resistance at J3 pin 1, 2, 3.

[bop2nite]

Hi all,
OK, I have my first C84 PCB stuffed. Checking J3 pins 1, 2, 3 this is what I get.

3 2 1 3 2 1
l l l l
+ - + - Leads from DMM
Meter does not even show continuity.


3 2 1 3 2 1
l l l l
- + - + Leads from DMM
6.9 mohms 4.5 mohms

Is my DMM broken???
Do I continue??? and apply power.
Am I not doing this check right?????
Thanks

[dkatz42]

I'm not entirely sure what your diagram shows (proportional fonts screw up the pictures) but you should see either very high or infinite resistance between pins 1/2 and pins 2/3, so assuming that you're looking at the right pins, you're in good shape.

[bop2nite]

My diagram did not translate correct.

DMM set for ohms
+ lead from DMM on J3 Pin 2, - lead from DMM on J3 Pin 1 shows nothing on Dmm. Not even continuity. No change. Nothing....
- lead from DMM on J3 Pin 2, + lead from DMM on 13 Pin 1 shows show 6.9 mohms. Great
Am I wrong thinking it should not matter which lead from the DMM I use on this setting. I should get a reading ether way ,, shouldn't I???
Thanks

[dkatz42]

Sounds like you're fine. No reading just means that the resistance is higher than the DMM can measure, which is a good thing. You're looking for shorts that would blow up the power supply and otherwise be smelly, and you don't have them.

Generally the polarity of the DMM when measuring resistance doesn't matter, though some polarized devices may show a different resistance value in each direction.

[tpryan]

I don't know exactly how your meter behaves when it's reading an open circuit, but your measurements look fine. The reason to measure the resistance "in both directions" is to check for problems on the far side of the protection diode.