On Thu, 30 Dec 2010 08:48:48 -0800, wrote:

Sorry if this type of problem has been discussed before, I didn't find
any useful usenet search of this newsgroup history. Boy, do I miss
DejaNews! If someone knows of a usable search of
sci.electronics.repair please post it. The google one was pretty
terrible IMHO.

I have a "computer" on a Schwinn exercise bike that the monochrome LCD
is nearly blank. I can see that it is working, but the display is very
light. When I turn it on I can hear the friction control motor in the
bottom of the bike working. That system does seem to work, I can
increase the friction with the buttons on the computer. So buttons
work, display works a little, other functions work.

A single failure in the display circuitry. The problem is just the
display.

This runs on 4 C cell batteries, I did check the voltage on the
batteries and when I press the soft "start" button on the panel the
battery voltage diminishes from over 6V to less than 1V. Something is
dragging it down!

I unplugged the harness from the computer to the rest of the bike, that
didn't change anything. So the short is likely in the computer related
to the LCD display.

Do the driver chips for such a display fail shorted? That seems to be
what I have here.

It seems unlikely to me that this is actually repairable since the large
LCD display probably has integrated drivers in it's module. But I
haven't disassembled it yet.

Is there going to be a whole bunch of driver chips along the edge of the
LCD and something that runs those that has failed shorted?

What should I be looking into?

If something is dragging the voltage at the batteries down 5 volts that's
going to consume a huge amount of current seeing it's almost a short
circuit. I doubt any of the internals would be able to sustain such a
current draw without making a little smoke. I'd check for a bad
connection within the battery cage itself. Maybe where the contacts are
riveted to a supporting structure. This makes more sense to me.



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