It’s not a matter of whether your meter can do 240V, can you do 240V? Because that can be the consequence of slipping with the probe.

Sorry, I don’t mean to come off all aggressive. I just want to make sure that you don’t hurt yourself because I wasn’t very clear in my communication.

Didn’t really understand, can you explain it a bit more? Sorry 😅 About your warning is it dangerous to measure a 230V current with my multimeter (with precautions, gloves mainly)

Depending on the meter and your approach it can be either safe or lethal. The more I think about it, the more I’d recommend that you just don’t do it at all. Working on 240V installations under voltage, that is something we teach electricians to do safely. Besides the training it involves some special and rather pricey equipment.

I cannot stress this enough, if you mess up, you will hurt yourself with enough severity that the can easily be fatal. If you don’t know what you’re doing, messing up will be exponentially more likely.

Desolder the transistor, does the rest of the board light up? If so replace the transistor. Otherwise, get trained assistance on person or replace the UPS. I’m all for learning electronics, but not on a live UPS.

1. Almost there is definitely a problem. It was working fine, but sometimes it would just not go to batteries and stuck in a fault with continuous beep. After that, I let it for 2 weeks, the batteries were 5V, but I tried to charge them and for now they went to 12.6V stable (as normal…), but even with that it does the problem described and does not works as before

That does sound like some part of the controller electronics has been dieing for a while, and has now finally keeled over.

3. I’ve tested the resistors, all proper to their written value, and relays, proper resistance too (85 ohms for one (just on the brown power plant cable), and 260 for the others)

You wrote originally, that you tested what you could with desoldering anything. Measuring resistance in circuit always renders a murky result.

The brown wire is likely what is known as phase or live. Blue will be neutral. But measuring resistance on the input only tells you how much current will flow in the present state of relays.

What could help you come closer to an answer is following the first law of troubleshooting “thou shalt check voltages”. With a device that operates two live rails this will not be both easy and safe at the same time, so don’t rush it. I suggest you figure out what voltages to measure, then solder wires to the relevant nodes. Terminate the wires in a terminal block, where you’re protected from touching the screw. Assemble the device as best you can with all the wires coming out, and then power it on, get your voltages and deduce from that.

Whatever you do, do not poke about a live UPS circuit with your multimeter probes directly.

My initial working theory would be that the transistor switching the fan is dead and I would be looking closely in that area. If that transistor has failed closed and is shorting the controller electronics VCC rail, that would explain a lot. Maybe I’d go so far as to test it without checking voltages (gasp!)

If you just desoldered the transistor and powered the UPS back on, that could give you a UPS with functioning display and an idea of what to replace.

Will try to find others batteries to try, but normally it charges batteries by lighting up the display properly + the fan does not start. And here the UPS is not connect to any AC power, only the batteries were plugged

If 12.6V is normal for your batteries, then there’s no reason to troubleshoot that route any further. 12.6 is little low for lead acid, but if it’s a different chemistry. Anyway keeping extra batteries is always a good idea.

1. Has it at anytime worked like you describe?
2. If it stopped working, what happened?
3. What have you tested, how, and with what results?

12.6V is low if it’s 12V lead acid. Could be that the UPS is just charging the batteries and attempts cooling them meanwhile.

I think tinkercad is a great place to start. It’s browserbased and doesn’t cost money. It may not have a lot of components, but it still have quite a few more than just resistors, caps and inductors. And it is aimed at newbies and hobbyists, which is reflected in range of the available components. Being able to drag an Arduino into your sketch and have it run your program is neat.

We used to use yenka, when I taught electronics. It was OK for teaching, but I don’t know if I’d recommend it for self-paced learning as a hobbyist. It costs money, requires software installation and is so much more than just electronics that navigating the program can be difficult. And default settings explodes components when you put too much current through them, that alway annoyed me.

So all we have is an unsourced entry in a list based article in a unnamed magazine?

I hope I’m not alone in having an issue with the statement then.

I’m sorry that I’m going to sound like a snob. If people claim to have health related information, I take it seriously. When I said I couldn’t find an article describing the correlation, what I meant was that I couldn’t find an article on pubmed. I went looking for abstracts for articles in peer reviewed medical journals, not pop culture entertainment in “octogenarians’ quarterly”.

Source? I can’t find an article linking PTFE with a metabolic change.

I can’t speak for Germany, but I guess that it won’t be much different than Denmark where my experience lies.

Almost all my recommendations has been mentioned before, but I’d like to point out:

• RS in my experience is reliable about 90% of the time. If you put in an order in can arrive in several shipments. I ordered 50 pieces of something got 46 from a UK warehouse and 4 from Germany. That’s another thing, some stuff ships from Frankfurt am Main, so no waiting for imports.
• Reichelt is good for cheap instruments. I’ve never used them for components, I prefer RS for that, but for instruments they carry some of the Chinese stuff that you can’t get other than on ebay or ali.
• Digikey stocks so much electronic components that sometimes you can’t avoid them. Where RS is really fast, their stock and prices are more suited for prototyping than production. Digikey is where you can get the specific series of cap and value you need for your repair project. Digikey will handle all the import and customs stuff as well.
• https://el-supply.com/ is new to the post. They’ve been in business since the 70s, but is primarily targeted towards Denmark. But they do have an international site. Some times they can be extremely cheap compared to RS and Digikey, especially with regards to stuff used for teaching electronics. I’ve been a customer since the late 90s privately, and I’ve placed several orders each year professionally since the early 10s as well. Never been let down.

Thanks for the update. In that case I would be looking at terminal block plugs. They can easily handle the current, they come in a wide variety including panel mount, and they’re cheap. What’s even better, they don’t require crimping and one I saw didn’t even use screw terminals https://www.digikey.com/en/products/filter/headers-plugs-and-sockets/370?s=N4IgjCBcpgHAzFUBjKAzAhgGwM4FMAaEAeygG0R5YB2BAFhCKtvgFZHKaBOMABg%2BY8ITbmABMA0QxHUuYhgF0iABwAuUEAGVVAJwCWAOwDmIAL7mgA

There’s also these that are rated for 300V 15A https://www.amazon.com/5-08mm-Terminal-Connector-Pluggable-Connector-Phoenix/dp/B0CM3Y1WS5/ref=mp_s_a_1_1?sr=8-1

I use something like this when repairing screw terminals that my students have applied too much torque to and broken the through hole pins on. It’s a great type of connector. But if we’re talking portability, then it’s maybe not the most ergonomic.

What are your other requirements?

• Is this for a production or a one of a kind hobby/repair project?
• How budget aware are you?
• you mention portability. How often would you need to unplug it? And will it be done by you or someone who requires a bit more user proofing?

Have you considered using more than one pin per pole? Ie if you had a 15pin connector, that can take 3A per pin, then shorting 3pins will give you 5 pins 9A. There will be more considerations to this though. Like how can you make sure that the parallel pins present a similar resistance, so you don’t get an unbalanced load.

This isn’t really what this community is for. We’re here to discuss circuit design and other subjects on that level.

I would avoid any 5€ solution that wasn’t a renowned brand second hand. I understand that you are budget aware, I too have a very close and loving relationship with my money, but I wouldn’t trust some cheap temu part to be plugged in without oversight. That’s a pretty easy way to wake up dead in a pile of smoking ashes.

I’m sorry if I’m coming off as an asshole, I’m really not trying to. If you think I’m being snobby I suggest that you go watch a few big Clive videos on youtube. The chinesium stuff can be really poorly constructed.

How much power does your fan use? Is it an ordinary asynchronous AC motor? Single phase 230V?

you will need the 12v adapter

Not if there’s something like a boost converter built in.

I don’t know what you can draw from a modern USB port, but 12.75W is required by the drive, and when I tried a couple of months ago, I wasn’t able to power a similar drive (it had a green and white label and was 1 TB, IDK what it was anymore) from a single USB-C port.

I have something like the product you’ve found. Except mine has a single USB-C plug. My device can’t power 3.5"HDDs nor optical drives. But it will power 2.5"HDDs and of course SSDs.

Your device has two USB plugs, one blue and another white. That the white plug is auxiliary power seems plausible. The USB standard specifies 0.5A max current per port. So two ports, 2.5W each, is 5W. 12V and 5V both 0.75A is 12.75W. So unless your computer has charging ports, capable of delivering extra current, it won’t work.

The compact device is nice, when you’re not working with 3.5" drives, but I have found the universal solution to be something with a separate SATA power connector, like this https://www.reichelt.com/dk/en/shop/product/usb_2_0_ide_sata_adapter_with_backup_function-88571?q=%2Fdk%2Fen%2Fshop%2Fusb-2-0-ide-sata-adapter-with-backup-function-logilink-au0006d-p88571.html&GROUPID=6196&OFFSET=16&r=1

It’s bulky, but it works.

I think I understand now. I’ve taught intro to electronics for years, and I’d recommend you start out experimenting with resistor networks and measurement techniques. In that case you really don’t need to spend much. All you need is:

• breadboards, plural
• a resistor kit
• some battery holders or clips
• jumper wire, just get the cheap bundles with only plugs and no sockets.
• pliers and sidecutters. Spend more than 3usd on the sidecutters, and do not use them for anything but thin wire and component leads.
• a decent entry level multimeter, a unitrend ut33a can be had for about 20usd plus shipping on ebay, and is fine for starting out.

Try designing networks of resistors with pen and paper, calculate voltages across the individual resistors to get familiar with Ohm’s law and Kirchhoff’s circuit laws (BTW don’t attempt to understand Kirchoff using Wikipedia, someone wanted to flex their brain when writing that article). Build more and more advanced circuits, start out with series, then parallel, and finally mix series and parallel resistors. Try to work out the power draw of each resistor, and just once try to blow one up… On purpose, that is :)

When you’ve sorta got the hang of it, you can progress on to adding capacitance and inductance in you circuits, or digital logics, or what ever you like. But getting the hang on basic circuit theory? well, that can take some time.

I don’t understand the list, the first don’t have a question mark, but then they do. Does that mean that the first items are already in your possession and you imagine needing the rest?

If you have all the stuff on your list, I get a book. Practical Electronics for Inventors by Paul Scherz is a terrific resource. With that in hand you can start dreaming up projects and realizing them.

If the question mark is the stuff you expect to need, I’d say that a lab power supply is almost a must have. Nothing fancy, something that’ll do 20 or 30V and a few amps, if you’re looking for something a bit more, then same specs but with current limiting. Something like this https://www.reichelt.de/de/en/laboratory-power-supply-0-30-v-0-3-a-risu-compliant-mcp-lbn-303-p324544.html but see if there’s a second hand market for this stuff in your area.

Some basic components kits like a resistor and a capacitor kit. Maybe assorted diodes and transistors. Maybe get some voltage regulators, 7805 7809 and 7812, they can come in handy, when you’ve only got a single output on the psu and need different voltages.

That should be enough for a few months of fun. Next you’ll maybe play with timing and triggers. So a pc scope opamps and some 555s.

I may be a simpleton, but I’ve always thought that MELF was just old school SMD, where the shape hadn’t evolved yet from the though hole package.

My thought was based on all the old junk I’ve repaired, where the older it was the more likely MELF seemed to be.

I haven’t designed with MELF before, but wouldn’t it make sense for assembly operations to add a MELF fee?

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It’s made to rotate. It isn’t made to be pulled sideways because the adapter and cable is too short to reach the ground on the way from the wall socket.

Power connectors have been the number one preventable laptop killer in my experience.

The thing that kills the power connector is physical stress. As in force being applied sideways to the plug. If the plug is angled, make sure the cable isn’t pulling on the plug. And if it’s straight make sure the cable isn’t dragged sideways.

The problem with the connector breaking is that it’s either

1. soldered to the motherboard, in which case you need to find someone who can solder (which is when I come in the picture) and can find a footprint compatible part, or
2. part of an assembly with a cable, in which case you need to find the exact part on ebay.

Either way it’s a PITA if the connector breaks.