Casio HT-700 Repair and Review 

This will probably be buried but my mom had this keyboard when I was growing up. Seeing this really brought me back. Keep up the good work, both of your channels are amazing!

I absolutely love how this keyboards sounds! It hits the spot right between realistic and synthetic.

I have no clue about electronics nor do I play piano/keyboard however between you and Markusfuller's channel I love watching these Teardown/Repair videos! Thank you, I appreciate what you do.

8-Bit Keys, the most criminally-underrated channel on RU-vid.

That new intro song is just pure love in my ears

Here's a brief look into the synthesis engine that the HT-700 uses. The HT-700 uses a synth method called "Spectrum Dynamics" or SD for short. SD works by using two digital oscillators where one is used as the main body of the sound and the other as overtones. The overtone and body oscillator have their own DCA that allows their volume to fade in and out independantly of each other. Both are then mixed together and sent to the analog filter section which has its own DCA as well. Then it's outputted to amp and thats it. The biggest issue with SD, or rather Casio's implementation, was that the Oscillator DCA's were nonprogrammable and thus you ironically had no control over the very thing the SD was special for. All you could do was choose waveforms and that was it. Hope you all found this tid bit interesting.

The sound of that keyboard is stellar. Just, what else can scream "welcome to the 80's" quite like that heavily synthesized audio? It's the sound of video games from the late 80's and 90's and it encapsulates the childhood of so many people and grants a feeling of anemoia for those who missed out on such media because they were born too late to grow up with it. Such a cool bit of kit and I'm glad you were able to get everything working again. It makes some great sounds for when you really want to embrace that synthwave genre.

If I'm using an old keyboard, I'm not really looking for "realistic" sounds. There's usually sort of an uncanny valley effect on these kinds of keyboards. A clearly synthetic voice is more appealing to me than a somewhat realistic voice that isn't quite realistic enough to pass off as a real instrument. If I wanted a good piano sound, for example, I'd just use a real piano. I like old keyboards specifically because they sound synthetic.

That doesn't sound like a bad keyboard. It has rather unique sounds for the instrumental music.

Excellent video as usual David!

I got this keyboard for Christmas 1987. I still have it. It’s still in great shape and I’m pretty sure I even still have the manual for it in my big box full of manuals in the garage. I haven’t touched it in quite a few years but you have made me want to dig it out and dust it off and your channel(s) has made me realize that it deserves a home in my retro game room. Thanks!

There's a rumor going around that Michael Jackson's change in appearance was due to the 8-Bit Guy trying to Retrobrite him.

My oh my, the Typhoon sound though! The 80's just blew through my headphones and into the cosmos beyond. Thanks, Casio and 8-bit guy!

You owe us no apology for setting your own schedule. Besides, 1-2 a month on a side channel is cranking them out pretty good.

I love these restoration videos

Did nobody else notice when he was going over the sounds he left it at synth bass for like 3 sounds?

I freaking love it when this man repairs stuff. I'd break something for him just to watch him repair it lol. Not something of his of course, but mine.

You make interesting videos, keep doing your thing, I enjoy watching them! :)

Hey David! I'd love to see you take on other older electronic drum machines, keytars, and other unique ones. I loooooove old electronics and love how you break down features and how they're made. I think one of my favorite types of videos you do are restorations, there's something so.. Calming about it! Thank you for the great content!

The sounds are very agreeable to me even though they are synthetic. The kind of stuff you pay a premium for these days.

I love how Enya is your go to demo song ❤️❤️❤️

"but these are pritty rare and i don't have one" WELP YOU KNOW WHAT YOUR MAIL BOX WILL HAVE NOW DON'T YA?!

You did an astonishing job of restoring this keyboard, you proved that even a cracked or rusty motherboard can be still used by desolder and wiring stuff directly to eachother. I am amezed that once you extended those screw holes by drilling that you did not end up drilling trough the other side of the plastic.

I've grown up always using this keyboard as a kid and I was always used to the bad harpsichord samples on this keyboard so I never knew what a real harpsichord sounded like until recently

Yes! Ace Hardware is my absolute go-to place for things like screws and fasteners. Lots more selection than at Home Depot.

This was my first keyboard. Loved it at the time. Interestingly, I really liked the data entry knob *because* it had a hard stop. Easier to "feel" without having to look at the display. Each to their own :-)

Glad to see the synth was easy to repair. It has quite a distinct sound across all instruments - the Typhoon one reminds me of Giana Sisters and the Level 1 music!

I have zero interest in keyboards and yet I very much enjoy this channel and have watched all videos because they are well made and very relaxing. Thank you 8-bit guy.

Oh, that backgroundmusic took me back to the eighties!

Happy today, 8-bit keys and techmoan videos.

No need to apologize. I think your premium quality content well worths the wait.

That outro tune is just magnificent. See you next time, David!

Wow this synthesizer produces great sounds!

2:48 Stewie Griffin pronunciation of "wHHeel!"

I love the new intro theme. It sounds a lot better in this episode than it did in the next episode.

your example of how-to doing small repairs is valuable and inspiring. thanks!

At 9:32, you should have held down a chord as you had fingered mode on or selected chord mode and held down 1,2,3 keys to the right of the root note. Also this keyboard had a built chorus unit to fatten up the sound, this was lost as the recordings sounded mono. The Data entry control pot was much quicker than just having up down keys, and was a luxury at the time :-) Sounded bright and interesting in it's day, a cheap multi timberal midi keyboard with a analogue filter with resonance although very limited + Song recording + chord + bass + drum programming.

8-bit keys makes my inner high school ebm goth kid smile.

I really liked the song you made!! The sounds of this keyboard really remind of the late 80s.

JB-Weld FTW! It's great stuff ...metal filled epoxy, dries at room temp, reasonably long work time, and it can be sanded and drilled once dry. I used to use it all the time in robotics projects in college. I even know a guy that fixed a crack in the engine of his WWI biplane with the stuff. It was a stop-gap solution, but he managed to fly it home! It should definitely be your go-to for any broken plastic.

I love that sound to be honest

The NEC D23C256 is a 32kByte mask ROM. Those other OKI 6294 Chips are 8KByte of static RAM each, no ROMs. And yes that D78C10 is in fact the CPU. From all I can see that "MIDI Controller Chip" is just another static RAM, but a very fast one, like the cache chips for old 80486 boards. Edit: The OKI 6294 are not static RAMs but percussion generators. Very misleading numbering. The small "MIDI controller chip" is a static RAM but not a fast one, just a small one.

I can't play piano or know much about keyboards but I love the synth noise and repair tips you give, you're making me a better repair person!

What made the Roland D-50 so great and groundbreaking was it used PCM samples for the attack/decay and synth for decay/release. So the sound started sounding real, but didn't have to end after the sample is finished.

you should cover one of casio's early 80s vowel consonant keyboards, the mt-65 is essential

Omg! I have a hardware store and I wish my clients tried to find the screws they need by themselves. They are always like: "too short.... too long.... too thick.... not the right type etc......" and I am so boreeeeddd.. I wish I had David as a client he could have as many screws he want for free!

I have one of these keyboards that I nabbed for $5 from a local yard sale. Its not the be-all and end all, but a few things that were overlooked in the video were the asdr envelope, the filter/resonance, and envelope controlling the filter. There's also chorus which is nice. Although you have limited access to your sound modifiers, you can get around this a little bit by setting your jog dial to something you want to control such as the cutoff for the filter , or decay...and sweep the dial- This is really nice for pads, arpeggios, etc. The jog wheel is a little bit steppy, but for so cheap, its permissible imo.

This was my first keyboard that I got back in the late '80s, and I still have it. For a consumer-focused synth, it has a surprising amount of flexibility. I actually ended up making my own sounds quite often. It is built quite cheaply, but mine has held up pretty well considering it's over 30 years old. The speakers occasionally come loose, and the power adapter has suffered years of abuse and had to be replaced eventually. There are also two keys whose hinges have broken, and now they are held in place with tape. I haven't taken it apart again to look at them, but I assume that the hinges are simply just bending plastic that eventually broke through. Even after I got a Boss DS-330 and eventually software synths, I still continued to use the HT-700 as a MIDI controller until a couple of years ago. In spite of the tiny keys and fixed velocity, it served that purpose well. I mostly do step programming, so it wasn't really an issue. I plan to hold onto this synth indefinitely. It may not be amazing compared to the other synths I've acquired since then (both hardware and software), but its hybrid nature creates sounds that I haven't encountered anywhere else.

1:30 The OKI chips are definitely some sort of ROM chip or something for sample storage. They were a very popular manufacturer of PCM sampler chips for arcade games (usually used with FM chips by Yamaha) so that's the only logical conclusion.

I'd like to see a casio cz series keyboard on the channel. They were aimed at amateur musicians and their sound is wonderful.

Yeah, I found that too. fixing old keyboards can be surprisingly easy. I have a 1998 Yamaha PSR-79 keyboard that I got around that time, and through my own bad judgement it ended up with battery corrosion, and about 1/3 of the keys stopped working. When I checked inside, the damage wasn't too severe, but I did notice how the keys themselves were basically just a dumb switch matrix attached to a ribbon cable. Sure enough, a continuity check on the ribbon cable with a multimeter showed that two of the wires were broken. So... I got some lengths of wire about the same size as the ribbon cable, and soldered it between the two ends of the broken wires... And that fixed it. Nothing complicated. Anyone with a very basic understanding of how to solder and use a multimeter and a bit of logic could have checked it, worked out what was wrong, and fixed it. It CAN be that simple in some cases...

Always enjoy watching your videos David, reminds me of my childhood, with all the "old" tech

That synth bass ? (at 7:48.. i think you forgot to change the preset name) with some little reverb would sound fantastic.

David, did you keep polarizing the speaker? If not, will be played in the counter-phase to another speaker.

Simply the best retro site I have ever seen. clear and easy to follow. Some of those old boards were so much fun. I owned a Casio Mt800, PT80 and a Poly 800. All the best and thanks

Man, I love this channel's content. It's two of my favorite things, electronics and music, combined into this eargasmic concoction of perfection!

i love my ht 700

Do you think it would be possible for you to make a video on retro game OST composition? What are the specifics compared to composing songs for anything else?

That multitrack sounded a lot like one of the songs for the game Raptor: Call of the Shadows, one of my favorite top-down fighter plane shooter games. Really fun to listen to!

That song at the end...total vibes of an 80's 16 bit adventure game of some kind

The end reminds me Dschinghis Khan - Moskau

Great video, as usual. You seem to have been infected by the "so" language tic in this one, count the number of sentences you start with "so" :P

Owner of an HT3000 here! This will come in handy if I need to repair it.

Thanks for the 8-bit Keys update David. I love the teardowns and the homemade demo songs!

We are number one but it's performed by David Murray

@7:00 enya

David, you are a darn good musician. Keep doing what you do!

Your song at the end got my son to start dancing. Thank you

"The electric piano sound doesn't sound that great". I strongly disagree!

I like this thing. But I don't like the new Intro track :(

that's why when I take apart things to salvage, I always keep the screws. I have amassed quite the stockpile, and I even have the exact ones you needed.

it's good to see these once in a while. I don't even like music (I usually skip the multi-track sample you do) I come for you (david) would pretty much watch all your channels

I always like your videos. But did you realized that you used the word "so" too many times... Without wanting to belittle the way you speak, you could improve on it. big thumbs up for you....

You know, I really love seeing videos where you repair a thing at terrible condition.

I had this keykoard back in the early 90s, it rocked!!!... it's mainly feature for me was the kinda sequencer it has, it allowed me to make complete cover of various songs like "Big In Japan", "The Year of the Cat", "I Love to Hate You" and others... I could program drums, bass and strings very close to the original songs... I mean, at 13 years old I made karaoke samples in my room... 30 years ago!!! Man, I miss that keyboard...

I got a HT700 a few years ago (picking it up is it's own story) and i love it. I use it for my side-project and already did the synth-pan flute sound in "Escape" with it.

The new intro song is just awesome.

I had one of this in 90's, had a lot of fun with it and used it in a rock band that I played.

I'm glad you don't love the HT-700 as much as I do, or the 2nd hand value would skyrocket! This is a beautiful, programmable, 80's Casio with a resonant analog filter! Thanks for down-playing it!

my Dad has that key board he bought it new in 87 and still has it tucked away in the closet we fired it up a few years ago it was a little dusty but still works well the midi options really wake that thing up lots of fun best 300 dollars spent back in the day !!

Coming for retro tech. Staying for the AWESOME music. I love the tracks you're usually playing

The more and more I watch this channel, the more curious I am about what an old true professional keyboard sounds like.

Gotta say you're an amazing engineer. I watch your explanations of how you fix the keyboards and kinda half-understand what's going on (still better than I've understood anything like that before :D). It's amazing what you're able to do with something that many people would just write-off as "doesn't work anymore". I've always liked these sorta synthetic instruments where you can still kinda tell what instrument they're "supposed to" sound like, but they don't quite make it and end up with their own colour and character instead. As opposed to something like general midi where the instruments do often make it most of the way but just end up sounding limited or simplistic.

After watching your videos for a while I decided to get a retro synth and I love it. Thanks David!

I'm a big fan of your channel!! I have the HT-700 and really appreciate the insight into its inner workings! Keep up the great work!

Love whenever there are repairs on this channel. Although, this must be the most time consuming type of video.

I remember really wanting this keyboard so much back in the mid 1980s! I ended up with a Casio MT-100 instead and then a Yamaha PSS-560. Finally I had a Casio MT540 and a Yamaha PSS-790 before moving on to a professional Yamaha SY55 which I still use. Oh I nearly forgot, in 2011 I bought a Yamaha DJX for a bit of fun and sold it a year later.

As person that loves channels like yours, I'm always dealing with the lack of screws

I do love the SD sound. I had the HT3000 but sold it when I got the Hohner version of the HT6000. It’s off-white and has ring modulation. So cool.

Been waiting on this for a while. Great video!

Awesome fix. Its always really fulfilling, being able to revive old equipment. 🐱‍💻

Is it strange I love this channel more that your main one

Great episode! I really like this kind of sound, as I grew up in the eighties.

Wow your intro theme remixes keep on getting better - you should put them all on your Soundcloud.

Thanks for fixing my HT-700, David!

I absolutely love you videos! The way you show every step is extremely helpful; I do stuff like this too from time to time and I have never heard of de-soldering braid until watching your channel. Needless to say, I'll be buying some!

I had the HT-700 way back in 1987. Thanks for posting.

You know its gona be a good video when the intro is different

I've worked at fastener warehouses, and I often frequent a warehouse near me for random stainless guitar screws. Look around your area for wholesale fastener warehouses and you can usually find a blister pack of whatever screw you need, retail hardware stores usually only carry what sells and special order from the. warehouse what they need. if you look up the warehouse and stop by, you can get your #3s, usually for free because they'd rather hand it over than deal with an invoice for a dollar's worth of hardware.

Those waveforms are great. Now I want one.