Faulty Smart Thermostats x 2 | Can I Fix Them?

A Friend asked if I would be able to take a look at his smart underfloor heating thermostat as the screen was flickering and it wouldn't respond. Then the guy who runs our local repair cafe gave me another for my parts bin. Let's have a look and see if we can repair them...
I'm not an expert, but I do enjoy trying to fix things.
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Some of the tools and equipment that I use:
Kaiweets KTI-W02 Thermal Camera:
15% off code: BIFI15
(15% off code Available site wide at Kaiweets.com and it never expires.)
kaiweets.com/p...
or alternatively on Amazon UK:
15% off code: GQ7SHK42
Date of expiry: 2024-10-31
amzn.to/3WAuuwc
Other Kaiweets thermal cameras:
kaiweets.com/c...
TOMLOV 4K AF Microscope:
TM4K-AF Flex: 8" screen
Official Website: bit.ly/3ZUMEe8
Amazon UK: amzn.to/4dFLyGn
Amazon USA: amzn.to/4dDc96E
TM4K-AF Max: 10.1" screen
Official Website: bit.ly/3Yg68bZ
Amazon UK: amzn.to/4eyDGYj
Amazon USA: amzn.to/47ZJ5FB
The Famous Blue Mat: amzn.to/47bPNGK
Infiray P2 Pro Thermal Camera: amzn.to/47c05Xm
170 piece electronics tool kit (security bits): amzn.to/3VnmHBh
SMD Tweezer set: amzn.to/3t9GlW4
Aixun T3A Soldering Station: amzn.to/3Xa8HMe
Soldering Flux: amzn.to/3UDC0py Alternative: amzn.to/4dVRdcN
Low Melt Solder: amzn.to/3QICZ5r : Cheaper Alternative amzn.to/3G4L3XK
Grinding pen: amzn.to/3QCHE7v
Component Tester: amzn.to/46UcHm6 alternative (slightly cheaper) amzn.to/49yZSzJ
Overhead Camera Mount I Use: amzn.to/3tX8Ar4
Microscope Light (I use on my Trinocular): amzn.to/3FEAPgy
AD409 Pro Microscope 10" Screen: amzn.to/3G0CI7P
Extra Long Torx Drivers(used on Milwaukee radio): amzn.to/40siUU3
DC Power Adapter plugs 38 PCS: amzn.to/49lCUMm
USB Power Meter Tester: amzn.to/3R6NX4g
SMD Component ruler 3x (for sizes of SMD components): amzn.to/3TvfcWO
Rework station: I was using a 858D clone but now using an ATTEN ST-862D .
Other Equipment:
Main Overhead camera: Sony HDR-CX450 with 3rd party remote and RODE VideoMic Pro
Other cameras: Canon G7X, iPhone 6s, Go Pro Hero Silver 7 (which repaired)
Microscopes: Amscope trinocular (clone) with FHD 48MP Camera V8
& Adonstar AD409 Pro.
Editing Software: DaVinci Resolve
The above links are amazon affiliate links, and I may receive a small amount from Amazon at no extra cost to you, if you choose to purchase an item.
#electronics #electronicsrepair #repair

[@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 👍

[@jlucasound]

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

[@BuyitFixit]

😂Thanks 👍

[@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!

[@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.

[@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.

[@canyondan]

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

[@BuyitFixit]

Cheers 👍

[@3dsmaxrocks699]

Oh...A Sunday treat. Thanks Mick!

[@BuyitFixit]

Cheers mate 👍

[@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 🙂👍

[@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 👍

[@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!!!!

[@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

[@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.

[@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.

[@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.

[@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 👍

[@Matta1224]

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

[@BuyitFixit]

Cheers Mat 👍

[@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 👍

[@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.

[@joelkist6493]

Nice troubleshooting vid...

[@BuyitFixit]

Thanks 👍

[@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.

[@The-four-o-five]

Nice one 👍

[@BuyitFixit]

Thanks 👍

[@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 👍

[@mikecass8306]

Thanks Mick

[@BuyitFixit]

Cheers Mike 👍

[@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 😂😂😂

[@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.

[@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.

[@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]

😂😂😂👍

[@VorlonFrog]

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

[@wattorockscr]

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

[@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.

[@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.

[@scaleop4]

👍👍

[@BuyitFixit]

Cheers 👍

[@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?

[@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.

[@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 👍

[@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.

[@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 😄😄 ❤️❤️❤️❤️❤️❤️❤️👏👏👏👏👏👏👏😊😊😊😊😊😊😊👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿👍🏿

[@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"

[@Electricworld-1]

That was awesome, excellent ❤🎉 fantastic.