wbo2 testing question

[bcroe at juno.com]

OK, here's a couple ideas on checking the heater circuit.

Connect a 10 ohm 10 watt resistor and a voltmeter to the
heater terminals.  Apply 14 volts to the battery input.  The 
voltage at the heater terminals should rise in a few 
seconds to between 10 and 10.5 volts.  Move the 
voltmeter to across the 1 ohm 5 watt WB resistor, and 
the voltage should be around 1 volt.  The heater LED 
should come on.

Repeat the tests using a 5 ohm  10 watt resistor.  A 
pair of 10 ohm in parallel will work.  The voltage across 
the 5 ohm should be around 6.25 volt, and across the 
1 ohm, 1.25 volt.  The LED should not come on.  Do 
not leave this powered any longer than necessary to 
make the measurements, or the heater regulator will 
get very hot.

Bruce Roe

On Wed, 26 Dec 2001 21:41:58 -0500 Stephen Andersen
<SAndersen at advan-tek.com> writes:
> Are you saying that if you power the circuit with nothing hooked
> up that the LED will come on in 10 secs?  I have not tried powering
> it without a load on the heater circuit.  With a 3.1ohm lamp
> the LED did not come on even after about 75 seconds.
> 
> I am getting about 6 volts (open circuit) at the heater outputs
> with 14 volt input.  That sounds kind of low isn't it?
> 
> Anybody got any ideas or recommendations on how to check the circuit
> thoroughly (for an electronics idiot) after construction but prior
> to connecting the sensor?  I really don't want to smoke $120...
> 
> On the ISO is the dot (pin 1) supposed to be in the top left corner
> when looking at it on the board with the heater circuit in the top
> left?
> 
> How about the LED?  Not sure that I put it in the right way...
> 
> Thanks,
> Steve

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