Problem with External PSU connection to Scan. 9571 panel

4 Aug 2008
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United Kingdom
Hello, I have an issue with starting up my alarm system.
I've fitted an additonal PSU (Elmdene EN-C17) with a 17ah battery to provide 1.4 amps additional load to my 9751 panel. I have connected the negative load from PSU to the 0v Aux on the panel.
The 12V load from the PSU is connected to the following devices:

Rear Bellbox
Internal Sounder.

On start up, the internal sounder & rear bellbox start sounding, and I cannot switch them off unless I disconnect the mains & Battery from the PSU.

Have I wired something incorrectly?

The internal sounder is connected to the 12V of the PSU, and OP3 on the panel.
The Rear sounder 12v is connected to the PSU, and the OV connected to the panel. Looks likes the ouputs are triggering.

any help appreciated.
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Output 3 defaults to "set latch" .

Your wiring is incorrect somewhere.
All you do with the psu is common the negatives.
Remember when the sounders go the panel will be supplying them.
Have the panel drive the sounders and the psu all other devices.
Hi alarm thank you for the quick reply.
As you've advised,I have commoned the PSU Neg & panel 0v Aux.

I have kept positive of the PSU separate & is currently connected to:
+12v supply of the 2 external sounders
+12v Red wire of the sound bomb.
+12v supply of SD1+ dialler.

The -12V of above devices is connected to Panel 0V Aux (which is commoned with PSU Negative).

All the PIRs & smoke detector are connected to the panel 12VAux & 0V Aux.

I thought it would be better to connect the power hungry devices li.e all 3 sounders to the PSU.
If I connect as you've said, i.e sounders to panel would this not overload the panel ? Sorry to sound stupid, trying to make sense of it all :oops:
Also, for the sound bomb, is it better to tie in the connection with the Bell output instead? That'll mean 3 sounders to OP1.
Thanks again
You never siad whats being run did you:D

Right you need a relay, powered from the panel a hard pos and OP1 to trigger and feed all sounders from the psu.
Use a Double pole relay and OP2 can run the strobes off the psu too.
SD1 direct to the panel.
Depending on how many detectors run some off the psu too.

You`ll need to check loadings in full alarm to see if it can handle it.
Thats Milli amp readings on the DC scale.
Sorry but dont know if you know so mentioned it.

That should sort out the loadings for you and keep the panel light.

How are you going to monitor the psu, got a spare zone to connect to in case that goes pop, so the panel can tell you?

should cover it for now.
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Hi, Sorry should have been more clearer in my 1st post.
Will this relay do the job?

I'm running 9 PIRs, 1 16ohm loudspeaker, 1 Smoke detector, & 1 Glass Break Sensor on the system.
I suppose I could power half of the PIRs from the PSU.

The PSU has dedicated fault outputs for
EPS Fault (mains fail)
APS Fault (battery fault)
PSU Fault (general fault)
Which fault is best to monitor?cos I have 4 spare zones left on the system.
Is it just a matter of wiring it as you would a tamper circuit & program as 24 Hr?

Thanks again alarm for your time and help :)-) very much appreciated.
Relay should be fine, the strobes will cut off with the sounders, not a bad thing in itself. Remember 15 mins is max ring time allowed now.
I would monitor mains fail and batt fail, each to own zone with correct descriptors, easier to find then.
Wire as EOL or DP depending what your doing and as a 24hr zone.
Relay should be fine, the strobes will cut off with the sounders, not a bad thing in itself. Remember 15 mins is max ring time allowed now.
I would monitor mains fail and batt fail, each to own zone with correct descriptors, easier to find then.
Wire as EOL or DP depending what your doing and as a 24hr zone.

Hi alarm, I think I will go with 2 separate relays, one for the sounders & one for the strobes, so that they can carry on after the sounders stop.
I've wired the system using EOL method so will do the same for the fault monitoring.(Thanks for the monitoring tip, didn't think of it until you mentioned it ;) )
I've attached a diagram in my album of the relay wiring to the 3 sounders, I'd be grateful if can you please check if I've done it correctly.

I understand the 2nd relay wiring to the strobes would be exactly the same except the trigger being OP2 from the panel right?
Thanks again
In the relay diagram I've shown the C terminals with Neg feed from the PSU (which is commoned with the Panel) but now that I'm using a relay, does the PSU neg still need to be commoned with the panel 0V? I suppose the panel OP1 energises the relay & closes the NO teminals allowing neg to the bells. So no need to common negs of PSU & panel for referencing?
Hi again, right stop right there!

Relay is wrong.

Take a +ve from the PSU to the HO+ to the bell/sounder
Take a -ve from the PSU to the HO- to the bell/sounder.

From OP 1 Go to Input, correct.
From panel take a +ve to the other side of the input.

From the Psu take a -ve to the C of the relay.
From the bell/sounder trigger to the NO of the relay.

Hope thats clearer.
You way you will blow the fuses on the PSU.

I would still reference the PSU with a -ve as you have zones attached, so it will need that reference.
Hi Alarm, thanks for looking at the diagram, sorry I made a mistake on the first diagram in that I did not show clearly the 'hold off' supply to the bell terminals correctly.

I've uploaded a new diagram which is more clear & wired up as you have explained. If you don't mind, Please take a moment to verify its correct.

I'LL be ordering the relays today, so will update you when I've fitted them.

Thank you for your time & kind assitance, couldn't have done it without your help & expertise :D

Better much better, Your taking the reference to the panel from the psu direct not from the relay I assume, if so thats fine.

No need to say sorry either, we have all been there. Everyone has to learn.

Good luck with the rest and plese do let us all know how you got on, or even if you have another question.

Hi alarm, yes I have taken the reference for the the panel from the PSU neg cable which is connected directlty to the panel 0V supply.

But one thing I don't seem to grasp is that by connecting together the 2 negs of the PSU & panel, will the load to the sounders be exclusively provided only by the PSU? I can see from the diagram that the panel only energises the relay.

Ps; I'LL def. let you know how I get on, like I said, it would have been impossible without your help on this site.
The PSU will run the sounders correct.
But without a reference to the PSU the zones monitering the PSU will not "talk" to the panel.
At the same time only the PSU will be providing the power required.
Think of it as a common.

Without it there would be no circuit.

Easier now?

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