Problems with ebay 12v Relay Board

Discussion of the physical aspects
MeLoveBeer
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Problems with ebay 12v Relay Board

Post by MeLoveBeer »

Hi All,
I was wondering if it would be possible for someone that has experience using the ebay relay boards (Link: http://www.ebay.com.au/itm/Eight-8-Rela ... 5d2fbe76dc) to give me a sanity check on my wiring? My suspicion is that the board is faulty, but any help validating this would be appreciated. The issue I have is that the moment I switch power on for the relay board, the LED light for channel 1 lights up, and regardless of what I do, I can't get the board to provide power to any attached devices. The LED for channel 1 remains lit with or without devices attached and regardless of whether or not a 5v current is added to an appropriate channel.

The device attached to the board (left hand side) is the following automated ball valve: http://www.oscsys.com/12-Motorized-Stai ... Valve.html

As I said, any help would be massively appreciated.
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JonW
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Re: Problems with ebay 12v Relay Board

Post by JonW »

(Edited after inspection of the valve specs)

The valve needs a continuous connection to both GND & VDD (12V) on the blue and red wires respectively. You should then have a jumper from VDD to the COM connector on the relay with the yellow wire on the NO connection of the relay. The additional application of 12V on the yellow wire is what triggers the valve to open (and removing power on the yellow wire causes it to again close). (edited for clarification)

Regarding whether the board is faulty, have you checked the functionality of the other channels? With just the power supplied to the relay board, you can use a jumper from the GND connector to the channel inputs and test each one to see if the relays activate.

Have you checked the board for any shorts on the channel input or a faulty solder on the back? When the channel 1 LED is lit, is the relay also energized so that there is a circuit closure between the COM & NO connections?
Last edited by JonW on Mon Aug 01, 2011 11:58 am, edited 1 time in total.
gbrewer
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Re: Problems with ebay 12v Relay Board

Post by gbrewer »

Just in case the terminology for open and closed regarding the valve/wiring confused anyone....

12 Volt constant power to the Red and Blue wire keeps the valve closed. (as instructions indicate)
The yellow wire is your "switching wire". When 12 volt is applied to the yellow wire, the valve opens.

+1 on what JonW stated in regards to testing the rest of the board.
JonW
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Re: Problems with ebay 12v Relay Board

Post by JonW »

Yes, good clarification - the valves are NC, not NO. The relay closure causes the valve to open, not close.
MeLoveBeer
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Re: Problems with ebay 12v Relay Board

Post by MeLoveBeer »

Thanks for the advice guys...
JonW wrote: The valve needs a continuous connection to both GND & VDD (12V) on the blue and red wires respectively. You should then have a jumper from VDD to the COM connector on the relay with the yellow wire on the NO connection of the relay. The additional application of 12V on the yellow wire is what triggers the valve to open (and removing power on the yellow wire causes it to again close). (edited for clarification)
Good pickup; stupidly I presumed that powering the board also powered each of the channels. I've now jumpered the VDD to the COM, moved the yellow wire to NC and at least got the intial power state (closed) happening, but still no joy getting the switch to occur.
JonW wrote: Regarding whether the board is faulty, have you checked the functionality of the other channels? With just the power supplied to the relay board, you can use a jumper from the GND connector to the channel inputs and test each one to see if the relays activate.
Yeh, I've tested multiple channels and get the same result everytime (channel 1 LED indicates that it is energized regardless of what channel is being utilised, and nothing else seems to work).
JonW wrote: Have you checked the board for any shorts on the channel input or a faulty solder on the back? When the channel 1 LED is lit, is the relay also energized so that there is a circuit closure between the COM & NO connections?
No shorts or faulty soldering that I can see. How would I test for a circuit closure between COM and NO? Do I just wire the yellow to the NO and see if the valve opens?

Once again, thanks for your help guys...
JonW
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Re: Problems with ebay 12v Relay Board

Post by JonW »

Do you have a multimeter? If so, can you verify your input voltage to the board at GND and VCC. Red probe on VCC and black on GND should give you around 12 volts. If it says -12V, then you may have your power input leads backwards. What are you powering the GND and VCC inputs from (not the BCS board I hope - they are only 5V and not enough milliamps to drive all the relays).

You can also use the multimeter to do a continuity test to see if you have a closed circuit between COM and NO when LED #1 is lit.

These boards have very simple circuits using darlington transistors to trigger the relay closure. A failure of one darlington (possible on channel #1) does not affect any of the other channels, so you should be able to get at least one relay to work. This is why I'm questioning your input voltage and polarity.
MeLoveBeer
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Re: Problems with ebay 12v Relay Board

Post by MeLoveBeer »

JonW wrote:Do you have a multimeter? If so, can you verify your input voltage to the board at GND and VCC. Red probe on VCC and black on GND should give you around 12 volts. If it says -12V, then you may have your power input leads backwards. What are you powering the GND and VCC inputs from (not the BCS board I hope - they are only 5V and not enough milliamps to drive all the relays).

You can also use the multimeter to do a continuity test to see if you have a closed circuit between COM and NO when LED #1 is lit.

These boards have very simple circuits using darlington transistors to trigger the relay closure. A failure of one darlington (possible on channel #1) does not affect any of the other channels, so you should be able to get at least one relay to work. This is why I'm questioning your input voltage and polarity.
Good to know that the channels are isolated... means that I've more than likely just buggered something up.

I'll pick up a multimeter this evening on the way home from work (been meaning to buy one for a while now) and will give it the once over... I'm powering the VCC and GND with a dedicated 12v 1.5A power supply, so I would have thought that it would be ok, but its well worth checking the polarity (fyi, only wire connecting the BCS and the relay board is from the out being utilised for triggering the switch).
MeLoveBeer
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Re: Problems with ebay 12v Relay Board

Post by MeLoveBeer »

Ok, so I think I've isolated the issue to the 5v being produced (or not produced) by the BCS. I borrowed a mates multimeter and tested both the polarity of the power supply wiring, and the switching capabilities of the channels (by jumpering ground to each of the channel inputs and verifying that it works as expected); seems that the next logical step would be to verify that the 5v current is being produced by the BCS out, however regrettably my mates multimeter has a minimum voltage of 12v (its pretty cheap and nasty).

I'll be picking myself up a decent multimeter tomorrow, but in the meantime has anyone got any other suggestions? Seems odd that the Out wouldn't be producing a voltage in manual mode when enabled?
MeLoveBeer
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Re: Problems with ebay 12v Relay Board

Post by MeLoveBeer »

Checked the voltage last night being produced by the out on the BCS and its only producing 2.7v. Is this normal? Looking at the spec on the relay board, that should be enough to trigger the switch regardless (anything above 2.5v should trigger the relay right?), but I thought that the out0-out17 produced 5v?
clearwaterbrewer
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Re: Problems with ebay 12v Relay Board

Post by clearwaterbrewer »

They do produce 5V when actuated, compared to the ground lead...

My first thought is that you have insulation in a terminal connector somewhere...

Troubleshooting..

turn off all outputs
Test voltage at the +5VDC terminal compared to the GND terminal right next to it.
Place the black probe on the screw of the BCS marked GND, and the red probe on the screw marked +5VDC
(take reading, if not greater than 5V, it is your input power or your power supply)

If >= 5VDC, turn on the output (assuming the LED for that relay still does not light up).
Place the black probe on the screw of the BCS marked GND, and the red on the screw marked OUT for your output.
(take reading, if not ~ 5V, talk to ECC)
If >=5VDC, move red probe to relay board
(take reading,if not ~ 5V, fix your output wire)
If >=5VDC, move black probe to relay board
(take reading,if not ~ 5V, fix your ground wire)
IF >=5VDC, replace relay board
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