using the wrong power supply with CZ101

[iamdamosuzuki]

i'm wondering what damage could be caused by plugging in a psu with a higher voltage. i bought a cz101 that came with an old universal power supply and on the 9v (center negative) setting the keyboard turned on then off - turns out it actually measures 13v on the 9v setting. it's with a tech now, but wondering if anyone here can tell me off hand the damage that could have caused. thanks! 

[Chas]

There are a number of components that can potentially get damaged by feeding a CZ101 higher than normal voltage,  it's impossible to say exactly what has happened to yours.

 

You may be lucky in that 13v is not a huge over voltage over 9v and it's possible that no damage has occurred. Unlike the time I fed 220v into my US spec CZ-1 that was expecting 110v... Luckily it just popped the PSU protection fuse, and with a new fuse it was up and running again.

 

There are a lot of unknowns with your CZ101. Has it ever worked since you got it? Has it for sure worked with that supplied AC adapter, or did the seller just throw in a universal adapter and kept the original? Have you tried it with batteries?

 

Personally I would try and see if it works with batteries and therefore bypass the AC adapter input. If it works fine, then that would rule out the main synth circuitry being damaged. Then you could try getting hold of the correct AC adapter and seeing if it will run off that. 

 

One last thing. The CZ101 has an unusual dimensioned AC adapter socket, and as such many universal adapters don't fit snuggly and are too loose, causing intermittent connections. Sometimes the connection is just enough to initially power it on but then it will switch off. Coincidentally, I had this very issue last night with my similar era Casio HT700. It would turn on and then turn straight off with a universal PSU, so I dug out my genuine Casio PSU and it worked absolutely fine with that. 

 

Hopefully your issue is just a poorly fitting AC adapter barrel and no damage was done. Let us know what you find out. 

[IanB]

Agree with Chas's comment. Also to add that looking at the schematics, the 9V heads straight into several voltage regulators internally, so it's probably pretty liberal about the incoming voltage. Bear in mind that the voltage of an old fashioned power brick is only a nominal voltage and can be much higher depending on its loading- so if you measure the voltage when it's not powering anything else the voltage will be significantly higher.

[CYBERYOGI =CO=Windler]

I do mostly use unregulated 1A wallwart PSUs with my Casios, those will always show a higher voltage than rated (e.g. 18V in 12V mode) when not burdened by the rated load (that would be 1A). Thus I set the voltage lower (e.g. 6V instead of 9V); too low voltage will distort sound (and may crash) and nor properly light the power LED of the instrument.

 

Really destructive is only wrong polarity. Casio keyboards (like most others) have voltage regulators those filter moderate overvoltage, but may overheat or short when way too high. Only cheap noname toy keyboards (Yongmei and such) may connect its single chip CPU directly to the battery compartment and PSU jack, so it may get fried by as little as 0.5V overvoltage if only the die itself contains a zener diode to pull down surge voltage spikes but will overheat and burn up the chip by few seconds of too high supply voltage.

Edited October 6, 2022 by CYBERYOGI =CO=Windler