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PCB Design Rules

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Initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the schematic diagram the component pin pads were laid out on the mylar and then traces were routed to connect the pads. If you have many questions of PCB Design, please come here!

Community > Groups > PCB Design Rules > The problem of PCB, power
The problem of PCB, power
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Alvydas Sidlauskas

There is a basic PCB seems the only difference is someone has added the power cable to the “f1” not sure why , now is exactly the same board apart from the power wires that someone soldered on! Mine has a 3a 125v lf459 fuse where the “f1” is on the board. I have tested the psu and it gets 24v power. I gets 24v power when tested the 3 big lumps of solder that are on the psb. It looses power passed the 3a 125v fuse that the place marked “F1” so I tested the fuse doing a continuity test and it failed so I guess that has blown, I have ordered Micro Pico Fuse Time Delay / Slow Blow Axial 3A 125v to replace that.Should I just replace the fuse and see what happened?
Statement: This post is only the personal view of the author and does not represent the opinions of


Probably be better if the fuse was faultyProbably be better off hoping the fuse was faulty Fuses are very good of protecting electrical components. but not so much with electronic components, such as transistors, ICs, etc. where operating currents are often in the low mA range.


The F1 position is meant for a fuse.If there are someone put those wires there to use with an outboard power switch.You can remove them and put a fuse in. The fuse end clips appear to be missing, too, so you might have to use an inline fuse holder. I doubt that the coil is bad,it's usually pretty obvious. If the fuse blows for no apparent reason, the problem is most likely to be a semiconductor.


L usually means conductor.

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