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Forum Index : Electronics : CLICK nightlight torch repair

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Dingdoc

Regular Member

Joined: 23/09/2009
Location: Australia
Posts: 76
Posted: 12:16am 01 Mar 2017
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Hi all
It's been quite some time since I last posted on the forum but I have been regularly reading most of the contributions.

Recently I was asked to see if I could fix a 'Click' nightlight/torch unit which had stopped working. It has an inductive mains charger cradle which holds the light unit and keeps its lithium battery charged until needed.
It seems that the electro filter capacitor in the charger dropped its bundle causing the emitter resistor in the oscillator for the coil to overheat and burn out.

My problem is that the resistor is now black and grey with no colour bands so I have no idea of its value. I am reluctant to try various values as the charger circuit is at potentially mains voltage and the value is probably quite critical due to significant load changes when the torch unit is removed and replaced.

I have traced out and attached the charger transmit circuit and included a couple of photos in the hope that someone will either have one of these and can have a look inside or otherwise be able to deduce the value required for the cooked R4.
Thanks
Trev





Edited by Dingdoc 2017-03-02
 
Dingdoc

Regular Member

Joined: 23/09/2009
Location: Australia
Posts: 76
Posted: 10:17pm 02 Mar 2017
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Forgot to give the transistor specs in the last post -

It's an MJE13001 400V (CEO) 750mW 200mA.

It looks like the whole circuit runs at a quite high voltage!

The inductor has a ferrite ring 'side-on' in the coil former to improve magnetic coupling with a similar 'secondary' coil in the torch.

Note that the cover is held on by 4 screws under plugs and hooks either side of the coil.
 
Dingdoc

Regular Member

Joined: 23/09/2009
Location: Australia
Posts: 76
Posted: 05:30am 10 Jan 2018
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Success at last!

After nearly 12 months wait I finally managed to get details of the cooked resistor.

Friends in the city happened to have 2 of these , one of which had 'died' just like the one I already had, and they sent me a good clear photo of the internals as well as the dead unit!




So, the cooked resistor would appear to be 2k4!

This was easily replaced but a check of the electro and transistor revealed they were not too healthy so I ordered some replacements online.

When the parts arrived and were fitted it was dis-appointing to find the charger would still not work, but a check of the transistor with the component tester revealed that its pins were BEC instead of ECB like the original!

Once it was reversed everything worked as it should and I quickly had the second one working too.

As a coincidence, the Aldi catalogue arrived in the letterbox the next day and I was surprised to see these same units on sale!



Edited by Dingdoc 2018-01-11
 
Peekay
Newbie

Joined: 08/04/2018
Location: Australia
Posts: 1
Posted: 03:15am 09 Apr 2018
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G'day Dingdoc,
The same model/unit as yours died in my workshop.
The 2.4K resistor had smoked itself to death cooking the adjacent capacitor as well. (It was turned inside out). Put a 5w resistor in with a new chunky capacitor from Jaycar This lot started overheating as well. Maybe the transistor was turned on all the time?
Put a new 13001 in and like you. Nothing! Found your post -thanks and turned the transistor around. Functioning well if not a bit physically oversize!!. The original tranny is not as per specifications. The pcb even has a transistor profile on it and they'd fitted opposite to the profile to suit themselves at manufacture.
It's a first for me
Hopefully if the same failure happens again the 5W resistor will survive and blow the fuse
Cheers
 
Guzzi
Newbie

Joined: 30/09/2020
Location: New Zealand
Posts: 1
Posted: 05:07pm 02 Oct 2020
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Many thanks Dingdoc,
This is exactly what I was looking for. I have one of the same chargers with the same burnt out resistor.
I traced the circuit and used a circuit simulator to try different resistor values but the results were inconclusive, partly because I was just guessing the effective inductance of the coil (particularly when the torch is in place).
You have saved me some head scratching and experimentation.
Cheers for your post mate!
 
CIL-E01
Newbie

Joined: 10/02/2021
Location: United Kingdom
Posts: 1
Posted: 04:04am 10 Feb 2021
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Thanks to this thread, I can now fix one of these devices which just came in for repair. Much appreciated for the circuit and component values. :)
 
disco4now

Guru

Joined: 18/12/2014
Location: Australia
Posts: 598
Posted: 05:37am 10 Feb 2021
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Just some keywords to help someone find it in the future.

CLICK NIGHT LIGHT TORCH
WIRELESS CHARGER
CLKRT410P
 
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