Casiotone CT-610 repair?

[anpap]

Have an old CT-610. Still works find, except that the volume of one of the speakers is very low.

Thinking of trying to repair it myself. Would help if I had the schematic and/or service manual.

 

Anyone know where I could get these?

 

thanks,

Andreas

[Chas]

I did a search but couldn't find a service manual. I did find this review of a CT610 though:

 

http://www.muzines.co.uk/articles/personal-keyboards/3224

 

It appears to share similar hardware with other Casio models such as the MT65/ 68/ 400V/ CT410, and also the stereo chorus is likely the same as fitted to the MT400V/ CT410.

 

It will be using the same Consonant Vowel sound engine that most early Casios use. The sound is entirely mono, the stereo effect is purely down to the stereo chorus.

 

Thus if one speaker is quieter than the other, it's either a problem with the chorus, the amplifier or the speaker. The simplest test I can suggest is to open up the 610 and swap the speakers over. If the problem moves with them, it's a speaker issue.

 

Also check the headphone output and stereo line out. Do those give an equal volume for left and right? If they do, then that will suggest a speaker or output amp issue. By a process of elimination, you should at least be able to narrow down the issue without needing a service manual.

[anpap]

Thanks for the info, it helps!

 

Already tested with headphones. Same issue, so I guess it has something to do with the amplifier.

Will try to open it up and see if I can find the amplifier and then check for replacement components.

 

[pianokeyjoe]

Do not know if this was solved but check your volume slider! Most of these older Casios use a left/right volume slider that IS true stereo left, and right amp channel connected and you can tell because it has a mini coaxial cable soldered to the volume slider pot with a black or white lead, a red lead and a bare(negative or ground)lead. If you slide the slider back and forth and it crackles, there is your first positive indicator. The CHORUS ALSO could be a culprit but it is usually the SLIDER for that as well that causes the volume to go out on one or both sides until you turn it off. So check with Chorus OFF and see. But it may not be the AMP but the sliders instead. On a whim, check the speaker connections too.. Does not hurt.

[CYBERYOGI =CO=Windler]

In my Casio CT-810 (from eBay in very poor condition) I had to remove, dismantle and clean every single potentiometer to make it sound again. To clean the carbon track, use isopropanol and a cotton swab. NEVER use contact cleaner spray - it is too aggressive and will dissolve the carbon track.

 

If the carbon track of a potentiometer is worn through, you can fix this by coating it with a soft pencil (the retractable fine type is more precise than wooden ones) until the resistance value is ok. If you accidentally short nearby traces, remove the unwanted pencil line with cotton swab and isopropanol. Pencil graphite may be less scratch resistant than the original material, but with unobtainable special (e.g. slide) potentiometers it is better than nothing.

If a rotary potentiometer makes shaky contact or crackles badly despite the inside looks clean, try to clean the (often tiny and badly visible) metal-to-metal contacts. If they are hard to reach and can not be dismantled, insert a tiny strip of paper between contacts and turn the pot a few times to remove oxidization. If the bolted lead at the carbon track end makes bad contact (and can not be tightened mechanically), you may apply some conductive silver paint. This also helps when given conductive metal coating has corroded or burnt away (by overload or humidity).