My concern was damaging anything else by testing these in-circuit, but =20
think I'm going to remove those parts and then be able to test =20
properly.  I can also probably pull one of the same chips from the =20
working drive and can compare test results if necessary.

I'm headed out to Melbourne tomorrow to check out the shuttle launch, =20
so will have to do this over the weekend -- unless I get trampled to =20
death by the expected 3/4-million people!

Cheers,
-Neil.



Quoting YES NOPE9 <yes@nope9.com>:

> The manual says the opto-isolators are HCPL-2630s.
>
> That datasheet is at http://www.fairchildsemi.com/pf/HC/HCPL-2630.html
>
>
> Pins 1/2 are the anode/cathode of one LED.
> Pins 4/3 are the anode/cathode of the second LED.
>
> Get a DMM with current measurement.
> Turn all power off and disconnect the leads that go to P1:4 , P1:2 , =20
>  P1:3 , P1:5 and P1:6
> ( page 43 of 84 of the manual )
> Get a good 5VDC supply.   Connect the 5VDC to P1:4 with the DMM  =20
> current measurement probes intervening.
> Turn on the 5VDC supply and ground P1:2.   The DMM should show a  =20
> current of  [ 5 - Vf ]/470  =3D=3D> 3.2 / 470 =3D=3D> ~ 7ma .
> If you now reverse the leads of the good 5VDC power supply  ( ground =20
>  now goes to P1:4 )  and apply 5VDC to P1:2 the DMM current should  =20
> read zero since the LED is reverse biased.
>
> You can skype me at WFTelectronics if you wish.
> 99guspuppet
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>




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