Dry Joints In Surrounding/Corresponding Components
Do you know that there are many cases of electronic problems were caused by dry joints in the corresponding components? Yes that means if you found a component or few components that have problem, please don’t just replace the component/s and retest the set. There are chances the component/s that you have just replaced could fail again. This would surely waste your valuable time and money. In order to solve electronic problem, one has to make sure that the corresponding components are okay before you replace the bad components and retest the set again. Sometimes even if the equipment did not breakdown at that time it may breakdown few days later.
Unless you have already know the common fault of the equipment then you may skip to check for dry joints in other section. In certain cases for example a dry joints in the flyback transformer pins may cause HOT to short circuit and the end result the B+ circuit components also suffered from it. That means it is not necessary to look for dry joints in nearby section, you should also check something that is located downstream the line.
To some repair technicians, they will take extra precaution by applying fresh solder to some suspected points even though the solder joints looks good. This will prevent callback from customer. That day came in a Dell LCD Monitor for repair and the complaint was intermittent shutdown. Just by normal scanning the board you could hardly see dry joint but when i took out the magnifying glass i could see very tiny mild cracks around the solder in the high voltage transformer pins. Resoldering the joints solved the intermittent shut down problem.
Conclusion- To prevent call back from the customer, make sure you have check all the surrounding/corresponding components.
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john preher
May 16, 2009 at 12:01 pm
These joints cause so many problems, I always carry opti-visors and a 30X loupe with me, the first thing I do on any repair is to scan the circuit boards and re-solder any questionable connections.It is a good practice as many failures are caused by these connections and also as you stated it is great for "preventitive maintenance" so the device does not have a failure shortly after repair.
admin
May 16, 2009 at 12:27 pm
Good post John!
Jestine
Waleed
May 16, 2009 at 3:42 pm
I could relate to this article in so many cases. I have equipments coming to the shop and the repair was only simply re soldering. I also agree with John preher and I also do the same thing. before working in any machine, I scan the board with a large magifying glass and check for dry joints. I had one case I that I could remember when a tv came to my shop and it shuts down after 15 minutes. and upon checking the board I found at the fly back section. one of the fly back transformer was loose and was making sparks and I could smell the burn. i resolder the joint and tested the tv for about 2 hours. it worked just fine
admin
May 16, 2009 at 11:44 pm
Hi Waleed,
Thanks for your good sharing!
Jestine