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Question about 9V adapter for Boss TU-2 tuner.

2/19/2005 10:28 AM
Question about 9V adapter for Boss TU-2 tuner.
I just bought a Boss TU-2 tuner and it requires a "PSA" adapter only.  
I don't have one of those but I've got a bunch of other types that are also 9volt, I was wondering if I could damage the pedal by using something other than a PSA adapter.  
BTW, I've got a Boss ACA-120, Baknor AX09V300, SoundSense ACA-120S, Danelectro ZeroHum DA-1.  
I'd sooner try using one of these but can it fry my pedal?
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2/19/2005 2:14 PM

I just measured the voltage of all my 9V adaptors(without a load) and the readings are a little surprising.  
The Danelectro ZeroHum is 9.76V, the SoundSense is 9.06V, the Boss ACA-120 is 14.76V! and the Baknor reads a whopping 16.3V!!!  
I've already used the Boss ACA-120 and the Baknor adaptors before with various other pedals and never fried anything or noticed anything funny. These voltage readings that I'm getting are without a load attached to the adaptor so I'm guessing that once you put a load on there, the voltage probably drops to appx.9 volts. Would that be correct or are these voltages just too high and maybe I shouldn't use these adaptors at all?
2/20/2005 7:02 AM
Steve Dallman

Some adaptors are regulated and filtered and some just have filtering. Unloaded, supplies without regulation will read higher.  
I would guess that your Boss tuner would work with any type of adaptor, but if you run it in line, unfiltered supplies may pass on hum.  
The hum on the output would be the problem to look for.  
It is possible that higher voltages, which may remain high if the tuner is the only load, could be a problem for the tuner. You should measure the voltage on your Boss ACA-120 and Baknor with the tuner plugged in.
2/22/2005 11:24 AM
TU-2 requires 9VDC regulated negative tip 200 mA supply. PSA-120 is cheap - better to buy the right thing than fry your pedal with reverse polarity or over-voltage from unregulated supply.  

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