Jaycar 5300 LED display

[Crescent Kao]

Hey Peter,
  Thanks for the information... Its strange that this happened to tell you
the truth. I finally got it all working and calibrated and it worked
flawlessly for over 5mins while idling.. then I shut it off, and about 5mins
later go to try it again and this happens.. Basically, i powered up the car
and the display didn't light up at all. So i thought maybe the power
connection came loose or something, so i checked it and it was fine.. I then
turn off the ignition and turn it on again, and the display lights up, but
isn't displaying correctly. Very odd indeed.

So, what do you think I should do in the meantime? I checked all the 7-seg
LED's and they are fine.. when I use the display with the WBO2, it still
works just fine.. the only thing wrong is the middle horizontal bar on each
7-seg LED doesn't light up any more, and a few of the bars on the 10-seg LED
aren't working either. Do you think the PIC chip was damaged and is the
culprit?

What I'd like to do at this point is just purchase another unit from you as
I would like to get a display working ASAP before the end of this month as
we have some big event coming up and the 2002 race season is starting as
well. Basically crunch time. If possible, I'd like to get some replacement
parts for this bad one now as well or I could send down to you if you'd like
to inspect it to determine the cause of the problem.

At any rate, let me know if you can send me another unit and possibly with
priority shipping (not sure how long regular shipping takes, but I'd like to
receive it within the next week maybe?). I can Paypal you the balance.
Thanks again Peter.


Crescent Kao
Director of Marketing and Sales
www.c-speedracing.com


----- Original Message -----
From: "Peter Gargano" <peter at techedge.com.au>
To: <diy_efi at diy-efi.org>
Sent: Friday, February 08, 2002 3:04 PM
Subject: Re: Jaycar 5300 LED display


> Crescent Kao wrote:
> >
> > The big 10ohm resistor on the lower board is burned!!! And now when i
power
> > up the unit, some of the LED bars on each digit don't light up
(including
> > some of the bars the vertical LED on the right)!!
>
> I think there's a problem with the power supply design in Silicon Chip's
> FMD design where shunt regulator ZD1 can overheat if the (vehicles) power
> supply goes much over 16 volts for anything other than short periods.
>
> If the display circuitry draws little current (no or few LEDS lit), then
> at a power supply voltage of 17 Volts, ZD1 will rapidly exceed its power
> rating and will overheat, possibly going short circuit and also causing
> the 10 ohm resistor to rapidly exceed its power rating. For a vehicle,
> 17 Volts is probably not an uncommon figure to see for short periods.
> There are a couple of ways to "fix" this, and I'll need to look into each
> possibility.
>
> In light of some feedback I've recently received, there is another problem
> area I'm looking into, that can be easily rectified, and has to do with
> calibrating the FMD (at 1.4 and 3.0 Volts). More info soon when I've had a
> chance to play with one of the few units exhibiting this behaviour.
>
> If you have any specific info you'd like me to know about then email me
> direct at <peter at techedge.com.au> ie. mailto:peter at techedge.com.au
>
> Peter.
>
> ----- End of forwarded message from owner-diy_efi at diy-efi.org -----
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