Problem with old casiotone keyboard

[Hoji]

I have a nice old Casiotone 403 keyboard. It's been sounding great for years, but after being unused for several months, it now doesn't sound right.
Symptoms are:

- Volume is pretty low, even with knob all the way up.
- Distortion, especially when multiple keys played together


Aside from that, everything "works" as it should.

Any ideas what could be wrong? Maybe not enough voltage getting to it? Note - this is A/C powered only (no batteries).

Thanks for any help!

[The Dude]

My best bet would be dried out electrolytic caps, based on 2 things- it's old, and it sat unused for a while. Of course, that's a bit of a guess based on the limited information we have. If you have a cap tester, check the electrolytics in the power supply. If you have a voltmeter, check for excessive power supply ripple and check that your supplies are up to snuff.

[Mick Bailey]

Check the mains plug isn't corroded - I've had two items in recently where the low voltage has been down to oxidized pins. Anything further would require the unit to be opened and voltages checked.

[rjb]

If you have a voltmeter, check for excessive power supply ripple and check that your supplies are up to snuff.

I just found this out:
Beware that cheap DVMs can give whacky results if you use the AC range to measure a voltage with a DC component.

Does multimeter measure Vrms or (Vripple)rms? | Electronics Forum (Circuits, Projects and Microcontrollers)
Quote: "My 1.5 volt AA alkaline cell reads 3.1 volts on the 200 VAC range."

[Hoji]

My best bet would be dried out electrolytic caps, based on 2 things- it's old, and it sat unused for a while. Of course, that's a bit of a guess based on the limited information we have. If you have a cap tester, check the electrolytics in the power supply. If you have a voltmeter, check for excessive power supply ripple and check that your supplies are up to snuff.

Thanks, dude. Do you mean these?

[Hoji]

"Fixed"

Well, I am happy to report that after opening it up, vacuuming out the 30-something years of dust, and making sure all connections were good.... it now sounds good as new.