only sometimes.

Adam

The moral of this story is DZ has had his hands up buffo' projector's skirt way too many times...

[CDBEAM]

Tonight I pulled the Laserpic scanner from my projector. Had to use a magnifing glass....but I spotted what looked like a small chip/sliver on the Y amplifier board....aaaa...hhaaaa...... an offending scarf perhaps ??? There where NO burn marks around it....it was just sitting there at an odd angle.....held in place by what seemed like static electricity. Upon closer examination....it was a very small rectangle....no...it was a SMD....looks like a capacitor. The SMD was not attached to the board. The ends where it should have been attached looked rough. I have no idea how or what broke this free ????? And what....if anything that had to do with enlarging the scanner head mount hole. Perhaps not a thing !!! Perhaps the vibrations from the hole enlargement physically vibrated the SMD loose??....awww...BS....WHO CARES........I put a small strip of yellow tape pointing to where the SMD was mounted and put a black outline on the pic...Just an aside...the PS checks out fine and the scanners do the same i/o operation....now as they sit on the workbench powered by the PS which was also pulled.....so.....I would assume that the SMD missing from its mount is the cause of the scanner failure. See the pics.....Thanx for all your suggestions !!!!!!!

CDBEAM / Terrawatt

[Experimentonomen]

Try to solder it back on

[CDBEAM]

I could try....but solidering on something smaller than a grain of rice ???? Sheeez !!!...and my solider job physical and electrical properties would be of questionable stabillity !!! Screw it !!! The unit will be takin a round trip to China !! Terrawatt agrees !!! Thanx !
CDBEAM