VCSMaster

I see. Mine is a model 1 as well but it has a later revision of the board that uses the VLSI chips and does not appear to have a 5v line anywhere. Same schematic as the SABA VideoPlay 2.

I'm aware, but I don't have the correct voltage present on the board. Is there an elegant way to get a +5v line added? Is your board the VLSI board or does yours have the more complex early one? This seems to change things.

I have been told by a few people now that a generic 4096 DRAM will work if I put a certain pin to +5v instead of +12v as it is wired in the console. However, I only appear to have -5 and +12 across the board. Any suggestions?

Is yours also the revision 2 board with the VLSI chips?

I'm not sure, I read in another thread and confirmed with the schematic that the 330470s use -5/+12/+12 whereas the MK4027s use -5/+5/+12. I don't want to risk damaging the board nor waiting for chips that might not work. Did you have to do any modifications to get this working or were they drop in replacements?

The SABA VideoPlay 2 schematics available here appear to match the layout of my unit. Hopefully this will help. All four RAM chips in my machine are already socketed, so an adapter would not be hard to install. My first thought was to try and adapt a standard single 4464 4bit x 64K DRAM to replace all four chips with one, but I'm not entirely sure how that would work or if it would work. I know absolutely nothing about the RAM chips in the Fairchild, and I cannot find a datasheet anywhere. I called ON Semiconductor's (who now own Fairchild) technical support line earlier today and they did not have any datasheets going back that far. Mouser was also unhelpful, though I was told they would look further into it for me. The chips in my machine are all marked 330470. Any help would be greatly appreciated.

With much further testing and probing, it appears that three of the four RAM chips are either stone dead (Don't even draw any current) or are in some way damaged (Producing totally random noise on their outputs). On the bottom of the machine is sharpied "5-78", which I think is safe to assume now is a prior service date. One of the RAM chips (the "working" one) has a different date code to the other 3. I'm going to guess whoever owned this machine in the past had a problem and enjoyed it enough to have it repaired instead of throwing it away or trading it for an Atari or something. Good on them! Now my problem is going to be tracking down discontinued Fairchild RAM chips from the 1970s. Any suggestions on where to start? I plan on calling Mouser Electronics and Arcade Components in the morning, but where should I go from there? I think it would be best to just get 4 brand new chips and replace all of them rather than only the ones that are bad. I will keep the "good " one for spare just in case.

Interesting, you can still start the games with or without pressing reset first. Also, PSU does not mean power supply. PSU stands for Program Storage Unit, and it makes up half of the CPU, the scratchpad RAM, an I/O controller, and the internal ROMs. Without it the console should not be able to boot at all.

Hello all. I've been reading these forums for a few years now, but this was an odd enough issue I felt I needed to finally create an account and ask for help. Unfortunately I realized about 10 seconds after making it that this may have been a poor choice of username. Anyways, I've acquired a Fairchild Channel F (I believe the second revision, with four 40-pin DIP sockets) as "Not working" for fairly cheap off eBay. It came with two cartridges for an Arcadia 2001 and a video cable which had been chewed off. I figured I could probably get away with repairing or replacing the cable and the machine would likely be fine. Wow, was I wrong! Opening it up, it looks like it's been underwater for some time. Rust and corrosion everywhere, and it left dirt everywhere on my desk. Victim of a basement flood? Who knows. I spent a lot of time cleaning the entire machine inside and out to the best of my abilities, cleaned and reseated all socketed chips (Only one is not socketed), and threw the machine back together. After lubricating the buttons and controllers, the machine started showing signs of life, for example it would occasionally make a beep when you powered it on. Never anything on screen. I made sure the TV was working using an Intellivision I had laying around. Came through perfectly clear on the same setup. Since this was cheap and I'm not exactly attached to the machine, I just left it plugged in on my desk for a few hours. It appeared to be improving by doing this, as I started to receive a very odd looking pattern on screen: The pattern kept changing, coming and going, with various odd sounds from the system's speaker. At some point, I left the room to get something to eat. Coming back up the stairs, I hear an oddly rhythmic beeping coming from the machine, still no picture on screen. Eventually it dawned on me that it was now playing Hockey! This is a very, very good sign. Video I continued to let the machine run for a while longer but never really got much more on screen. Eventually, I got tired and packed the machine up for the night, which is when I made my account here and made a post on Reddit in "Console Repairs" asking for help. When I came back from work, I set it back up and the machine did have some very fuzzy video output, but it was only white vertical bars and it went away immediately as soon as you pushed any button or touched the controllers, at which point the picture went back to black and never came back. Following my policy of "Leave it running," the machine mysteriously has self healed a bit more. At the recommendation of a Reddit user, I used a plastic screwdriver to adjust both the slug inside the RF can (This made the picture significantly sharper and clearer, as you can see above, but didn't change much else, including that it would eventually disappear) and the variable capacitor on the oscillator crystal. Turning this had virtually no effect on the machine at all, if turned too far one way the machine stopped running and the video went to static, if turned too far the other way the machine stopped running and the video went to static. No help there, I just twisted it back to where I found it and put it all back together again. Now, on first power up of the machine, I receive these white bars until you push Reset. When you push reset, the bars clear and a garbled "G" appears at the top of the screen. Pushing 1 or 2 causes the screen to flash wildly and then a bunch more garbage is drawn on screen. If you push Start, the game will actually audibly start (you can hear the beeps and fiddling with the controllers will cause the game to change) but the picture is mostly unintelligible. In Hockey, the left player's score is repeated four times in two rows across the bottom of the screen, the ball is duplicated four times in two rows across the top of the screen, the paddles, goalies, and playfield are all invisible, and there is no color. It appears as if only every other pixel is being drawn. Video After a few minutes of this, the picture will eventually start to flicker and lose sync until it just plain goes away, fading totally to black and not coming back unless you unplug the machine for several minutes. Video The game logic is fully working for both Hockey and Tennis. I do not have any cartridges to test with at the moment. If you fiddle with the controllers enough, you can actually score points in Hockey and win a game! To me, this looks like an address problem. Maybe a crossed address line somewhere? I'm not sure. I'd love to hear any suggestions. The poorly scanned "Service manual" available here has a few photos in the back for "diagnosis." My output most closely resembles photo 114, to which the fix is replacing the PSU. However, I am lead to believe that my PSU is not bad. -The CPU is clearly running, which means that the instruction decoding MUST be working -Both games run and their logic works properly, which means that the internal ROMs MUST be working -Both games keep track of score, and the position of paddles and balls, which leads me to believe that the RAM is probably working -Both controller inputs and all hard keys on the machine are working, which means the IO lines MUST be working These are all functions of the 3899 Program Storage Unit, so I do not think mine is bad. tl;dr "Video output wrong but game is working, I don't trust the sketchy service manual I found online" If anyone has any further thoughts on what this could be, or if it turns out to be a PSU then has a spare I could buy, that would be very much appreciated.