If you are competent with electronics, open it up and check the fuse(s). Especially if no lights come on. If you get voltage, then check the jacks you plugged into- they may have dirty interrupt contacts. When you plug the jack in- it opens those contacts that otherwise are closed making the circuit to the cabinet's built in speaker. Contact cleaner should clean them up if that is the issue.
While it is possible there is a power supply issue, you can see that quick with a voltmeter, it is not likely you did much more than blow a fuse.- very possible if you unplugged speakers with the amp operating..
If you think you killed it- you usually still get distorted noise.
Testimonial: "Thanks - I'll pass this on to the guy looking at it. I'd like to believe it's just a fuse, but I'm preparing for a blown output transformer. I'm still not sure why it blew - two 8 ohm speakers in parallel should be 4 ohms, and that's what the amp was rated for. Even when (for a short time) I had only 1 speaker hooked up, those 8 ohms would just decrease the efficiency, right, not cause the transformer to blow? Obviously, I'm trying to understand this so that it doesn't happen again! Thanks for your help!"
SOURCE: Marshall MG100HDFX 100-Watt Amplifier Head. The
You'll have to take it in to get it repaired. From what you described it sounds like you blew the output stage out. You can't run from your speaker output jack into the input jack of another amp. You should go out of the recording out, line out, effects out or in the least case your headphone out. What happens usually is your output transformer short circuits due to a mismatch of impedances. It sounds like you still have a transformer though so you might have gotten lucky. You will need to take it in though. Sorry.
SOURCE: I have a budda superdrive
You best rewire the cabinet to put the two speakers in series. Wire one speaker plus to minus of the other and bring the other lead, one from each speaker to your jack on the cabinet. The amp output impedance is what is set on the switch... for two 8 ohm speakers you would use both jacks to the two speakers BUT ssince you have 4 ohm speakers the ONLY option is for two in series and set the switch to 8 ohms. The amp is ONLY 30 Watts so don't expect too much sound output... You should get a nice CLEAN sound at a reasonable level. If you drive the amp too hard it will clip and you will get garbage.
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BTW - I checked the fuse - that's fine. And when I attempted to plug the speakers in to the headphone out, FX loop send, or any other "out", nothing worked, thus I plugged into speaker out, which caused the problem. Several of you have said it sounds like the output transformer, so I'll be bringing that into the shop. Thanks to all!
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