Casiotone 701 (CT-701) No sound on musical guide half of keyboard

[TomAgain]

I was using my Casiotone 701 keyboard and I left the power on for 30 minutes without using it and when I tried again, the right half of the keyboard aka the “Musical Guide” half no longer made noise. The left side and drum sounds all function as usual. I am trying to figure out what the problem is and how to fix it. Thanks guys.

[IanB]

Hi Tom. It's always hard to tell from a description, but it's likely this is an electronic fault. The 701 was a pretty complex design with several LSI chips generating the tones digitally. If you've tried all the usual things like flipping all the switches, this would probably require experience with electronics and some test equipment. Does the melody/accompaniment balance control do anything?

[TomAgain]

No. I’ve tried all switches. I get a dim clicking noise when playing any of the keys in the upper half but everything else on the lower half of the keyboard sounds good as new. Perhaps I can replace the fuse? The issue is I don’t know anyone locally who can fix it

Edited August 13, 2022 by TomAgain
Misspelling

[IanB]

Hi Tom, this will be a problem with the electronics, and changing the fuse (which fuse?) won't do anything. The CT701 contains three separate tone generator circuits, one of which does the right side of the keyboard, and it sounds like there is a fault with that tone generator. Unfortunately unless you can do fault finding or can find someone who can do it, there's not much you can do. You could maybe open it up and have a look to see if anything is obviously frazzled, and unplug and replug all the internal connections in case one is not seated properly. Here is a video of somebody opening up a similar CT602

 

 

 

[TomAgain]

Thanks for your help Ian it means a lot. I have no experience with this kind of stuff but perhaps it’s time to learn!

[IanB]

@TomAgainHonestly learning to repair stuff is very satisfying, and it's stuff you can learn bit by bit. You can do a lot with just a cheap multimeter and an audio probe (a wire connected to an amplifier input so you can "listen around the circuit"). And there's something very satisfying about soldering. The nice thing about this older gear is that the components are quite large and "human sized" compared to modern stuff. Of course we all only have time in life to learn some things and not learn most everything, but there are worse things to learn than electronics