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how can i tell where the ground is on a pcb?

modifying antenna on a radio need to make sure it is grounded to the board. How can I tell where the old antenna was grounded?

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Schmidtn7 years ago
Depends on the type of circuit, AC or DC.

DC's - easy... ground will flow to the negative end of your power source (battery pack)  Find where your batteries go into your circuit and find the negative hook up (normally a black wire).  That's your ground.

AC - could be trickier.  It's harder to tell neutral from ground... three prong outlets have a: "hot," "neutral" and "ground" plug.  Electricity flows through your product from hot to neutral.  The ground is a safety feature.  So manufacturers ground out their products so that if a hot connection comes in contact with whatever their product is housed in it wont kill somebody.  Instead, it'll connect to the ground, throw your breaker/fuse and cause your product to quit working BUT it also wont kill you!  So I'm not sure if you're looking for neutral or ground.  Ground will be physically connected to whatever your product is housed in.  Neutral will be on the circuit board and normally has a thicker trace than other traces on the circuit board.  Also (as frollard mentioned) all components with polarity will have their negative leads attach to this trace.  The none striped side of diodes, the striped side of electrolytic capacitors, etc.
camb008 years ago
There should bee a large amount of solder on a component those are normally grounded
notmyfault8 years ago
A lot of times the mounting screws will be grounded (if your radio has mounting screws to hold the pcbs) Also some heatsinks will be grounded. NOT all, some can be tied to collector voltage. Look real good with a loupe ( magnifying glass) sometimes you can see where it used to be hooked up. NMF
That depends if it was.
...if it was grounded to the pcb, or if it needed to be. Look for where the negative power is connected to. The ground plane is usually the largest surface area on the board, usually circling all other parts. Look at the polarity of components like diodes going to a common plane. They will often tell which is the ground.