Korg Poly 800 Battery replacement and factory reload.


In last month’s unboxing video, you may
have seen an unexpected surprise there as somebody sent me a rather nice keyboard. And, so thank you Benjamin Rumore for this
very generous donation. Before I get started, I wanted to address
a couple of issues. First of all, people are always asking me
to review professional keyboards like Korgs and Rolands and Yamaha DX-7 and stuff like
that. And, typically, I don’t do that here. I tend to focus on the older, amateur keyboards. There’s two reasons for that. Reason number one is because generally there
are other youtube channels covering the professional keyboards. Nobody else seems to be covering the amateur
keyboards like I do. So that’s kind of a niche I’m trying to
fill. The second thing is though, I can take a keyboard
like one of these and I can do a full episode on it in about 10 or 15 minutes and explain
everything that there is to need to know about that keyboard. But if you were to hand me a Yamaha DX-7 and
ask me to do a review on it, it’s going to take 2 hours to cover it in the same level
of detail. Not only that, but when I go to create some
music on it, people’s expectations are going to be a lot higher. And my musical skills are, you know, not nearly
as good as a lot of other youtube musicians and so I do better with more primitive instruments. Having said that, when Benjamin contacted
me about possibly donating this Poly 800, I almost said no, because, you know, I saw
the name Korg on it and I’m like “ehhhh, probably going to be too professional for
me.” But, I looked it up and I kind of looked at
some pictures of it and I’m like, “Well, that doesn’t look too complicated so maybe
I can do an episode on that without it being 2 hours,” so I decided to do it. Here’s a little overview. It was released in 1983, and originally priced
at a very reasonably $795. It has 49 full sized keys and it can play
either 4 or 8 notes at a time, depending on how it is configured. With the more simple sounds you get 8, but
you can combine voices to get more rich sounds and then it falls to 4. Looking at the rear, you have MIDI in and
out, although this keyboard does not fully support all MIDI features, after all 1983
was one of the first years for MIDI. This is for a foot pedal that can actually
change programs on the fly. These switches and jacks are for the cassette
interface, which I’ll explain later in the episode. These two switches can write protect the RAM
so that you can’t save changes to program or sequencer data. These are stereo line outputs, and a stereo
headphone jack, and last is a power plug. It uses 9V with negative center just like
the Casio keyboards I have. One thing I am going to tell you right off
the bat about this keyboard, though, is that it stores all of its program patches in RAM. In actual, like, volatile memory. But, it has a battery backup on the motherboard
that stores that information. It even stores the factory settings that way. Like the actual factory instruments, patches,
whatever you want to call them. So, I don’t even know, and neither did Benjamin
who sent this to me, if the current patches that are setup on here are factory original. So, I’m going to take this thing apart here
in a little while and I’m going to clean it up and I’m probably going to replace
that battery because they are known to leak and possibly damage the board. But, before I do that, I wanted to play some
of the patches that it has on it right now because I don’t even know if those will
still be around after I change the battery. Because, after I change it, all of the patches
are going to be gone and I’m going to have to use a cassette tape device to load the
factory patches back on there. So, let me show you some of those before I
even try to start restoring this keyboard or anything. One thing I wanted to mention that really
annoys me about this layout is that the numbers are labelled below the button they represent. And for some reason or another it always gets
me off and I’m always pressing the wrong button. But anyway, we’ll start with number… oops,
see, I did it again. I wanted to do 15 and I typed in 12. So really I needed, there we go. This is one of those sounds that grows the
longer you hold it. Ok, so patch 21 is a cool synth bass. 23 is a cool square lead type instrument. 31 is some kind of bell, reminds me of the
Babydoll instrument on one of my Yamaha keyboards. But if you hold the keys down, it changes. And 32 sounds like a flying saucer. Ok, now that I’ve shown that I want to start
trying to clean this thing up. It’s really not in bad shape, but it’s
very dusty and even makes me cringe to play the keys because they feel gritty. I started with my first line cleaner, which
is Windex. That removed most of the dust and dirt, and
you can see how much of it I got off just by looking at the paper towel. But, it didn’t help this spotted look on
the side over here. So, I tried some alcohol. Unfortunately, it appeared to just be taking
the paint off, and looking closely, it really didn’t help any. It may have even made it worse. So, I was thinking about the best way to solve
this. Since this area here actually looks really
good. And this part here is just a big sticker and
also looks good. I could just mask this whole area off here
and paint the thing. I wouldn’t need to mask the keys, of course,
because I’d do this when the keyboard disassembled. But you get the idea. Anyway, I recently did such a paint job on
an old Tandy computer on my other channel and that job took me 2 days just to do the
paint. So I’ve decided NOT to do that for now,
but I could always come back to it some day and do that. In the meantime, I wanted to go ahead and
disassemble the thing and have a look at the inside. This thing has some nice, big screws, very
easy to take apart. I did notice that it is supposed to have two
big rubber feet like this. However, over here it is missing a foot. However, on the back the feet are part of
the molded plastic. And here’s the first time opening. I was actually shocked at how dusty it was
inside. I mean, just look at this thick layer of dust
on everything. Believe it or not, this thing actually has
8 separate circuit boards inside of it. Thank God they used connectors on their wires
that can easily be snapped on or off. Most of the cheap toy keyboards I work on
just solder these things in place, making it a real pain to get the boards out. This thing seems to have been built really
well, though. There were a few wires I had to desolder,
such as this ground wire on this RF shield, and the two wires going to the battery compartment. And oddly enough, there was a resistor soldered
to another RF shield. I’ve never seen that before. Finally, I managed to get the main logic board
out. And eventually some of the other boards. Here are the little buttons, I’ll have to
remove all of these. And I haven’t figured out what is holding
this volume knob in place yet. And I have no idea why there are packing peanuts
crammed in here. But, I have been wanting to remove these little
things for the straps. They tend to get in my way and I don’t even
plan on wearing this and playing it on stage. So I’m going to remove them! I can always put them back if I change my
mind. The last thing to remove was the key mechanism. And this is also a really well built keymech,
too. Actually, I lied, there was one other thing. The battery compartment. This is also a well built compartment, as
most of the cheap keyboards just let the batteries ride up against the back of the circuit board
or something. I eventually decided the only way this knob
could possibly come out is by prying it. So I started work on that gently, and eventually
it did come off. It revealed a little nut down inside that
required a socket wrench to remove. But it wasn’t hard. And at last I could finally give this thing
the cleaning that it really needed. Being able to use the garden hose like this
also means I can get into all of those little crevices like these and get them cleaned out. While waiting on that to dry, I turned my
attention to this logic board. First thing I did was hit it was some compressed
air to remove most of that dust. Now I can finally get a look at that battery
that I need to replace, and some of the chips on here. Speaking of chips, this is the main CPU, which
is an 8085. Many of my Yamaha keyboards use this same
CPU, as well as several personal computers from the 1980s. Next to that is a general purpose IO controller,
an EPROM, and a communications chip, which I think this probably runs the MIDI ports. And a 4 kilobyte S-RAM chip. This is what holds the program information
that I mentioned earlier that is powered by that little backup battery. In fact, the very next thing I did was desolder
that battery. It’s actually in a weird position because
it’s not flush with the circuit board, rather it sits up just above those two chips on either
side of it. I’m at a loss why they did it this way,
knowing that this battery would need replacing every few years. I went to Fry’s Electronics to look for
a battery. They didn’t have anything with leads like
this, but they did have the standard type CR2032. And I happened to have one of these little
holders in my stash that I think I desoldered out of some other board years ago. Now one problem with this is that if you look
at the board you can see that this has to essentially surface mount. If you look at the back of the board, you’ll
see there are no through holes for it. Now, the thing is, I could probably just solder
this right down like this. There’s a big enough blob of solder that
it would hold it. But I’m concerned about how sturdy it would
be. In fact, it looks like the pins are just slightly
too wide anyway. So, I decided to bend them inwards a little
bit on both sides like this. And sure enough, it seems that this will make
it fit. So I tried soldering it in place. So, that’s actually in there fairly sturdy,
I’m kind of surprised. I don’t think there’s any problem putting
the battery in, but I worry a little about prying it out. So I decided to desolder it again, and this
time I put down a big blob of hot glue right in the center before I pushed it back down. That should help add some stability to this
thing for when it comes time to pry a battery out of it. And this is how it came out. I didn’t catch it on camera because I had
to be really quick to solder that back down while the glue was still hot. But, it’s actually sitting on a big blob
of hot glue and it’s on there really sturdy now. So I’ll go ahead and stick the battery in
there. So, I feel like I made a good improvement
here so if a few years from now I need to change that battery out again, it will be
an easy job. And just to make sure it’s actually working,
I’m going to check the voltage on the S-RAM chip, and you can see a steady 3 volts at
the S-RAM chip.. So I think it’s going to work. And now, to re-assemble it. I’m impressed with the build quality on
this little joystick. It’s held in place by 8 screws. It can take a beating. Unlike that Casio I did in my last episode
that was held in my two screws and had broken off. And once again, I’m very glad this keyboard
uses connectors. OK, so everything is all cleaned up on the
inside and put back together. Time to close it up and see if it works. I’m not even going to bother putting the
slider controls or the volume knob back on until I know everything is working. OK, so essentially I got no sound out of it. Normally, I would be worried, but I was kind
of expecting this due to the battery change. I played with some of the different patches
and eventually found one that made some weird noise. I started playing with the parameters until
I was finally able to get something that could at least confirm the keyboard was working. Now, I could, in theory, program in all of
the sounds one by one by hand. However, I haven’t really been able to find
a list of the sounds, much less the parameters that go with them. To make matters worse, I’ve read through
the owner’s manual for this keyboard and it doesn’t even tell you what the names
of the sounds are. In fact, all it says is to “try selecting
and listening to any of the 64 pre-programmed factory programs in in any order you like.” That’s about all the manual has to say about
the factory sounds. But even if I had a list, remember there are
50 parameters to be set for each of the 64 instruments, so that would take quite a long
time to program in by hand. Now, keep in mind this thing has a tape interface
designed to connect up to something like this where you could save and load digital information
just like an old computer from the 1980s. Well, I found a sound file on line of the
original default program settings. So, all I needed to do was load that file
into an audio player on my laptop. I just needed a standard male to male 1/8th
inch phone cable, with one end going into the headphone jack of my laptop, switch this
tape control to enable, and plug the other end in here. When I power on the keyboard, it says “TAPE”
on the little LED screen. Next, I press the button for load, go over
to my laptop and press play, and I notice the screen starts to flicker a little bit
while it is loading. After a few seconds, the screen changes to
“GOOD” and I guess that’s it. So it turns out the majority of the sounds
that were on this keyboard when I first got it were in fact not the factory default sounds. However, all of the ones I cherry picked for
you and played earlier in the episode are all the same except for sound number 32, which
I’ll play that one for your now. Number 12 is probably about as close to a
piano sound as you will get on a synth like this. 18 is a traditional saw wave. I’m not sure what to call this one. And if you like sci-fi sounds. 42 sounds kind of like strings. And 56 has a ghostly type of sound to it,
which is cool. So, that about wraps it up for this episode. I do apologize for not having a multi-track
recording for you but I was really having trouble coming up with anything on this keyboard
and also it has no percussion sounds built into it, so that also limits what I can do
with it. Anyway, thanks for watching and stick around
until next time!

8 Replies to “Korg Poly 800 Battery replacement and factory reload.”

  1. It's nice to see a "synthetiszer doctor" making a diagnosis and proposing – and realy doing – a very well working treatment. I'm sure that all the viewers of your 8-Bit Keys channel are all "old synth-stuff"-owners and/or they like to buy second-hand-synthesizers but are afraid to get something in hand that needs a repair. Yes, than it is realy satisfying to see someone who is not afraid to 'open te box' and making that very needed 'surgery' and knowing all electronic compounds and how to get them new and to replace them in a technical good way. Yes, this are all 'feel good videos' 🙂

  2. Thanks!! I do it with my smartphone and the app SoundCloud, the max level on the smartphone and sound level on Korg Poly 800 at 6.

  3. hey 8 bit keys look at this keyboard
    https://www.ebay.com/itm/Casio-ToneBank-CT-670-61-Key-Keyboard-USED/264183362345?epid=1523695285&hash=item3d828e3329:g:6DoAAOSwQqNcWwKY

  4. Below is an 80s Russian music video featuring this keyboard, most of the synth sounds in this song is made on this keyboard, and this one has black keys!

    https://youtu.be/tUBVEKzsZ-k

  5. I don't think the distinction between "professional" vs. "amateur" keyboard is so drastic in the sub $1,000 instruments. In fact, some amateur keyboard instruments are often more feature rich than their professional counterparts. I mean, a "consumer" market Technics AX7 beats this little "professional" Korg keyboard many times over in terms of complexity.

Leave a Reply

Your email address will not be published. Required fields are marked *