Faulty Smart Thermostats x 2 | Can I Fix Them?

[@jlucasound]

When you cleaned that IC and its pads, it was SO satisfying. 😌☺

[@BuyitFixit]

😂Thanks 👍

[@jeisonsanchez4842]

Just like going to the dentist 😁

[@alfredocuomo1546]

That glue has killed more CB radios then I care to remember. Also you've proven once again anything worth doing is worth overdoing... Nice job as always.

[@BuyitFixit]

Thank you 👍

[@rory9174]

Amazing the damage the glue caused and becoming conductive, that was a shock. Great video, I'm always learning something valuable from your content.

[@BuyitFixit]

Thanks 👍

[@3dsmaxrocks699]

Oh...A Sunday treat. Thanks Mick!

[@BuyitFixit]

Cheers mate 👍

[@canyondan]

super sleuth. Lots of circling to figure out what the problem was on that last one. Absolutely the best. Thanks

[@BuyitFixit]

Cheers 👍

[@Rustybritjunk]

Another strong and tenacious fix (well conclusion and understanding)… thank you for putting the content out. Please keep up the good work!

[@BuyitFixit]

Cheers mate 👍

[@luckywetland]

Don't worry Mick about the second thermostat, your skills in troubleshooting are phenomenal I really enjoyed this one. 🤩

[@BuyitFixit]

Cheers mate 👍

[@terrym1065]

What a brain teaser the second one was, the troubleshooting was agonizing but rewarding. I'm not surprised the glue on the first one was the culprit, the solder joints were def bad and you were right, when the temp raised so did the joints...good job bro. Always a good watch mate, thanks for the work. See ya next time.

[@BuyitFixit]

Cheers Terry, yes the 2nd one I had my head done in for a bit. I thought it was the chip but with it being intermittent at times it was very bizarre!

[@MikeB_UK]

#2 was interesting. 10/10 for persevering with it. I wish someone could find out if the micro controllers that do fail just give up with age and maybe some not perfect silicon in their construction, or whether it is long term mains spikes that causes failures. One of life's mysteries! Keep up the great videos.

[@BuyitFixit]

Thanks Mike, someone suggested static could have damaged it if they had touched next to the thermistor, which is plausible.

[@neiltheplayer]

#1 - brilliant #2 "oh well" you can try but sometime you can't fix them all. Thsnks for posting Mick

[@BuyitFixit]

Cheers Neil 👍

[@BruceBoschek]

I had convinced myself that you had forgotten to replace C45, but then you even said you did, so that isn't a factor. They're so darned small! 🙂I admit I had a lot of trouble following your logic through this one, but I'm glad you found the culprit. Thanks for another captivating detective story! Best wishes for a pleasant week ahead.

[@BuyitFixit]

Yes, I suspected the microcontroller a bit earlier on, but when the fault went away I thought it might have been something else, so that's why I checked everything else to rule all the other things I could think of out.

[@VintageProjectDE]

Congrats on the ESR70! Jez certainly is an awesome guy! The ESR70 will do you good around these repairs. You'll probably want a DCA55 next to allow for more in-depth testing of semiconductors. Or even the DCA75 Pro. Its companion tool (PC software)allows for some nice curve tracing and comparison. ;)

[@BuyitFixit]

Yes he's an awsome guy. I've got the DCA55 as I bought a broken one and repaired it about 2 or 3 videos back. That's how I got chatting to Jez 🙂👍

[@cheapasstech]

Peak has the best stuff and is very repair friendly

[@VintageProjectDE]

@@BuyitFixit Oh, yes! I totally forgot that that was the DCA already. 😁

[@BigJohn5662]

Good to see the Warmup 4ie could be fixed. I have multiple of these at home and sold them for years. They're generally good thermostats, and were only discontinued as the manufacturer couldn't get hold of the screens any more. I know now where I'll be sending mine if they fail 😉

[@BuyitFixit]

😂😂😂😂Thanks (hopefully they'll last a while) 👍

[@wattorockscr]

Nice catch on the glue I had no idea about that, THANKS for the new knowledge!!!!

[@BuyitFixit]

No problem!

[@SCOTE991]

Very smart man. Thanks, I learned a lot. You fixing things that most people throw away. There is knowledge to be gained regardless.

[@BuyitFixit]

Thank you 👍

[@mr__No]

You fix lots of stuff and i admire that even though i cant always follow your logic. Your instruments can test most of that you desolder in circuit. Thanks for the videos.

[@BuyitFixit]

Thanks 👍yes that peak tester can test in circuit. I've not long had it so forgot and I'm used to doing it old school 😂😂

[@wisher21uk]

Fabulous content again Mick thank you, the first controller as soon as you showed the caps and I saw the brown glue I was shouting at the screen!. The second controller was a bit of a rabbit hole, things just weren’t adding up at all end result had to be the micro controller, I really enjoyed it many thanks Mick😊.

[@BuyitFixit]

Cheers Gary 👍

[@VoeViking]

I was getting worried. Another great video with excellent fixes and diagnostics. Thank you, sir.

[@BuyitFixit]

Cheers 👍Yes was a bit late getting this one out as I'd other stuff to tend to.

[@sapperdeflap]

0:58 By the looks of it, the thermostat is already fixed 🙂

[@brianwood5220]

Great diagnostics as always, Mick. Plus as the guy said who owns that, you've got some spares for the next time you get one of those. Thanks for sharing and have a great week.

[@BuyitFixit]

Cheers Brian 👍

[@darrenwardell3079]

I thought for a moment that second one was somehow displaying Fahrenheit with a Celsius label🤔. Nothing worse than intermittent faults to find as you say. But you got there as always Mr Methodical Mick.👍

[@BuyitFixit]

Cheers Darren 👍

[@tomharris1457]

I use GE Silicone 11 if I need to stick things. I read it is safe for electronics, no formaldehyde smell and won't damage traces. Easy to remove, but sticks caps well.

[@BuyitFixit]

Cheers for the tip Tom 👍

[@kellyherald1390]

You win some, you lose some. There are times you have to determine if it is economically viable to repair something. Either way, you learned something in the process.

[@BuyitFixit]

Absolutely 👍

[@johnHAMMOND-l3u]

your video was late today i did not think you was going to do a video happy you did

[@BuyitFixit]

Thanks John, yes just been a bit too busy but still managed to get one done 👍

[@chrissavage5966]

I've got one of those 'Warmup' controllers - now I know what to look for if/when it plays up ;) Re the second one, @33:30, the voltage both sides of R31 was the same, showing that the input impedance of the micro on that pin was very high, as soon as you measured about 0.1V dropped across R35 @34:07 it was apparent the issue was downstream of the thermistor and bias chain. It had to be either an issue with the input of the micro itself, or some leakage on the PCB. Removing the microcontroller proved it to be the culprit. Shame you couldn't do the full fix due to parts, but you get the score for the diagnosis :) I miss fixing things so it's great to play along at home. Thanks for taking us along for the ride.

[@BuyitFixit]

Thanks Chris and a good summary 👍

[@chrissavage5966]

Apropos of not much….seeing your ‘famous blue mat’ prompted me to buy one for myself a few days back…and I christened it yesterday doing the motor and battery swap on my Philips 7070 shaver as prompted by MyMateVince :) I’ve now ordered some flux, low-melt solder and the SMD tools kit you recommend from your links….and based on how small stuff is getting these days and my ever failing eyesight, I can feel a digital microscope/screen combo coming on soon as well. I’ve had an optical binocular microscope for years, but it’s really limited as it’s fixed focal length, with an additional lens so stuff tends to be either too big or too small, and it’s far from comfortable to use. I keep looking at these fancy new soldering stations as well…. It’s all your fault :)

[@BuyitFixit]

@@chrissavage5966 😂😂😂Sorry mate 👍Yes all the newer stuff is way too small to tackle without a microscope. The trinocular one I have I paid £500 for which was second hand from Ebay. Over £1000 new. It came with the stand and camera and I use an external display. I recently got a Tomlov 4K AF microscope that Tomlov sent me to test out and I've used it a few times now. I used it on the recent video of repairing the motorcycle headset which was ridiculously small and hard work.

[@doogulass]

Well done on the fix on the first one and the diagnosis on the second one! That yellow/brown mystery glue that becomes conductive over time is so strange. I don't understand why any manufacturers are using it at this point. CyberPower is notorious for using it in their UPSes. It seems dangerous!

[@BuyitFixit]

Thanks 👍Yes I was surprised to see it in something this modern.

[@MoseyingFan]

AKA the brown snot of death. Sony started using this glue. The glue is tan coloured when fresh but turns brown with age and is supposedly hygroscopic (absorbs water). Korean display manufacturers loves this shit. I've got a Samsung Syncmaster 2443 where the snot has corroded some resistors in the PSU.

[@gorjy9610]

@@MoseyingFan Samsung TV PSU was first place for me to find out how dangerous it can be. One day it just pop, at first with burned NTC (exploded) and fuse I expected shorted semiconductor but everything was fine. At least until I applied high voltage again :D

[@TinMan-jb5gf]

I remember that JVC valve stereo. Someone in the comments said that corrosive glue was a Sony thing. Hard to believe that Sony and JVC would let something like that through. They aren't amateurs.

[@BuyitFixit]

From what others have said it seems to be in a lot of older devices such as CB radios and other electronics of that era. I was surprised to see it in something as modern as this.

[@Matta1224]

Always a treat. Diagnostic is on par :) -Mat

[@BuyitFixit]

Cheers Mat 👍

[@599miata]

Win some and fail on other ones. Cheers mate. It was still a great troubleshooting video.😊😊

[@BuyitFixit]

Cheers mate 👍

[@CTCTraining1]

Well done on the repair and diagnosis. I note that Warmup have a co uk website - might be interesting to know if they have a product recall out for that first stat and if they still use dodgy conductive glue when fabricating their boards. Also … if I were you I’d add the brand name into the video title so folks with that broken stat will be able to find it more easily. Keep up the great work 😀👍

[@BuyitFixit]

Thanks, and Great suggestion. I'll also add it to the description as when people search for things like "faulty Warmup thermostat" or "broken Warmup thermostat" etc

[@joelkist6493]

Nice troubleshooting vid...

[@BuyitFixit]

Thanks 👍

[@karlfell3768]

I forgot to mention on your Peak repair video, there is a set of needle probes available for the ESR meter. Not cheap but well worth the money. Ideal for in circuit measurements.

[@BuyitFixit]

Thanks, I'll look into that 👍

[@ISquishWorms]

Thank you for the content, it was nice to see the Peak Gold in action, it looks like you do not have to worry about discharging the capcitors prior to testing either as it seems to sugges that it does that? Think I will be adding one of them to my wish list.

[@BuyitFixit]

Thanks 👍yes it automatically discharges first 🙂

[@ISquishWorms]

@@BuyitFixit After watching your videos I have found out that there is a repair cafe in my local town. So I am planning on volunteering. The site says that I need to contact them so was thinking about sending them an email. So was wondering if you have any tips about what I should include in the email etc?

[@BuyitFixit]

@@ISquishWorms sorry, unfortunately not. I'm sure they'll just be pleased to have a new volunteer! I kind of stumbled into volunteering at ours as there was a village fair where they had a tent and I got talking with some of the guys, one was talking a look at a little battery powered guitar amp and I helped diagnose the problem... that's how I got involved 😂😂👍

[@ISquishWorms]

@@BuyitFixit You just can't help fixing things can you? 😂 I bet he was greatful of the help. No worries on what to include in the email. I might just pop in there at the end of the month instead as our repair cafe is only open on the last Saturday of every month. I will be telling them all about your youtube channel and how I found out about them from your videos. That way they will know who to blame when I destroy some capacitors etc. 😄

[@BuyitFixit]

Thanks 👍our cafe is usually on the first Saturday of every month 🙂

[@johnmolnar2957]

another great video

[@BuyitFixit]

Thanks again!

[@mikecass8306]

Thanks Mick

[@BuyitFixit]

Cheers Mike 👍

[@NicksStuff]

I thought the PEAK tested ESR at very low voltage and high frequency, thus allowing you to check it in-circuit most of the time. Would you accept to try that next time?

[@BuyitFixit]

@@NicksStuff Yes, completely forgot about that as first time I've used it. I'm used to having to take them out and test 😂😂

[@pgprentice]

On the second controller was it displaying degrees F with a degree C symbol? Does the chip have a F/C toggle line? Thanks for another great video. Cheers.

[@BuyitFixit]

Thank you 👍

[@The-four-o-five]

Nice one 👍

[@BuyitFixit]

Thanks 👍

[@generaldisarray]

13:08 - Quick tip, and only the tip mind... Get a small paint brush, the cheap sets that Aldi or Lidl sell from time to time will do, chop down the bristles, and the handle, until you have a nice little stiff scrubbing brush. Then you can use IPA or other solvent and your scrubbing brush to get into tight spaces to clean off flux, or crap glue like this stuff. A toothbrush is useful, but can't get into those tight spaces. You can also buy "anti-static PCB cleaning brushes" but they're really just cut down paint brushes.

[@BuyitFixit]

Cheers for the tip mate 👍

[@oefzdegoeggl]

There's no need to unsolder the capacitors (usually). The capacitance you can usually ignore, you're more interested in the ESR and that can (usually) be measured fine by the ESR70 in-circuit. Very very unlikely that you find one which has a bad capacity but a good ESR. If you see an ugly high ESR value, you can still desolder it, or save some time and throw it in the bin right away 😄

[@BuyitFixit]

Cheers for that. Yes I guess I'm just used to removing them and testing in my other component tester, I forgot this one can measure in circuit 😂😂

[@frankcarpenetti5776]

Nice video again Bro! Even if you were able to purchase that chip, i am thinking it probably has firmware encoded on it? What do you think?

[@BuyitFixit]

Thanks 👍Yes as it seems to have 192K flash memory. I did notice an external Eeprom but that may just be used for saving user settings.

[@jonathansperb]

Did you check if any of the ceramic caps closer to the micro pins were connected to the temperature signals?

[@BuyitFixit]

Yes, none were connected. There are for power pins next to the temperature sensor input pin 👍

[@carlszymanski5812]

Perhaps that unused pin on the micro controller in unit 2 should be tied to ground as it could be floating and giving false readings, I have seen that some years ago on a machine that the company I worked for made, an unused pin on a 6502 microprocessor was picking up motor noise and causing the machine to crash...tieing the pin to ground solved the problem.

[@BuyitFixit]

I'm not sure if it's unused. It can also be configured as an i/o pin or as an input or output voltage reference for the ADC. It just measured 0v.

[@manolisgledsodakis873]

At 4:02 I saw the brown glue and said "uh oh!" (BTW, on that first unit you didn't clean the brown glue under the SM resistors and capacitor so it might fail again.)

[@BuyitFixit]

I've not really came across it that often. I think it's only the 2nd time I've had it in a device. Good catch on the resistors, hopefully now it's fully dried out it might not be as corrosive, but at least I know where to look if there are problems with it again.

[@mxslick50]

Great repairs mate, well done! A question, what temperature do you usually run your hot air at? I just got a hot air rework station for some power amplifiers I am working on, and can't seem to find out what the proper temperature should be to not cook the components or the boards.

[@vadimbellous8313]

Get some aluminum tape and take the time to shield the surrounding components where you are working. 470 to 500C with 60% airflow is what I work with but a lot depends on the model hot air you are using

[@BuyitFixit]

I tend to run mine at 400C at 6% but depends on the station.

[@Shinquapin]

I wonder if that pin on the micro has a latch-up issue? It's not very common anymore on modern semiconductors, but it would maybe explain the failure.

[@BuyitFixit]

Could well be 👍I've not came across that before.

[@j81851]

FYI om the second device I think maybe the second thermistor, the glass one, is in a Wheatstone bridge to balance the output. All the resistors must be the exact rating to work. Just thinking out loud...

[@BuyitFixit]

Seems they both went to different pins on the microcontroller, so I think it's for temperature compensation from the hear inside the enclosure so they can subtract that from the reading of the other NTC to get a more accurate reading.

[@zaprodk]

Second one looks like ESD-damage from a finger getting near the NTC bead, partially frying the input stage on the micro.

[@BuyitFixit]

@@zaprodk I like it, very plausible 👍

[@ralphj4012]

Very good, at least one was saved from landfill. The Solflex correcting itself was odd, but investigating the ADCs and references on that IC would be too horrific and time consuming. 82C is nothing, it was 404C in Nottingham.

[@BuyitFixit]

😂😂Cheers Ralph 👍

[@danwyan]

For the US watchers, 82°C is around 180°F. That's hot 🔥. Mick would be cooked to "well done".

[@BuyitFixit]

Yes, burnt to a crisp 😂😂😂

[@GlennHamblin]

I think you should clean up the pads and solder the microcontroller back on. My bet is some dodgy connections on the chip.

[@BuyitFixit]

Nice thinking but If it were a bad connection, it wouldn't have been pulling the voltage down, and there wouldn't have been lower resistance than on the other input pin.

[@GlennHamblin]

@@BuyitFixit Ah, but you don't know that. It may not be that pin. It may be a different pin on the uC that causes the odd behavior of that pin. 🙂

[@mahlapropyzm9180]

I was on the edge of my seat waiting for you to hook up the serial header again - not that it would have helped.

[@BuyitFixit]

😂😂😂👍

[@dubsydubs5234]

Why did they glue the capacitors in the first place, I was under the impression they glued parts subject to vibration, a wall thermostat is as non vibrated as it could be. I would have thought if your wall was vibrating the last thing you'd be worried about is heating.

[@BuyitFixit]

Agree, the only reason I can think is perhaps during shipping?

[@phillipsvanderwesthuizen800]

That glue is probably for, sneaky bult in obsolescence.

[@BuyitFixit]

More for mechanical support, but nothing would surprise me these days.

[@seedmoreuser]

That second one is almost like the microcontroller was switching over from Celcius to Fahrenheit but not displaying the correct symbol.

[@BuyitFixit]

Yes someone else mentioned that.

[@VorlonFrog]

Wondering if the vias at J1 on the PCB were not a serial port?

[@BuyitFixit]

Probably a programming port for flashing firmware 👍

[@wattorockscr]

any chance of cold joints or anything else messing with the mricrocontroller, waht if you clean and resolder the old micro?

[@BuyitFixit]

I don't think so because a dry joint wouldn't pull the voltage down on the pin, or cause lower resistance. It should cause the opposite.

[@djandyparks8438]

I have a technics amplifier it all works but when you turn it off and then back on it has no sign of life untill you tap it on the side and it works again would you be interested in looking at it for me

[@BuyitFixit]

It sounds like a dry joint (bad solder connection). A classic sign is banging it and it comes on.

[@dean6816]

I thought you could test the caps in circuit with that ESR meter?

[@BuyitFixit]

I think you can, I guess I'm just used to using my other one which doesn't 😂😂

[@RichardSloan65]

You should have put back the MCU to see if it was a dry solder on one of the pins causing the vault... :-)

[@BuyitFixit]

I don't think it was a dry joint because the pin had less resistance than it should have had, if it were a dry joint it wouldn't have been pulling the voltage down.

[@RichardSloan65]

@@BuyitFixit True, in my experience I have seen many very odd things happen that seem 100% no related yet it fixes the issue, like a dry joint on a ground... and not the exact pin for the ADC, or some other joint that just somehow throws the whole part off for some reason.... :-)

[@ginocussen5899]

comparison temp sensors on the 2nd one? how many of us are internally shouting at him to crack out the thermal camera at the very start?

[@harkbelial]

How can any company put CONDUCTIVE GLUE in it's products!?!?!?

[@BuyitFixit]

Indeed 👍

[@scaleop4]

👍👍

[@BuyitFixit]

Cheers 👍

[@peatmoss4415]

I watched a repair where the fellow blew hot air on the micro controller and the fault went away. I don't know if it had balls or not.

[@BuyitFixit]

Sometimes hot or cold can reveal a fault. I used some freezer spray on the Tascam 4 track recorder video, where the IC in the screen wasn't working, a quick blast and it came on. I guess the cold made the IC shrink closer to the glass and it started working briefly.

[@TheEmbeddedHobbyist]

I think if the inside of your wall got up to 80°C the rating on the caps would be the least of your problems. 🙂

[@BuyitFixit]

😂😂😂👍

[@Tekwyzard]

It's more a problem of whatever heat the thermostat is generating through the mains to LV power conversion process being able to satisfactorily dissipate. A lot of these thermostats will be fitted to 'backboxes' and such, or solid walls, with little to no ventilation, so in marginal cases ambient heat on the circuit board could get uncomfortably close to the capacitors rated temperature shortening their lives. It wasn't the case in this instance, just that wretched glue stuff that everyone once thought was such a great idea, which really doesn't like warm temperatures.

[@TheEmbeddedHobbyist]

@@Tekwyzard i would not fit a device in my walls that got anywhere near 30°C above ambient let alone high enough to be a problem for 80°C rated caps. if your design is pushing components 40°C above ambient then I'd stop designing. the designer should design the unit for worst case which would be a non-ventilated enclosure. To ensure all components remain well within ratings, if they are getting too hot you have something wrong.

[@SuperBoobaloo]

I tend to avoid any product described as "smart" these days for a number of reasons.

[@BuyitFixit]

Sounds good to me, I'm not a fan of the stuff either 👍

[@ianleitch9960]

probably irrelevant, but a DS18B20 temperature sensor typically gives an 18.2C temperature when it is has a bad connection. Now to watch on further to see how wrong I was!

[@danieladam86]

Is ESR 5ohm fine?

[@xXsch3ricXx]

@@khagaroth It's not at all high when you respect it's rated voltage. There are lookup tables online if you're unsure.

[@khagaroth]

Should be fine for such low capacity value.

[@BuyitFixit]

It is on a 400V capacitor, the table that came with the meter gives a "typical" value of 13 Ohms for a 4.7uf 400V capacitor, obviously lower than that is better 🙂

[@khagaroth]

@@xXsch3ricXx Looks like you managed to reply while I was editing my reply. You are right, I initially overlooked it was such a low capacity.

[@Electricworld-1]

That was awesome, excellent ❤🎉 fantastic.

[@BuyitFixit]

Thank you! Cheers!

[@222inverter]

bit of advice...make sure you discharge the caps before connecting to the test equipment...as I've broken test equipment before!!

[@309electronics5]

He actually got that peak tester which had the fault you described and due to good customer service they sent him a new programmed mcu for it and some other chips

[@peatmoss4415]

He did, pay attention....

[@BuyitFixit]

Thanks for that, I had measured them to see if they were discharged earlier. I think that the esr70 gold has an inbuilt discharge device (you can hear the relay clicking) update: "If your capacitor is charged, the unit will automatically carry out a controlled discharge procedure before measuring the capacitance and ESR"

[@222inverter]

@@BuyitFixit okay cool...a great repair as always 👍

[@hillppari]

unnecessary complex things. all this could be achieved with a bimetallic switch.

[@BuyitFixit]

Yes and less likely to be hacked 😂😂😂👍

[@ninaevans4501]

@buyitFixit We have seen this dreaded ("Brown Glue Syndrome") issue before. The glue itself absorbs moisture, causing corrosion and short circuits. If seen, scrape it out, before further damage occurs. With regards to the 2nd thermostat, it may be possible to still purchase the MC's for them. Then again they would have to be programmed before soldering to the pcb. This firmware may not be available(?). A typical crafty trick as pulled by many electronics firms world wide. They would rather it got thrown into landfill, than get it repaired. Thanks for your video Mick. Warmest Regards Wayne, Barbara, Nina and Archie the new budgie 😄😄 ❤️❤️❤️❤️❤️❤️❤️👏👏👏👏👏👏👏😊😊😊😊😊😊😊👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿

[@BuyitFixit]

Cheers guys 👍

[@kareno8634]

HI! Past^ fix may cure Present issue, or stop one from creating. ^^ Great 'Hunt', Thanks besides [not] knowing connections, (No arrows leading to) 'who feeds what'. More to watching, Quite Interesting, as i see Maze of possible road maps, You trace components. Fun Journey! 41:45 where's Capacitor? 44:22 ok. : } ... _now that we know issue,_ had to ask, Battery, really Only for time\ date? [glue heats \ corrodes solder] -> Uncleaned Flux [type?] under glue ? perhaps Not --> ^ ... glue to hold down larger components that has dried out and turned brown ... This glue can become conductive and corrosive. It literally eats the leads off of components on the board." ... 'Dry environments, glue brittle, flakes off, moist/humid, reaction is nasty.' 'From Yamaha to NAD to...? What's my next move?' 11Dec'17 ^^ via: 'Corrosive glue...or leaked electrolyte?' 11Feb'18 JVC noted [audiokarma] org.

[@BuyitFixit]

Thanks 👍Yes battery is for date / time RTC.