Tested power supply, before moving on to the ICs, something odd

Hi again,

Almost there! I’m near the home stretch but i think i’ve hit a snag.

I’ve gotten to the point where the boards are fully populated, but i havent installed the chips yet. i followed the instructions, and tested the power supply i’m using. maybe someone can point me in the right direction here:

I’m using a 500mA 9V DC tip positive supply.

plugged it in and tested between the point on the power jack and the GND on the hack me pin, but i’m getting around 13v!

i’ve double and triple checked all the components, and everything seems to be in the right place.

is this normal? the instructions said between 7 and 10v so i’m thinking i might be doing something wrong.

any ideas from you folks who’ve already gotten yours running?


Your ac adapter could be outputting 13v even if it says it is 9v. Once I got a multimeter I tested 3 different 7.5v adapters and the output of all of them was significantly higher 7.5v. I also tested the ac adapters of some other gear that I have (it all works fine) and even those were outputting higher voltages than what was printed on the adapter. I thought my multimeter was bad, but it wasn’t. It seems common for ac adapter to be off. You could just test the adapter without plugging it into shruti to see what the output is.

you’re right, i tested the adapter and it was putting out a pretty unstable range of voltages. i switched to a different 7.5v which i tested and i did see it was putting 7.5v, and that did the trick! all the test points were putting out the correct +5 or -5.

i have it up and running now, everything seems fine with the firmware, lcd, butons, knobs etc. but so far i can’t get it to recieve MIDI. well, one step at a time, i guess!

cool. I also had a problem with not receiving midi (I had alot of problems actually). Mine turned out to be solder points looked ok, but where actually loose. So check the solder points of the midi input jack, the diode, R6,R7 and the 4n28m. make sure they are solid.