# universal adapter polarity help - don't want to burn the effect pedal

#### sitter07

##### New Member
so i have this is Boss dd7 effect pedal, which needs 9V 1A . I have some universal adapter with extensions but not sure which is the right way to turn it in.

first pic is the back of the pedal. which of these two examples (E1, E2) is correct ?

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#### ChrisP58

##### Well-Known Member
Your first picture shows that the center pin should be negative, and the outer shell should be positive.

Rather than depending on the somewhat cryptic markings, I would recommend using a voltmeter to see which of the two positions produce the correct polarity.

#### upand_at_them

##### Member
As ChrisP58 said, E2 is likely correct but if you don't want to risk damage you should check it. If you're in the US you can get a cheap (often free) multimeter from Harbor Freight.

#### Visitor

##### Active Member
As ChrisP58 said, E2 is likely correct but if you don't want to risk damage you should check it. If you're in the US you can get a cheap (often free) multimeter from Harbor Freight.

#### unclejed613

##### Well-Known Member
Most Helpful Member
if i'm reading the polarity plug correctly E1 is correct with the icon lined up with the sleeve lined up with the + on the other part of the polarity plug.

#### Visitor

##### Active Member
The + and – symbols on the part showing the connector make it somewhat ambiguous. The safest thing to do is verify the polarity with a meter.

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