Short Soldering Video By A Working Professional Who Does Not Waste Time - Page 1
Forum section: electronics / general

author: SgtRock
author_rank: Unknown
timestamp: December 08, 2012, 03:20:16 am
content: Greetings EEVBees:--Video of a very competent TV repairman. He wastes no effort. Several good tricks are included. Excellent soldering technique. SMD soldering with an iron. No futzing around cleaning everything 3 times with endless flux and wire braid, and no hot air or IR. This guy uses only the level of Tech necessary for a given task. Bonus! This is the guy you want working in the back. Also excellent camera voice and editing work, in a class with DJ himself.There is a great satisfaction in building good tools for other people to use.Freeman Dyson 1923 -Best RegardsClear Ether

author: Pentium100
author_rank: Frequent Contributor
timestamp: December 08, 2012, 04:16:28 am
content: Why did he replace that ceramic cap with an electrolytic? I ask because I recently fixed a power supply where a ceramic cap had high leakage, but I replaced it with another ceramic.

author: FenderBender
author_rank: Super Contributor
timestamp: December 08, 2012, 04:50:29 am
content: Quote from: Pentium100 on December 08, 2012, 04:16:28 amWondered the same thing. I wouldn't think electrolytic would've been appropriate.

author: george graves
author_rank: Super Contributor
timestamp: December 08, 2012, 04:56:09 am
content: a.) I'm amazed that there are still TV repair guys.b.) I bet that guy doesn't get paid nearly enough

author: Pentium100
author_rank: Frequent Contributor
timestamp: December 08, 2012, 05:23:24 am
content: Quote from: george graves on December 08, 2012, 04:56:09 amWell, some TVs fail before the warranty expires, so the manufacturer has to repair them (or replace, but repairing a $1000 TV is probably cheaper, especially if most of the failures are common and it does not take long to find the fault) and even after the warranty is expired, if I buy a $1000 TV I will try to get it repaired first (or repair it myself) before paying another $1000 for a new TV.

author: rbola35618
author_rank: Frequent Contributor
timestamp: December 08, 2012, 05:42:39 am
content: Nice video. It reminded me of my TV repair days ar RCA Service Company. I got put when the manufactures started using SMD parts. Parts are too small to handle by hand.

author: necroscope
author_rank: Regular Contributor
timestamp: December 08, 2012, 06:19:44 am
content: Quote from: george graves on December 08, 2012, 04:56:09 amI have repaired 2 lcd tv's in the past month,and let me tell you if an amatuer like me can repair them anybody can,Total cost to repair both lcd's $18 including shipping for parts,I can imagine most repairs would cost about the same in parts and with a little experience they would take next to no-time to fix and there is probably good $$ in repairing them.

author: SeanB
author_rank: Super Contributor
timestamp: December 08, 2012, 10:17:39 am
content: I would guess it is a decoupling cap, and with it being ceramic it dropped in capacitance with voltage applied, and then was insufficient. Then it killed the SMPS controller.

author: Neganur
author_rank: Unknown
timestamp: December 08, 2012, 10:40:31 am
content: His soldering iron sounds like an old Weller MagnastatRegarding braid or wick, as some call it, I was taught not to use it to desolder but rather to clean up the pads after you remove components. My boss would also have slapped my hand for not securing that electrolytic with some hotsnot!

author: SeanB
author_rank: Super Contributor
timestamp: December 08, 2012, 11:26:09 am
content: Looking at the chip it probably is the high side bootstrap capacitorr. most likely the ceramic ones are marginal at best, and when they are at the bottom of the capacitance range and with the high voltage across it it has insufficient capacitance and this then is not enough to keep the high side driver operating and it fails. the electrolytic generally will be on the plus side ( with these small units) and more importantly can stay at the same capacitance.One of the reasons why a manual and common fault info are so useful.

author: robrenz
author_rank: Super Contributor
timestamp: December 08, 2012, 12:46:41 pm
content: Quote from: Neganur on December 08, 2012, 10:40:31 amI was screaming " L bend the leads to form feet to match the footprint". I know it is small but easily done to increase the surface area that engages the pads.

author: SeanB
author_rank: Super Contributor
timestamp: December 08, 2012, 02:28:50 pm
content: I won't tell you what i do to used tants to fit them in a remote fob to increase battery life then..... Suffice to say it involves a file, pliers and often a short wire lead to reach a scraped off track on the one side.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 08, 2012, 02:56:15 pm
content: I'm pretty sure it would take a lot less time to replace the chip without removing the board from the main board. And if the problem with that cap is being a little too low value (as opposed to actually failing), I would add a second cap on top of it.

author: saturation
author_rank: Super Contributor
timestamp: December 08, 2012, 03:03:26 pm
content: Good repair work. User tom66 has an impressive dossier of the TVs he's repaired and should be a good link to anyone interested with TV issues.https://www.eevblog.com/forum/reviews/teardown-pictures-of-lcd-and-plasma-tvs/msg155618/#msg155618

author: zaoka
author_rank: Frequent Contributor
timestamp: December 08, 2012, 05:31:15 pm
content: Most of us in TV repair business does that the same wayExcellent video and great tech. He deserve better soldering iron, one JBC station would make things like this even more enjoyableAlso if he had FLUKE 117 he could use Loz feature to discharge capacitors instead of resistor

author: StubbornGreek
author_rank: Frequent Contributor
timestamp: December 08, 2012, 07:33:54 pm
content: Nice find - I really like his workflow. I'm also sure his avg of 300 or so views per video is about to go up.

author: T4P
author_rank: Super Contributor
timestamp: December 08, 2012, 07:38:41 pm
content: Quote from: zaoka on December 08, 2012, 05:31:15 pmIf he had a UT61E he could use the capacitor range to discharge the caps

author: IanB
author_rank: Super Contributor
timestamp: December 08, 2012, 08:17:17 pm
content: Quote from: T4P on December 08, 2012, 07:38:41 pmIn case anyone's misled by this, you must discharge capacitors before connecting them to the capacitance range of a meter, not after. You probably won't damage the meter if you don't do so, but it's better to follow safe procedures just in case.

author: Monkeh
author_rank: Super Contributor
timestamp: December 08, 2012, 08:55:41 pm
content: Quote from: IanB on December 08, 2012, 08:17:17 pmSome meters (like the UT61E) are capable of discharging capacitors.I wouldn't try and discharge a 200V cap with a UT61E, though.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 08, 2012, 09:42:29 pm
content: Interesting that some TVs are running the backlight inverter directly from rectified mains. It would theoretically give an efficiency advantage but all of the efficient TVs are using LED backlighting nowadays.

author: free_electron
author_rank: Super Contributor
timestamp: December 08, 2012, 09:59:50 pm
content: shottdy work on that cap. it is going to fall off under mechanical stress/ temperature stress. if you are going to mount em like that you need to quirt some silkit in there. ( silicone specially to tack down parts on a board. )

author: IanB
author_rank: Super Contributor
timestamp: December 09, 2012, 01:06:56 am
content: Quote from: NiHaoMike on December 08, 2012, 09:42:29 pmBut that was a plasma TV, not an LCD. I don't believe plasma TVs use backlights since the plasma display is inherently light emitting. Plasma displays run hot and are quite energy hungry.

author: george graves
author_rank: Super Contributor
timestamp: December 09, 2012, 01:16:14 am
content: Quote from: free_electron on December 08, 2012, 09:59:50 pmYea, I kinda cringed too. But it seems like 1/2 his job is quickly and efficiently fixing TVs. I'm sure that cap will survive the ride home and being carried into the house. Where it won't be moved again until they upgrade the TV.Thermal stress? Wouldn't all SMD electrolytics be falling off boards then?

author: IanB
author_rank: Super Contributor
timestamp: December 09, 2012, 01:42:40 am
content: Quote from: george graves on December 09, 2012, 01:16:14 amI'm sure engineers everywhere cringed when they saw that (just as I did). But the reality is that a properly made solder joint is like a weld. There is fusion of metal to metal and it will only fail if you exceed the breaking stress of the metals involved. There is no way that a miniature electrolytic capacitor, even perched on "stilts", can pull apart such a joint. It won't fail under normal scenarios. (And if you drop the TV, the resultingcrunchwill break plenty of other things before you become concerned about that capacitor.)Try an experiment. Solder the end of a copper wire to a copper clad board and then try to pull the wire free after the joint has cooled. See if you can detach the wire before you either break the wire or pull the copper cladding free of the substrate. And you had better go visit the gym before you try. It will take a lot of muscle.

author: free_electron
author_rank: Super Contributor
timestamp: December 09, 2012, 06:01:21 am
content: Whoa. A solder joint is absolutely not like a weld !In a weld there is no foreign material introduced.. You can only weld one metal to itself. You cant weld copper to aluminum... Both parts need to be identical ( surely some smartass is going to remark . What about thermocouples ? Thats not a weld either, not in the metallurgic sense at least )When soldering copper using tin/lead you are not meltingg copper. The bond is formed through diffusion. You never reach high enough temperature to melt copper. The diffusion process is actually an ionic exchange. You are dissolving part of the copper electrochemically in the bond.If you make a crosscut of a solderjoint you can clearly identify the different zones. There is even a zone containing iron from the soldering tip in there. It is needed to create the correct bond. In wave soldering part of the pot itself dissolves in the bond. They need to swap those out. To prolong life of the wave soldering machine they actually att iron pellets.You can also not start to throw random metals in the solderjoint as it will cause problems.The layerstructure is what creates the bond. I forgot the exact layer order but it is copper to a copper-iron-tin , to tin lead to the other side i believe. I posted the crosssection pictures on the forum already. It was a nasa document. These are called intermetallic compounds. Look it up.Defects happen in the area where you go from one compound to another. One such a problem is thermal stress. That cap hangs sideways during its life. Granted it is small and light but it is still a load. Plasmas run hot. Given enough time the solder joint will break or the copper will peel off the board. It may take 30 years but it will happen.Besides, i'm puzzled why an electrolytic. He should have put back a ceramic.

author: SeanB
author_rank: Super Contributor
timestamp: December 09, 2012, 06:28:53 am
content: Probably the ceramic was specced to save a component height size change on the pick n place machine, which probably was doing all the low profile component placements. Possibly another use of the board ( a common component) had a height/thickness limitation, and this carried forward.