VeriFone 9V-4A power supply. This time, model AU1370933g.

Hello again, everyone, and I wish you good health. This time, I’ll be looking at a VeriFone 9V-4A power supply. This time, model AU1370933g.
I dug this power supply out of a box. It looks like it’s never been used; even the cable is still wound up the way it came from the factory. This one is already compact and has a 2-PIN connector. Here it is next to the previous model, though in reality it’s noticeably more compact than it looks in the photo (it’s both shorter and lower).



The specifications are shown in the photo.


I’ll say right away that this power supply isn’t for me. It’s excellent, but I like being able to repair things myself without too much trouble.
This one has tiny resistors and hard-to-find spare parts. Soldering it won’t be much fun. The cable is 16 AWG. I was surprised there’s no LED on the case (that’s unusual for VeriFone). The case came apart fairly easily with a knife and hammer.
As for the board, it has relatively small heatsinks, especially on the output side. The fuse is 3.15 A. There’s a varistor, an X capacitor, and a common-mode choke. The input electrolytic capacitor is 82 µF/400 V (18/25 mm). A large blue high-voltage ceramic capacitor is installed in parallel with it. I couldn’t identify the PWM controller. The switching transistor is K10A60D (600 V/10 A); it uses synchronous rectification with an mdp1923 transistor (100 V, 69 A).
I couldn’t identify the synchronous rectifier controller; it’s probably an MP6902DS. There are three 680 µF/16 V capacitors on the output. There’s also a footprint for an LED. There’s no conventional filter inductor. The inductor on the ring isn’t a filter inductor. Like the input common-mode choke, it replaces the ferrite bead on the cable. There are two Y capacitors. I’m not quite sure what the unpopulated resistors across the common-mode choke (R9 and R11) are for.





A few things about the board bother me: the current-sense resistor lead is uninsulated, and the resistor was touching the heatsink. The same goes for the blue high-voltage capacitor. I really don’t like that the second Y capacitor is also touching the heatsink. The lack of a filter inductor may also be an issue.
I’m not a fan of modern solder, so I resoldered all the components with regular POS-61 solder and cleaned the board.
Time to see how this synchronous rectifier performs. I put the board back in the case, connected a load, and set the current to 4.2 A. I left it running for an hour. I was going to check the temperature, but that turned out to be pointless. Everything was just warm, all the components included. It wasn’t even hot enough to burn my finger; I could have kept it there indefinitely. The overcurrent protection trips at a generous current on all these power supplies, from 5.5 A to almost 6 A.
In the end, I desoldered the current-sense resistor and put heat-shrink tubing over its lead. Then I secured it with sealant. I also put heat-shrink tubing over the blue high-voltage capacitor and the Y capacitor with the varistor. I put heat-shrink tubing over the output inductor too
and added a drop of varnish. I installed a green LED (3 mm) in the original spot. Set it as high as possible, put two layers of heat-shrink tubing on each lead, then cover both leads with another piece of tubing (this makes a rigid assembly). Then secure
it with sealant. Choose the resistor for the LED to suit your preference—some people like it dim, others bright. Make a hole in the case cover above the LED, then cover it from the inside with clear plastic.
Finally, I secured all the components with sealant, gave the board one last clean, and coated it with inexpensive PLASTIK 71 varnish.


I put the power supply away for now. I’ll try to check it with an oscilloscope soon.
That’s all from me. Good luck, everyone, and once again, stay healthy.