i have a used fender tuner pedal from my brother. and it worked great when i first used it. but now i turn it on using a adapter, and then the light indicator fades off. my other tuner works fine in its place, any help?
if i understand the question, you mean, you used to power it with a battery and now you switched to a power supply?
check if both have the same voltages and if the adapter can provide enough current.
Make sure you use both the correct voltage and polarity when you use an adapter for your pedals. If you used one with the wrong polarity it is likely fried. Do not use use just any adapter from your househould, as most are the wrong polarity required for pedals, which is negative centre.
"Your signature can not be longer than 250 characters."

How you know you have too many guitars...

Apparently once also known as PonyFan #834553.
What i use is a korg 9v power adapter from my synth. and it works fine with everything. but nothing works with the fender tuner. ill look into polarity
Might just be broken?

If the power you are providing to it is correct voltage and polarity, using an adaptor that works with other pedals then it looks like your tuners buggered