momo Posted July 21, 2022 Author Share Posted July 21, 2022 I think I have to revive this thread ^^ Sadly I was in no luck with my repair attempts of the Casio CZ, however I got hold of a replacement PSU Board, for which I hope it turns out to be working... However whereas the board that was in the CZ is labeled with a "B" the board I have now is labeled with a "C". I suspect them to be different revisions and wonder if anyone knows if these are interchangeable? 1 Quote Link to comment Share on other sites More sharing options...
IanB Posted July 21, 2022 Share Posted July 21, 2022 According to the service manual, the board should be labelled either MA2M or CN5M. Where is it labelled "B" or "C"? Giving us a photo always helps 1 Quote Link to comment Share on other sites More sharing options...
pianokeyjoe Posted July 23, 2022 Share Posted July 23, 2022 This stinks of wrong power adapter. Seems this issue of suddenly no power or power issues tends to be related to the power supply input board due to the wrong polarity being introduced(CASIO,ROLAND,KORG,BOSS). In my experience I have only had to replace the whole power supply board to fix the various power related ghostly issues. Even one very annoying issue with the power switch board which has several wires coming to and out of it! Check the zener diodes and the bridge rectifier diodes in the PSU input section. Also the power regulator 3 pin IC with the built in heatsink. Sometimes(not always), the main electrolytic power cap may be blown or blowing and is in need of replacing. Sadly AFTER the wrong PSU has been introduced into the Casio, using batteries does not help.. Quote Link to comment Share on other sites More sharing options...
pianokeyjoe Posted July 23, 2022 Share Posted July 23, 2022 The "B" or "C" he refers to is the PCB revision and is no real consequence for the issue at hand. You need a matching PCB as in the circuits and ribbon cable hook ups.. CZ101/CZ1000 used the SAME internal parts. 1 Quote Link to comment Share on other sites More sharing options...
momo Posted September 28, 2022 Author Share Posted September 28, 2022 phew, sorry, summer hitted over here and now i am back with my misery with the cz... I soldered in the new board quite a while ago and gave it a try with some batteries. All LED's on for a short while, nothing on the screen and then nothing. Since then it was safely stored away and now i am trying to resurrect it once again... 2 Quote Link to comment Share on other sites More sharing options...
pianokeyjoe Posted October 23, 2022 Share Posted October 23, 2022 Ok, all LEDs lit and nothing on the screen is a dead CPU chip sadly. This is the same issue in Yamaha V50 keyboard I got rid of. And if you did suffer battery leakage on any of the main boards, then the CZ is toast. y HT3000 has eaten up circuits due to battery acid leak all over the main board that the CPU is on. Usually CPU chips do not just up an die even with bit rot as bit rot happens more with external conditions that degrade the chips like moisture, acid,rust,liquids spillage,etc.HEAT,HEAT, annnnnddd HEAT.. Quote Link to comment Share on other sites More sharing options...
CYBERYOGI =CO=Windler Posted November 16, 2022 Share Posted November 16, 2022 Check if the clock oscillator (needs oscilloscope) and reset capacitor are ok. In my AVR Transistor Tester the crystal died and so made it not start and make random problems. After soldering a new quartz in, the thing works perfectly. If reset is stuck (shorted cap) it will pretend totally braindead. Also an interrupted (high resistance) cap may make it not wake up properly. I have a Sharp talking alarm clock which reset input is such sensitive that when the cap develops only minor internal short of some 10 megohms (even temporary by air humidity), the display stays blank and nothing works. I replaced that same capacitor already 3 times and other in related hardware. Even rosin flux residues from soldering can conduct enough to make the thing fail, and of course battery leak residues (even vapours) also may make the epoxy conductive enough. Adding a pullup/pulldown resisitor of 1 megohm or such would likely permanently fix that, but also eat a bit more standby current and so drain batteries. 1 Quote Link to comment Share on other sites More sharing options...
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