DIMITRIS73GR

Hello,the ICs were brand new.I ordered 2 of them and tried both...

No,my test meter is simple and doesnt have frequency meter...Thanks for your help..I am searching for the main board on the internet...I hope one day I ll find one to replace the defective board...

Hi,I tried the diagnostic program,no respond.I have the correct voltage on cpu ic but I dont have an oscilloscope. The only button that working is the power on.If I try to power off from the same button nothing happens...You are right I think also is CPU or bootloader.

Hello,how are you?.. I received the vram ic i changed it but nothing...still the same...I think this is the end of my keyboard...the m1am main board cost 228 us$ so I will stop repairing it..

Thank you very much for your interest and help...I will replace the ic and I will inform you for the results...Have a good day!!🙂👍

Thank you for your help...All other ics are not hot in the board.The cpu is almost cold just a very little warm.The only hot ic is a regulator wich is normal to get hot.It has a heatsink and the output voltages are fine.. If this repair does not work how to use another mainboard?..Is ti possible?..I think only ctk-900 is identical but I cannot find that either.. I visited the casio unkyard but no spaares fro my model...

voltage goes to ic is 3.3v.

Thank you very very much for your help...These ics are identical.The one is not hot,the other is really very hot.The voltage on the ics is fine..You said if vram is shorting definetely would cause to no boot..That makes me very happy because I found the ic on ebay (its very common) and i have the knowledge to desolder and solder the new ic with hot air gun..

Hello, I own a casioctk-691 that was working fine but suddenly stopped working.When I press power button the LCD goes ON but on screen shows something like I press a lot of keys/buttons at the same time,some letters are half.Also none of the keyboard buttons and keybed keys working.No sound at all.It looks like cannot boot or load the firmware to continue.Also I cannot turn it off from power button and I have to unplug the ac/dc power plug..The 9v adaptor is fine and also I used another bench adaptor with the same results.With batteries same result also. I disassembled the keyboard.The power supply board is fine.All dc voltage/capacitors/diodes according the service manual are ok.The cpu board gets all the 5v,9v,3.3v power..I found only that 1 of 2 Vram ics getting very hot quicly.If Vram is faulty IC can this be the reason for no booting or Not?..I tried the factory reset but because buttons not working nothing happens..I sent message to CASIO for a spare pcb but with no luck..It is my favorite keyboard and I will be very glad if someone with knoledge can help me or any ideas? Sorry for my long message, Thanks, Dimitris. 😊