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750c Display Documentation

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  • ykick
    commented on 's reply
    My 1st job out of college was working for GI (General Instruments) Jerrold division cable box depot which opened a new production rework line for replacing defective button batteries on PCBs. Large number of new cable boxes were found to have defective Sanyo button batteries and the “settlement” reached was that Sanyo financed the creation of the rework line and 2 shifts working to fix the engineering recall.

    It was not a bad gig and they kept me on as a bench tech once the project was completed.

    Oddly there's no soldering to PCB here? That sounds like a problem waiting to happen....

  • cajk
    replied
    I do not think the 750c "forgetting time of day" problem is caused by insufficient internal button battery capacity. I can set the time and ride my bike (with 750c) in the morning, then turn off the display and the battery pack. That same evening, if I turn on the 750c display and check the time, it has already "lost time" and is incorrect. Surely ANY button battery would last longer than that!

    In contrast, my DPC-14 display will retain the correct time over many days of inactivity. Anybody know what type button battery it has?

    There must be a difference in the way the two displays are wired, either to the button battery or to the main battery pack. If the 750c was not designed to retain the correct time setting, then that is just plain dumb engineering.

    Of course, if the button battery in all these 750c displays is defective (non-functional), then that is a different problem entirely.
    Last edited by cajk; 07-05-2017, 07:21 AM.

    Leave a comment:


  • paxtana
    replied
    The battery is a Japanese cell that is spot welded on those metal contacts at the battery factory. It is sold that way before installation at the display factory. Those contacts are then held into place on the circuit board with what appears to be some sort of clear resin. It is unclear to me how we could retrofit this with another battery, there is nothing to desolder. Only way I see to remove it would be to cut it out, maybe with wire cutters.

    Leave a comment:


  • MichaelT
    commented on 's reply
    I'm going to try to upgrade the battery to a CMOS cell. I will hard solder the leads on and hopefully this will solve the time resetting after pulling the power.
    Cross my fingers the voltage is the same.

  • MichaelT
    commented on 's reply
    If the dash is independant and all that is needed is a larger battery, then its worth a try to open it up and stick a bigger one in.
    If the time is dependent on the reserve held by the capacitors in the motors controller, then a circuit will have to be made and a battery squeezed into the the dash with it.
    This is worth investigating further.
    ***EDIT***
    I see further down that there is a teardown and the CB is exposed, the internal battery can be upgraded to a larger one, I will try a CMOS battery leads hard soldered in.
    Last edited by MichaelT; 07-04-2017, 10:09 AM. Reason: info edit

  • ykick
    commented on 's reply
    Sweet, thanks! Also no doubt it uses a button battery. I suppose for volatile stored settings?

  • paxtana
    replied


    Here's how to open the screen if moisture develops. You need a spudger (electronics pry tool set) and just work it along the edges of the outer plastic until the clips come off (it's easy)
    Then you have a few screws, remove those.
    Now you are down to the screen itself.
    You can remove a couple more screws on side if you want a peek at the circuitboard on the bottom.
    In any case if you leave it for a day or so it'll dry out and fogging will go away.


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  • neilio
    replied
    Hello from NZ. 750 C posting an error message 0CH which is not on the list of error codes above. Any ideas?

    Display fogged up after a light shower yesterday. I totally agree with Skymon above. Spot on.

    Leave a comment:


  • Stagehandman
    commented on 's reply
    I have also noticed that even when the 52V mode is selected the battery graphic and percentage options are still scaled to 48V so are not accurate.

  • jaymz77
    commented on 's reply
    I have tested leaving the power on and it will keep time but even being plugged to the battery the whole time and the display turned off, the time changed once turned back on.

  • metalrookie
    commented on 's reply
    I email Luna about this, they said it is an internal battery issue, and all the units have this problem. It is disappointing..

  • Stagehandman
    commented on 's reply
    I'm having this issue even when the display is just turned off and is still connected to the battery. Set the clock, rode to work, bike sat for 10 hours, and was already significantly off. Is this an inherent flaw or is there a solution to this?

  • animalss2
    commented on 's reply
    Mine is doing that too.

  • ykick
    commented on 's reply
    I personally like the font size of the 750C much better. On the DPC-14 the PAS is same size as the Speedometer digits. But the power/Watt meter readout is small font. I prefer the 750C displaying Speed/Watts in largest size numbers. The Watt meter seems to be faster on the 750C too.

    They all have pros/cons and nothing is really ever gonna be "perfect" in the industry yet. It's come a long way but there's still a long way to go, IMO....

  • paxtana
    commented on 's reply
    Probably a fair assessment, though it is important to consider each version has its upsides and downsides. For example the DPC14 will not mount on everything depending on the stem, which is a definite dealbreaker for some bikes.
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