I am currently trying to wire a cable to connect the RGB output of an Apple IIGS to the Analog RGB input common amongst high-end Japanese TVs, but am running into some difficulty. First, some background... If I can solve this problem, I am confident that I can connect the IIGS to a regular, modern VGA monitor! There is a device called the XRGB2-Plus which takes the same Japanese SCART connector as input (at 15.75 kHz sync), and outputs regular VGA. So I was planning on buying this box next after I got it working with my TV. For more information on the XRGB2-Plus, check out: http://www01.u-page.so-net.ne.jp/ra2/shimura/knowhow/xrgb2/ http://www.tiptonium.com/videogames/reviews/other/XRGB2.htm The Japanese RGB analog input is a 21 pin connector that looks just like a SCART connector, but the pinouts are totally different. Here is some info: (In Japanese, but you can read the pinouts -- slightly more detailed): http://www1-1.kcn.ne.jp/~sarming/handa/cbl_21pin.html An English version of the pinouts of the Japanese connector: http://www.gamesx.com/avpinouts/rgb21pinj.htm On another web site I am told (in Japanese) that the R, G, and B signals are 0.7Vp-p, 75 ohm, and the sync is 1Vp-p, 75 ohm. I also am told that pin 16 is a Ys input (low level 0-0.4V, high level 1-3V). I wired up a cable that connects the Red, Red Gnd, Blue, Blue Gnd, Grn, Grn Gnd, and sync pins on the Apple IIGS RGB port to the corresponding pins on the Japanese RGB connector but it is not quite working. Since there is only one sync input pin on the Japanese connector, I am assuming that it is composite sync. The Japanese RGB connector also has a pin for Sync ground; I tried tying it to the IIGS Ground (shield), as well as to the R/G/B grounds, as well as leaving it disconnected (!), and all result in the same effect. I did not connect anything to the Ys input of the Japanese connector. What I produced was a signal that shows up ever so faintly on my TV. If I turn off the lights in the room, I can make out the outlines of the IIGS's display (in black and white, although in perfect sync), enough to select menu items. However, it is VERY, VERY dim, and not in color. Are there any experts out there who might have an idea about what I'm doing wrong? Are the signals just incompatible? Or am I not connecting the composite sync ground correctly? Or maybe I need to connect the Ys input? Any help would be very appreciated! thanks, -Jim Jim Maricondo wrote: >An English version of the pinouts of the Japanese connector: >http://www.gamesx.com/avpinouts/rgb21pinj.htm > >On another web site I am told (in Japanese) that the R, G, and B signals are >0.7Vp-p, 75 ohm, and the sync is 1Vp-p, 75 ohm. I also am told that pin 16 >is a Ys input (low level 0-0.4V, high level 1-3V). > >I wired up a cable that connects the Red, Red Gnd, Blue, Blue Gnd, Grn, Grn >Gnd, and sync pins on the Apple IIGS RGB port to the corresponding pins on >the Japanese RGB connector but it is not quite working. Since there is only >one sync input pin on the Japanese connector, I am assuming that it is >composite sync. The Japanese RGB connector also has a pin for Sync ground; >I tried tying it to the IIGS Ground (shield), as well as to the R/G/B >grounds, as well as leaving it disconnected (!), and all result in the same >effect. I did not connect anything to the Ys input of the Japanese >connector. > >What I produced was a signal that shows up ever so faintly on my TV. If I >turn off the lights in the room, I can make out the outlines of the IIGS's >display (in black and white, although in perfect sync), enough to select >menu items. However, it is VERY, VERY dim, and not in color. Are there any >experts out there who might have an idea about what I'm doing wrong? Are >the signals just incompatible? Or am I not connecting the composite sync >ground correctly? Or maybe I need to connect the Ys input? Interesting, Jim. Since the raster, however faint, is properly synced, you don't need to worry further about the sync signal. The multiple grounds are there for the shields of separate coax cables--electrically, they are all the same point. Though at high frequencies, the lack of separate coaxial cables for the separate signals may lead to some crosstalk, the sync signal is always guaranteed to be in a portion of the raster that is blanked--so no worries there. It sounds like you have a signal level problem. Can you verify that you actually have something close to 0.7v at the various component inputs? Does the IIgs drive 75 ohm loads to this level? The Ys signal should be luminance, which can be created by combining R, G, and B, in an appropriate weighting matrix. It may be that without the luminance signal, you are just getting a very low-brightness picture. For example, internally, the R, G, and B signals may be multiplied by the luminance signal. Try hooking the green signal to the luminance input to see if that makes a big difference. If it does, then you'll need to use a video op-amp to combine the weighted R, G, and B signals to construct a proper Ys. -michael Check out 8-bit Apple sound that will amaze you on my Home page: http://members.aol.com/MJMahon/ [posted and mailed] Michael, > Interesting, Jim. > > Since the raster, however faint, is properly synced, you don't need to worry > further about the sync signal. The multiple grounds are there for the shields > of separate coax cables--electrically, they are all the same point. Though at > high frequencies, the lack of separate coaxial cables for the separate signals > may lead to some crosstalk, the sync signal is always guaranteed to be in > a portion of the raster that is blanked--so no worries there. > > It sounds like you have a signal level problem. Can you verify that you > actually have something close to 0.7v at the various component inputs? > Does the IIgs drive 75 ohm loads to this level? > > The Ys signal should be luminance, which can be created by combining > R, G, and B, in an appropriate weighting matrix. It may be that without > the luminance signal, you are just getting a very low-brightness picture. > For example, internally, the R, G, and B signals may be multiplied by > the luminance signal. > > Try hooking the green signal to the luminance input to see if that makes > a big difference. If it does, then you'll need to use a video op-amp to > combine the weighted R, G, and B signals to construct a proper Ys. > > -michael Thanks for your reply. I feel like I am getting closer to solving this problem. Today I decided to search the Japanese web for any more information I could get on people wiring up their own cables for the Japanese SCART-like connector. I found a couple of pages from people who said that they needed to amplify the video signals (R, G, and B) signals using a chip such as the NJM2267 (dual video 6dB amplifier with 75 ohm drivers.) http://www.njr.co.jp/pdf/be/be05039.pdf Here is a page (in Japanese, but the schematic picture is in English) showing how the signals are amplified using the NJM2267: http://www2.incl.ne.jp/~ruming/eparts/rgb.html As their problem sounds a lot like mine, I think I will go ahead and build the circuit. Unfortunately this is making my cable more complex, as I will now need to build a box to house the amplifier. I can just tap the 5V from the IIGS RGB port for Vcc right? So it is my guess that the IIGS can't sustain the 75 ohm load. However this is just a guess based on my noticing a couple of japanese web pages of other people trying to connect other computers/video game systems to their TV's analog input, and they say that without the amplifier the signal is very very dark, which kinda sounds like my problem. As none of these pages talk about connecting the luminance input (unless I'm missing something, which I could be..), I am hoping that it won't be necessary. Have you ever seen the NJM2267? Would there be an easy way to measure my output to see if it is close to 0.7v? Would a regular DC voltmeter/multimeter get by or would I need an oscilloscope? One other question, would it make sense to connect the 5V from the IIGS to the 5V pin on the TV RGB input? What is the 5V on the TV input for? Or is it also an output? If I get this all working I plan to make a nice little web site showing how I did it. It would be really cool to have my IIGS hooked up to my flat panel VGA monitor I think! thanks, -Jim Jim Maricondo wrote: > Here is a page (in Japanese, but the schematic picture is in English) > showing how the signals are amplified using the NJM2267: > > http://www2.incl.ne.jp/~ruming/eparts/rgb.html > > As their problem sounds a lot like mine, I think I will go ahead and build > the circuit. Unfortunately this is making my cable more complex, as I will > now need to build a box to house the amplifier. I can just tap the 5V from > the IIGS RGB port for Vcc right? Yes. It can supply a limited amount of power, but it should be more than enough for a simple video converter. > So it is my guess that the IIGS can't sustain the 75 ohm load. Quite likely. > One other question, would it make sense to connect the 5V from the IIGS to > the 5V pin on the TV RGB input? What is the 5V on the TV input for? Or is > it also an output? It will be an output from the TV, for the purposes of powering an adaptor circuit of some kind. Don't connect it to the IIgs 5V pin. -- David Empson dempson@actrix.gen.nz In <1TP39.5$nH.3369@newsall.dti.ne.jp> Jim Maricondo wrote: > I am currently trying to wire a cable to connect the RGB output of an > Apple IIGS to the Analog RGB input common amongst high-end Japanese > TVs, but am running into some difficulty. First, some background... .. > The Japanese RGB analog input is a 21 pin connector that looks just > like a SCART connector, but the pinouts are totally different. Here > is some info: > > (In Japanese, but you can read the pinouts -- slightly more detailed): > http://www1-1.kcn.ne.jp/~sarming/handa/cbl_21pin.html > An English version of the pinouts of the Japanese connector: > http://www.gamesx.com/avpinouts/rgb21pinj.htm I found an interesting page at http://vhd.co.kr/tech/if/d/d.htm#RGB which calls it an EIAJ RGB connector. It has a bit more detail too. > On another web site I am told (in Japanese) that the R, G, and B > signals are 0.7Vp-p, 75 ohm, and the sync is 1Vp-p, 75 ohm. I also am > told that pin 16 is a Ys input (low level 0-0.4V, high level 1-3V). According to the page above, pin 16 is used for Ys (luminance?) _and_ for the RGB switch, presumably in much the same way as the SCART connector's RGB Status, which is also on pin 16. .. > I did not connect anything to the > Ys input of the Japanese connector. > > What I produced was a signal that shows up ever so faintly on my TV. > If I turn off the lights in the room, I can make out the outlines of > the IIGS's display (in black and white, although in perfect sync), > enough to select menu items. However, it is VERY, VERY dim, and not > in color. It sounds like the TV isn't in RGB mode at all, it may be just picking up "leakage" from the RGB inputs. I think if you pull Ys high it should work. > Are there any experts out there who might have an idea > about what I'm doing wrong? Are the signals just incompatible? Or am > I not connecting the composite sync ground correctly? Or maybe I need > to connect the Ys input? > > Any help would be very appreciated! > > thanks, > -Jim I'm not an expert in video connections, but I have wired up my Apple IIgs to a SCART input (details at http://homepage.mac.com/rojaws/apple2/ scart.html) and it works well :-) -- Roger Johnstone, Invercargill, New Zealand Apple II - FutureCop:LAPD - iMac Game Wizard http://homepage.mac.com/rojaws ________________________________________________________________________ "But what is it good for?" Engineer at the Advanced Computing Systems Division of IBM commenting on the micro chip, 1968 [posted and mailed] > I found an interesting page at http://vhd.co.kr/tech/if/d/d.htm#RGB > which calls it an EIAJ RGB connector. It has a bit more detail too. Wow, I didn't yet find that one! I've never seen it called EIAJ before, wonder where that is from. At least it's in English! > According to the page above, pin 16 is used for Ys (luminance?) _and_ > for the RGB switch, presumably in much the same way as the SCART > connector's RGB Status, which is also on pin 16. > > It sounds like the TV isn't in RGB mode at all, it may be just picking > up "leakage" from the RGB inputs. I think if you pull Ys high it should > work. > > I'm not an expert in video connections, but I have wired up my Apple > IIgs to a SCART input (details at http://homepage.mac.com/rojaws/apple2/ > scart.html) and it works well :-) Cool web site! That is an interesting theory that pulling the Ys high like the same way the SCART has to have one pin pulled high to put the TV in the right mode. This korean web site is actually the first place I have seen this documented (but maybe my Japanese just isn't good enough to notice it otherwise?) Two questions then: 1) In this case for Ys, high si supposed to be above 1V. Would I be able to get a 1V Zener diode? 2) What about Ym - I am a bit confused by what "switch for R, G &B signal to half tone level, L: < 0.4, H: > 1.0" means. thanks! -Jim Jim Maricondo asked: >1) In this case for Ys, high si supposed to be above 1V. Would I be able to >get a 1V Zener diode? No, but you won't need one if you're just supplying a level to be sensed--see below. >2) What about Ym - I am a bit confused by what "switch for R, G &B signal to >half tone level, L: < 0.4, H: > 1.0" means. This is a true/false sensing input. L: < 0.4 means that it will be interpreted as low (false?) if the input voltage is less than 0.4v. H: > 1.0 means that it will be interpreted as high (true?) if the input voltage is greater than 1.0v. It should not be at any level between these voltages. Typically a "low" would be 0v (grounded) and a "high" would be 3.3v or 5v. I don't know about Japanese pinouts, but Ys sounds like the luminance _signal_ and Ym sounds like the _mode_ (RGB vs. Luminance (monochrome or component video?). Try pulling the Ym low (ground) and high (+5) and see whether that does it. -michael Check out 8-bit Apple sound that will amaze you on my Home page: http://members.aol.com/MJMahon/ > I don't know about Japanese pinouts, but Ys sounds like the luminance _signal_ > and Ym sounds like the _mode_ (RGB vs. Luminance (monochrome or component > video?). > > Try pulling the Ym low (ground) and high (+5) and see whether that does it. Doh! I forgot, the IIGS RGB socket only provides -5V and +12V. What is the best way to get the +5V? Do I need to use a 5V zener diode similarly to Roger Johnson's SCART cable at http://homepage.mac.com/rojaws/apple2/scart.html (but that is generating 3V..) I will need the +5V both to test the AV switch input, as well as if I should decide to build the video amplifier circuit.. thanks, -Jim