CX102B voltmeter and ammeter configuration

[mnmlistmktg]

Hello All,

I'm working on my very first project, a 0-20V variable power supply from an old ATX, and had a question about some meters I installed.  The CX102B meters are 5V common ground, so I set one up as a voltmeter and another as an ammeter by measuring across a 1R shunt.  The voltmeter, which I installed first, worked perfectly.  However, when hooking up the ammeter (which also worked when tested by itself), both meters stopped working.

I've gotten it to work (with two new meters) by connecting one of them to a battery instead of the common ground.  You can see the schematic here:


Anyone have any experience with this?  Was it the common ground? Something else I screwed up? 

Thanks for any input.

[digsys]

Very hard to understand the circuit, because it isn't clear but - if you don't want to use a dedicated current sense IC, why not put the
current sense resistor in the -ve line, then make the junction P/S x Resistor the 0V for both meters, while the other side of the resistor
becomes 0V for the equipment. There'll be a very small error in the voltage meter (0.1V max?), but it will simplify wiring.

[mnmlistmktg]

Sorry if the circuit wasn't clear... I just put boxes in to represent the two LM317 circuits, one for constant current and one for constant voltage, pretty much right out of the LM317 datasheet.  If you click on the schematic, it will take you to circuitlab.com and it's much easier to see. 

My concern is having both meters on the same common ground... doesn't make any sense to me why that would fry them, but that's what it did (I had them both hooked up to the same 0V out of the ATX).  Is there any reason at all why you couldn't hook both meters to the same ground?  Just trying to figure out what broke the meters.