Pure Electronics Repair - A Live Session. Transmodulator Does Not Power Up, Can We Fix It?

[@LearnElectronicsRepair]

Just to clarify - all the Transmodulators are in a 'TV Room' on the roof of the apart-hotel, and they connect into a powerful UHF Amplifier which then feeds the signal containing 75 digital TV channels to distribution cabinets on each floor, which then connect to the TV in each of the 105 apartments

[@biproservices1346]

Another great video! 100% for having a thermal camera in every shop. Every time I need to use my one in the shop I am so thankful for it! Saves me a time to have another cold beer instead of digging a rabbit hole to faultfind.

[@RickL_was_here]

I'm really hoping to get my hands on one of those myself, just a bit out of reach at the moment though. They look to be lifesavers for sure, I'm running in circles sometimes without one.

[@DanShepherd72]

Thanks for your video’s, I’m enjoying watching them and learning from them. Silly suggestions, but from the dirt under the fan I thought perhaps the fan was mounted backwards, blowing sand into the device rather than sucking it out?

[@davesdigitaldomain]

excellent video. due to all the sand and sea air in the Canary Islands causing corrosion,I would certainly invest in a ultrasonic cleaner.

[@jct4647]

I would replace broken capacitor, re-flow the corroded section and use some form of conformal coating on that section (even clear nail varnish will do).

[@LearnElectronicsRepair]

Some good suggestions - thanks

[@maks886]

You need smd soldering pliers (not sure if that is the correct word in English) to easily unsolder small parts like this capacitor.

[@hervedonner1864]

Hi Richard, another amazing repair and thought process on this one, thank you! 1. I think I would attempt fixing the bad cap with a soldering iron (no hot air) extremely carefully. but yeah, a bit risky maybe. 2. Thermal cameras are I think AMAZING for electronics repair. I see a lot of technicians on YT relying on it and saving hours/days of work if not the whole device (like in your case here). I absolutely need one as I'm getting more and more into the electronics hobby and I especially love repairs. 3. It's crazy how Canary Islands weather makes a damn good job at corroding all PCBs. Perhaps these transmodulators could benefit from some kind of mesh filter behind the case fins. Also what about applying some conformal compound on everything? especially after repair work. Personally I use MG Chemicals 422B on some of my FPV drone electronics, works great.

[@Silverfox0786]

That bend probe was wreaking havok with my OCD

[@aagsantos]

Hi Richard thanks for another nice video. I mostly repair lab devices and they all come with a lot of chemical residues and also salt corrosion (I'm working at about 200m from the sea), that's why I first clean the boards with an ultrasonic cleaner. I could say that 30% or more of the problems are due to residues and corrosion. When that appends I usually apply a special board varnish coating after the repairing.

[@breakingignes]

I would personally caution you about cleaning with an ultrasonic first. If you pop a couple of photos of visible corrosion before the ultrasonic bath, you can isolate areas to look at if the ultrasonic alone doesn't do the trick.

[@d614gakadoug9]

The 10 ohm resistor removed at around 30:00 does not go to ground. It and the brownish disk capacitor next to it are in series across the diode. This sort of snubber network is sometimes used across schottky rectifiers. The fact that removing the resistor increased the measured resistance is clear evidence that the capacitor must have been defective and "extremely leaky." These caps are typically in the range of a few tens of picofarads.

[@it-sd]

I’ve got a Klein TI250 thermal camera. It’s only 160x90 resolution, lacks any edge detection, and can only take still pictures (no video) but it works well enough. I’ve used it to find shorts on circuit boards numerous times. The parts that heat up aren’t always the shorted parts but at least the IR camera gives some indication of what’s going on. I’m happy I purchased one.

[@Dutch_off_grid_homesteading]

Heya, that is a nice repair corrosion is a bad thing so by removing it the "short" has gone away. the cap I would replace with a new 1 that's all

[@Electricworld-1]

Well l think the unit stated working because it knows not to mess with the master. Well done.

[@garethmilne6887]

I'd clean the whole PCB as well as possible with iso and contact cleaner. Then as I've done before spray the PCB with a clear epoxy paint to prevent further corrosion. It prevents further oxidation of the traces and seals gaps where oxygen can get in. It works well and I've had corroded PCB's I've repaired and then used this method run fine for many years after. The clear epoxy spray cans are available from your usual hardware shops. It sticks well to anything that's clean of debris. I've usually user Rust-Oleum in the past. Hope this helps

[@RickL_was_here]

That's interesting to see that there's so many buildings without the proper climate controlled rooms for this stuff. Seriously, add an air con unit/dehumidifier, make sure the room is as close to airtight as possible and you're good for relatively cheap. The biggest problem I set with people and fans, they always try to direct the airflow towards the interior when they should actually be using the fans to pull the air out. That too, could alleviate a lot of the problems.

[@RickL_was_here]

I wish I had a thermal camera but don't want to get stuck buying some cheap thing that I'll be disappointed with. Can't afford the real thing at the moment so who knows...

[@wherami]

Your troubleshooting is excellent.

[@orion310591RS]

What we learned from this video? One more time we dont need thermal camera. I believe thermal camera will prevent users from learning electronics. Kids will just buy camera look for shorts, burn things believing it will show on camera etc. Masters in electronics use multimeter, not thermal camera. Magnifier glass with LED lights (10 euros) and ESD brush (5 euros) first, then dive into deeper troubleshooting. If you dont do it at start, then later you come back to those steps. I speak from experience, I fixed many electonics that others couldnt, they failed to find where is problem, just because they didnt clean board properly.

[@LearnElectronicsRepair]

I definitely asked for opinions. I definitely agree using a thermal camera detracts from actually learning electronics, this is why I took the route to the repair that I did as I am trying to teach electronic diagnostics. The main reason I didn't clean all the mess of the PCB first BTW was because I am so used to seeing that on electronics here and it normally just brushes off and I rarely saw it cause corrosion like this. I'm still a bit puzzled how the corrosion on the PCB got to be wet/conductive. Firstly this hotel located in the south of Gran Canaria near to Tauro Valley/Amadores is in one of the sunniest and driest places on earth - average annual rainfall ~88mm. Secondly you may have noticed, the fan is on the bottom of the transmodulator blowing air upwards and damp still got in to it. I think this happened due to the tropical storm over Cape Verdi we caught the edge of, a couple of weeks ago. We had 300mm of rain and that is a serious amount here in a place so dry we don't even have storm drains! It was like 3 years of rainfall in 24 hours!! This sort of weather only happens here about once every 15-20 years. it was after soon that event the German channels stopped working so I guess it is pretty much related to it. Once I got to the point it was obvious the PSU works and also obvious the various VRMs were either not running (enabled) or producing a very low voltage, and given the fact I am not familiar with these devices nor do I have any schematics to work from, I felt it was justified to try thermal imaging at that point and as it happens it paid off. I stand by my comments regards IR cameras, I never had one before, like I never had a Dremmel at some time - but in both cases once I got one I have to question why I never did it before 😁

[@slam4815]

@@LearnElectronicsRepair "I'm still a bit puzzled how the corrosion on the PCB got to be wet/conductive. " The days following the storm you mentioned fog coming from the ground and I assume this was a form of condensation/humidity. Sand in humid environments will absorb this and can cause corrosion. Given the right conditions, some sand (containing more iron) will be very conductive.

[@ianhewitt1858]

Hi Richard. I am a long time suffering hobby enthusiast who takes just about anything apart once it is broken, whether electrical or mechanical and a software engineer by trade. Solving software issues is not unlike solving these electrical problems where it is getting a good understanding of the issue that takes the time and then the fix is quite simple. Putting my 'software hat on', I would be tempted to plug my laptop into each of these units and make a record of how they are configured while they are still working. Keeping a record now could pay dividends in time saved in the future should/when a unit fails. Regarding the capacitor, I was hoping you would replace it as working on small objects like this seems to be a skill in its own right and I was interested on how you would tackle it.

[@LearnElectronicsRepair]

Yeah that is a good idea as I kinda inherited this system from a previous installer so I don't have a record of the settings. Normally replacing a capacitor like this one id not very difficult, I've done it on other videos, but the way this is constructed with the capacitor on a module surface mounted to the main PCB makes it potentially a lot more tricky

[@tiporari]

I'd be concerned about the longevity of the repair especially if I charged for it. Most of the board looks pretty stable, but that module got wet. Possible to sort a replacement or alternative that would be guaranteed to last. Then conformal coating at least on what's in the path of air intake. Some filter media or gauze on the intake side to reduce dust and debris? You never know what's airborne day to day. Sometimes could be metallic, corrosive, organics that decompose over time. I like your approach and thoroughness. IR camera really helped nail down where the problem was on that tiny module. You can forget making money for your time trying to reverse engineer some Chinese commodity part (VRM). Best to just bin them and replace. Hobbyists don't seem to get the economics of trying to earn a living. Purity is for spare time . Efficiency is for work.

[@ianhaylock7409]

I would add leaded solder to each end of the cap. Then add flux and heat both ends of the cap simultaneously using two soldering irons. When the solder melts lift off the cap with the soldering irons.

[@daz41262010]

awesome job Richard what a great fault finding video :)

[@wherami]

Ill try to get through this all day. Should be interesting. Ill watch in shifts. Thanks .

[@davidv1289]

Nice repair! I had hoped you would plug a LAN cable in and see if it was working, maybe you could let us know if it was truly fixed. I would put a blop of conformal coating or use a solder mask repair pen on that cap just to keep moisture out. An effective method for removing small areas of corrosion from pcbs is to use flux, heat it with a hot air gun just enough to activate it, then clean with isopropyl alcohol or acetone. Thermal cameras, now that they have come down to reasonable prices, are a must have tool. Regards, David.

[@LearnElectronicsRepair]

That I will do 😉

[@19ag92]

When you need to diagnose a PCB on a PCB then a thermal imaging camera is correct to use because there are two different circuit designs being implemented. Once you learn the first PCB circuit design it is difficult to correlate what that first PCB circuit design does with the 2nd PCB circuit design acting as a variable to the first PCB circuit design. If you do not want to diagnose a PCB that is a slave to a master PCB then it is true that a thermal imaging camera is important to solve the repair with. This has been indicated with how R tends to reference computer motherboards Without an additional graphics card in the the PCI slot. "Is the boot problem the GPU or the motherboard?" Then remove the GPU to solve it first.

[@davet3804]

If you can’t afford a thermal camera, like me Mount a thermistor in the end of an old biro and measure resistance around circuit Takes longer but surprisingly effective! I can detect where my coffee mug was 5 minutes after removing it ! If the unit works, seal and mark unit with the issue for future reference.

[@haddaphone7266]

Thanks for the interesting video. I think the corrosion is caused by the fan mod. It concentrates the sand and moisture on the regulators. There is a risk that all other modules will suffer the same fault.

[@LearnElectronicsRepair]

Yes I think you are correct

[@andymouse]

Great fix there! but with a touch of irony perhaps as it seems clear from the state of the fan grill that is where all that nasty conductive rust was blown in from and into the unit as you can see the way it spread on the board. Nice example of if you have a FLIR then you can save a lot of time and by extension money ! Maybe put plastic finger guards on the fans as only a few quid. The cap needs to be replaced out of good conscience and best practices...cheers.

[@stevedebeukelaer1424]

Hi Richard i would flux and boil the circuit. Also an ultrasonic cleaner use it after you flux and boil . I woult use pure rosin to isolate the circuit it easier to remove and rosin when it is hard is good isolator.

[@juliehills6143]

Well done cracking video I definitely thought it would be a no fix and I sure the hotel will understand you can’t guarantee it and hopefully it will last a fair time and they will get a few more years out of it.

[@dayane15568]

muito obrigado pela tutorial professor o senhor e muito bom no que faz, tenho uma duvida o conserto foi concluido pela troca do capacitor eletrolitico ou foi pela limpeza e resolda do capacitor smd com oxidacao?

[@davidhollfelder9940]

I’d try to tack the loose cap in, and then try to seal the corroded area with a coat of potting material.

[@m.m.m.c.a.k.e]

Aught take two so you can a/b em', eh? Thank you for the great content, my guy!!!!

[@mathewsnachuma8086]

First to comment Wow love your channel

[@karlharvymarx2650]

One of those thermal camera might have stopped me from making a mess of Raspberry Pi HQ camera. Aside from not knowing what I'm doing yet my best excuse for irrational fault finding is insomnia and not learning to love burnt fingers. I attempted to lift the power supply pin to the smd voltage regulator that I thought was getting hot and sent it flying into the void. Worse, it now seemed it was the regulator next to it that was actually getting hot. This time I wised up and sent what I thought was a jellybean resistor to the land of lost socks. Little did I know that 10% of it remained on the board and was conductive and was actually a ferrite bead in an smd package, never knew such a thing existed. So I burnt my fingers again. Only then did I notice that what I thought were a pair of low resistance resistors were labeled with C's, thanks to the high power magnifying lens I finally found. I rechecked he capacitor's resistance and they seem to be zero ohms connecting 3.3V to ground. I'm currently waiting for inspiration to strike with a way to verify that one or both caps are the problem without risk of sending them to the land of lost socks or burning myself again. It did at least finally dawn on me that I could download the schematics for free. Anyway, if I had an IR camera, I think them glowing like xmas tree lights might have clued me on to a more direct and less destructive path to fixing the camera. Assuming I have found the problem, replacing the lost parts looks like it will cost about $3 which is still a savings over $50 for a new camera, plus I furthered my education at the school of hard knocks and burnt fingertips.

[@kriswillems5661]

You said in the beginning of the video that when you disconnect the first transmodulator from the satellite signal, the second one started working. So, it's kind of obvious there is a short on the satellite input. Satellite inputs also act as DC outputs (for feeding the LNB). If the LNB supply circuit is shorted the power supply gets overloaded (and the unit will not power up) and the satellite input of the second transmodulator in the chain will also see the short and thus get no signal. These systems are nightmare to maintain..... especially if you live in a country were frequencies/modulation/PIDs change often.

[@jay1st1st]

I used to see thise on offshore drilling rigs like 20 years ago, the radio man was in charge.....mostly porn and BBC

[@juliusvalentinas]

To me it seemed the thermal camera is more difficult to use then similar quality camera on phone with overlay, this way you can see components better.

[@ricardoferreira2811]

At 26:30 I always imagine some solder blob falling to the PCB and then causing a short. But that's my paranoia.

[@fisforfriendship6093]

i thought you should always test fuses when theyre not in the holder

[@dragonlard4595]

They first should do something about the room, where these Transmodulators reside. Seems very moist and dusty in there.

[@LearnElectronicsRepair]

Dusty yes, but but normally moist as this hotel is located in an area where the average rainfall is 88mm/year but we got hit by the edge of a tropical storm over Cape Verdi a couple of weeks ago and we had 300mm rain in 24 hours. That's more than three years worth in a day! It caused havoc, we don't even have storm drains here, but fortunately this only happens once every 15-20 years here. I may never see another one.

[@steve6375]

@@LearnElectronicsRepair You will! Global warming means wilder weather patterns.

[@gordthor5351]

I'm going to buy the same thermal camera that you have. I have been putting it off because I wasn't very impressed with the lower resolution cameras. Also, I have a bigger and better screen, processor.......on my phone than the stand alone versions. Why spend money on something less versatile, bulkier and just not as effective? I would rather just pay for a much better camera and let my phone be the brains :)

[@LearnElectronicsRepair]

Good decision, having used three different thermal cameras now I can thoroughly recommend the T2S Plus - it represents an excellent 'bang for buck' ratio and 256x192 60Hz is a good spec. I'll put an affiliate link on this video - if you choose to use it you will pay the same price as normal but I get a few quid commission 😉

[@Takashita_Sukakoki]

NorthridgeFix uses a thermal camera often on GPUs and has saved him a bit of time. He has a different philosophy from you less searching voltages and injecting voltage and viewing it through a thermal camera. A time=money method. Then again, he gets electronics in from all over the internet, so he needs to be efficient.

[@bogdansava1523]

Northridge fix has speed, good soldering skills and quite an attitude. But when it comes to actual diagnosis technique, Richard is in a totally different league. You can watch northridge fix video with the ssd data recovery. It took him way too long to figure out that that screw hole was not a ground. Richard would have spotted that instantly :)

[@Takashita_Sukakoki]

@@bogdansava1523 he uploaded 24 ripped pad repair today that was insane, I don't know if Richard would have the patients :D

[@bogdansava1523]

@@Takashita_Sukakoki like I said, good soldering skills. And seeing him actually do all that work makes me thing he probably charged around 500e for the repair :))

[@Takashita_Sukakoki]

@@bogdansava1523 1/5 of the used part as (repair) price isn't unreasonable.

[@bogdansava1523]

@@Takashita_Sukakoki I see you are a fan so I am not going to argue. I am sure he is a great business man and makes a lot of money. My point was that if you want to actually learn something you should watch Richard's videos, he actually takes the time to explain how things work. If you want to watch someone that seems to always be in a hurry, and if something takes more than 10 minutes he says "No fix" you cand do that on his channel. That tv with ripped hdmi connector comes to mind. I am sure Richard would have found an ingenious way to fix it :)

[@juliusvalentinas]

This what happens when you (the manufacturer in mind) does not apply lacquer or anti corrosion spray and use equipment in harsh dirty conditions.

[@MsKelvin99]

God bless you

[@winstonmartin6179]

would love to et one

[@weerobot]

Cool...

[@Dutch-linux]

Leave it off it may not be needed

[@remu3881]

Omg did you train as a butcher in previous life?? God don't you have ultrasonic bath cleaner how you going to repair it ? (properly)

[@MultiVoiceofreason]

what a comment! troll alert!!!! go back under your bridge 🤣

[@LearnElectronicsRepair]

I was offered a cheap Ultrasonic bath recently (for free to review) but didn't take it as it isn't really big enough IMHO. Maybe I will get a bigger one myself - we used to use them when I worked in an industrial electronics workshop. Actually the corrosion on this was so unusual it threw me a bit. I'm so used to seeing devices covered in sand and dust here that blows over from the Sahara and it does not cause this sort of problem, I was probably too complacent about it initially. Live and learn eh? 😉

[@remu3881]

@@LearnElectronicsRepair lol funny thing is they are now under £100 and gallon of liquid is £10 -----NO EXCUSES-------

[@LearnElectronicsRepair]

@@remu3881 OK then I'll tell them to send me the free ultrasonic cleaner for review (was 600ml capacity and about €40) and we see if I made a mistake and it was worth trying after all