Tuners and Power Transformers

[rayc]

Gentle Folk,
Are Tuners influenced by Power Transformers?
Dead battery time in my place and I wanted to tune my new toy.
I plugged in with a generic cheapie power supply and had heaps of trouble. Tried an older, problematic tuner with the same power supply and found the old plus the new problems.
The tuners seem to hover around G# when an instrument is plugged in then give me all sorts of grief when I try to tune.
If the power supply is supplying the aggravation would it also have an impact on pedals?

[Lt. Bob]

need to check the output of that supply ..... if it's not putting out the correct voltage it might affect the tuners