[Diy_efi] DIY-WB construction & testing... help

[rr]

Andrew Brownsword wrote:
> 

> 
> The UEGO circuit fails two tests:  pin 5 of U3 measures 7.2v instead of 7.8
> - 8.0, and J5 measures 1.8v instead of 1.9 - 2.1.  

For U3 pin 5 lift one leg of the cap C12 and re-measure. IF the voltage
goes up that cap is leaky. 

J5 should really be closer to 2 volts. Is the +4 volt (VGnd) measurement
on the low side? This would contribute to a low J5 reading. If not then
double check the resistors R31, R32 & R35; as to being 1% to and 10K &
100K.

> 
> When I power on the heater circuit the LED doesn't come on.  The site says I
> need 13-16 volts and the (R/C model) battery I'm using is only 12.5v -- is
> this likely the reason?  When I measure the voltage across the LED it seems
> to read -11.5v which makes me wonder if I put the LED on backwards, but I've
> got the flat spot opposite the stripe on the PCB which is how the
> construction guide indicates it should be.

If this is w/o the sensor or any load connected then the 12 V is enough
to light the LED. Hmm, I thought that the flat went w/the stripe. Let'me
check. . . Yes, the board I looked at has the LED flat on the same side
as the footprint stripe end.

BobR.

P.S. note that the checks #34+ are not entirely valid. If they work OK,
If
not then do not worry about it.

> I'd greatly appreciate any help you could provide -- either privately or on
> the list.  Thanks in advance,
> 
>   Andrew
>

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