Just installed a 3 wire cord and now there's a huge hum... Ampeg V4

[Iplayloud]

I did a really good job and soldered the green wire on one of the transformer's bolts. Only thing is I didn't use the amp since 2 weeks. Is it possible that a power capacitor died or it's really the job I did on the cord ? The hum is very loud and the amp still works but the volume is weak.

[Mars Amp Repair]

Where's the rest of the thread?

I'm thinking there was another part to this Thread....was the grounded ac cord all the amp needed before or did it have some issue before you replaced it?
Am wondering how you were able to 'solder' a wire on to a bolt of the transformer...would think that would take an incredible amount of heat to do that. Also you need to be certain that the bold/transformer are well grounded to the chassis of the unit. I've seen where using a bolt on the transformer to use as a ground for my meter ends up in some of those bolts not actually getting to the chassis ground...Unlikely, but something to consider.

To isolate the grounded cord you just attached, try inserting a gound lift adapter on the ac plug end to emmulate how the amp was before you added the ground wire...if the hum goes away, then you know it has something to do with the grounding of the chassis.

You also should be certain that the outlets in your home are properly grounded/polarizes to begin with. The polarization is not really as critical in this case, but the grounding is.

They sell a really simple cheap gadget at the hardware stores to verify the connections in your home outlets....or you can also do it with a meter if you know what to expect from a properly grounded/polarized outlet.

glen

[Regis]

Here is a page I did on how to rewire Fender amps to a new grounded cord. See if that jives with what you did.

MAP is right, get one of those socket testers and check your AC lines.

Did you connect the black and white where they were connected before?

Are you using this with another amp in an A/B situation? You could get hum that way via a ground loop.

Are you using this with a pedal power supply or any other device that is AC power and has a grounded cord? Ground loops again.

What kind of amp? Pics? MAP is again right in wondering how you attached the ground, it had to have been a ground lug you put under the transformer bolt right?

You sure you didn't disconnect/detach/otherwise screw up any other component?

You have to be careful with AC, you could destroy your amp and/or kill yourself.