4 relay module no second GRD connection for relay coils

I've got a 4 module relay board. all the tutorials on the internet tell you to remove the jumper between the VCC and JD-VCC pins and then connect VCC and GRD to a 2nd power supply to maintain isolation. The problem i have is I've not got a second GRD only to one that connects to the arduino. The link below shows a picture of my relay board but still doesn't explain how to connect the 2nd power supply for the relays.

any help much appreciated. thanks

I think that the Arduino should only connect to the Vcc and INx pins. No connection from Arduino to the relay module GND pin. Remove the JD-Vcc jumper and connect the external supply to the JD-Vcc pin and the GND pin.

See the schematic:

Thanks Ground fungus, i thought that might be the case but i wanted to make sure before i connected it up and blew something. I've connected a 5V DC power supply across the GRD and JD-VCC pins and still the relay's don't click on and off. I've also tested the output pins and i get the same continuity on a powered relay as i do un-powered. I know the relays are being triggered by the arduino as the LED's come on. Do i need more than 5V DC to power the relay coils perhaps?

What are the relay coil voltages? Are you sure that they are 5V? Post photos of your relays.

Did you connect the Arduino 5V (Vcc) to the Vcc pin? The Arduino output will be LOW to activate the relay.

I assumed they are 5v as all the info on the internet says to connect a 5vDC supply to power the relays. They will be switching a 24V DC circuit but that's something separate. Yes the arduino VCC is connected to the relay board VCC and the arduino outputs connect to the IN1-3. The leds on the relay board come on and off as the arduino code runs so i know that bits working fine. I've tested the relay contacts NO/NC and common with a multimeter and i get the same results wheather the LED for that relay is on or off. I just cant get the relay coils to operate to close the relays contacts.

What is written on the top of the relays.

Show us a good image of your ‘actual’ wiring.
Posting images:

I'll upload a photo in a bit when i find my camera lead. The info on the top of the relays all relates to the switching contacts capacity i think. It says 12VDC, 10A 250VAC, 15A 125VAC, 10A 250VAC, JQC-3FF-S-Z. I brought this one as it can switch both 250VAC and 12VDC curcuits, as i need to control a 12VDC and 240VAC pump and valve with it.

Is this like your relay? The coil voltage is the second line, 5VDC here:

It appears that your relay coils are 12V. The LED is powered by the Arduino, not the coil supply, so the LED will light without coil power.

jamesb123:
I brought this one as it can switch both 250VAC and 12VDC circuits, as i need to control a 12VDC and 240VAC pump and valve with it.

Almost all of these relays are rated to switch either AC or DC so that is not a matter of choice but you will note that the rated DC voltage is below 30 V as above that voltage a DC supply may maintain an arc as the contacts open and damage or destroy the relay.

ill give it a test with 12v dc and see it it closes the relay