Hello and thank you for your help, first and foremost! This post is broken into two parts .. the back story, and the following steps.
Last Sunday, I was putting back-together a synth, which I was trying to restore. I wanted to test the synth, so I connected it as follows: The line out of the synth (no ground) was plugged into a channel in a sub mixer (no ground), the sub mixer main outs were plugged into another (grounded) mixer's stereo line in, and finally this mixer's main outs were going into an audio interface (grounded).
I made a huge mistake. I had not yet secured the AC mains connector to the synth chassis, but I had never-the-less plugged it into the wall socket to test the device. Don't ever do that!!! As you can imagine, the connector became dislodged from where it fits in the chassis, and the legs that are soldered to the cables that connect to the power switch touched the chassis of the synth.
A bright white light emerged from the contact point, followed by a loud buzz from the loud speakers, followed by the smell of smoke, followed by panic from yours truly. Miraculously, I didn't get hurt ... for which I am very grateful. Unfortunately, this wasn't a victim-less "oopsie."
I expected everything mentioned in the chain above to be fried - from the synth all the way through to the interface .. yet, only the second mixer down the line - the grounded one - bit the dust. Everything else seems unscathed, at least to my untrained eye.
So - what happened?
My best guess is that when the prongs touched the chassis, the voltage of the ground on the synth was simply raised by 120V. Everything that wasn't grounded ended up with no voltage, but the grounded mixer did have the reference needed to "feel" the 120V at the line in. Because this voltage exceeds pretty much every possible component's max voltage, the mixer experienced extreme "clipping" to the point where stuff got burnt up, but ultimately could not send 120V out of its line out to cause harm to the interface. Can this be what occurred?
And what about the mixer? Is it gone forever? I've opened it up and can make a few observations. The first is that a lot of the components are surface mount. The second is that there were 8 through hole resistors, and these were all cooked up. The third is that the power supply is still smoking if I turn the mixer on.
I have the schematics for the all the boards in the mixer, so replacing the 8 resistors was painless ... all things considered. The problems are that - #1, with a power supply that is still busted, I can't test the mixer and #2, while only a few components were visually broken, my gut says everything got burnt to a crisp.
I would never the less like to find out, so how do I test a power supply that is still smoking when turned on? .. Do I let whatever is in there fail completely until it's obvious it was X, Y, or Z component? .. Are some components more likely to smoke, and should I just attempt to replace these first? .. Or should I just cut my losses before I burn up something else or myself?
Last Sunday, I was putting back-together a synth, which I was trying to restore. I wanted to test the synth, so I connected it as follows: The line out of the synth (no ground) was plugged into a channel in a sub mixer (no ground), the sub mixer main outs were plugged into another (grounded) mixer's stereo line in, and finally this mixer's main outs were going into an audio interface (grounded).
I made a huge mistake. I had not yet secured the AC mains connector to the synth chassis, but I had never-the-less plugged it into the wall socket to test the device. Don't ever do that!!! As you can imagine, the connector became dislodged from where it fits in the chassis, and the legs that are soldered to the cables that connect to the power switch touched the chassis of the synth.
A bright white light emerged from the contact point, followed by a loud buzz from the loud speakers, followed by the smell of smoke, followed by panic from yours truly. Miraculously, I didn't get hurt ... for which I am very grateful. Unfortunately, this wasn't a victim-less "oopsie."
I expected everything mentioned in the chain above to be fried - from the synth all the way through to the interface .. yet, only the second mixer down the line - the grounded one - bit the dust. Everything else seems unscathed, at least to my untrained eye.
So - what happened?
My best guess is that when the prongs touched the chassis, the voltage of the ground on the synth was simply raised by 120V. Everything that wasn't grounded ended up with no voltage, but the grounded mixer did have the reference needed to "feel" the 120V at the line in. Because this voltage exceeds pretty much every possible component's max voltage, the mixer experienced extreme "clipping" to the point where stuff got burnt up, but ultimately could not send 120V out of its line out to cause harm to the interface. Can this be what occurred?
And what about the mixer? Is it gone forever? I've opened it up and can make a few observations. The first is that a lot of the components are surface mount. The second is that there were 8 through hole resistors, and these were all cooked up. The third is that the power supply is still smoking if I turn the mixer on.
I have the schematics for the all the boards in the mixer, so replacing the 8 resistors was painless ... all things considered. The problems are that - #1, with a power supply that is still busted, I can't test the mixer and #2, while only a few components were visually broken, my gut says everything got burnt to a crisp.
I would never the less like to find out, so how do I test a power supply that is still smoking when turned on? .. Do I let whatever is in there fail completely until it's obvious it was X, Y, or Z component? .. Are some components more likely to smoke, and should I just attempt to replace these first? .. Or should I just cut my losses before I burn up something else or myself?
I certainly would like to try to repair it.
