Scantronic transformer Hum??

[phlize]

A couple of weeks ago I bought a Scantronic  9651EN-41 (9651 c/w 9941)

panel from you.

Having now installed it I'm surprised that the transformer in the panel has a

noticeable hum/buzz. The problem is that the panel is located in the

living room rather than out of the way in the attic or similar. It is

where it is because I wanted to do a straightforward replacement for a

Menvier stand-alone(ie no RKP) panel that had gone on the blink, with

minimum re-wiring.

 

Is this hum/buz normal? The Menvier was totally silent.

[Secware_Tech6]

phlize

Some buzz is normal and all transformers buzz slightly. The metal box of the 9651 will also slightly amplify it.

But it may be too loud its impossible to say from here lol as i cant hear it.

 

You may try 2 things first

1. ensure the screws/bolts holding the transformer are tight.

2. ensure panel is well fixed to the wall and no part is slightly sprung

 

(to test 2 just slightly loosen all the fixing screws and see if it goes quieter) but this is a temp test the panel must be securly fixed.

 

As a last resort if you have really sensitive hearing and its not a faulty transformer you will need to damp the transformer where it mounts the control panel. Small rubber washers are best and need to be inserted between the 2.

If the vibrations are the lid, backplate etc then you can remove these by adjustment.

If the transformer is faulty and is delaminating (the bits of metal in the former are vibrating together) then we will replace it.

 

Hope that sort of helps

 

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[phlize]

Ok, thanks for the advice. The rubber washers were my next job - I've already tried the other things, in fact the buzz reduces with the cover on as it holds the metal sides tight, without the cover you can actually feel the sides vibrating. Believe me my hearing is not that sensitive - the buzz is loud!! i'll let you know how I get on.

[Secware_Tech6]

SOunds like it isnt the transformer but the case vibrating.

It isnt over loaded is it? ie what is the standby current of the system?

[phlize]

I'm only using 3 zones, all with PIR's plus the bell box so it can't be overloaded, the case vibration stops when the front cover is screwed on. Also, putting a finger on the transformer you can feel the vibes.

Phil.

[Secware_Tech6]

they do vibrate, a faulty transformer is when the laminations of the transformer buzz (ie the transformer itself)

 

but your system could be overloaded (not by design ie your equipment is fine) by a fault. You need to test the day mode current to ensure its correct. Also a faulty battery can draw too much current you might want to check the charge current also.

 

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[phlize]

ok, I'm pretty sure it's the transformer. If it was overloaded surely the 250mA fuse would blow??

[phlize]

Also, forgot to mention - I measured the transformer output at 18.3v

[phlize]

Ok, now understand that the fuse wouldn't blow as they can take up to 10x rated current. I've now measured the current drawn at 163mA.

[Secware_Tech6]

that sounds ok, however i waqs meaning the xurrent draw of the dc side (ie put meter in series with battery and remove mains power, check resultanct dc current draw.)

 

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[phlize]

Yes, That's how I measured the 163mA. current draw.

[Secware_Tech6]

thats very low. But is certainly more than ok.

[phlize]

It looks like a straightforward job to replace the transformer. This would be my preferred route rather than disconnecting everything to send the whole box back - that's quite a big job & leaves me without an intruder alarm for days.

[Secware_Tech6]

from a returns point of view the whole unit will need to be swapped. but be sure it is a faulty transformer.

 

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