noreyn Posted February 10, 2009 Share Posted February 10, 2009 From what I gathered, Atari produced a 64 pin (RP2A10) ic on the Jr. model. heres a pic of the board inside the rf sheild the rp2a10 chip There seems to be an open location between the cart pins and the chip. So my research tells me Atari assimilated some chips together and made this one. I hear the NES uses one similar to this chip! Is there any schematics for the stereo out mod that pins (pun not intended) the audio location? I've searched days and can't seem to find anything other than "C19 resistor or the 12 & 13 tia pins". I found the C19 resistor but that would just give a mono signal, right? Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted February 10, 2009 Share Posted February 10, 2009 (edited) Cool! I have never seen that before. Its like an Atari on a chip accept really old. I will see what I can dig up about this chip. Man basically zero info about this. Just a old thread in 2001. http://www.biglist.com/lists/stella/archiv...8/msg00278.html I am going to guess you have already seen this. For the audio look for a 18K resistor in series with a .1uF Ceramic cap. One lead of the cap should be connected to two pins (unless they combined them inside this chip) and connected to a 1K pullup. edit// How rare are these types of Juniors? I would like to pick one up for testing purposes. Edited February 10, 2009 by Longhorn Engineer Quote Link to comment Share on other sites More sharing options...
yorgle Posted February 10, 2009 Share Posted February 10, 2009 Funny, I just noticed earlier this morning that there's a similar empty space on my light sixer (ca 1977) pcb. No IC socket, just the solder pads. Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted February 10, 2009 Share Posted February 10, 2009 (edited) Funny, I just noticed earlier this morning that there's a similar empty space on my light sixer (ca 1977) pcb. No IC socket, just the solder pads. From what I have gathered that is was where the Combat rom was going to be placed. Then Atari decided to make it a standalone cart. Btw can you post all the info thats on that chip? Thanks! Edited February 10, 2009 by Longhorn Engineer Quote Link to comment Share on other sites More sharing options...
noreyn Posted February 11, 2009 Author Share Posted February 11, 2009 Cool! I have never seen that before. Its like an Atari on a chip accept really old. I will see what I can dig up about this chip. Man basically zero info about this. Just a old thread in 2001. http://www.biglist.com/lists/stella/archiv...8/msg00278.html I am going to guess you have already seen this. For the audio look for a 18K resistor in series with a .1uF Ceramic cap. One lead of the cap should be connected to two pins (unless they combined them inside this chip) and connected to a 1K pullup. edit// How rare are these types of Juniors? I would like to pick one up for testing purposes. I got this one of two from a manager at work. I found out he tossed the other into the garbage! I see a cap joining three pins (see photo above?), but what I'm looking for is resistor with a brown ring followed with a grey ring, then black? Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted February 11, 2009 Share Posted February 11, 2009 I would look in the lower right hand corner. What does the casing look like? I am going to need two of these for my video mod guides so I need to maximize my chances of finding one. Quote Link to comment Share on other sites More sharing options...
potatohead Posted February 11, 2009 Share Posted February 11, 2009 That same empty location exists on heavy sixers too. Was there a provision for deselecting it when a cart was inserted? Saw that as a kid, and thought about soldering a socket in there. Might do it today, if it's not going to break anything. Would be cool to burn a ROM that says, "Power Down, Insert Game", along with My Name and system Serial Number!! Quote Link to comment Share on other sites More sharing options...
yorgle Posted February 11, 2009 Share Posted February 11, 2009 Funny, I just noticed earlier this morning that there's a similar empty space on my light sixer (ca 1977) pcb. No IC socket, just the solder pads. From what I have gathered that is was where the Combat rom was going to be placed. Then Atari decided to make it a standalone cart. Btw can you post all the info thats on that chip? Thanks! Do you mean the pcb. There is no chip in the spot I'm talking about, just pads and traces leading to/from it. I wonder if I soldered a socket in there and plugged an eprom in if it would work. If I get time, I'll try it. Quote Link to comment Share on other sites More sharing options...
potatohead Posted February 11, 2009 Share Posted February 11, 2009 Yeah, that would be interesting to see. Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted February 11, 2009 Share Posted February 11, 2009 (edited) Do you mean the pcb. There is no chip in the spot I'm talking about, just pads and traces leading to/from it. I wonder if I soldered a socket in there and plugged an eprom in if it would work. If I get time, I'll try it. No no the 64-pin rp2a10 chip. There should be a CO number on it. And yes if you solder a game rom there on the board it will work. You just have to figure out a way to switch between cart and onboard rom. To do so you have to pull one of the pins on the rom to ground i think to disable it... Edited February 11, 2009 by Longhorn Engineer Quote Link to comment Share on other sites More sharing options...
BigO Posted February 11, 2009 Share Posted February 11, 2009 (edited) I see a cap joining three pins (see photo above?), but what I'm looking for is resistor with a brown ring followed with a grey ring, then black?18K ohms is brown, gray, orange. Brown, gray, black would be 18 ohms Edited February 11, 2009 by BigO Quote Link to comment Share on other sites More sharing options...
yorgle Posted February 11, 2009 Share Posted February 11, 2009 Do you mean the pcb. There is no chip in the spot I'm talking about, just pads and traces leading to/from it. I wonder if I soldered a socket in there and plugged an eprom in if it would work. If I get time, I'll try it. No no the 64-pin rp2a10 chip. There should be a CO number on it. And yes if you solder a game rom there on the board it will work. You just have to figure out a way to switch between cart and onboard rom. To do so you have to pull one of the pins on the rom to ground i think to disable it... I'll have to pull it apart again tonight to check. Quote Link to comment Share on other sites More sharing options...
shadow460 Posted February 11, 2009 Share Posted February 11, 2009 That same empty location exists on heavy sixers too. Was there a provision for deselecting it when a cart was inserted? Saw that as a kid, and thought about soldering a socket in there. Might do it today, if it's not going to break anything. Would be cool to burn a ROM that says, "Power Down, Insert Game", along with My Name and system Serial Number!! that would be totally awesome. It would at least let the user know that the VCS is, in fact, on and working. If you figure out how to switch the ROM in and out, let me know, 'cause I'd actually like to do something like this with my Sears HS. Not that I ever expected to have trouble with the unit... Quote Link to comment Share on other sites More sharing options...
noreyn Posted February 12, 2009 Author Share Posted February 12, 2009 I see a cap joining three pins (see photo above?), but what I'm looking for is resistor with a brown ring followed with a grey ring, then black?18K ohms is brown, gray, orange. Brown, gray, black would be 18 ohms I see... found it. Quote Link to comment Share on other sites More sharing options...
noreyn Posted February 12, 2009 Author Share Posted February 12, 2009 I would look in the lower right hand corner. What does the casing look like? I am going to need two of these for my video mod guides so I need to maximize my chances of finding one. I found the 18k resistor labeled R15. Its connected to a diode at the top where the shadow covers detail. I follow the diode to the 1K resistor. Another 1k resistor, cap... Then... I'm lost. I hate to say this, but I need to hold off for a week or so. I've neglected my domestic tidiness and my girlfriend is hosting foreign friends this coming weekend... I'll definitely be back at it and hope to have some result. Good or bad, whatever it may be. Quote Link to comment Share on other sites More sharing options...
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