How To Repair A Nikon MH-25 Battery Charger
This is a fault finding and repair guide for the Nikon MH-25 battery charger.
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This article is a general repair guide for the Nikon MH-25 battery charger and shows:-
- How to fault find the Nikon MH-25 battery charger when the LED light fails to blink to indicate a charging state.
- How to dismantle / take apart the Nikon MH-25 battery charger.
- How to inspect the Nikon MH-25 printed circuit board (pcb) for common electrical faults.
- How to repair the Nikon MH-25 battery charger pcb.
- How to reassemble the Nikon MH-25 battery charger.
Step 1 – Conduct Simple Tests
- Make sure the power cable is pushed firmly into the Nikon H-25 battery charger.
- Try a different power outlet.
- Try a different figure of eight cable from another device.
- If you have a UK model, change the plug fuse and re-try the Nikon MH-25 battery charger. The fuse rating is 3 Amps.
If your Nikon MH-25 battery charger is still non functional after these tests and you want to attempt a repair yourself, then jump to step 2.
Alternatively, find a replacement MH-25 battery charger here:
Step 2 – What You Will Need
To take apart the Nikon MH-25 battery charger you will need the following items:
- A precision Torx screwdriver set.
- A flat blade screwdriver with a long shank to assist with leverage.
For any electrical repair on the circuit board, you will need:
- A soldering iron with a fine tip.
- Sheathed wire.
- Wire cutters or scissors.
- Long nosed pliers.
- A knife.
Work in a well lit area and consider having the means to magnify the pcb board if your eye sight is poor.
Step 3 – How To Take the Nikon MH-25 Battery Charger Apart
The Nikon MH-25 battery charger is held together with one small Torx screw and lots of glue.
The head of the Torx screw can be seen at the rear of the charger, next to the power connector. Unscrew it and store it safely at one side of your work area.
Using the flat bladed screwdriver, start to work your away around the unit, applying gently pressure to prise the two halves of the case apart. The glue is strong and this part of the procedure may take some time. You can see in the image above, the small amount of damage that is inevitable in prising the case apart.
When the back of the case is removed, the circuit board, rotary power connector and spring battery clip can be taken out easily.
The rear of the Nikon MH-25 circuit board has two areas clearly labelled Primary and Secondary.
The Primary circuit deals with transforming incoming voltage to the lower voltage requirements of the Secondary charging circuit. It is possible to receive an electric shock by touching any of the points in the Primary circuit even when mains power is disconnected. The capacitors will hold charge for a significant period after mains power has been removed. The capacitors should dissipate their charge to reasonable levels a few minutes after the removal of mains power.
Step 4 – Inspect the Nikon MH-25 Printed Circuit Board
More than likely, most faults will be on the underside of the circuit board; the side with the printed tracks.
An examination of the printed circuit board from my Nikon MH-25 battery charger shows the track-side to be peppered with indentations and other mechanical induced marks. In my case, there are clear pot-marks on the incoming power rail, which have caused my unit to fail.
This youtube video shows an example where solder joints have not been completed properly during the manufacturing process and a small knock can be enough to dislodge components from the electrical circuit.
However, it is worth taking a look at the electronic components too while the board is out of the case.
Top side / component side of MH-25 pcb
Check the condition of the capacitors. Look for capacitors that may have blown and replace them if necessary.
Bottom side / pcb side of MH-25
Look carefully at the tracks and solder points all over the board. Look for poorly soldered / loose joints and tracks that appear to be damaged or broken.
Re-solder loose/dry joints. Patch broken pcb tracks with solder and wire.
In order to solder to a broken rail, use a knife to scrape away the green insulation to reveal the copper surface beneath.
The image above shows two breaks on the same pcb track for incoming mains power. The larger red circle shows a repair that I made to the pcb track with wire and solder. The smaller red circle shows another potential break on the same pcb track
Scratching away the discolouration on the pcb track with a knife clearly shows that this part of the track is broken too.
Broken tracks can be bridged with wire and solder. In this instance though, I decided to bypass the pcb track all together and run a sheathed wire between the two solder points rather than make another fiddly repair on the same track.
Step 5 – Reassemble the Nikon MH-25 Battery Charger
Reassembly of the Nikon MH-25 battery charger is relatively easy to do provided you follow these steps.
- Take the rear part of the MH-25 battery charger case and lay it flat on your work surface.
- Slot the circuit board on to the charger case.
- Put this assembly to one side.
- Lay the front part of the MH-25 battery charger case on your work surface.
- Insert the rotary power connector so that it latches in the slide lock mechanism.
- Insert the spring battery clip as shown.
Carefully bring the two assemblies together until they snap shut. Take care not to damage the LED.
Insert the Torx screw and tighten.
Connect the power cable and test.
Obtaining a Replacement Nikon MH-15 Battery Charger
If your repairs are unsuccessful, or you want to purchase a spare Nikon MH-25 battery charger then check out the prices on Amazon:
Dual MH-25 battery chargers, USB MH-25 battery chargers and non Nikon MH-25 battery chargers:
Search Amazon for MH-25 battery charger variants