Hi, There are several common reasons why this and most similar keyboards have this problem.
If you can fit known good batteries, and it works, this confirms the problems will be with the external power supply or connection.
Usually batteries are not available, so.......
Do the obvious.
- Is the power supply plugged into a known good mains socket?
- is the mains socket switched on?
- is the power supply plugged into the keyboard?
- is the keyboard switched on?
If the power supply is not the one supplied with the keyboard, then check it is compatible.
(You do not have to buy an expensive replacement power supply, a universal, regulated one, with a selection of connectors will be fine. Supermarkets and the like sell them.)
The manual, or a label on the bottom of the keyboard will tell you the voltage, current consumption, and whether the current is AC or DC.
Invariably the current is DC.
All the Casios I have are 9 Volts, (9V) and very few are more than 300 milli amps (300mA) More milli amps is fine, so the current can be the same or greater.
A TYPICAL power supply is likely to be:-
BUT DO CHECK
The power supply needs to be REGULATED.
This is the way round the connector is wired.
Usually the center is negative (-) and the barrel is positive (+)
This information is molded into the plastic or on a label next to the socket.
On a replacement (universal) power supply, there will be a set of connectors, and when you have selected the correct one, the arrow on the end of the lead should point to the correct polarity symbol on the connector.
The most common fault is the power connector being broken or the solder has been broken.
moving the connector round, to find it works in some positions, is a sure indication that is the fault.
Repair is quite simple, but there are a lot of screws to take out.
Ideally, drill a hole in the case, where convenient, and fit a metal connector. Now connect to the PCB, in place of the original socket, with flexible wires.
Other wise if it is just solder failure, re solder and glue the socket with epoxy resin (Araldite) or hot glue from a glue gun.
Hope this helps, Chris.