Power problems with Anushri synth

So i built my synth a couple of days ago and it worked great! Love the sound of it. The power supply i was using was a 9v dc plug. It was just a little wobbly on the socket. So i plugged in a different power supply wich i thought was another 9v DC but turned out to be 9v Ac. My synth got really hot so i unplugged it. Now when i put the old plug in it wont light up, it only makes a hum noise. Is there any way to fix this?

Can you do the ‘power distribution’ test under ‘troubleshooting’ on the Anushri build page? Specifically the voltages on all pins of the 7805 and 7905 ?

im sorry im not full sure how to do that? do i need any special tools for that?

Just a multimeter … all you need to do is measure voltages.

Follow the instructions on the MI website´s Anushri DIY section Troubleshooting.

Just use your multimeter and measure voltages.

You probably busted something, but don´t worry, it should not be difficult or expensive to fix. This is one of the upsides of a DIY synth, no expensive services or replacements with authorized service agents!

You live and learn, I have made a couple of silly mistakes myself.

I suspect the LT1054 is fried. There’s a diode in the input circuit to protect against polarity errors and it will also block the negative AC component, but I suspect that ‘9V AC’ means the effective voltage, so the peak voltage would be well above that, in the danger area for the LT1054. You could just blindly replace the LT1054 but doing the voltage measurements will confirm if it’s defective, and to me it’s a more sensible approach.

Thank you so much! I thought i destroyed my synth. This gives me hope.

my multimeater has manuel ranging. what range do i set it to? if i want to get an accurate reading?

With the knob set to 20v on my multimeater i get +.25v and -.25 on my LT1054 ic.

> i get +.25v and -.25 on my LT1054 ic.

On which pins?

the 1st and 4th pin on the upper side of the IC. if thats not the problem that what could it be. if so can you break down how to do the power test. i fairly new to voltages and diy projects in general. i really would love any feedback or help. :smiley:

Count pins with the notch up, from top left to bottom right.

Set the range to the closest superior value to the expected target voltage.

Please measure the voltage on each of the 3 pins of the 7805 and 7905.

so 20v is a good indicator? it goes from 2v to 20v.

Yes, 20V is the right scale. Things would have been very ugly if your power supply exceeded 20V.

on 7805 i got +.18v and .18. on 7905 i got.001 and +0.2

what would happen if i exceeded 20v?

now on 7805 i got +.02v and .00v. on 7905 i got +6v and -6v

> what would happen if i exceeded 20v?

Meter will be damaged.

What is the voltage on each side of the 1N400x diode near the power jack?

0 and +5