how to check pcb

Guest

Like Del pointed out , it is indeed patience testing workout , it is ahuge task and to the best satisfying if you make it to work . you gota know circuit diagrams for transistors , mosfets , diodes and other components with there specs , have acircuit diagram at hand , make primary obeservation and let your eyes , noses sense for burned component , with the help of multimeters check resistances , diodes ,fuses , transistors ,checking mosfets is different from checking transistors , divide the circuit in part of there operation from the circuit diagram with thin marker , check the relative components also. replace all the mosfets even if one is defective , change transistors with there relative components like diode , capacitor if found .this quiet tedious but odserve economics as Del mentioned replacing a set of components should not over ride the cost of getting new one forget time you put for fault location . I took it as a hobby and became professional , with little experiance you will make it faster and accurate ,but its under valuation kept me away due to better and cheaper technology comming up regularlly .

best of luck

Oof! That's a pretty tall order to ask!

It took me two years of schooling to learn troubleshooting and you expect to have it all given to you in one thread.

Back when I was repairing stereos, I had an advantage if only one channel was defective. The other channel would usually be working! So, I'd take my multimeter and started comparing voltages at each transistor. Eventually, I find a big enough difference to identify a defective part.

For televisions, I usually relied on the schematic. Most schematics had voltage test points with the expected voltage printed on it. If there was a difference, I'd change the most likely part.

Sometimes, as Del said, the defective part would be obvious. A blackened resistor, a capacitor with its guts all over the place, two wires sticking out of where a resistor is supposed to be (as in obliterated out of existence).

If you don't have experience or were never taught how to troubleshoot in school, I'd say stay away from fixing PCBs. It's not your expertise or even your skill. You can do more damage to the equipment or even hurt yourself or someone else. Stick with an expert and learn from him.

You say "we"...indicating a group effort, possibly a manufacturing group effort?

You did not say whether prototype, a single board, or one of many in lots with a recurring problem....which could indicate either a design or a mass (manual or machine) fabrication or assembly problem?

When I TS & R'ed on a high-volume, TI assy line on graveyard shift during college, sometimes flexing a board, one way then the other, would help find (by momentarily fixing) a board trace or solder flaw. Also, if I had an idea where the fault must physically be, sometimes heating a joint or skimming the iron over the traces would reveal a problem's location. This in combination with close-up viewing under the glass, of course.

But this might not apply in your particular situation.

Do not try to fix a PCB unless you are sure of the components to be used and the trouble.

PC-AT motherboard would not recognise the memory. It took two days to figure out that the problem was just dry solder. By this time I had already replaced several components.

I suggest you keep away from this unless that is your basic job.

Is the failure in a newly assembled PCB or did it occur at some time after the board was functioning properly?

For a newly assembled PCB, the most likely cause of failure is poor solder joints. Inspection of all the solder joints with a fairly strong magnifying glass will often reveal the poorly soldered joint.

When was troubleshooting pcb boards, I would take a good pcb and start measuring the voltages of each component moving from the output of the pcb to the input of the pcb in the area of circuitry that I'm experiencing the problem. I would write them down as I'm doing this. Then I would do the same with the bad pcb and compare the voltages. As you compare the voltages from output to input, look for the area of the circuitry where the voltages start to match up. That is usually where the problem lies.

Dear Guest ,

Trobleshooting with comparision is ok perticularly when you don`t have circuit dia with necessary check points , you do assign check point your self and apply to faulty circuit than detect damaged component/s , what you do when circuit board under repaire is unique ,or is not very popular in your area or region , is imported , also designs are changed very rapidly ,probably at every lot , you have to have basic knowledge of circuit as whole , components , circuits , perticular when you tackle a circuit pcb not very familiar but know what it functions , you still can repaire it .I too started like you did/do , eventually new components(IC's perticularly) emerged making it difficult but developed other ways to detect faults effectively. than you

How to check?

very easy, send us by mail and we repair it and return you.

ok that simple.