220v or 120v?

[gogofast]

If you plug 220v amp into 120v socket, what will happen? Will it even power on at all? The reason I ask this is I have a few Marantz pieces that were once converted to 220v for overseas use. They have the red warning stickers indicating this voltage conversion. I didn't realize this before plugging the amps. When I did, they do power up and pass signal but lots of hum and only one channel does. Now, does it sound like they need repair or input voltage issue? Since I bought these in the States, maybe the previous owner converted them back to 120v and didn't care to take the warning stickers off? and now they just need recap? I know this may be a dumb question, but I don't have any experience with 220v equipment so I had to ask before starting the repair.

 

[Pioneered]

Ya know you can get a Step Up Transformer without spending a lot and you can run two or more on some models. These obviously step 120V up to 220V using your 120V outlet and have one or more 220V outlets on them.
Of course make sure it's still setup for 220V 1st.

 

[Tom B]

A good indicator of being set for 220v and plugging into 120 is that the front panel lamps will be very dim, as they will only be receiving 1/2 of their required voltage. If the front panel is bright, they were probably set back to 120v.

 

[gogofast]

A good indicator of being set for 220v and plugging into 120 is that the front panel lamps will be very dim, as they will only be receiving 1/2 of their required voltage. If the front panel is bright, they were probably set back to 120v.

Well, it's a 250 power amp with the blue meters and they do light up very bright. I guess it was converted back to 120v.

 

[OMGCat!]

The best way to check would be to see what voltages are coming off of the transformer and compare them to the service manual.
I don't see that there would be any harm in plugging in a 220v unit into 120v mains as it's similar to bringing something up on a Variac which repair people do all the time.
You'd really need to make sure that your transformers are giving the proper voltage to the amp before trying to troubleshoot any further. If you've got major hum and one channel out with the proper voltages it sounds like you're in for some diagnosis rather than a recap.

 

[gogofast]

The best way to check would be to see what voltages are coming off of the transformer and compare them to the service manual.
I don't see that there would be any harm in plugging in a 220v unit into 120v mains as it's similar to bringing something up on a Variac which repair people do all the time.
You'd really need to make sure that your transformers are giving the proper voltage to the amp before trying to troubleshoot any further. If you've got major hum and one channel out with the proper voltages it sounds like you're in for some diagnosis rather than a recap.

Just checked the DC offset and bias. Was able to zero the offset, but the bias is way way high. I had to quickly turn the amp off when turning the bias pot all the way down didn't lower the bias enough.