I’ve built the Frequency Central MicroBus. The wall supply I am using is 12v AC. 1000ma. I’ve tried two different ones, but only the 12v- LED lights up. Neither the 5V or the 12v+ LEDs light up.
I’ve quadruple checked and the regulators are in the right place.
Does anybody have any bright ideas before I smash everything up and vow never to do any other DIY projects ever again?
p.s. the 1k LED resistors are installed on the bottom of the board, as I previously had the wrong resistor values in there, so had to replace them.
LED orientation all good, yeah! Short leg = cathode = negative = square pad.
I just built a second one of these I had, testing every component with one of those component checker things, and triple checking every bit of the PCB… carefully soldering, and same issue on this one! o_O
I must admit ignorance on how to do this. I have a multimeter, so I presume I would connect up the two pins from one of the header connectors to confirm? Any tips there greatly welcomed, as I am a multimeter n00b.
Found the pins to confirm with the multi-meter, and I’m getting -12v at the expected place, but no voltage reading at either the +5v or +12v pins. The only thing I can think of is that maybe one of the batch of Regulators is fried? but I’m not sure which one that would be.
Ah, you know what. I bet the power supply I’ve been sent is DC output. The ones I bought were advertised as AC output, but it might not actually be. I’ll try source a reputable AC plug and confirm.
It would either be the LM7812 or LM7805 (without looking at the schematic I can’t tell if the 7805 is downstream from the 7812 or has its own capacitors), otherwise there has to be a problem with one of the diodes on the positive rail.
Are you sure the ‘component checker thing’ is measuring the diodes properly? I’d imagine so seeing as your capacitors haven’t exploded.
Do you have an oscilloscope or access to one? You could use it to check if the power supply is actually putting out 12AC and it isn’t mislabeled. Where did you get it from?
I can’t be sure. Would there be a better way to check? I do have a scope, but my knowledge in how to use it is errr… limited beyond for audio.
I got the plug from eBay. It was advertised as AC 12V 1A adaptor (no reference to DC). On the actual plug it doesn’t reference DC either, but I should have noticed that it has a polarity, which would obviously mean that it isn’t AC. That’s my own fault. Eugh. Sorry, what a dumb mistake!
My only issues with the FC boards is I found the barrel connection to have quite a large footprint and took a lot of heat to flow a reliable solder joint. Barring that get the flux out and lather the b. Board
