Author Topic: Galvos no movement need help  (Read 49 times)

zhang

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Galvos no movement need help
« on: January 08, 2019, 01:04:37 AM »
Hello Nelson, this year I finally have time to do something on openlase with Lasershark.
But there seemed to be something wrong with the hardware or the install steps. (I first do it on WIN10)
 The laser can work under the TTL signal, but only the galvos no movements at all. I just want to know where is wrong. (I did make the lasershark composite device with Zag.)

(IMG2 and IMG3 are two different PC with WIN10.IMG4 is what it shows when I open the Zag the second time.)

Macpod

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Re: Galvos no movement need help
« Reply #1 on: January 08, 2019, 10:23:28 PM »
Hi Zhang,

That is an interesting daughterboard between the lasershark and galvo amplifiers. I have not seen this before.

It certainly looks like the LaserShark is successfully connected in the app. If it was not you would not be able to read the firmware version, ringbuffer sample count, etc.
I see that you also say that ttl signals work so it sounds like you can turn on and off a connected ttl laser suggesting the software<->lasershark link is working

While it is hard to tell from the image, it does appear as if you have connected the X and Y connections to the associated pins on the daughterboard correctly.

I am unable to read the text on the daughterboard which the power cable is connected to. Are you confident it should go there? Are there any LEDs on the galvo amplifier board to indicate it is successfully receiving power? Also, are the heatsinks warm to the touch? Even at idle the heatsinks should feel warm to the touch usually.


zhang

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Re: Galvos no movement need help
« Reply #2 on: January 09, 2019, 01:37:11 AM »
Hello Nelson,

Thanks for your reply. And the laser can be on/off depending on the app.

But the galvos amplifiers have no movements. The left LED is off and the right LED is on. But when I first used this, I used to think the 15V+- pins on the board are the power pin by mistake, so I used a 15V PSU to input the power to it, and only the LED on left side turned on. But then I found it wrong and use a 24V PSU to power it through the pins on the daughterboard. Was this action broken the amplifier down?

And the heatsinks are not so warm even if turn on the power with the LED on.
Or can it be something wrong with the 2.54mm 3pin cable? As you can see, the ones we bought can't match them on the board perfectly. But I've changed them for 3times and make sure the X+ matches the X+, .etc.
---------------modified---------------------

And I'm now trying the circle example on Ubuntu 16.04, and the galvos only still not work.
Seems to be something wrong with galvos or the connections between lasershark and daughterboard.

Pictures:
https://drive.google.com/file/d/1llD3GhxdPVHf1LYIwx9nGjf89DKt9QcL/view?usp=sharing
https://drive.google.com/file/d/1vjns5bgrxW8rpC3SIZJ85z9LCjWMEu4V/view?usp=sharing
https://drive.google.com/file/d/1OyX43ezoL8todQkPEGcPeStLVHMaAuMZ/view?usp=sharing

------------modified again----------------
And now the galvos finally moves and two of the LEDs got light on. But, it may rotate even if I have not open the .exe yet.(Maybe the signals in buffer?) And here is the video.
https://drive.google.com/file/d/1Thw7bvIWZxR_ihNSIudDVhPxHaHSWoFP/view?usp=sharing
And when I turn on the .exe, the left LED turns OFF and galvos mirror no longer work... I don't know what just happened..
« Last Edit: January 09, 2019, 04:10:35 AM by zhang »

Macpod

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Re: Galvos no movement need help
« Reply #3 on: January 10, 2019, 01:46:20 AM »
Thank you for these pictures and video.

Often times galvo boards will have two 3-pin connectors on them.
- One is used for power INPUT from a power supply
- The other is a power OUTPUT. This is used to provide a +/-15v power supply to an external DAC (Digital-to-Analog Controller) board.

If you attempted to power the galvo board via the OUTPUT power connector it is possible this could have damaged your board. It looks like the LEDs are intended to indicate if you have +15v and -15V. If neither or only one are not turning on this is not a good sign.

If you connect a multimeter to the the center pin (gnd) and then the side pins of the +/-15v connector what does it read? it should be a stable value close to  +15V on one side and -15V for the other.

Do you have a datasheet for your galvo kit?
What did you do to cause both LEDS to turn on?

In the video, were you running the circle_maker app or was this just with them plugged in. It looks like they are slowly turning clockwise/counterclockwise but slower than I believe they should (unless you modified the code). The galvos should not make that buzzing noise, that means a spurious signal is being generated or the galvo amp circuit is damaged. It could also mean a bad/intermittent connection.

zhang

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Re: Galvos no movement need help
« Reply #4 on: January 13, 2019, 07:43:01 AM »
Hello Nelson:

Thanks for your reply!

Using the multimeter, it shows that the +15V side is normal but the -15V side only outputs -0.7V. :( How I made both the LEDs on is just plug them in. After 5s random turning, the left LEDs turns off with a big sound, and the galvos mirrors no longer move.

Here is the Galvos kit And there seems no full datasheet or Galvo kit provided by the seller and little information about the kit.
Sad to say but it seems amplifiers were damaged. Just did a mistake reading the datasheet "working Power Supply: 15VDC" and then plug it onto the 15+V OUTPUT 3PIN connections. Any remedial measure? Or to buy another set.
 :'(
Zhang

Macpod

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Re: Galvos no movement need help
« Reply #5 on: January 13, 2019, 03:38:20 PM »
If you also heard a loud noise it is likely something "let out the magic blue smoke". That's a shame as this was an expensive kit.

The good news about this situation is that there are generally no embedded controllers on the boards. If you have an electrical background and are strapped for cash you could try and identify potentially bad parts (i.e. the -15v regulator which is one of the 3-pin chips screwed to one of the heatsinks) and any op-amps/resistors/etc.

The power supply likely isn't bad (but you could check to make sure it is still  outputting +-24v). It is possible the galvos are fine too which means you may just need to replace the galvo amplifier board itself vs everything.