Need tips for locating shorted components.

Thread Starter

Ivan Viduljevic

Joined Aug 8, 2019
8
HI all. New to circuits and repair so i just need some guide lines to get me started. For now what i can for repair is to locate some burn components and then desolder and solder new ones. In some cases that works the trick, and some times id doesn't. Can you give me some links to tutorials that you might find useful to speed up my learning process. I have to take my tv to repair and i saw guy takes multimeeter and put in in diod mode, put one side on ground and with other check component side for ground, and in other cases i seen people on YT pulling out components and then test them out. I have plan to buy one of component tester to check for bad components but still i would like to learn about technique that you use to find out short in circuite.
 

LesJones

Joined Jan 8, 2017
3,195
You need to understand both how the component behaves out of circuit and also how test readings will be affected by other components that connect to it in the circuit. If you do not have the schematic for the item you are trying to repair then you may have to trace out the part of the schematic in the area where you suspect the fault is. A faulty component does not always fail short circuit.

Les.
 

Thread Starter

Ivan Viduljevic

Joined Aug 8, 2019
8
Ok, i saw a lot of schematics but not sure how to follow one to test components. Is there a tutorial about that that you might find good for beginners?
 

narkeleptk

Joined Mar 11, 2019
524
i saw guy takes multimeeter and put in in diod mode, put one side on ground and with other check component side for ground
That is not usually how diode mode works unless he was checking some specific components he already knows. I think you may be misunderstanding what he was doing, Sounds more like he was using continuity mode and testing for shorts or tracing something out. I suggest you look up some manuals or youtube video's on how to use a dmm (digital multi-meter) first. Hard to diagnose faults or understand whats being done in video's if you don't know how the testing equipment being used works.
 

dl324

Joined Mar 30, 2015
12,873
I have to take my tv to repair and i saw guy takes multimeeter and put in in diod mode, put one side on ground and with other check component side for ground,
It depends on the circuit and components involved. You can do junction checks on diodes and transistors in-circuit to look for shorts and opens, but you can't do any quantitative checks.

in other cases i seen people on YT pulling out components and then test them out.
A lot of what you see on YouTube is crap but, in general, you need to remove components from a board to test them. Or remove enough connections to prevent them from interacting with other components.

You mentioned looking for shorts specifically. I've used sensitive voltmeter, freeze spray (with power applied), and an HP 547A current tracer. Sometimes I use a HP 546A logic pulser in conjunction with the current tracer. I have used these techniques on boards with 4-6 layers looking for manufacturing defects.
 
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