[Diy_efi] My WB doesn't pass the test: The return...

[rr]

renaud wrote:
> 
> Hi everyone,
> 
> I already posted this problem at least a month ago, but had problems with
> my server and had to redo my subscription on DIY-EFI list, so I apologize
> for the repeat...
> 
> My WB doesn't pass TEST 26:
> Heater circuit powered up, J7 to U2 pin 13:  I have 0v!!! (instead of
> 0.9/1.2v).
> 

With the heater ready LED on and the voltage at U3 pin 5 < .1V, 
there is either a solder short or U3 or U2 is bad.

If U3 is socketed remove it from the circuit & re-test. If it passes
then U3 is bad.

If it does not pass, then a solder short exists or U2 is bad. You
can remove U2 to see if it is bad or a solder short exists.

BobR.


> I disconnected one end of R39 from the board and measured an almost normal
> resistance: 67.8K (versus 22K when on the board).
> 
> I checked there was continuity between pin 13 U2 to U3 and between U3 and R40.
> I also by mistake measured resistance between U2 pin 13 and ISO1 pin 4, and
> found 133K (I hope it did not damage U3 doing this...).
> 
> What should I do next to find the problem?
> 
> Thanks so much for your help.
> Renaud.
>

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