Revenant

Sams Technical Publishing has original service manuals for both the MT-400V and CT-410V purchasable as either paper copies or scans: https://www.samswebsite.com/en/photofact/details/index/id/31197 https://www.samswebsite.com/en/photofact/details/index/id/31708 I don't normally recommend "pay to download" manual sites but Sams is a legitimate publishing company that's been in business selling repair manuals since the 1940s. They also have a number of other 80s/early 90s Casio documents that I don't think anyone has archived online yet.

Oops, yeah, I meant 4, not 7. It should be pins 7 and 8 on both ends of the ribbon cable (pin 1 should be marked on both PCBs).

The FI and SI signals work together to let the keyboard measure keypress velocity. If one of them is having issues, it can cause notes to play at the wrong velocity, and if you're only able to press each key once, then the keyboard is also probably not able to tell when the key is being released. I'd just check the FI4 and SI4 solder pads on both sides of the ribbon cable and make sure they're not damaged or shorting out with anything nearby (or shorting to ground).

The user memory on the WK-1800 is just battery-backed RAM. It's totally separate from the actual firmware, which uses pre-programmed mask ROM inside the microcontroller. Check out the service manual: https://www.manualslib.com/manual/2572980/Casio-Wk-1800.html LSI9 is the Hitachi MCU with built-in ROM, LSI7 and LSI8 are the RAM for user stuff, LSI3 is the sound chip, and LSI1 and LSI2 are the wave ROMs.

I assume they're the same aside from slightly different control panel colors, etc

I got the author and title ("Mei Wenti") from the service manual. He also did several of the demos for other similar keyboards from that time period (usually the titles/credits are on the specifications page in the user and service manuals.) Surprisingly, I found someone posting photos of one with a Russian-language user manual, so I guess it wasn't completely exclusive to China like I thought (which might also explain why the service manual is in English.) https://youla.ru/moskva/hobbi-razvlecheniya/muzykalnye-instrumenti/eliektronnyi-sintiezator-casio-ct870-5c37125fd138b375cc3427c1

The CT-870 uses pretty much identical hardware* to the CTK-630, but is about a year newer according to the dates in the service manuals (August 1995 vs. September 1996). You can find both service manuals online pretty easily. It was also re-released as the CT-877 a few years later. (* = NEC uPD912/913, 24-voice chip (and separate DSP chip) also used in the CPS-7, CTK-5x1/6x1 series, CTK-620L, early LK series, and others) Casio seems to have kept using the "CT" prefix for their Chinese localized keyboards until some point in the 2000s. Most of them are based directly on existing models from the CTK series, but as far as I know this one seems to be a China exclusive. You can listen to a recording of the very good demo by Ed Alstrom here: https://lifesea.org/keyboard/casio/ct/ct-877

See the MIDI info on page 59 of the manual: https://support.casio.com/storage/en/manual/pdf/EN/008/CTK591_EN.pdf The "control change" section mentions how to use the Bank Select CC to access the additional tones and drum kits.

A while ago, I tried to find some comprehensive info about the Casio models that were rebranded by Radio Shack, but it seems like the only big list I could find floating around had a bunch of omissions or outright mistakes, so I've tried compiling a more complete/accurate one. I also learned about a few models from OEMs other than Casio (namely Medeli, Kawai, and probably other companies from China or Hong Kong). The original makers of a few of these are still unknown, but I listed them anyway. Hopefully this is helpful to anyone who's interested in getting their hands on any of these models. Let me know if you spot any mistakes or anything that I left out. Concertmate 200 = VL-1 Concertmate 300 = PT-1 Concertmate 350 = PT-10 Concertmate 360 = SA-9 (= SA-7) Concertmate 370 = SA-3 (= SA-8) Concertmate 380 = SA-5 Concertmate 400 = MT-35 Concertmate 410 = unknown (not Casio, similar to Steepletone SEK-929) Concertmate 450 = SA-20 Concertmate 460 = SA-38 (= SA-21, SA-39) Concertmate 470 = SA-35 Concertmate 500 = SK-1 Concertmate 570 = SA-40 Concertmate 575 = MA-100 Concertmate 580 = Medeli MC-6A Concertmate 600 = MT-100 Concertmate 650 = SK-5 Concertmate 660 = CT-360 Concertmate 670 = CA-110 Concertmate 680 = CTK-50 Concertmate 690 = CTK-80 Concertmate 700 = MT-205 Concertmate 750 = MT-140 Concertmate 800 = SK-8 Concertmate 800 RapMaster = RAP-1 Concertmate 900 = CT-636 Concertmate 950 = CTK-500 (= CT-647, CT-648, CTK-510) Concertmate 970 = CTK-480 Concertmate 975 = CTK-485 Concertmate 980 = CTK-511 Concertmate 990 = CTK-611 Concertmate 1000 = CT-700 Concertmate 1000M = MT-240 Concertmate 1070 = Kawai FS630 Concertmate 1100 = CTK-630 Concertmate 1500 = CTK-650 CK-480 = SA-45 LK-1161 = LK-40 LK-1261 = LK-45 LK-1500 = LK-90TV MD-500 = unknown (not Casio) MD-501 = unknown (not Casio) MD-981 = CTK-451 MD-982 = CTK-481 MD-992 = CTK-496 MD-1121 = CTK-671 MD-1150 = CTK-541 MD-1160 = CTK-551 (= CTK-558) MD-1200 = CTK-631 MD-1210 = CTK-651 MD-1600 = WK-1300 MD-1700 = WK-1630 MD-1800 = WK-3000 MK-420 = unknown (not Casio) PK-200 = CTK-100 PK-210 = CTK-510 (= CT-647, CT-648, CTK-500) The "PK" models were sold under the "Genexxa" brand in non-US Radio Shack stores. Most of the rest were branded as either Realistic or Optimus. Thanks to BatteryCoverMissing for helping fill in some of the blanks.