Oops!! 5:25 plugged into 220V
- Thread starter sprucetop
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sprucetop said:
If you did this in the USA, and did not have some sort of adapter to fit a 220 outlet not sure how you managed it unless where you were does not meet NEC. If that is truly the case, the power supply for the amp is probably toast (electrolytic caps do like to be operated above rated value), Perhaps the amp is okay, but there may be a chance something shorted out which cause the fuse to blow. On the other hand, if were elsewhere say Europe, I believe that would be 240VAC, or china which is 250VAC.
Since you stated "Don't ask how" makes me want to ask you how or why.
I opened it up--the ceramic disc cap is visably toasted. I can probably get that here (West Africa) but if there's more serious damage can I get parts from Mesa Boogie? And do you think there is more damage given that the power was on only about 1 second before the fuse blew?
I am not sure if the large ceramic capacitor is a capacitor. It may be either a MOV (metal oxide varistor) or an NTC Power thermistor. Sometimes these components are used to reduce overvoltage (MOV if across the inputs to the power supply) or to reduce inrush current (NTC power thermistor). Both parts look identical, however I think it is an MOV since the power supply is a linear type and not SPS (switching power supply).
You diodes are probably toast as well. If the MOV blew out it's sides there may be circuit trace damage or melted wire insulation somewhere. MOV's become a short circuit when the threshold of the trigger voltage has been reached. The transient response of the MOV is faster than the fuse. As the MOV was vaporizing the fuse took a bit longer to overheat and blow out. Perhaps the overvoltage device served its purpose and saved most of the rest. Hard to tell if there would be other damage done, all of that energy had to pass though the filament transformer first in order to step up the voltage. There are also step down windings for the low voltage circuits including heater voltages for the tubes.
I hope your amp is repairable. It may be more cost effective to just buy another one. You may as well invest in a step down isolation transformer with power conditioning 220/120 so you do not have another oops. If it turns out you need to replace the amp, check if Mesa has a European /export version. That way it would have a voltage selector switch for 250/120.
You diodes are probably toast as well. If the MOV blew out it's sides there may be circuit trace damage or melted wire insulation somewhere. MOV's become a short circuit when the threshold of the trigger voltage has been reached. The transient response of the MOV is faster than the fuse. As the MOV was vaporizing the fuse took a bit longer to overheat and blow out. Perhaps the overvoltage device served its purpose and saved most of the rest. Hard to tell if there would be other damage done, all of that energy had to pass though the filament transformer first in order to step up the voltage. There are also step down windings for the low voltage circuits including heater voltages for the tubes.
I hope your amp is repairable. It may be more cost effective to just buy another one. You may as well invest in a step down isolation transformer with power conditioning 220/120 so you do not have another oops. If it turns out you need to replace the amp, check if Mesa has a European /export version. That way it would have a voltage selector switch for 250/120.
EtherealWidow
Well-known member
I'm no expert but I would imagine everything is toast. Even if it was only for 1 second, audio equipment relies on frequencies far smaller than that. The capacitors take less than a second to charge, and trying to charge them at twice the rated voltage is... bad. You can go ahead and try it on the proper voltage, but I think I would just send it in.
One more piece of advice. I was using a 110V guitar amplifier from North America after I moved to China. I had a very large and quite stable power transformer that I used to step donw the voltage from 220V down to 110V. Even so, the amp fizzled out after about 18 months. The amp still turned on, but made strange noises in the background that made me think that the uprocessor had problems (this was a DSP modeller amp). This was after I had already used the amp in Canada for 8 years with zero problems. One possible explanation is that the power transformer was sending in a transient spike of voltage that well exceeded 110V, occuring when I turned on the transformer. I know for sure that the transformer does indeed have transient spikes on power up, and maybe over time this broke down something in the power supply chain or even down to the processor in the amp.
So in hindsight, if you must use a 110v amp in a 220V country, then unplug your amp from the transformer when not in use. Turn off the amp first, unplug the amp, then turn off the transformer When you power back up, turn on the transformer and wait a few seconds. Then plug in the amp and turn in on. This way you should avoid most or all spikes from reaching the amp's power supply circuit.
So in hindsight, if you must use a 110v amp in a 220V country, then unplug your amp from the transformer when not in use. Turn off the amp first, unplug the amp, then turn off the transformer When you power back up, turn on the transformer and wait a few seconds. Then plug in the amp and turn in on. This way you should avoid most or all spikes from reaching the amp's power supply circuit.
