daveb22 Posted December 31, 2021 Share Posted December 31, 2021 Hi, looking for some advice. I acquired a CZ-1 with a faulty keyboard. The first octave works but triggers on both key down and release and then holds the note continuously. None of the other keys do anything. I removed the keybed and cleaned and reseated all the ribbon connectors and cables but hasn't helped. The synth works fine over midi so i'm assuming it's a component issue on the board. Would anyone happen to have seen this issue and maybe know what would need replacing? Thanks - Dave. Quote Link to comment Share on other sites More sharing options...
IanB Posted December 31, 2021 Share Posted December 31, 2021 Hi @daveb22, just looking at the service manual it looks like the keybed PCB is split into three parts with jumpers between them? Is that correct? Is the octave that kinda-works on its own PCB? Does the CZ work okay controlled by MIDI? cz1.pdf Quote Link to comment Share on other sites More sharing options...
daveb22 Posted December 31, 2021 Author Share Posted December 31, 2021 Hi @IanB, yes the synth operates fine over MIDI. The 3 PCB's are connected by soldered ribbon cables which all looked to be in great condition. There is also a master ribbon that connects the 3 PCB's to the main board. It is soldered at the keybed side but plugs in on the mainboard side. I cleaned and reseated this but didn't help. I suppose it could be a dry joint issue but the connections are a little close for me to start weilding my untrained soldering iron at them! I followed this video for the teardown - Quote Link to comment Share on other sites More sharing options...
IanB Posted December 31, 2021 Share Posted December 31, 2021 Hi @daveb22, something to do would be to get those keyboard PCBs out, shine an angled light source (shadows help) and use a magnifying glass to look for cracks. If the problem isn't there, the bad news is that the whole keyboard is controlled by one custom VLSI chip so it would mean finding a donor machine to donate a PCB more than likely. If you have a tester (multimeter) check the continuity of those jumpers and ribbons. Solder joints can look fine, but be in fact dry. Looking at the dodgy photocopied manual, it looks like the controller chip "MSM-6200GS" is on the same PCB as two octave s(and a bit) of keys. Is the octave that's working on that PCB? Quote Link to comment Share on other sites More sharing options...
IanB Posted December 31, 2021 Share Posted December 31, 2021 Just skipping around in the video, it looks like the keyboard VLSI is approximately in the middle at 13:14. Oooh, I see an awful lot of connections between PCBs there! Quote Link to comment Share on other sites More sharing options...
daveb22 Posted January 3, 2022 Author Share Posted January 3, 2022 On 12/31/2021 at 4:14 PM, IanB said: Hi @daveb22, something to do would be to get those keyboard PCBs out, shine an angled light source (shadows help) and use a magnifying glass to look for cracks. If the problem isn't there, the bad news is that the whole keyboard is controlled by one custom VLSI chip so it would mean finding a donor machine to donate a PCB more than likely. If you have a tester (multimeter) check the continuity of those jumpers and ribbons. Solder joints can look fine, but be in fact dry. Looking at the dodgy photocopied manual, it looks like the controller chip "MSM-6200GS" is on the same PCB as two octave s(and a bit) of keys. Is the octave that's working on that PCB? Thanks for the advice, i'll give that a go. The working keys are the first octave C0-C1. As I say, they trigger on press and release but then just stick until power cycling. 1 Quote Link to comment Share on other sites More sharing options...
pianokeyjoe Posted January 6, 2022 Share Posted January 6, 2022 The issue seems to be the keybed processor ic in the center board sadly. How to verify? Unplug that keybed, and use the synth with midi. If everything works as it should through midi without the keybed plugged in, you just isolated the issue. The following keyboards have this same or similar keybed and contact board assembly: FZ1,VZ1,CZ1,CPS201,CT6000,HT6000, and there maybe another keyboard model out there that is not in the archives for US based models, that will have it too. Check for these models to make sure. I have the FZ1 keybed, CT6000 and CPS201 keybeds and contact boards... Not wanting to sell them as I need them for my perfectly working units but you need to look for any of those other models for your donor parts.. Quote Link to comment Share on other sites More sharing options...
Chas Posted January 16, 2022 Share Posted January 16, 2022 I wonder if the HT6000 key bed might not be the same as all the others you listed @pianokeyjoe, as the others all have aftertouch as well as velocity. The HT6000 only has velocity. Also, my CZ-1, VZ-1 and CT6000 keyboards all feel the same to play (or very similar), whereas my HT6000 keys feel noticeably lighter. Probably not an issue that is going to affect anyone looking for a replacement key bed for a CZ-1, as HT6000s are on the rare side and unlikely to be parted out! Quote Link to comment Share on other sites More sharing options...
pianokeyjoe Posted January 17, 2022 Share Posted January 17, 2022 6 hours ago, Chas said: I wonder if the HT6000 key bed might not be the same as all the others you listed @pianokeyjoe, as the others all have aftertouch as well as velocity. The HT6000 only has velocity. Also, my CZ-1, VZ-1 and CT6000 keyboards all feel the same to play (or very similar), whereas my HT6000 keys feel noticeably lighter. Probably not an issue that is going to affect anyone looking for a replacement key bed for a CZ-1, as HT6000s are on the rare side and unlikely to be parted out! Well sir, the HT6000 is non weighted like the CPS201 keybed. And like the CPS201 keybed ,is velocity only. The contact boards are the SAME across all models involved however. How I know? I have my CPS201 contact boards, the CT6000 contact boards and my full FZ1 keybed assembly.. The aftertouch is just a resistive strip under the front felt strip under the front of the black keys/middle of white keys, or an aluminum bar under that same area that the key HOOKS push down on. In both cases, the AT wires lead to the mainboard and not some small board under the keybed like you would find on a YAMAHA DX7 or something of the same era. The weight of the keys of the CZ1 are LEAD weights under the front of each key HOOK, hidden. The CT6000 is the SAME but STEEL instead of LEAD, so it is slightly lighter. Also of note, is the SPRING tension of the key springs, which aid in the weighted feel(bounce). The FZ1/VZ1 are the only keyboards to feature a more traditional flat lead weight under the very front of the white keys(you can SEE it and FEEL it), and a more heavy lead weight hidden under the front of the black keys. Think Roland D50 keys. The HT6000/CPS201 where non weighted at all but CAN be weighted DIY or just do what I did, take a spare set of VZ/FZ keys and swap them out or use the ones off a CT6000. REMEMBER to swap the SPRINGS too! But outside the plastic keys, the contact PCBs are the SAME and you can fix that lovely CZ1 with a center PCB from one of the other LESS costly units like the CPS201. Quote Link to comment Share on other sites More sharing options...
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