Hello and welcome back to the 8-Bit Guy. So, I’m sure you guys have seen this little
TV in a lot of my episodes. I’ve been using it for years, and I’ve
actually had this in my possession since 1997. I have a little story to tell you about that. I was actually working at AST computer. I worked in the tech support department and
I actually have a lot of stories about that. And I actually hope to compile some of those
little anecdotes for a video at some point. But, one of the things that actually happened
around 1997 is that AST was having some financial problems and they were actually being bought
out by Samsung. And, one of the things Samsung wanted to do
to help enlist the trust of all their newly acquired employees was to give them all a
gift. And, we had the option of receiving either
a little TV like this one, or a VCR, or a microwave oven. I actually opted for the TV. And it’s actually been a really fantastic
little TV. Now, I want to point out that when I first
received this, it was 1997 and I was 22 years old, and I was living in a 1 bedroom apartment
with my newly married bride. Well, at the time we didn’t have a lot of
money and this actually became our bedroom TV and we actually watched TV on this. This is, this little 13 inch TV, it’s hard
to imagine, this is actually what we watched TV on every evening for probably a couple
of years. So, for the last 15 years or so, this has
become essentially just a monitor for me. I don’t really use the TV part of it anymore. In fact, I couldn’t even if I wanted to
because analog TV doesn’t exist anymore. But, it makes a really good little composite
monitor for hooking up to a Commodore, Nintendo, or Atari, or something like that. But, it has been brought to my attention,
repeatedly, over the last several months, that it is actually possible to mod consumer
televisions like this to display an RGB signal. Specifically, an analog RGB signal. Now, why would I want to do that? Most every computer made since the late 1980s
has either supported some sort of RGB video signal, or just flat out required an RGB monitor. However, there are a variety of different
standards. So the Amiga, for example, used this 23-pin
connector. The Apple IIgs used this 15-pin connector. IBM CGA and Tandy machines used a 9-pin connector. And of course, VGA is also a type of RGB signal
as well. An RGB signal typically consists of 3 separate
wires carrying the red, green, and blue signal. There is also typically a sync signal and
a ground. Of course, any Color CRT television has to
break the signal into RGB at some point because that is how it is delivered to the back of
the cathode ray tube. However, that is a high voltage signal at
the back, so ideally you’d want to feed the RGB signal somewhere on the low-voltage
part of the board. Let’s take this one apart and see what we
can find. OK, this is all pretty standard stuff for
a TV from this era. First thing I’ll want to do is discharge
the tube. This spring appears to be connected to DAG
ground, so I’ll attach my alligator clip to that. I’ll attach the other end to a screwdriver. And I’m not really expecting anything since
this has been powered off for days and most TVs from this time have a discharge resistor. And yep, there’s nothing. I’ll go ahead and remove the suction cup. And now I just need to start unplugging things. I’ll start with the tube itself. And eventually, the board will come out. This thing is a bit dusty. I’ll go ahead and hit it with some compressed
air. OK, so looking at this board, there are only
two chips we need to focus on. One is this micro controller. This chip drives the on-screen display, tunes
channels, listens to the remote control, etc. This other chip here is what is commonly referred
to as a jungle chip. Almost every TV from this time period has
one. This chip does most of the signal processing. One of the things the Jungle IC does is it
takes in the composite video signal, and then decodes that into RGB and outputs it to the
high voltage part of the TV. However, it also accepts a direct RGB signal
from the micro controller for the onscreen display. But in order to know when to switch to that,
there is another line called the blanking signal, which the micro controller will output
when it wants to use the screen. So, what we need to do is tap into this RGB
signal here and take that to the back of the TV. And then we need to locate 5V somewhere on
the board and run that to a switch at the back of the TV that we can use to force the
blanking signal whenever we want, so that the RGB signal will override everything. There’s still one piece of the puzzle left. You still need to get sync from somewhere,
well, we can use the regular composite input for that, because the jungle chip is designed
to overlay the RGB on top of an existing signal, so it will still be looking for the sync signal
from the composite input. OK, so that’s the rough explanation of how
this works. Now, I’m not going to go into great details
about resistor values and stuff like that because every single TV is going to be a little
bit different. In fact, analog electronics is not exactly
my strong suit. I actually got a lot of help from a guy named
Mark Cowan who looked up the schematic diagram for my particular TV model and he actually
helped me figure out which resistor values I needed for mine. Now, let’s get to modding. One of the first things I’m going to do
is place a jumper wire across this resistor. I’ll be honest in that I don’t fully understand
why I’m doing this, but I was told it would improve the picture quality. This has something to do with the closed-captioning
circuit where it dims the background around the text, and apparently we want to turn that
feature off. And that should do it. Now, these 3 resistors here are on the red,
green, and blue lines and their purpose is to lower the voltage coming from the micro
controller to the correct input voltage for the jungle chip. Now, what we need to do, is add in another
3 resistors in series to these, like this, and then we want to run our external lines
in between them, like this. So, the way I’m going to do that, is I’m
going to heat the legs up on one end of these resistors and pry them out. Then I’m going to straighten the leads on
them. I’ll use some desoldering braid to soak
up the solder and open these holes back up. Then I’m going to take these 3 new resistors
and put them in those same holes. Like this. And then I’ll solder in those resistors
from behind. And so what I’ve done is connected the resistors
together in 3 little triangles and soldered wires to the top of the triangle. I’m putting some heat shrink on just to
make sure they never touch each other. And there we go. There was also this unused connector port
on the board, not sure what it was going to be, but it has a ground available, so my 3
signal grounds are going to connect here. And there’s also a 5V signal in this same
unused port, so I’ll connect to that for our little blanking switch. And I’ll just solder those in from the back. And then we need to connect a wire to the
blanking pin on the micro controller. That’s where our 5 volts will go when the
switch is turned on. It’s pin 25 on this chip, so I’ll just
put some solder on the leg here, and then I’ll come back and just solder my wire directly
to it. Like so. Believe it or not, that is all of the modifications
that need to be done to the board itself. So, I’ll go ahead and reassemble everything
for testing. Now, I have this really long ribbon cable
coming out of the TV. But, for the moment, I just want to find out
if the TV is still working after all that I did to it. So, I’ll connect up the Apple IIgs from
the composite port and hopefully the TV doesn’t blow up or anything. Well, here goes. Ok, no smoke or anything, so that’s a good
sign. I did notice the onscreen display is a little
dimmer than before, and I think that was to be expected with the mods that were made. But it is still plenty readable, so that’s
fine. Let’s power on the Apple IIgs. And we have a picture, exactly like it should
be. OK, all good so far. Next, I want to do a quick and dirty hack
here to test the RGB. So, I’ve taken the ribbon cable and wired
it straight to this 15-pin connector. I’ve also just tied the blanking wires together. So, I’ll plug this into the back of the
Apple IIgs. And let’s fire it up. To my amazement, it worked first try. And the signal is amazingly clear. Although my camera isn’t cooperating since
the polarization is causing a moire pattern on camera. But I’ll try to get some better closeups
later. But for the moment, I’ll just run through
these colors to make sure everything is correct, and it is. I will also set it to 80 columns for a quick
test. Typically 80 columns on a television is unreadable. However, it is very readable here. Again, I apologize for the moire pattern,
but I’ll get you some better footage later. So, what I need to do now is figure out where
in here I can mount my connectors. I want to mount this switch and these 3 RCA
jacks. The trouble is, if you look back here, there’s
a lot of stuff potentially in the way. I definitely don’t want to have the wires
or back of the jacks bumping into these heat sinks, the flyback, or anything else. Now, there’s actually space on the side
of the monitor, but I don’t think that would be particularly elegant. So, I think I’m going to put them up here. As always, I’ll put down a piece of masking
tape to mark my holes. That way if I mess up, I can just put a new
piece of tape on there. I like all of my stuff to line up nicely,
so I’ll start with a straight line. Then I’ll mark 4 spots that are 15 millimeters
apart. Then I’ll use a tiny drill bit to mark a
pilot hole on each one. After that, I don’t need the tape anymore. Then I’ll drill the larger holes. And as you can see, perfect fit. OK, so I’ve mounted the RCA jacks and toggle
switch. Since I was not able to find any colored RCA
jacks in time for this video, I’ll just add a little label here for that. And, this switch of course will enable or
disable the RGB input. Now what’s left to do is solder wires to
all of these things. And so skipping forward a bit, I’m just
about finished with that. Now, this is an entirely separate ribbon cable. And so my plan is to place an IDC connector
at the end of this ribbon coming out of the TV. The goal is that I want to still be able to
remove the back cover of this TV without having to desolder stuff. So I need a way to disconnect things. And so, I thought adding this connector would
work well for that. Unfortunately I ran into a problem on the
other side. I thought I ordered a pack of male and female
IDC connectors for ribbon cables. But the male connectors ended up being for
PCB mounting, not for mounting on a ribbon. And I didn’t even notice that until just
now. You see, I was thinking these would be just
like the female versions where I could put the ribbon cable in. Since it could take several days to get those
ordered, I’ve decided to take a shortcut for now. I’m going to plop one of these little guys
here on my quad hands. And then I just soldered all of the wires
directly to these pins. And then, to make sure these don’t contact
anything inside the TV, I’ll coat everything with hot glue. Now, I did order the correct replacement part,
which I’ll have in a few days. But for now, this should work. And so, as you can see, I can now take the
two halves of the TV and connect them together like this, before I reassemble everything. And now, I’m going to need 4 RCA jacks I
can connect to my Apple IIgs. I’m still going to use this little prototyping
connector for the moment as it is fast and easy. But ideally, at some point I will want to
properly build a permanent cable for each of my systems. And here’s another annoyance. This cable set was originally advertised as
being several feet long, and it’s actually really short. Originally I planned to cut it in half so
I could use it on two systems. Now it looks like I’ll need to just cut
these off at the end here. And so I’ve now wired these into the video
connector. And on the other side I have red, green, blue,
and sync. So I can go ahead and plug these in here. And the sync actually goes in the original
composite port. Pity the cable didn’t have a yellow plug
to match. OK, lets try this again. OK, on first try, I got nothing at all. But then I thought, maybe I mounted the toggle
switch upside down. I’ve been known to do that. So, let’s flip it the other way. And try again. Yep, it works! OK, so let’s try some games. Wow, this looks really amazing. I want to show you some comparisons with composite
mode. So I’ll flip the switch back to composite
and check out the difference. It’s probably more noticeable on a closeup,
so we’re still in composite, and look how much clearer it gets when I flip to RGB. So, let’s try another game. So again, we’re in RGB now, and here’s
composite. Let’s zoom in a bit. Here’s composite. And now back to RGB. So, let’s try this Tandy Color Computer
3. It has a funky RGB port on the bottom, so
I constructed this little cable for testing. I could probably make something more elegant
later. So, let’s give it a try. And it works! So, again let’s do some comparisons. I’ll switch it to composite mode and the
text is much harder to read. And back to RGB. Let’s try a game. Wow. This looks great. I’ve never seen a Tandy Color Computer connected
to RGB before, and it looks like a whole different computer. It’s really amazing. So here’s another comparison, let’s switch
to composite mode. And back to RGB. OK, well, how about this Tandy 1000 It is
designed for a digital RGB monitor. So it does require some slight modification
to the signal to convert to analog RGB. Just to help you visualize the difference,
if you looked at an analog RGB signal through an oscilloscope, it would look something like
this. By varying the voltages, almost an infinite
number of colors can be created for any given pixel. And that’s what we’ve been working with
up to this point. But what would digital RGB look like? Well, by its nature, digital is either on
or off, a 1 or a zero. So it would look like this. However, this setup would only allow a combination
of these 8 colors to be produced. So, what they do in this case is add an extra
pin into the mix called the intensity pin. By using this extra pin, it doubles the number
of colors, by creating brighter versions of each color, thus giving you a total color
palette of 16 colors. And that is how CGA video works. So you need some extra circuits to convert
a signal like this to analog Fortunately, I have this prototype device
here from TexElec which will do just that. So I’ll just plug in my RGB cables. And let’s fire up the Tandy. And check it out! It works! Now, there’s some overscan but I’ll deal
with that in a minute. Now the Tandy also outputs a composite signal,
which you are seeing now, so let’s put it back to RGB mode. Yeah, the difference is quite remarkable. So how do we get rid of the overscan. Well, this TV has a secret service menu that
you can access. The service manual tells you the code to press
on the remote, and here it is. There are a variety of adjustments I can make
in here. And, as you can see, I can move the picture
around and make it smaller. And, so, I’ll try Planet X3 in CGA mode. Looks good! Next, I’ll try it in Tandy mode. And looks good there too! Well, the Commodore 128 uses the same type
of monitor as the Tandy, when using the 80-column display, so let’s try that. And there we go. And it’s definitely readable. So, let’s find something with some color. I mean, I guess I could have booted up GEOS,
but it’s all black and white anyway. So this is great, I wish I had known about
this years ago. I wanted to try one more thing before concluding
this. I wanted to try a game console. I chose the Sega Genesis because it has a
standard DIN socket on the back, which was easy to just poke some of the wires into for
a quick test, rather than build an appropriate adapter. Now, the thing is, the Genesis has a pretty
good composite output already. But RGB does gain some additional clarity. For example, look at this yellow text here
on this blue background. Now, when I switch to composite mode you’ll
see like a black outline that isn’t supposed to be there, and that’s an artifact of composite
video. And when I switch back to RGB mode, you can
see it is gone. This is going to be more noticeable in areas
of sharp contrast. For example, looking at the edge of this tree
in composite mode you will see that same artifact, but when I switch to RGB it will be gone. However, when looking at soft colored graphics
like these, there isn’t a lot of noticeable difference. And although nearly every game console supports
RGB video, I don’t think you’ll get as much improvement as you will with a computer,
mostly because a computer is going to have a lot of text and sharp contrasts on the screen,
where a game console won’t. So, personally, I am really amazed by this
mod, mostly because how easy it was to do. And, you know, I’m sure the people in Europe
aren’t too terribly amazed because all of their TVs from that time period have the SCART
connector on the back, which does essentially the same thing. Well, SCART connectors are nowhere to be found
in North America, so this is far more useful to someone who lives in North America. Now, I’m sure a lot of people are going
to be wondering why I didn’t put BNC connectors or a SCART connector or something like hat
on the back of my TV. And, I certainly could have. I mostly just wanted to use the stuff that
I had available at the time. But, if you decide to mod your TV you can
use whatever connectors you want on it. Myself, I’m just happy that I was able to
essentially double the usefulness of this little TV without sacrificing any of its original
functionality. And the other thing I wanted to tell you is
that it should, in theory, be possible to to run a VGA card on this TV. And you might be thinking, well the frequency
is wrong, but many VGA cards can be programmed to work at 15 kHz. And you can do that either in some Windows
applications or there’s actually a DOS TSR that I’ve seen before that can actually
change the frequency of your VGA card down to 15 khz. In which case, you could put that in your
AUTOEXEC.BAT or whatever, and then you could run DOS games in VGA with this monitor, and
it would probably look pretty good! Anyway, so that about wraps it up for this,
I hope you guys enjoyed it, and stick around for the next episode and thanks for watching!
I mean it's not really a Guide. Just a video of a guy modding his consumer set.
He even points out that he had someone else decipher his set's schematics and told him what to mod. He obviously has work experience with electronics so already knew how to Solder and had all the equipment on hand. I mean heck he even made his own cabling.
Cool video but not really a guide.
So would the idea here to be salvaging old TVs for use as arcade monitors?
I love this guy. I watch all his videos
The discharging part is enough to make me not want to mess with modding a tv. My arcade monitor is starting to show signs of aging, but I am too afraid of messing around with that stuff.
Oh god every time he says “actually” I cringe slightly more
Ive been wanting to try adding vga to a consumer tv, you can get them for free and for some reason seem to be more durable than traditional arcade monitors.