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

[Andrew Brownsword]

Hello, I recently joined the list in hopes of getting a bit of help putting
together this DIY-WB kit (which I need in order to test my VAF -> MAF
conversion on my car).  Hopefully somebody out there is willing to help!

I'm a bit of a novice when it comes to electronics and soldering, but I've
managed to assemble the thing and get to the testing stage.  I've gone over
all of the solder joints several times, and I carefully measured all of the
resistances before mounting the resistors -- selecting the best ones from
each package.  All the chips are socketed and weren't on the board during
any of the soldering.


Unfortunately testing has not gone flawlessly.  Nothing is THAT easy, right?


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.  I have checked the
resistors and the solder joints that are related, according to the checkout
page and I don't see anything untoward.  I don't know how to test the
capacitor, and I swapped the ISO for another (no change).  No shorts are
visible although I think there is more flux on the board that ideal.

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.

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

  Andrew


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