„People’s” power supply 24V-4A…

Then I smeared the solder with varnish and fixed this resistor with sealant (I made the resistor with the output into heat shrink). I put ferrite beads on the extreme conclusions of the diode assembly. Thermistor 5D9. There is a large (long) dispenser spout and a spatula included. As for the sealant, it is optimal in terms of price / quality, neutral gray RTV.
The connector for connecting wires (at the output) was simply removed. If you look at these resistors for https://jiji.com.et/building-and-trades-services/stamped-concrete TL431, for example, in the calculator from Kirich (a) on the blog, then R1 from the table is our R18 ( R1 with a plus
output power), and R2 from the table is our R19 (R2 from minus output power). Samwha RD has standard-rigid conclusions, they are well magnetized. In principle, if you are not going to do anything on the board, then you can also varnish the front side of the board. The rarest case for TL431, so that instead of 2.5V, it was at 1.25 Volts (these did not even occur). But to increase the capacitance of the capacitor to 100 / 120uF (branded 400V) is now very problematic, because of the allotted size by 16mm. At home now I often use "Sealant-gasket (KERRY)". Now about what I categorically dislike about this particular version of the PSU. Photo from the Uncle_sem review. With a simple search for capacitors on Ali, this seller did not appear in the search. Output diode assembly – MBR20100 (20A / 100V). I bought sealant in a regular stall in an auto shop. He didn’t shine much, he left links only with Krich (a) on the blog and gave him in a personal. I always make the voltage at least 0.5V, take into account the losses on the wires and connectors. When the varnish dried up, I turned the board over and completely smeared the reverse side of the board with PLASTIK 71 varnish, except for the soldered nickel. wires. After several attempts, I got 24.89V. PWM chip CR6842S, high voltage capacitor 82uF/400V (16/25mm). I did not take a photo of the PSU out of the box, all the photos are after a little refinement. Several times I was offered to give him a link to Muska, in
RD 2200uF/25V. There is such a ratio of resistors under 24V that their slightest deviation and voltage fly away by a large amount. As a result, I installed R18 – 27 kOhm (2702) and R19 – 3 kOhm (3001). High-voltage smd-ceramics are more pampering – the capacity is quite small, as I saw in Kirich (a) in reviews, in small Mean Well PSUs. Temperature from -50 to 330°C. Snubber elements – green film capacitor 2J472J (4.7nF / 630V), smd diode RS1M ( 1000V / 1A), large smd resistor 104 (1W, 100kOhm). Possible technical and grammatical errors. I replaced the diode assembly – it was not available at 150V, I installed it from the MBR30200CT store (30A / 200V). He drew his conclusions horizontally, tried on his native nickels, bit off the excess and soldered it to a regular place. More details HERE. It seems nothing complicated. In the column (U B fb) we always put 2.5 (V). Then I sealed large elements with sealant. I have, for a long time, had a "favorite Chinese" on Ali. I had to order rare 35V/1000uF (10/28mm) capacitors for the output. But there is no talk about Low Esr. Diode bridge KBP307 (3A/700V). "Current" resistor-shunt R300 (1W, 0.3 Ohm). At first I didn’t get it, the radiator didn’t want to be dismantled. The minus of the sealant is more expensive than the Kazan sealant, but Kazansky does not have a dispenser nozzle in the kit. At the end, I degreased the surface of the board under the heatsink, glued a 20mm (width) thermal tape to the board (under the heatsink). Removed the native load smd / resistor 1 kOhm – put the usual 1W at 1.5 kOhm. Therefore, it was decided to solder the radiator. The same thing with the Y-capacitor, I put ferrite beads on its conclusions (two bags lie idle at home). Then I added a comment to the review. If in the first version of the PSU from Kirich (a) there was exactly the same capacitor 82uF / 400V (16 / 25mm), only the place there was reserved for a capacitor with a diameter of 18mm.

There are complaints about the diode assembly, especially in the case of using a PSU in self-made LBPs (with increasing voltage) – this assembly is only 100V. But it is very problematic on a 24V power supply, precise resistors are needed. All the main elements of the BP remained almost unchanged. I found a 100uF/400V capacitor in the box, from the old "favorite Chinese with Ali", 16mm in diameter (30mm high, PAG series). I took another (other) 27kOhm and 3kOhm. I replaced a small capacitor for PWM power supply (I always change them to branded ones) – I wanted to put a thug Samwha WL 33uF / 50V, but at home I got the first Jamicon TK 47uF / 50V, I installed it. Standard capacitors 35V/1000uF with a gap with a radiator (at 12.5/13mm in diameter) were suitable for the output. The link to the PSU was given randomly, where he took his PSU, the link is no longer working.

"People’s" power supply 24V-4A (version with one-sided mounting of elements).

That is, you can take two identical resistors, but from different bags (from different sellers) and get a very different voltage from the PSU. Several times I have had a 24V PSU on my nerves. The last batch of correct PSUs was in the uncle_sem review. I use a brush from the old FKSp flux (20 ml). The review is very amateurish. I played with these resistors several times (with the same ones) – at first the voltage flew away much beyond 25V. According to the selection of the diode assembly – we take the current with a margin of 3 times, we take the voltage with a 5-fold margin. In the first column (U B out) we put our voltage 24V (or 24.5 necessarily through a dot). For example, inexpensive conventional Samwha RD capacitors are sized this way in 25V/1000uF capacitors. I already put a 5D11 thermistor (in heat shrink) on a 100W PSU. These capacitors are not in DATASHIT, but it is these capacitors of the YXG series that are put in some expensive computer PSUs. Added smd ceramic to the output and added high voltage smd ceramic to the 100uF/400V capacitor. And there they (16V / 2200uF) have a size that is also not in the datasheet. Immediately stopped — I think normal voltage. The common drawback of these PSUs is that Chinese capacitors 35V/1000uF are installed at the output. What did you do about this BP. The main point is that the Chinese have cut the place for capacitors.
Weight 85gr. Capacitors, at the output, were set with a diameter of 13mm (simple Jamicon TK 35V / 1000uF). This number won’t work here.
Load smd resistor (1W, 1 Kom). I just really don’t like the even voltage at the PSU. We changed only the key transistor, in my case it is FQPF10N60C (600V / 9.5A) (plastic case). With alterations, everything went quickly, except for the operation to slightly increase the voltage. Two Chinese, supposedly Low Esr, 1000uF/35V (10/20mm) capacitors. They have a ridiculous size of 10/20mm. I applied a little glue-sealant to the sole of the radiator and soldered it into place. Varnish KO-921 is thicker than varnish PLASTIK 71. I have nothing to do with electricity and electronics, PSU and soldering are my favorite hobbies. Negotiations – a 1kΩ load resistor (heats up), a large ripple range (it was known) and the absence of thermal paste (easily fixable). To increase the voltage, we need to change the resistors according to TL431. There are no normal capacitors with this size.

Immediately about buying branded capacitors on Ali and following links to sellers. Firms have miniature series, such as Rubycon PX with such dimensions. Here it is resistors R18 and R19 (size 0805). The first photo is from Kirich’s review, the second photo is my old one, from the correct (double-sided) version of the PSU. Initially, I made a plan for improvement – to increase the output voltage (native 24.07V), replace the load resistor, change the diode assembly with capacitors. Now all folk PSUs on 24V-4A are only in this version. According to the characteristics of Rubycon PX, these are the most common capacitors. It turned out that the Chinese glued it – glue was applied to the entire sole (keep in mind).
I turned on the PSU under load for 30 minutes – while the board was hot, I smeared KO-921 varnish (Rexant 09-3789) into the common mode choke and into the transformer windings. And here in BP, just pure China.

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