Mistakes you Learnt from! (might be helpful for beginners) - Page 4 - diyAudio
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Old 15th April 2013, 09:59 PM   #31
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Join Date: Sep 2009
Originally Posted by pinkmouse View Post
Don't try to catch a hot soldering iron that's falling off the bench...
Agreed, been there...
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Old 15th April 2013, 10:32 PM   #32
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Join Date: Apr 2008
Location: Carlisle, England
One of the big problems that comes up time and time again is hum because of grounding problems.

The usual cause is mixing power and analogue grounds.
Under no circumstances should these be mixed, but they should join at one star groun point.

I designed a pcb for a audio mixer and the hum was terrible.
I just laid out the pcb with as short a ground as possible.
The power supply was being charged up from the transformer via a bridge but these charging pulses puts 50Hz into the power supply ground.
The 50Hz was modulating the audio ground and causing massive hum.

I relaid out the pcb with the power supply seperate from the audio.
The grounds met at one point only at the connector to the pcb from the power supply.
This time the hum was extremely low and I had difficulty hearing it.
Murton-Pike Systems PCBCAD51 pcb design software. http://www.murtonpikesystems.co.uk
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Old 13th May 2013, 05:31 PM   #33
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Join Date: May 2010
Location: South East USA
There are two things I do (as a beginner myself) that seem to help greatly when populating a PCB.

First, I measure every passive component before it goes in. Verify that the 1K resistor is really 1K, and that the 10pf cap is really 10pf. I've found several near misses this way.

Second, once I've soldered a component in (any from resistors, to transistors, or RCA jacks) I measure continuity across the PCB. To do this, set your multimeter to beep for continuity. Place one probe on the lead of your component (before the solder joint) and the other probe on the next location on the PCB. You may have to inspect both sides of the board to find a suitable probe point, but shouldn't be a problem unless you are using a multi-layer board (unlikely for beginners anyway).

This does take quite a bit of extra time. However, it's certainly less time that troubleshooting an unknown error that could have been prevented. Plus, this is my hobby - I don't care how long it takes <g>
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