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Thread: Help needed with 506 scanners and modified DT40 AMP

  1. #1
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    Default Help needed with 506 scanners and modified DT40 AMP

    I modified the DT40 AMPs per Pangolin specs, made sure the wiring to the galvos is correct, set the DC offset to zero, turned the servo gain 7 turns clockwise for zero, plugged them in and got an acceptable ILDA pattern. Great. A little tuning and I'm all set. Then I blew the power supply when a small shard of aluminum got between a resistor and a cap. OK, no problem, I got a new 24 volt power supply plugged it in, set the DC offset back to zero, plugged the galvos and got a Y oscillation. Tried backing off the Low Freq Damping, but that did not work. Tried turning down Input Gain, no help. Now the ED1 green LED goes out when either galvo is plugged in. They go back on when both galvos are unplugged, so the boards seem to be fine. I've only touched the Position Scale , Servo Gain, Low-frequency Damping, High Frequency Damping, Input Gain and Input Offset. What I need is a recommend starting point for all these pots for the 506 scanners (3mm mirror). I do not have a scope, just a decent DVM.
    Thanks for any help.

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    I would drop Bill an email whilst you're awaiting a response here.
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  3. #3
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    PM sent. I'm not ready to publish the full startup procedure yet. I'm still working on making it somewhat foolproof.. Its also going to be different on a DT as some of the pots rotate in opposite directions etc. I don't have any DTs so......


    Steve
    Last edited by mixedgas; 12-19-2014 at 07:01.
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    Thanks Steve, But I fould the real culprit. The red and white wires on the Y galvo were crossed. Because both seem connected on my continuity meter, I missed it. Also, they seem to prefer one way with regard to the soft stops that Pangolin provides. I'm back in business.

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    Yeah, That error happens often when making the cables from the pre-made supplier cables. Some times they flip both red/white pairs when making the cable at the factory. It resulted in a fairly substantial test jig here for pre-testing the cables. Glad you found it. Let me know if you have any further issues tuning.

    Steve
    Last edited by mixedgas; 12-19-2014 at 08:06.
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    Steve,
    would you happen to know the max scan angle for the 506's, with your modded amps?

    thx,
    Carlos

    nevermind,, I just found the datasheet , and its 60 degrees optical. (still not close to the 6215's 80 degrees).

    thanks!
    Last edited by carlos3621; 12-19-2014 at 18:36.
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    You can push a good bit more then that out of them, but the rating is 60' Optical
    Steve
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    thanks Steve,
    was wondering about the pro's and con's , of the 506's vs the 6215's (aside from the obvious price difference!)
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  9. #9
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    The 506 is a wonderful scanner--but a few cavats: the mini TE connectors are a real pain, especially with old eyes. I do not have the proper crimp tool for the tiny inserts, so I use a regular crimp tool, and then solder the connection to make sure it is tight. I then used some shrink tubing to cover the wire that was melted. That was a big mistake as the connector no longer fits properly into the holder and then pops out when connected to the scanner. It became such an issue that I just hard wired the wires right to the scanner. But that is were I made a big mistake--I switched the position A and B wires, and when I started tuning everything was upside down, and then the Y started oscillating like crazy and tripping the AMP. I was ready to send the blooming this back to Bill, when I thought I better check the wiring ONE MORE TIME. After an hour or so tuning, I get a beautiful 12K and 30K pattern with a centered box in the Beyond software. One strange thing I have notice is when I start to expand the box in software, or move the box around the field the image starts to go wacky big then small, every goes out of tune, and then I trip the scanners. The position scale is turned to the stops, as per the instructions from Bill and Steve. So how do I resolve the issue?

  10. #10
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    Which stop are you on? You should have absolute minimum position sensor gain. Do you have an oscilloscope?

    Where did you set the DC offset to? Measure voltage from offset pot wiper to ground with input floating or grounded, not connected to DAC.

    Are you wired for single ended input or double ended input?

    Where is the image size pot set at?

    Did you add the paralleled resistors on R3 and R4, the position sensor resistors?

    BTW, your not alone, most crimp tools do not work. Adding the solder is treacherous.(spelling> I just drove 11.5 hours.)

    Considering probably less then 5 people have tuned their own 506 on PL, you might want to clear stuff with Bill or I before you try any advice or on-line guides. Buffo's tuning guide sorta does not completely apply to the mod, for example.

    Steve
    Last edited by mixedgas; 12-23-2014 at 15:21.
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