Faulty Chinese MAX31855K Modules: Fake Chips? No! Just a Capacitor Missing!
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- Опубликовано: 25 июл 2024
- They don’t work and I bought the internet “fake chips” stories …
↓↓↓ Complete description, time index and links below ↓↓↓
… so I (unfortunately) made a video about that (link below). Meanwhile I got my hands on a Maxim Integrated MAX31855K engineering sample and it exhibited exactly the same “fault” as the chip on my Chinese module.
The solution to this riddle can be found within the MAX31855’s datasheet in a text passage on page 11 (of 13!). There, a “strongly recommended” differential capacitor is mentioned (not included in typical application circuit!).
00:00 Intro - internet wisdom and Maxim engineering samples
01:02 Markings - Maxim sample vs Chinese module vs SparkFun module
02:01 Breakout board - for engineering sample similar to Chinese module
02:23 Behavior - of engineering sample same as Chinese module
03:37 Datasheet - “strongly recommended […] differential capacitor”
04:46 Modified breakout board - with differential capacitor works fine
05:40 Modified Chinese module - with differential capacitor works fine
06:31 Lessons learned - read datasheets to the very end and trust no one
07:43 Wrap-up - rewrote title/description of first video, bye
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#fake #counterfeit #chinese #thermocouple #modules #boards #board #mailbag #postbag #robertssmorgasbord 
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Thanks you, Found a ceramic capacitor with "104" on it and now it's working as expected
You're welcome! BTW 104 is a big large (100nF). It might make reactions to changes in temperature a bit slow. Better use an 103 (10nF) as recommended by the manufacturer. However, if the 100nF works for you there's no need to change it.
Big thanks! Its really handy for me, as i bought similar modules and planned to install them to my water heater tanks. You just helped me to prevent lot of headache troubleshooting them!
You're welcome! I'm always happy when my videos are actually helpful to others.
Thanks Sir. Nice of you to share !
You're welcome!
Good for you Robert. Glad you found the root cause and were honest enough to share the misplaced conclusions.
Thanks! I kinda still feel bad about the first video I made (already mentioned that in the comments below). Ah well, that's my punishment for trying to save a few bucks by buying that module instead of ordering the naked chip from my usual distributor. My only solace is that these modules really don't work out of the box (Chinese plastic bag) without modification.
Not all heroes wear capes. I thought I was losing my mind. This was EXACTLY my problem. You sir win the internets today!
How do you know I don't wear a cape? Anyway, you're welcome! Always happy when my videos are helpful to somebody :-)
Hi Robert, job well done! As described after the last video, several Chinese chips were already on their way to me. Then I purchased just 1 original from the Dutch Farnell distributer. Just to be sure when I build the reflow oven controller from Andy Brown. Good to know I can experiment further with the Chinese chips as well! Thank you for posting.
You're welcome! I'm actually feeling kinda bad about the initial video. Should have dug deeper - my bad! But then, the Chinese modules actually do not work - without modification.
Nice! Many thanks!
You are a nerv saver.
I am buying these capacitors now and hopefully this board is going to work.
You're welcome! And good luck with fixing your board!
@@robertssmorgasbord Works!
Again thank you very much.
@@warmesuppe Sometimes it's the little things - like a capacitor 😁
Blazing material! Thank you for sharing it, found it very useful 😉
Thanks for the praise! And you're very welcome!
Thank you for the information! Amazing video!
I had the same problem. I didn't believe that the capacitor would solve it. I had to apologize to the Chinese supplier :)
You're welcome! And don't apologize to the Chinese supplier - they should have supplied (pardon the pun) that capacitor ;-)
Good find!
Thanks!
u saved my day, thank you :)
You're very welcome :-)
Just a quick note to say that the lettering on the top of chips is laser etched, not printed, so no ink or stamping involved. Really enjoying your videos with my coffee on a Sunday morning, keep up the good work!
Thanks for the info! And while you completely destroyed the part of my theory about different inks 😓, the part about different machines, albeit laser etching and not ink stamping machines, is still valid 😅 Anyway, I'll try my best to keep the videos coming.
you saved my project
I'm happy to hear that - and you're very welcome!
Wow ! Great work, its become very easy to shout " Fake Chip" its nice to see a story like this pan out this way, with a real engineering solution, there's gonna be some red faces out there...cheers.
Well, one of those red faces is certainly mine. I'm definitely not proud of my first video in that matter. Not wanting to deflect blame here, but Maxims statement in the datasheet that this capacitor is "strongly recommended" to suppress noise from the thermocouple lines is kinda BS. The temperature measurements without that capacitor are not getting overly noisy, they are way off. I guess there are configurations where you can get away without that capacitor, e.g. with the thermocouple on the board near the chip. But in real world scenarios it's usually required. And of course the Chinese won't include a part on their modules that's just "strongly recommended" and not required.
Hello, what is Volts have the capacitor, please...
Uh, it's a run of the mill 10nF ceramic capacitor. The one I used is rated for 50V, but a 6.3V or 10V type should be sufficient.
I have a set of three of these. These are 'fake' ie. not genuine maxim. There are a couple of differences. The 'fake' do not work at 3.3v. The internal temperature will be very low. They work at 5v though but the readings are 'off' but not in the way you described. Adding a capacitor helps but isn't a 100% solution. I had to 'adjust' the temp in code. They advertise that the chips work from 3 to 5 v with an LDO regulator and that the boards have level shifters. They do not have either. But they work at 5v and not 3.3v as the maxim chips do. The maxim chips specify a max voltage of 4v. So the internal voltage reference is 'wrong' on the fake chips and the allowable voltage ranges aren't quite the same. They are definitely advertising the chips to be a replacement for the adafruit and are stealing the copy for that board. So someone is pumping out good 'fakes'. These may be engineering/qa rejects that are getting shunted to chinese manufacturers for less accurate boards. They are usable with some mods. I think the key difference is the accuracy. Having to calibrate lower quality chips is not unusual. The 31856 from adafruit worked right out of the box with no modification and provided a correct value within 1C of an RTD PT100. The three fakes even with a capacitor were all over the place with a variance of about 20C. The thermocouples were fine with the 31856 but not with the 'fake' 31855. So there is definitely some thing 'not legit' about these. I am going to be ordering a few of the adafruit model and see if they have similar behavior.
Thanks for the info. Please do update us when you have checked the Adafruit version.
Thank you very much for that really detailed report. Guess I got lucky and they just "forgot" the filter capacitors on my breakout boards. Honestly, after some more borderline experiences with Chinese breakout boards (an FTDI FT232RL USB to Serial Module with no programmable EEPROM - ruclips.net/video/27zx9MMKbAE/видео.html - and a GPS Module with an U-Blox Neo-M8N module missing the flash memory for firmware update - video coming up) I decided to start sourcing breakout boards from reliable sources (Adafruit, Seeed, SparkFun etc.) only. We'll see how long I will stay true to this resolution 😉
@@qcnck2776 I second that!
I received the adafruit. It is a much more complex board and much more expensive. But it works flawlessly. The chip is being run at 3.3v from a 5v input. The internal temp on these reads fine at 3.3v. It has a number of capacitors including one on the temperature probe. It is about a degree off of the pt100 which is similar to the adafruit 31856 board. Another anamoly with the cheap ones. They seem to load the spi bus much more heavily leading to bad readings with more than a pair of devices. With the adafruit max31856/55/65, I have 4 devices with no issues. I suspect I could get 8 of the authentic chips.
@@mackmcbride5028 Appreciated!
Sck and cs was touched together while putting in the box after testing on lcd the chip was burn 🔥 and show not real values 😢 what your advice to me
Well, shit happens. I once soldered in a chip into a board the wrong way around and killed it. The only thing you can do is get a new MAX31855K and/or (!) a new microcontroller. Shorting the chip select and slave clock lines can damaged those pins on the microcontroller (CS high while SCK low and vice versa). However, I can't imagine how shorting those lines can damage the attached slave (here the MAX31855K).
Sir, it's applicable to Max6675?
Your channel is a treasure ❤
No, the MAX6675 modules work as they are (at least the ones I have). That decoupling capacitor between the inputs of the MAX31855K is not even mentioned in the MAX6675 datasheet. And thanks for the praise 😅
When I trying put 12v in vin pin of this Chinese arduino nano it’s burn 🔥 😢
Well, the VIN pin of an original Arduino Nano v3 can easily take 12V (absolute maximum ration 20V, LM1117 linear regulator). So I guess your Chinese clone cheaped out on that linear regulator.
👍
😁
I'll give this a try. thanks. What an irritating product 😠
You're welcome! If soldering the capacitor to the screw terminal pins doesn't work, try soldering it directly to the pins of the chip (like I did with my homebrew breakout board).
Das Rumgefuchtel mit den Händen, noch dazu im Makro, nervt gewaltig.
Vom gewaltig nervenden Rumgefuchtel mit den Händen abgesehen, hat Dir das Video inhaltlich was gebracht?