Disadvantages of Mean Well LRS series power supplies

This post will not include information about power supply heating, ripple size, etc. Because it is all in the previous post: https://teardownit.com/posts/review-teardown-and-testing-of-lrs-150-24-mean-well-power-supply

In this post, I want to share a subjective and perhaps picky view about the LRS-200, and LRS-350 sources as a person, a user, not as a professional.

I have examined at least four revisions of these boards. The manufacturer made minor changes. Three transistor types were used at different times and in different batches (not depending on power). Thermal gaskets-caps were always used, even if the transistor body was plastic.

18N60M2 transistors. The transistors were installed in different packages (220), both in plastic and metal
6R280P6 transistors (plastic)
OSG65R290FE transistors. Package 220, plastic

I've only seen the identical diode arrays. The package is 220 metal; in the 24V version, it is metal and plastic.

Screw hole for the clamping bar screw

I think Mean Well made a mistake with the transistor clamping bar screw hole. If you try to tighten the screw any tighter, the clamping bar will turn out. Mean Well tightened the clamping bar as best they could and added a lot of thread locker. The hole should have been about 1/16" lower, and then there would not have been a problem. This also applies to the screw holes for the clamping bar screws for the diode arrays.

No second X2 capacitor

Now, about the reduced version of the input filter, namely for the second X2-capacitor absence, although a place for it is provided.

I think standardization and developers' fear of disturbing another department are to blame for this flaw :) The designer/developer made the correct diagram, but small details interfered. The diode bridge is fixed with a clamping bar, and the factory standardizes these bars and uses a bar from paired elements (transistors/diode arrays)). When the engineers started to install the board into the case, it was found that the standard diode bridge clamping bar interfered with the X2 capacitor case.

The developer needed to change the clamping bar type. But to do so, he had to contact another department, order it, etc. The developer may get a nasty remark from the manager, "Where did you look right away?" So, the engineer made a simple and ingenious decision—not to solder the second X2 capacitor at all. The cost of production was also reduced.

The power inductor

This element can be one of the hottest or the hottest on the board—up to 200F or more, depending on the power supply design.

The choke is generally made on some power supplies, with a gap with the near capacitor. This choke touches the capacitor on other power supplies (or batches). What is 200F on the capacitor?

Separation of the cold and hot board side

Now for a problem that has plagued Mean Well for several years. The manufacturer kept making changes to the boards, starting with just holes and then adding slots.

My speculation and assumptions. In 2018, developers made changes in a hurry, perhaps because of safety certification requirements or licenses to sell in some countries. Engineers made an almost continuous long slot from the input connectors to the optoisolator. In 2019, another revision of the board started to be produced.

The long slit severely weakens the board in bending and torsion; the board can break along the slit if dropped even from a low height (box in storage). The flaw was noticed by Mean Well, and after a few months, they are making changes again. The slit is getting short.

Differences between 200W and 350W versions

Different fuse rating
Different capacitance of high voltage capacitors for 200V (LELON). For 200W - 200V/330uF (18/35mm). At 350W - 200V/560uF (16/45mm). The board limits capacitors to 1 3/4" long (longer will interfere with the transformer)
Different ratings of current resistors
Different number of soldered capacitors on the output
Different number of soldered diode arrays. Except for the 24V version - diode arrays do not change with power (a surprising solution for me)
No fan in 200W version and no soldered fan assembly

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Soldering quality

I advise checking the soldering of diode arrays with a magnifying glass and under good light. On two LRS power supplies, I encountered poor soldering of one of the diode arrays. However, I have no questions about the transistor soldering.