WBO2 testing

[bcroe at juno.com]

Crescent Kao,

I am repeating a couple of messages I sent out before, 
this one on why your WB overheated (U1).  The second 
will be a diy WB heater control test that has worked for 
a couple of people.  

Seems like we need to get some of the testing means 
and results together into a document, so people can 
just go step by step.  Better than having to wait for the 
list.

Bruce Roe

On Tue, 18 Dec 2001 00:34:46 -0600 bcroe at juno.com writes:
> Measure the voltage across the lamp, and across the
> 1 ohm resistor.  If the lamp has less than 10 volts (and
> the LED is out), you are probably running in the current
> limiting warmup mode.   The resistor will measure 
> about 1.25 volt in that case.  
> 
> You probably are using too large a lamp.  With a small
> voltage drop across the lamp and maximum current, you
> have a large voltage drop (at max current) across the 
> LT1086.  This heating it up, apparently to the point of
> thermal shutdown which dims the light.
> 
> I would find a smaller bulb, which should run at 10 V
> with reduced voltage across the 1 ohm (crossover to
> voltage regulation).  A 2" by 3" heatsink is not very 
> generous for this application, unless it has a lot of fins.
> 
> Bruce Roe 


> On Mon, 17 Dec 2001 01:04:09 -0500 Glen Beard 
<gbeard1 at nycap.rr.com writes:
> > OK, I've gotten everything soldered up, and I am testing the
> > heater circuit using a tail lamp.  The lamp turns on nice
> > and bright building its current to 1.003 Amps.  Is the LED
> > supposed to turn on after a while?  Is the LT1086 (VR)
> > supposed to get sizzling hot even with a 2x3" Al heat sink? 
> > With the smaller heat sink I had on it, the bulb would light
> > up and then start to dim again.  If I blew across it and it
> > got brighter.
> 
> > Glen Beard 

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