dim rows

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waxweb
Posts: 5
Joined: Sun Dec 14, 2008 5:10 am

dim rows

Post by waxweb » Fri Aug 28, 2009 6:05 am

hi Paul,
I've got two dim rows on one of my 8x8's... what are you suggestions on debugging this?
best,
David

paul
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Posts: 700
Joined: Mon May 12, 2008 4:19 pm

Re: dim rows

Post by paul » Fri Aug 28, 2009 6:31 am

The first thing to check the resistor that controls the current on the LED's - it's really the only resistor on the board I think, so should be easy to find. One resistor controls one chip, which controls two rows of LED's - so there's a smoking gun pointing at the resistor.

Check the value on the resistor (a packing error is always possible - my shop slogan is: you can't get good help, even if you do it yourself). Also reheat the solder joints.

If that doesn't do it, feel the chip to see if it's getting hot, to look for excess current draw and take a look at the voltage at the power pins (1 & 24, I believe), and reheat those solder joints. Try swapping chips too, if you used the sockets provided, to definitively locate the problem.

Write back if you don't find the issue.

Paul

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