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!

Korg Poly 800 Battery replacement and factory reload.

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