Trunite MCC-4 LCD Battery Charger Repaired
Here I will describe repairing a Trunite MCC-4 LCD charger. This charger is being sold on the internet (China export). Also known as the Fenix Are-C2 advanced multicharger.
One of the (the most left Cell charger) Charger positions of the charger gave an error when a Lithion or NiMH AA or AAA cell was inserted. (The three other cell chargers of an total of 4 charger positions worked without any problem). My friend had brought it to me to have a look inside because the new charger went defect without any known reason.
The blue display blinked when inserting a cell and the cell did not charge at all. No matter if it was a Lithion or a NiMH cell.
Opening the cabinet was no biggy but the plastic housing was sealed and originally not to be opened by screws because there were none. So I used a small screwdriver at first and furtheron I used a bigger one to be able to break open the cabinet.
I now know what had happened with the Lithion-Charger and why cell charger position one (Most left one of all four charger positions) went out of order.
It presented a blinking blue display when a 3.7 Volt Lithion accu cell was inserted in Charger one. My friend did mention this failure at the Dealers sellingpoint on internet right away but strangely didn’t get a positive reply until yet, so that´s why he decided to let me as being a more than qualified notebook/laptop repair-engineer have a look at the new but now defective charger.
After opening the apparatus it was obvious why the charger went partly defect (1/4 defect) !
Because one of the toroids was shorted with solder on the solder side (both pins were unintendedly connected in the production factory) the charger cell current went too high and it’s accordingly connecting 9435 P-channel Mosfet went entirely shorted. It not only went shorted on Source-Drain but also on Gate to Source and to Drain ! And the 2 regulator’s on the pcb are the same as can be found in many battery cell chargers in laptops/notebooks. Each regulator charges 2 cells PWM independitly. And every cell is switched on and off to the charger current by previous mentioned 9435 mosfet’s.
After replacing the unmistakenly defective P-channel 5.3A 9435 Mosfet by an also more current capable 4407A P-channel smd version (I didn’t have the identically 9435 mosfet at hand) and removing the toroide shortcut, it all works as it should have worked in the first place ! The mosfet is visible as a small smd 8 pins little Mosfet chip with big switching abilities. If you for instance should type on the internet Datasheet mosfet 9435 you´ll get a full explanation of how it works and looks like.
My friend received this charger defect although the producer/dealer stated that all products leave the factory fully tested. After these repair facts that must be not true. So their firm didn’t deliver the service that they should have been given. And replacing the badly functioning charger by a new one is probably what they should have done but still didn’t. And they still kept my friend as a paying customer waiting for no reason. The Dealer only seemed to care for the negative publicity that was generated on their selling site and only did send a mail that the negative content had to be removed a.s.a.p.
The now at the customer costs repaired charger still didn´t close safe easily. Because the plastic was not made to be opened. But it closed okay again finally. (I used thicker not dripping superglue for that !).
And it is more then certain that the faulty working charger went defect without it being caused by the customer.
These kind of P-channel and N-channel mosfet´s are allways used and can be found in many if not all laptop´s-notebooks. They can be switched on and off with a little signal from a simple digital multimeter between gate and source and when the red and black meter wires are reversed the mosfet changes from active to inactive or vice versa. Which can be meassured with an ohm-resistance check between Source and Drain. Very low resistance means an active Mosfet. It´s like an effective but simple digital switch which is capable of switching tens of Amperes at almost Ideal circumstances (almost no heat dissipation internally).
This article was prepared for you by Albert van Bemmelen, Weert, The Netherlands.
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