repair help CZ-5000, Help, I broke something!

[dragonroll1]

Hello,

I recently acquired a Casio CZ-5000, and it has been having some issues I have been trying to fix. Originally, it was working well, minus the mod wheel, a couple broken keys, and the volume and chorus sliders working intermittently. I took it apart, replaced the mod wheel, and cleaned some of the buttons and the sliders with DeOxit. When I turned it back on, I was getting no sound in the lower ranges, with a very, very quiet signal in the last 3 upper keys, almost not enough to hear even with headphones. I did some research and learned it could be a relay problem as they tend to go out, so I replaced it with this one from syntaur.

https://syntaur.com/Part-3889-Relay-5V

Still, I was having the same issue and do not know where to go from here. All the buttons and lights work, and the presets are still there. 

I am thinking of testing the volume potentiometer but am unsure how to do so with a multimeter.

Any help would be appreciated, and thank you in advance!

-dragonroll1

Here is my video of the first repair: at the end of it, it stopped working.

https://www.instagram.com/p/DIKU3NFTVTO/

 

[Chas]

@dragonroll1 - Firstly, welcome to the forum!

 

With regards to your CZ issue, this is what immediately sprung to mind:

 

Before you carried out any repairs, you mentioned that the volume and chorus sliders were working intermittently, indicating that these components already had issues. After cleaning them, they now appear not to work at all. DeOxit  can be used for cleaning some potentiometers/ faders (there's different types, one is specifically for faders) , but it is also not suitable for all and can actually damage the carbon tracks causing total failure.  See this link for a big caveat regarding using DeOxit to clean pots/ faders:
 

https://gearspace.com/board/electronic-music-instruments-and-electronic-music-production/1367899-deoxit-slider-potentiometer-snake-oil-best-caigless-method.html

As you were getting some sound before using DeOxit, and then virtually no sound after (and when replacing the relay made no difference), it does seem to suggest that the DeOxit may have damaged the volume slider. You can test this by connecting a multimeter, in resistance mode, to the + and - connections of the volume slider, then move the slider and see if the resistance reading on the multimeter changes or not. Another test you can do with the CZ switched on (risky if you're not careful) is to bridge/ jumper the circuit connections in and out of the slider. The idea is to bypass the slider and put the volume circuit at maximum volume. If you get a strong volume output like this, then that would isolate the slider as being the culprit.   

 

Hope this helps!

[IanB]

I agree with Chas, it may well be that the volume fader is kaput and what you're hearing faintly is "stray" signal that being high pitched happens to be just audible. You can also plug a jack or RCA phono lead into an amplifier and touch the tip to the input connection of the volume fader to see if you can hear anything through the amplifier.

[CYBERYOGI =CO=Windler]

Never use random contact cleaners (these are solely made for metal) in potentiometers. I only use isopropanol, but even that can be slightly risky (at least moving the wiper while still soaked). Early 1980th slide potentiometers (also found in Bontempi/Farfisa etc.) seem particularly vulnerable and hard to replace because size was not standardized.

 

If the carbon track is ruined (dismantle the pot and test with multimeter), you may try to recoat it with a soft pencil until you get roughly the correct ohm value. This won't be very robust (and stereo balance may be awful) but will be enough to get some sound. Often carbon tracks break only at the connection point to metal (e.g. a rivet) which can be fixed with a drop of conductive paint.

[dragonroll1]

Hello everyone! Just a quick update. I purchased a replacement slider from synth parts that just got here, as it was shipped from overseas. Will update as soon as I test it against the one I have removed from the CZ.

Best!

-Dragonroll