Alesis PercPad repair (no power) - ideas?

[raketenmann]

Hi everyone
I am cleaning up my space. I found my Alesis PercPad I used to hammer in some drum demo files (because I am no drummer ). Well, this unit was working well when I stopped using it - but however when I tried to power it up it did not work at all, means: no sound, no display, no nothing. It seems that somehow that somewhere is a problem with the unit getting power. So I thought: pobably not so difficult - but in the end I just don't understand enough from electronics to know where the problem lies. I opened the unit up and checked if the 9V input socket has a bad connection or the power button: this is not the case.

So my question is: doesn anyone have any idea where on the board I could make some further investigation? Probably some could imagine weak spots in such devices I could check? I would love to give the unit to my son to play - but if it's to complicated I will throw it in the trash.
unfortunatelly I didn't find a shematic online - so I can only provide a photo of the main board....

 

[raketenmann]

 

[Youngwhisk]

Check the legs of the 7805 regulator near the biggest capacitors. The left hand leg should be 9v DC, the middle should have a ground connection, the right hand leg should be 5 volts DC

 

[ccaudle]

checked if the 9V input socket has a bad connection

Did you check that the 9V power supply is operating correctly? That seems like the obvious first step, but you did not mention if you verified.

 

[raketenmann]

Check the legs of the 7805 regulator near the biggest capacitors. The left hand leg should be 9v DC, the middle should have a ground connection, the right hand leg should be 5 volts DC

Hey @Youngwhisk Thanks for that input. I measure the middle leg to ground, but between ground and left leg (left on the picture, but probably right technically) I measure 0VDC. Between ground and the other leg I measure 0.7VDC. So obviously there's a problem. The solderjoints do look good - any ideas how to fix that? Could it be this part?

Did you check that the 9V power supply is operating correctly? That seems like the obvious first step, but you did not mention if you verified.

Yes, I have 8,7VDC on the input from the battery. I also checked with a power supply, didn't work either....

 

[raketenmann]

Oh my oh my - problem solved: The original power supply must be broken (Probably someone in the rehearsal room used it on another device). I didn't check because I thought all of this gear has center negative polarity - the Alesis doesn't, it's center positive. So I flipped the battery on the 9V adapter and the pad started working.

Sorry to bother you guys - totally stupid of me.

 

[pucho812]

Oh my oh my - problem solved: The original power supply must be broken (Probably someone in the rehearsal room used it on another device). I didn't check because I thought all of this gear has center negative polarity - the Alesis doesn't, it's center positive. So I flipped the battery on the 9V adapter and the pad started working.

Sorry to bother you guys - totally stupid of me.

It’s always the simple things we overlook but glad you found it

 

[Brian Roth]

Wall Warts and Line Lumps are Satan's Spawn! LOL.....I am the Ace of Alliteration.

So many devices use the "barrel" power connector. But, barrels come in different diameters and lengths....some differences very obvious, others very subtle. Even the center pin can have subtle variations.

And....is the power required AC or DC? How many mA? With DC, center positive or negative?

When I cleaned out my old house and moved to my current city, I found several dozen "orphan" Warts and Lumps in various drawers. So, I have a small box-full "just in case". It's come in handy a few times.

Always LABEL the lump/wart when it's brand new so you know what is what.

Bri