Repair of the pulse power supply unit PRN150M-6 (EM9005 PS / AC)

The power supply PRT EM9005 PS / AC (PRN150M-6) from MRV, 150 W, 12V, 12,5A, AC Input 100-240Vac. Production - China (sometimes - Israel).

EM9005 PC / AC power supply units are part of the network of industrial optical switches MRV OptiSwitch 9xxx series in an amount of usually two pieces. There are no questions for network equipment, which cannot be said about power supplies that often fail. In most cases, repair of these switching power supplies (UPS), private repair organizations are not taken due to the lack of repair schemes and high density of placement of radio components. In addition, the cost of one power supply from official representatives exceeds 50 thousand rubles per unit (53 tr. Aug. 2016).

The gap in the absence of a repair scheme was solved by reverse engineering, a “donor” power supply unit, a soldering iron and a flashlight. Who is interested in the scheme of this power supply and its description, please:

One unit was unsoldered so that it was possible to examine all the tracks of the circuit board and get to the hidden radio elements. The printed circuit board, as it turned out, is remarkably translucent with an ordinary lantern. Thus, the scheme, gradually, was copied on paper, and then in Visio. The scheme has the character of repair and does not claim to be the factory assembly scheme, because the values ​​of all elements (especially SMD capacitors) could not be considered. But, if the face values ​​are very necessary, they can be “pulled out” of the official datasheet to the main components of the scheme. For example, the scheme of the KKM power supply unit scarves almost completely corresponds to the description of its UC3854N controller.
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Switch MRV, which consists of these power supplies.


Our switches MRV OS9048FX-4G

Other perspectives of the power unit:


Power Supply Tag PRN150M-6 (EM9005 PS / AC)


Top view of power supply PRN150M-6 (EM9005 PS / AC)


Rear view of power supply PRN150M-6 (EM9005 PS / AC)

So, if you have identified your “beast,” I will not weary, I enclose a description of the power supply, a diagram to it, a description of the most characteristic failures, a power supply check form, and test checkpoints. I drive everything under the spoiler:


For the "mass" repair of this power supply, I recommend to make a kind of "stand" for fixing the printed circuit board, so that it is safer and you can reach all the radio elements. What is a “stand” of:


Stand of check and repair of the power supply unit PRN150M-6 (EM9005 PS / AC)

Two hard plates capable of removing heat. Plates of the same size, but with different placement of holes for fasteners for cooling radioelements. I found some kind of sandwich panels for wall decoration. Aluminum panels with a layer of an insulator, thickness, millimeters 5. In the area of ​​mounting of the printed circuit board, the plate should be insulated. I just scraped one layer of aluminum from a sandwich:


Stand check and repair power supply. The board is isolated from the “stand” plates.

In the right places on the plates are fixed small corners for attaching the printed circuit board to the "stand". After assembling and screwing all the radio elements, the stand behaves tough, removes heat well, makes it possible to "poke" in the entire "stuffing" of the power supply. There is another option to make a stand for checking these blocks. Take one "donor". The case is cut with an engraving machine, or rather, cut the bottom, leaving all the fasteners in the right places. But - sorry. On the other hand, if you have 30 pieces of these blocks, and besides you no one can repair them - flag in hand - safely cut one case. For, as in any repair, there comes at least one non-repairable power supply unit, in which the transformer has burned down and, frankly speaking, is too lazy to mess around with it.


Stand check and repair power supply. All electrical circuits are available.

Even for the test, you will need a power cord with an E27 watt incandescent lamp at 95 at the break (the worst option), or a 220/220 V isolation transformer, also with a restrictive safety lamp in the secondary winding (the best option, especially if you have RCD machines). This is all described in the * .doc file. All this is necessary for your own safety, and you don’t burn radio elements in case of “unsuccessful” repair.

Special thanks to the guys from the cxem.net forum for their help in explaining the principles of operation of the CMC. Here is the discussion of the failure of the CMC in this power supply .

Thanks for attention! Hope the article was helpful.

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PS A big request not to write messages like: “But I have a power supply and it has a fuse blown. So that it could be with him? ”

1. First: I know perfectly well what the Habr effect is.
2. Secondly: I am not a devil for repairing all power supplies, I just figured out well how to repair this power supply.
3. Thirdly: with the power supply unit there can be anything! There are, of course, certain regularities, but they correspond to their type of BP.