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

LER #310 This repair video was recorded in one session with practically no editing. I have a Transmodulator that needs to be repaired. This is an expensive piece of equipment so it was worth spending a little time looking at it. Don't know what a Transmodulator does, or want to know if I get it working? Then sit down and invest 90 minutes watching this video! This is genuine repair work exactly how it happens in real life. I'm sure you will find it entertaining and you may well learn a few things too.

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Gran Canaria Uncovered

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TEST METERS
Aneng AN8009
KM601
VC480C+
MESR-100 ESR METER
XC6013L CAPACITOR METER
TM-902C TEMPERATURE METER
FNB58 USB ANALYZER
PCI POST ANALYZER
TL460S Plus PCI_E ANALYZER
MULTIMETER PROBE KIT KET05
OSCILLOSCOPES
FNIRSI 1014D
FNIRSI DSO-TC3
FNIRSI DPOX180H
BENCH PSU
NPS3010W
SOLDERING
T12 Station with M8 9501 Handle
SUGON T26D
QUICK 861DW
PROS'KIT SS-331H
THERMAL CAMERA
Infiray P2 Pro
MICROSCOPES
Amscope Optical Microscope (copy)
ANDONSTAR AD407

EEPROM Programming
TL866 II+
CH341A

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Thank you
Richard

[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

[biproservices]

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.

[maks]

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

[jct]

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).

[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.

[garethmilne]

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

[ag]

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.

[DanShepherd]

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?

[hervedonner]

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.

[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.

[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.

[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.

[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.

[dgakadoug]

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.

[orionRS]

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.

[Silverfox]

That bend probe was wreaking havok with my OCD

[ianhaylock]

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.

[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

[ianhewitt]

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.

[bigsscore]

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