How to test a circuit board?

[ACsellers]

Basically I am a amateur TV fix it man using forums and general knowledge to help me out. I was wondering is there an easy method to test a circuit board to see if the whole thing works?

Just as an example:
If I take the power supply board out of back of a TV and its not plugged in to anything can I test to see if the whole power supply circuit board works?

Thanks in advance

[tonyuk]

Re: How to test a circuit board?

you can look at caps to see if tops have blown also check mosfets fuse on board ect i norm plug tv in then do power checks to fuse ect first befor i take board out hope this helps there is a page on this site that will tel you how to do checks on caps ect

[budm]

Re: How to test a circuit board?

Beside looking at the board for bad component, you can force on the power supply, but the key is that you need at least to know the basic first such as how the TV operate. So read up my post under my sig.

[ACsellers]

Re: How to test a circuit board?

Cheers lads and just wondering if can use maybe a multimeter or something to see if the whole circuit works in general. Does anyone also know how to determine a faulty component on a circuit board to see which one doesn't work?

[3d0]

Re: How to test a circuit board?

Cheers lads and just wondering if can use maybe a multimeter or something to see if the whole circuit works in general. Does anyone also know how to determine a faulty component on a circuit board to see which one doesn't work?

Well you'll have to read a little first, or watch youtube.
There is plenty of tutorials on how to test various electrical components like fuses, capacitors, resistor etc. using a DMM.
To test them in circuit, like budm said you will have to know the basic of how the tv operates.
I'm a beginner in electronics, but trust me your in the right place to learn.

[Microbe]

Re: How to test a circuit board?

ok ACsellers,

it's not that easy to learn that with just two words. however each electrical or electronic device has a method to be tested.

for example,
eletrolic caps can be determined by its shape
semiconductors like diode, transistors.......ect should not measure as short circuit with multimeter

hope that help you

[senz_90]

Re: How to test a circuit board?

likes budm said. look at his signature. there is a lot of useful knowledge on there likes retiredcaps threat and budm threat. you can use retiredcaps guide on all almost circuit board that you are troubleshooting. I found that thread very useful especially when test transistor or mosfet, before I read that, sometimes i have to guess transistor or mosfet that i checked was fine or not, but after read that you will know the thread a amazing !! Also jestine yong book about test electronic components good too, especially on the bonus book which teach us check components "in-circuit" without remove the components.

budm test using old cfl were very good too. you can test the psu board with some load likes a resistor if you know the circuit board design.

Yes, "in-circuit" test likes retirecaps and jestine yong guide didn't makes 100% true, but it is almost 90% will help you to save a time if you are seasoned repairer.

[budm]

Re: How to test a circuit board?

Example of power supply testing:
http://s807.photobucket.com/user/bud...?sort=3&page=1

I use low wattage (<10W) lamps first, then go to higher Wattage later once you get the power supply to run. High Wattage lamp will have very low cold resistance that small power supply may not be able to handle the inrush current unless you add Thermistor in series with the lamp to limit the in rush current.
But most of all you need to know about safety and how work in the PRIMARY (HOT side) of the circuit which can kill you so just do not touch anything on the board with your hands or body, at least plug what you are working on into the GFi outlet, Isolation transformer will be good to have.
The inverter High voltage transformer can put out up to 2000V so do not even try to measure it with your meter.

[Ashroyer05]

Re: How to test a circuit board?

If only most boards had the pins labeled on them.....

[tvtanner]

Re: How to test a circuit board?

I found best method to check circuit board is to check it against a known good one. I do this some time when I order new board to replace a defective one. I place them side by side and hook the grounds together and use multimeter to find trouble it's easy that way and if I can find and fix I will have a spare panel on hand and that way I will save lots of money. Hope this help

[budm]

Re: How to test a circuit board?

"If only most boards had the pins labeled on them...." You can try tracing out the connection and draw out the diagram when it comes down to it. Just have to willing to spend time doing it, done that many times here.
That is why it is important to have good base of understanding of electronics and how each components functions, when you looks at lots of diagram, you will starting to see the pattern on how the circuits are being implemented.
Spec sheets and application notes of the components are also good sources to learn.