Re: strange electrical issue - anyone have any knowledge of what to do.


Woody Schlom <woody@...>
 

Jimmy,
 
Thank you for this.  I'm no electrical engineer, but I think I ran the test you suggested.
 
1) I set my meter to read DC volts.
 
2) I turned the PS ON.
 
3) I put the red meter lead on the red +13.8v DC screw terminal on the front of the PS, and the black meter lead on the chassis ground screw.  The meter read -11.72v,  not 0.
 
4) I put the red meter lead on the black -13.8v DC screw terminal on the front of the PS, and the black meter lead on the chassis ground screw.  The meter read -25.58v,  not 0.
 
So it looks as if I have a definite problem.  I don't see any obvious stray wires or strands.
 
Could this be caused by a bad cap or two?  Or am I just wasting my time with this thing?
 
Woody
 
 

 


I remember one member had warm cables back last year(?)

His DC power supply +13.8 V DC lug was touching the power supply chassis.

I think the current loop would be from
 +13.8 V DC to chassis to protective ground (green wire) to Desktop computer protective ground.
 The Desktop pc protective ground is connected to DC ground inside PC
 DC ground wire connects CP3/4 and then to the negative lug on 13.8V DC power supply completing the ground loop.
 
 With a DC voltmeter,
 I would check voltage from power supply chassis to it's negative 13.8 Volt lug at front and
 then chassis to positive lug on front of power supply.  Both should be 0 volts.
 
 The member from last year saw -13.8 volts from power supply chassis to negative lug on front of power supply.
 That means his +13.8 volt lug on front was shorted to chassis.
 
 As always, I may be! wrong again.
 
 Jimmy
 

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