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More about chinese wallwarts...

Hardly I mentioned bad elcos in wallwarts or the next one happened

I bought this DVB-S2 satellite receiver box last year, it came with a 12 V 1 A supply. But always when it was moving the sat dish (drive the dish motor) it gave a big hum in the audio. Well OK, never measured the current that I can remember my dish motor used and as in the previous (USB) sat receiver box I had to replace the LM317 4 or 5 times before I tossed the thing and as everything else was working, I left them the advantage of the doubt,

But now.. since yesterday, it also gave a hum when not moving on some channels (H polarization and V polarization have different voltages to the LNB) I went looking for a 12V wallwart in boxes full of stuff and found a big one 12 V 1.5 A.. Even the connector did fit. No more hum, no more hum when using the dish motor either.

So.. and as 12V cable on this one was much ticker, 2 wire, I split it in half for a small section and used the clamp-on DC meter to measure the current Less than 850 mA even when dish moving... So the old 1 A wallwart was not even 850 mA... when new!

Had a good look at the label:

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you look close it does not say 1A DC, but _____

- - - So with free ripple let's say! A look inside, and for sure this is the SMALLEST wallwart I have!!:

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bridge, 2 x 10 uF 400 V in parallel, a small transformer, secondary 330 uF 16 V.., diode, inductor, 470 uF 16 V No power transistor???
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dunno this chip, but 12 W output ???? No cooling? Efficiency?

It took a vice, 2 big pliers and a hammer to open this thing, still in one piece so can put it back together, the 470 uF is clearly swollen and needs replacement.

But from 100 V to 240 V? That means between 339 and 141 V primary on the converter. But for 12 W out counting efficiency say 80 % makes 15 W input

15 W at 141 V input makes i = 15 / 141 = 100 mA 20 uF at 60 Hz so 120 Hz so 8,3 ms between mains peaks Q = C.U = i.t so ripple U = i.t / C = 41 Vpp

So that converter chip should at least work between 141 - 41 = 100V DC input (min US) and 339 V DC input (nominal EU).. Seem a bit hairy to me :-) Well it did not even do 1 A when new at 230 V in...

What's in a spec?, any legal issues here?

Now that chip, on it it says

125360 OB2502PCP

google

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Well!! Build in power MOSFET, no reference needed....

Will replace the 470 uF and use it for things that need less than 1 A at 12 V ...

Reply to
Jan Panteltje
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That doesn't look awful, for a cheap Chinese wart. Sounds like a cheap Chinese electro cap failed. There are a newish generation of chips that do the offline PFC regulation function.

We have used about 12,000 of various Phihong and MeanWell warts and laptop-style supplies, and they have been excellent.

We are now shipping a rackmount box to a big laser facility and using a 24v laptop supply to run it. That got around massive safety reviews and test lab hassles that we would have had if we ran AC to the box.

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That uses a 65 watt 24v Phihong supply, and we switch down to various other supplies inside.

Reply to
jlarkin

Excellent tear-down, Jan! Your link to the datasheet needs an "f" at the end to seamlessly work:

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Phihong also makes adequate (eg cheap, dependable) PoE injectors, John. On the other hand, some marquee name companies seem to struggle to provide an injector with enough oomph to power even one Wireless Access Points (WAP).

Although PoE Texas makes a nice injector:

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don't let its 16-ports fool you. At best it only reliably powers about three WAPs.

My company's DIY alternative product consists of a 1U shelf:

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populated with these injectors:

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The DIY product enhances modularity - even the injectors are modular. One module for power conversion and another module for injection. Such modularity makes it easy to keep plenty of spares on hand and avoid Just In Time like the plague it is.

Danke,

Reply to
Don

On a sunny day (Fri, 8 Jul 2022 15:00:19 -0000 (UTC)) it happened "Don" snipped-for-privacy@crcomp.net wrote in snipped-for-privacy@crcomp.net:

Thanks for correcting the link, seems triple click from Chromium does not work very well. .. was reading in newsletter.gsb.bund.de that the lastest Chrome now has 14 new security issues .. need to upgrade... ?? ;-)

  1. Google Chrome: 14 Schwachstellen Bericht und Anleitung zum Patchen bei Chip:
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Reply to
Jan Panteltje

Firefox lately wants to eat my trusty Win7 PC. It opens something like

30 processes and uses all my ram. There is an about:config fix for that. There seems to be a new version every week or so and some of the fixes need to be redone. Nuisance.

Welcome to the age of bloat. I wonder how much ram the Star Trek computer used.

Ironic that things like wall warts keep getting simpler and more reliable and software goes the opposite way.

Reply to
jlarkin

On a sunny day (Sat, 09 Jul 2022 07:05:56 -0700) it happened snipped-for-privacy@highlandsniptechnology.com wrote in snipped-for-privacy@4ax.com:

Who was it that said: "Things should be as simple as possible, but not simpler than that"? I still use my own Usenet newsreader I wrote around year 2000 or so. As long as they do not change spec its fine.

All the hacking and security hype changes internet into a stress zone.

Reply to
Jan Panteltje

Einstein, about theories.

IBM made a tragic mistake when they selected Microsoft and Intel for the PC.

Reply to
jlarkin

On a sunny day (Sun, 10 Jul 2022 06:31:30 -0700) it happened snipped-for-privacy@highlandsniptechnology.com wrote in snipped-for-privacy@4ax.com:

Not sure that was bad.. what changed things for the worse was when Microsoft integrated the GUI with the multitasking kernel. I remember running win 3.1 on top of DRDOS (Digital Research DOS) and Trumpet Winsock to go online... MS was afraid of the competition and then integrated the GUI...

Now Linux is in every small device you can imagine, often no GUI needed, but X11 is available, and gcc was a free compiler. Found a CD with SLS Linux that came with a magazine in 1998 and that was it for me, no going back to MS. But Linux is getting ever more bloated .. too, many things that run when I type 'ps avx' I do not really know how those work or what those do, dbus (introduced by RatHead) made an ever more complex mess. So back to BSD Linux perhaps... I like the small micros, PICs now those become ever more powerful have integrated ADCs and DACs, all sort of interfaces, PWM out, and PICs are cheap, using more than one in one project is no problem. And then there is FPGA, make you own processor if you want, all glue hardware is there..

Was just watching Wimbledon final on TV.. Am working on some solar project here now, just ordered some extra panels, 300 W extra flexible that can also be glued on a boat.. There is sort of panic about power now in this part of Europe, fear that Russia may cut gas to Europe altogether, cannot blame them after all the silly sanctions, but when it starts freezing and no gas no heating no nuclear plants (*Germany and over here now also delayed building more) and the water pipes freeze too I see BIG problems. Having some electrickety and big battery backups allow you to boil water and use the microwave to cook. My garden is big, plenty of space for solar panels, so why not, 30 degrees C predicted for next week.. If not.. sail away south to where the butter melts in the winter..

Reply to
Jan Panteltje

NT was good, authored by the VMS guy, until morons broke it. That's in the book: Showstopper

But really, x86 is barbaric. When in doubt (code, data, stack, buffers) execute it.

We can survive here without power for a while; it never freezes. I have a little propane BBQ.

We had a few days without power after the 1989 earthquake. First thing was an ice cream party with the neighbors.

Reply to
jlarkin

On a sunny day (Sun, 10 Jul 2022 10:28:34 -0700) it happened snipped-for-privacy@highlandsniptechnology.com wrote in snipped-for-privacy@4ax.com:

Yes, fridge needs power too...

Reply to
Jan Panteltje

On a sunny day (Sun, 10 Jul 2022 10:28:34 -0700) it happened snipped-for-privacy@highlandsniptechnology.com wrote in snipped-for-privacy@4ax.com:

Solar panels arrived today. amazing everything is in short supply but these not.. Three 100 W flexible panels so 300 W on the grass in the garden, quite a bit of power. Came with cables and charge controller...

Reply to
Jan Panteltje

Europe may be facing a serious energy shortage this winter. Some solar and batteries and LED lighting would help, but it won't keep your house warm.

Reply to
jlarkin

That depends on the house. Super-insulated houses don't need much heat at all to stay warm.

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"The house is heated primarily by waste heat from appliances and the occupants"

Reply to
Anthony William Sloman

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