How to Think like a Repair Pro - Learn to Fix Random Electronic Devices, PART 2

Let's complete this repair - in part one we worked out how the circuit works and what components were definitely faulty. The parts needed were not available to buy locally so how about using some similar salvaged parts? It's all about the method of thinking it through to work out what we can use to fix the fault. Learn to think in this methodical way and you will be able to tackle most repairs

I work in collaboration with:
The Electronics Channel (live streams with Carlos and Detlef)

Gran Canaria Uncovered

For All Your PCB needs: free $5 discount coupon

Equipment used in my videos. These are affiliate links, you pay the normal price and I make a small commission.

TEST METERS
ANENG AN8009 MULITIMETER
KAIWEETS HT118E MULTIMETER
VC480C+ MILLIOHM METER
MESR-100 ESR METER
XC6013L CAPACITOR METER

TM-902C TEMPERATURE METER
LCR-T4 COMPONENT ANALYZER
FNB58 USB ANALYZER
PCI POST ANALYZER
TL460S PLUS PCI_E ANALYZER
TOOLTOP ET120MC2 SCOPE
FNIRSI 1014D SCOPE
NPS3010W 30V 10A PSU
T12 STATION WITH M8 9501 HANDLE
M8 9501 HANDLE
YIHUA 982 Soldering Station C210/C245
FNIRSI HS-02 PORTABLE SOLDERING C210/C245
QUICK 861DW
PROS'KIT SS-331H

INFIRAY P2 PRO IR CAMERA + MACRO LENS
TOOLTOP ET13S THERMAL CAMERA METER
ET13S MACRO LENS
OPTICAL MICROSCOPE
TOMLOV TM4K AF FLEX
TL866 II+ PROGRAMMER
CH341 PROGRAMMER
NC-559-ASM FLUX

DESOLDER BRAID (I use size 8045)
HX-T100 SOLDER (0.6MM)
ESD-11 TWEEZERS

Learn Electronics Repair is now on Discord! Come and join the fun, it's free.

If you would like to support this channel
You can send donations
You can subscribe to Patreon
You can click Join to become a channel member

Thank you
Richard

[russellmccoy]

almost 12 for us but im in Arizona with 120 F today keep up with the training and knowledge. Thank you

[reacey]

I massively respect your chin up and keep cracking on attitude. Youre a strong man . And a good man from what I can see . Sorry to hear about recent events . Appriciate every video you upload . Keep going mate . Alot of people youve never met are thinking of you and hoping youre alright.

[TheEmbeddedHobbyist]

Only a few points to note, on the electrical safety aspects of this heater.

1. The protective earth is via a painted hole and all panels of the case are not electrically bonded to earth.
2. The mains to 12V board is only mounted with a tie-wrap under the sticky backed foam to the case.
3. You did not use a mechanical mount for the relay, the relay may get warm a soften the glue.


Anything carrying mains should be mechanically mounted and a layer of extra insulation provided.
I would never just use a mains earth as the sole means of protecting life.

I would have done the extra work to make it safe and charged for it or thrown it in the WEEE bin, or just given it back with the plug cut off. then tell the customer that it could be made safe but that will be extra to the repair costs, The plug was removed as you would not return an item back to a customer in an unsafe condition. if they want to replace the plug then they are accepting the risk to their own life is in their own hands.

[romancharak]

I recognize that collection of relays! It looks a lot like mine, with salvaged TV relays, automotive and others. 😸

[marcellipovsky]

Hi Richard, I was hoping you would show us how precise can one fine tune the heater using the small blue potentiometer and also using the thermal camera to show us how well the preheater distributes the heat. Thanks!

[tarotsuperstars]

I have a LCR-T4 Transistor Diode Capacitor ESR meter. I think Richard has one. Can this meter be used for short circuit tracing in the same way Richard used the mesr-100 ESR meter in his beginner repair playlist to find shorts in Mostfets?

[NZHippie]

Having lived in Jamaica for many years I can tell you that it is just about the same as you are experiencing Richard...

[LYHTSPD]

I think I would have mounted that relay on it's side so the next poor schlep (probably yourself!) that has to work on it can read the relay part number and values. I always try to be kind to future me.

[alanrichardson]

Richard, did you check the heater element for a possible earth fault?

[MarkHunterLionstar]

I was wondering what the trim pot was for? Maybe to adjust the temperature probe to actual?

[mrtom]

Nice job Richard. Quick question...with incandescent bulbs getting harder to find by the day what would you suggest as an alternative to the 'Dim bulb tester' that doesn't use incandescent bulbs? Thanks.

[Dutch_off_grid_homesteading]

Heya nice easy repair IF you have some spaare parts

[Dutch-linux]

Richard how are you doing and coping? well i hope we are here for you .

[chrishartley]

I found it concerning that it was the normally open contact which was burnt on the original relay, especially since that wasn't even connected to anything. That would suggest that something else had been making contact between that leg and possibly the case. A fault in the relay would only have made it "always on" so that could not have been the problem.

Since you could see that someone had already done repairs I would suspect that something had been left inside the case and had got behind that circuit board but as soon as you started opening the case it released the pressure and it fell out.

Ideally there should have been some insulating material inside the case, behind that board, in particular where the live connection is made.

Your method of fixing it means that can't happen again so it isn't a worry going forward.

[jonathanrose]

Relays/contactors often stick in low voltage applications.

[RuneInternational]

think now that the relay is glued down, it would be good to put a sticker inside the case with the relay specs for the next time it might need replacing

[mikecro]

Personally, I probably wouldn't stick a power relay directly to the metal chassis. If the Relay goes faulty like it did before, it is possibly sitting with a 230V potential, which may then create a path to earth with the 12V still working and powering the relay coil. Yes, that should trigger the circuit protective device if everything is functioning correctly within the household wiring, but I would prefer to mount it to an insulator.