Alarm Panel - Swap Transformer Live?

Hi all
OK so I got a Texecom Excel panel earlier in the year and the transformer has started humming/buzzing loudly. The supplier has sent a replacement transformer for me to fit. The question is, can anyone see a problem with doing this (semi) live? To avoid disarming the bell box etc., I was considering simply turning off the mains and running the system on battery in "engineer mode" while I swap out the transformer. Providing I am careful not to short anything, am I taking any risks here? Also, if I do turn the whole thing off and disconnect the battery, will I lose programs etc.?
TIA
Phil
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TheScullster wrote:

As long as you don't short anything you shouldn't, then the panel will just see it as a power failure.
Make sure you turn off the mains first though!
You may find you need to remove the panel from the wall, if the transformer is bolted from behind though.
If you power the system down totally, you will need to go up a ladder and open the the bell box and disconnect it's battery. Powering the panel down should not mean you loose any settings, otherwise an extended power failure would do the same, the programming should be in non volatile memory.
Toby...
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"Toby" wrote

Thanks Toby I will check the transformer mounting. Looked last night and it seems accessible - the securing screws are cross heads but may have nuts on the rear of the panel. Hopefully not - I would rather not have to demount the panel and risk disturbing all the zone wiring. Although I am happy with the operation of the Texecom alarm and keypads, the panel box is a bit "waffy". Annoying that costs are cut so close that the rigidity of the panel casing is affected.
Phil
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Texecom transformers are notoriously short lived, that having been said I've never had an issue with any of their other kit. The mounting screws on the plastic case Excels don't have back nuts. A metal cased version of the panel is available for about another 30.
Neil
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No nuts on the rear of the panel.
Power down both then mains supply and the battery and let the bell box ring while you do the work. 5 minutes work at most.
Adam
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I had a panel that lost its settings when the power went, they were quite common types and lots of places sold them. The current one doesn't.
I didn't take the bell box battery out, I used the 12V battery as a dummy panel while doing the swap.
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Older technology.

Newer technology.

Personally I'd let the bell box ring. Good opportunity to check its internal battery still works ok. No one will take any notice anyway.
--
*My designated driver drove me to drink

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Well, at least they certainly won't _next_ time.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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Inform the neighbours (if they're in). As I said others will ignore it. Unless you live in the sticks. There's alarms going off round here regularly. The vast majority through faults - or at least not due to a break in. One main offender is the house on the corner at the end of this road - appears to have two alarms judging by the different makes of bell boxes. They are away frequently and you can near bet it will go off. If they were all break ins the house would be a shell. ;-) I've spoken to the owner about it and he says he reports all these faults.
--
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 1 Oct,

Or else feed the battery directly to the appropriate leads to the bell box.
(or use the secret switch to do the same, very handy for 2am faults with the tamper switch on the bell box!)
--
B Thumbs
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You can do it viajust the battery connected but as you said be careful. Disconnect the mains and take out the protection fuse to the transformers output side.
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Blutak pressed into the screwheads should reduce the chance of dropping a screw into the circuitry. Its always a risk though
NT
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"TheScullster" wrote

Thanks to all respondents. Job done last night - just turned off mains and did a careful swap. That buzzing/humming noise from the original was getting annoying.
Anyone know what a replacement costs when the panel is out of warranty? Is there an alternative better quality item that will slot straight in?
TIA
Phil
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If the transformer still works ok but is simply noisy, checking the way the laminations are held together may show some way of tightening them. Also potting in epoxy, etc can work.
Other way might be to substitute a toroidal type - but that might not be physically possible due to space.
All the big electronics suppliers have a fair range of standard transformers - and most have data sheets with dimensions, etc. RS, CPC, Rapid, Maplin, etc.

--
*I started out with nothing... and I still have most of it.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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That can come from either the transformer, or be due to the way it's mounted.

ISTR a replacement transformer for my panel (not Texecom) is about 50 from a distributor. A similarly rated one from Maplin or CPC would be under a tenner, but the mounting holes might not be in the right place. If I ever needed to replace it, I would go to Maplin or CPC or similar. I might even drop in a SMPSU nowadays, although that might mean more modifications.

It's actually quite difficult to find good quality ones nowadays. Noise isn't normally a problem (that's easily avoided by vacuum varnishing the built transformer), but finding efficient transformers is now much harder as they're mostly all made in china and as cheaply as possible, and that isn't consistent with being efficient.
--
Andrew Gabriel
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The same cost as a new panel :-)
Adam
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For future reference, if you're using a texecom bellbox there's a special mode that you can set by switching the strobe input on and off 3 times within 30 seconds (most panels have a test feature to do this). After this you can power down the panel entirely and save possible shock therapy!
David
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"David R" wrote

Good call David Now you mention it I do remember the "hold off" mode. Very convenient when setting up the bell box in the first place.
Phil
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