Bypassing Multi Function Controller - Model: LJ-05

zero959

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Dec 2, 2015
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I have a new type of LED multi function controller that I can find no instructions for bypassing. The model is a Linhai Lingjian Switch of Festcon Lamp Factory - Model: LJ-05. Like other controllers it has multiple settings and doesn't remember the last setting after you turn it off. I would like my lights to stay on so would be really grateful if anybody can help me bypass it.


Here are some pictures of the device:


https://drive.google.com/file/d/0BwGGKotmrlyXZUN1dFp2Z0tzT3M/view?usp=sharing
https://drive.google.com/file/d/0BwGGKotmrlyXQ1RSU0t6YzRwLWM/view?usp=sharing
https://drive.google.com/file/d/0BwGGKotmrlyXOFV4dmpxaEtjbm8/view?usp=sharing
https://drive.google.com/file/d/0BwGGKotmrlyXZmFBbkp5OEtncVE/view?usp=sharing


Many thanks
 

David_AVD

Bite my shiny metal ass!
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The bad news is that you can't do a bypass mod on this MFC as it's a 2-wire string.

Out of interest, are you able to read the numbers on the 8 pin chip nearest the wires?
 

zero959

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Dec 2, 2015
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Thanks for the reply

This is all of the info I can get off the board:

MFC:
GC282
150210

Transistors:
D4

Resistors:
472
104

Capacitor:
H.E.C
-40+105oC
50V
100μF

Number on board:
K1554

The lights work off a DC transformer so I have cut off the controller and wired the lights directly to the transformer. The lights work but flicker a little bit, I assume because there is no smoothing being performed without the capacitor. Is it possible just to add the capacitor to the circuit to stop the flicker?
 

David_AVD

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If all the LEDs are lit, the transformer output is AC. You can't add a capacitor to smooth that out.

The MFC rectifies the AC, smoothes it out then spits it back out as a sort of AC signal. Ironic eh?

The alternating output from the MFC is now at a much higher frequency so you don't see the flicker.
 

zero959

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Dec 2, 2015
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Ah, makes sense that the transformer emits AC as the LEDs light when wired either way round.


I can't see an obvious rectifier in the MFC but assume one of the ICs rectify the current or perhaps the two tiny diodes achieve this?


The capacitor in the device is polarised so I assume must be used post rectification.


This has become more a matter of electrical engineering interest to me now rather than perhaps a solvable problem but appreciate all comments.
 
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