Scannermax 506s

[mixedgas]

Five more pairs went out. Four more orders are setting here, tuned, but needing final testing. I'm waiting on a repaired Galvo from Pangolin, as I only have one pair to test with, it was inevitable that eventually something would happen working on this many amps. The good news is that 506 is reasonably repairable.

Damaged Galvo went FedEx for repairs, and a second set 3 mm was ordered.

The cables are the holdup as far as my work goes. I'm working on getting that contracted out to a vendor overseas. I hate to do it, but time spent on cables is a real bear.

The more I work with 506, actually the happier I am with them.

I run a custom show during tuning, and even a badly tuned pair does well on complex animations. LD2000 users will be Familiar with the complex Lightspeed Soaring Eagle animation on the animation CD. The Eagle looks good, even at very, very wide angles.

Steve

[laserbiker]

I received my red boards and cables today! Thank you so much Steve.
I really like the job you did on the cables, they look very sturdy and I like the small-diameter
shielded cables you used as that makes it easier to hermetically seal the optical deck.

I am installing them in my green beam projector. Pictures coming soon.

[skot]

Hi Steve

Can you explain the damage done to the galvo, and what caused it. You alude to it being the result of the tuning process.

[mixedgas]

Hi Steve

Can you explain the damage done to the galvo, and what caused it. You alude to it being the result of the tuning process.

I should have alluded to it being part of final test on a tuned board.

Damage to the galvo is a damaged photodiode, one of two in the position sensor. Most likely caused by a damaged connector or internal short on the galvo cable. I do test the cables before connection, however my LED based test rig will be slightly revised to look for conductor to conductor shorts.

One must be really careful on both brands of galvos that use the 1.5 mm "Mini CT" style connector.

It does not come in a "reverse sex" PCB mount version, or I'd simply have adapter boards made.

http://www.google.com/url?sa=t&rct=j...JYe9KA&cad=rja


I will stress again, DO NOT PULL ON THE CABLE LEADS when using this connector, use a tiny screw driver to gently pry at several points along the gap formed on the underside of the joined connectors!

The self resetting 3 amp "Polyfuse" polymer fuse on the amplifier output covers for most mistakes including oscillation while tuning. It will not always help you with a mis-seated cable.

Pangolin stresses connector seating in a PDF on line.



Steve

[mixedgas]

The Galvo Amps as shipped should be very close to a 30K tune for 3 mm mirror pairs. Most users should only have to touch up the Input DC Offset, Servo Gain, and HF/LF damping. Then later on move to linearity.

In rare cases one will move the Error Limiter once one is experienced with the slight touch of tuning required. One should not be cranking in several turns of any control with 3 mm mirror sets. Control inputs should be gentle.

One should also NOT follow the common procedure of turning servo gain and low frequency damping to zero, thus starting from scratch. Servo gain starts to become active about seven turns clockwise from zero, there is no reason to start with it fully zeroed. There is a risk of oscillation if High Frequency Damping is set very close to its end of travel, and Servo gain is near zero.

If the Galvo oscillates on startup, during course tuning, turn off the amp, and back off on Low Frequency Damping by turning it CCW two turns.

These amps use 20 turn potentiometers, the actual tuning region on each pot is a few turns.

One does "Climb the Stool" with Servo and Damping, in the classic sense, but it is easy to have too much damping. I often find myself backing off on damping a bit when switching to the Laser Media and Grid patterns.


First thing to do when you receive your amps and wire them is to set the DC offset, which is the right most potentiometer with the heatsink facing away from you. Ground the amplifier inputs, and using a voltmeter with the black lead grounded and the red lead touching the wiper terminal of the potentiometer on the bottom of the board, set the offset to as near zero millivolts as possible. +/- 20-30 mV is achievable, often better then that if you have a good DVM or scope.

Pangolin suggests this method of configuring the galvo "Optical Zero". Use of the amplifier's input DC offset control (IDC pot) for moving the image around the room is strongly discouraged. You can easily move the galvo in the mount to zero the beam relative to the projector.

I'll write up a in depth tuning document soon. Once modified, these amps do act a little differently then the classic amp. Slight turns of the potentiometers are preferred.

One should leave the "Breakpoint" potentiometer alone until one is very experienced with these amps. Altering it and the AGC potentiometer can result in the need for a total retune.

The AGC potentiometer configures the intensity of the LED in the position feedback sensor on the galvo, changing it has radical influence on how the amp tunes. Moving it will totally shift the position of the Servo Gain and Damping potentiometers, and it is best to leave it alone. While initially tuning, I set both AGCs as a XY pair for as equal image size as I can.

506 has very strong position sensor outputs, in most cases I have to set the AGC potentiometer full counterclockwise when initially tuning.

The Breakpoint potentiometer sets the crossover point between the Low Frequency Damping and the High Frequency Damping. I went to SELEM to meet with Bill to see how to adjust this potentiometer, and it takes a bit of training to recognize how to set it. I'd strongly suggest leaving it alone, unless you have real problems with larger mirrors. To demonstrate how it works, I'll need to shoot a video. It really affects small, angled, straight line features. I actually made a special test pattern for this.

When you receive your amp, the input gain potentiometer (image size control, ISC) will be wide open for maximum image size and full scan angle. Feel free to back it off and reduce your image size as needed. In the future I may set it to say 1/2 angle.

Steve

[jors]

Steve,
really interesting post.
Have you tried modifying MediaLas Micro Amp (CT6210 version)?.
As I see on .pdf from Pangolin, only few mods are needed (much less than PT20!!), also its 8 pin-out to 506, so I expect no modifications on cables...isn´t it?
Also, this driver seems even smaller than Pt20, great for micro projectors
Thank you & congrats for your work!
Jordi

[mixedgas]

I'm not aware of nor have I tested the microamp. My goal is to provide a cost effective amplifier. I'm working with my amp supplier so I do not even have to modify the amp nor make the cables.

Batch two of the amplifiers is here. When Pangolin gets me the replacement galvos, the rest of batch one will ship within a Day.

Steve

[jors]

Many thanks Steve, really interested in 506 along with small-size drivers for my new micro-projector. So, could you provide modified PT20? Are these the smaller ones at a cost effective-modified drivers?

[mixedgas]

Many thanks Steve, really interested in 506 along with small-size drivers for my new micro-projector. So, could you provide modified PT20? Are these the smaller ones at a cost effective-modified drivers?

Mine are not PT20, I have a much more sophisticated driver then the PT20. The raw amplifiers are made for me by a vendor that makes most of the Chinese scanner amp boards. They are not available without buying through a distributer. Thus I import them.

Steve

[jors]

Ok, really interested in ) Please Could you provide driver sizes, pics, price? Want to know if they could safely fit inside my design
many thanks!!