Jump to content

Macross_VF1

New Members
  • Content Count

    93
  • Joined

  • Last visited

Community Reputation

28 Excellent

About Macross_VF1

  • Rank
    Star Raider

Recent Profile Visitors

1,193 profile views
  1. That would likely work as well, though I think I have found an easier solution, should I ever want to try it out in the future. I have spent some time looking into the schematic of the PAL SC-3000 and it solves the clock exactly as I suspected it could be solved. It features a TMS9929 (PAL version of the TMS9928) and has a separate crystal 3.58 MHz crystal and a 74HC04 chip to generate the clock for the CPU and sound chip. It should be easy to copy that part of the SC-3000 and insert it into an SG-1000. However I do find it a bit odd that the PAL SC-3000 runs on 3.58 MHz, same as the NTSC SC-3000, as that was primarily an NTSC frequency if I have understood it correctly.
  2. The SG-1000 does have an RF modulator and I did try to get the composite and audio signals from there but again, I wasn't happy with the result. Now it should be possible to get RGB from this system. As stated earlier the VDP is the TMS9918 and it can only do composite but the later TMS9928 outputs a set of signals that can be converted to RGB. However they are not completely pin compatible, the 9918 provides both the CPU and sound chip with the clock signal on pin 38, something that the 9928 does not. In fact, pin 38 on the 9928 outputs one of the video signals necessary for RGB. It should therefore be possible to build a separate clock circuit for the CPU and sound chip and swap the 9918 for a 9928, isolate the necessary pins on the 9928 and get RGB that way. However I don't know how to build a clock circuit with the proper MHz.
  3. I recently added Segas first home console to my connection. I had a hell of a time getting it to work properly, though that turned out to be two broken traces to the cartridge connector. Anyway, I figured I should add composite to it but the very few references I found on the subject was to add a 470 ohm pulldown resistor to pin 36 on the TMS 9918 and then pull the video signal directly from the same pin. This works but the picture quality was quite frankly worse than the RF-signal. Instead I looked to the sister system, the Sega SC-3000 home computer, which was released at the same time and was pretty much the same system. It featured composite out as standard so I dug up the schematics for it and straight up copied both the composite video and audio circuitry and this made a big improvement to the picture and sound output on my SG-1000. I'm pretty sure this will work with any system using the same SN76489 and TMS9918 chips though I haven't rested it yet. I've included a cobbled together schematic and the red marks are the parts I had to substitute due to lack of components. Now it's still only composite but when run trough a Retrotink 2X the picture quality is certainly decent. At the very least I hope this will stand as a better alternative to the crappy 470 ohm pulldown resistor method.
  4. That one looks promising. Thanks! I hadn't really considered that angle but you are of course correct. Now to be clear I don't really collect games, but rather systems, and I do own a fair amount of systems that would be considered quite rare. I obviously have lots of games as well, but that's not my aim with the collection.
  5. Aww, you make me sound so noble. Anyway, I know most would consider it a bit early to start thinking about this stuff at the age of 40, but I like to plan ahead and I really don't want my collection to end up in the 'wrong' hands.
  6. I'm not sure this is exactly the right category but I figured it can't be completely off topic. Anyway, serious question time, I'm currently thinking about writing my will and testament and since I have a rather large collection of video games, consoles, computers and other related stuff, I need to give that special consideration. Ideally someone could inherit the collection and continue it but I have no children of my own and my sister's children might not be interested. Not that I'm planning to die anytime soon, I plan to celebrate my 40th birthday this year and continue at least 40 more years. One viable option would to donate to museums but I know very little of the museums around the world that would want this stuff. So this is my question to you guys. Are there any really good museums, preferably in Europe, that deal with these items? I mean I can google as well as any one but that doesn't truly help me narrow it down a whole lot.
  7. Yup, that's exactly the site I have been using. Thanks for confirming!
  8. So I might be able to score a pal Atari 800 computer in just a few days but it is missing the power supply. I have a pal Atari 400 with PSU and from my research it would seem that it should work with the 800 as well, but just to be on the safe side I figured I should confirm that it actually is compatible?
  9. If the specs I can find for the Adam are correct it does feature the same TMS9928A video chip as the standard Coleco. That means it should be no problem fitting a TMS-RGB to it. The mod chip pulls the necessary signals directly from the VDP, without any other inputs necessary, making it independent of the rest of the computer/console. The only reason I can think this wouldn't work is if the VDP itself aren't supplied with all the signals necessary for the TMS-RGB to function but that does seem unlikely.
  10. OSSC firmware updated and unfortunately no difference. Next I started fiddling around with the TV settings and I found that the right mix of the 'sharpness', MPEG-artifact reduction' and 'noise reduction' settings on my TV can pretty much eliminate the jailbars. The overall picture quality does become a bit blurrier as a result but it's a compromise I can live with. I'm usually a bit hesitant to fiddle too much with these kinds of settings as they can introduce strange artifacts and lag but this time it proved to be necessary. As for the TMS-RGB itself, I can really recommend it to any owners of a system which feature the TMS992xA video chip. While it isn't exactly something a complete novice can install, it doesn't require too much in the way of equipment and skills. And it's hard to beat the price. I was prepared to buy and solder the necessary components myself as I have both the tools and skills to do so but for $30 it's just not worth the effort.
  11. Aw crap, that's an old photo from before I attached the shield wire (I think that's what it's called) to the DIN socket . With it attached the ringing is gone. As for the offset controls I have tried those and experienced no difference, but I did just realize that my OSSC has never been updated. Maybe it's time to do so?
  12. So I got myself some of the new TMS-RGB mod chips intended for any system equipped with a TMS992xA video chip. I first installed one in one of my MSX computers and next I did it in my Colecovision. Pics below to prove it because we all know it didn't happen other wise. Some notes on the install, I first mounted the chip the wrong way around so the length of the wires were measured from that position. This of course meant that when I turned it around the other way, the wires were longer than necessary but I cut them down somewhat and changed the placement of the DIN socket. The second picture shows where I pulled the sound from and picture three shows how I placed the wires inside the case. Finally, I know I'm going to catch some flack for the hole I drilled in the case for the DIN socket but I honestly don't think it's a big deal. So how's the picture quality? On an old CRT and an old flatscreen TV (2006) it looks bloody awesome (picture 5), however my current flat screen behave really strangely if I connect to it directly, as if it has trouble locking onto the signal (attached video). Now this isn't much of a problem as I plan to run it through an OSSC first but then I run into what looks like vertical scan lines. Picture six shows them though they are much more noticeable in real life. It's not the worst problem though somewhat irritating. Of note is that I see the same lines on my TMS-RGB modded MSX, and other than sharing the same video chip, they only share that they are both PAL machines and the Scart cable so the cable might very well be the culprit. VID_20200928_205850.mp4
  13. Visited RetroRGB today and found some very helpful info about this project. As it currently stands I probably need at least three, possibly five of these boards. I currently own a MSX Canon V-20, MSX Spectravideo SVI-728, TI-99/4A and a Colecovision (all PAL). Also looking to add an SG-1000 to my collection. At first I thought I could just build these on my own but if the price for a complete board is just $25 (please confirm) plus shipping, I don't think I can justify trying to do it myself.
  14. Thanks mate! I have the necessary photos and material to do a similar tutorial for a PAL light sixer if it is of interest.
  15. Since this forum has been quite helpful and provided a good amount of assistance to me (and will probably continue to do so in the future) I figured it was time to give something back. Hopefully someone will be able to benefit from this. Background This actually started with an Atari 5200 that I added to my collection. I figured I should do something about the video signal as I live in Sweden and old NTSC RF-signals just isn't very good or easy to tune into when you live in PAL territories. I settled on doing an S-video mod on my 5200, this particular one in fact and got a good result. A few months later, I added a PAL Atari 2600 'Vader' to my collection and I started looking into video mods for it as well. I found another S-video mod, the instructions can be found right here on Atari Age. What really struck me was the similarity between the two. However the instructions were not quite clear enough for my taste, as they really didn't seem to take into account PAL consoles, only NTSC. So I figured why not make my own tutorial. Now while this is aimed at the PAL Vader I would be highly surprised if some/potentially all other four switch Atari 2600 versions/revisions can’t use alot of the information I’ve provided. Why S-Video? Partially because I have invested in a Retrotink 2X and it’s a great little device for this sort of stuff. The other reason is cost; an S-Video mod is far cheaper than a RGB mod, probably just a tenth of the cost and I have several Atari 2600 consoles. Plus I really like the kind of mods where I can pretty much put together everything on my own. Schematic I’ve cobbled together a schematic using photoshop and various resources found on the net. I have no idea where I got the base schematic so I fully admit to being a filthy, dirty thief (credit goes to whoever made the first one). What I’ve hopefully done is make it easier to read and interpret. Before attempting this you should really read up on the instructions I linked to above as it covers the essentials. There are a few differences however, for instance I haven’t used quite the same order for the inputs and outputs from the CD4050 chip. However that shouldn’t matter as the chip has several unused pins already and any of them should work. Also, a quick note on the 4050, many Atari consoles have this chip inside so you could potentially use the outputs from it instead; however my Vader did not so I had to buy a brand new one. It’s not a strictly necessary component but the picture quality is improved by its’ inclusion. There are also references to resistors and capacitors in the original instructions, which are not particularly helpful, partially because the part numbers are hidden underneath the components on the circuit board and also the numbers seems to be different on PAL consoles. Finally, my one personal contribution to this schematic is the circled 6.8k resistor for the chroma signal. I highly recommend replacing it with a 10k trim pot. Not only were it used to great effect in the very similar 5200 S-video mod, but as I discovered when I did this exact same mod on a light sixer, a 6.8k resistor made the colours really faded. My Vader on the other hand was fine with a 6.8k resistor but having the ability to make fine adjustments is a nice and potentially necessary bonus. Unfortunately I was out of 10k trim pots when I did this mod. *grumbles* Installing the mod Once the circuit has been assembled it’s time to crack open the console. Turn it upside down and remove the four screws. Take note that the screws comes in pairs and are ever so slightly different from each other. I don’t think it really matters but better safe than sorry. Flip the case over again and remove the top. It can be a bit fiddly due to the protruding switches but it shouldn’t be too difficult. When the circuit board is free, the RF shield needs to be removed. There are several tabs around the shield that must be straightened out. I know there’s somewhat of an ongoing debate on what to do with RF shields. Some claim that it’s rather unnecessary in this day of digital devices and just throw it away. Others feel that the shield was put in for a reason and it should be left in place. Personally, I like to keep my consoles as original as possible and besides, RF shields are sometimes truly integral to a consoles design, providing protection against interference as well as odd ball purposes like acting as heatsinks and providing Ground. With the circuit board fully exposed, take note of the TIA chip in the middle, the marked point to the right and the trim pot to the left. The last one is important because the pot might have to be adjusted before everything is put back into place. Besides, it’s a common failure point, giving it a bit of TLC when the console is already open is not a bad idea. I’ve also, provided a better close up of the smaller circle. This is the point where C212, C213 and R214 all connect and the place where I picked up the Chroma signal. I’m not completely sure it’s the best place but it certainly worked out well enough for me. Now you could solder the wires directly to the top but personally I found it easier to flip the board and connect everything there. It also meant I could make a fairly small cut in the RF shield for the wires to pass through. I used some Velcro to fasten the mod circuit to the lower RF shield and a zip tie to keep the wires collected. On the back of the console I drilled the appropriate holes and installed the necessary connectors. You don’t actually need two RCA connectors, it’s not like the system provides Stereo but it’s nice to have. I also installed a molex micro-fit wire to wire connector on the output wires, visible between the plastic case and the circuit board. It’s not at all necessary to do so but it will be really handy if I ever have to open up the case and do further service. All that’s left now is decide what to do with the old RF cable and then put the top case back on. As stated earlier, I like to keep my consoles as close to original as possible and that includes the RF cable. However since it’s not needed and the plastic case have a lot of spare space I just left it disconnected inside the console. And the result? Well take a look! The signal has been routed through my Retrotink 2X and then into the TV. Not bad for something cobbled together by a blithering idiot. Closing words I fully expect some of the smarter/more knowledgeable of you to point out all my mistakes and what I could have done better. Heck, I invite you to do so, especially if it turns out I’ve made any terrible and potentially dangerous mistakes with the S-video circuit. However, I really hope this will at least provide some help to someone out there.
×
×
  • Create New...