SignGuy81

I wanted to provide a tip for anyone who has poor RF picture with a TV/Game switch and doesn't have an RCA to coax adapter or wants a fix meanwhile until you can get one. All you need is a little bit of wire, soldering gun and some solder, and some optional foil tape. I recently got two Atari 2600s, and only one switchbox came with them. When I first hooked it up one to test I noticed the RF looked horrible. I opened the switch box and checked continuity on the switch when set on Game across the leads where I was supposed to have continuity and one side I didn't have any unless I kept messing around with the switch, it was intermittent. Instead of fooling around with taking the switch off and cleaning the contacts or anything I thought since I don't need the switch anyway instead I just soldered wires across where I need them, eliminating the selector switch altogether. Then I put everything back and wrapped foil tape around the entire box to help keep out any interference. Now the picture is very clear.

I forgot to add that the board I used was Rev 14. They all differ on the video output section on boards from 2600/2600A, for example the removal of the buffer chips, different resistor values, addition of 2 diodes on Rev 14 to prevent feedback on the sync and one of the luminescence lines on the TIA. A transistor has been removed from oscillator circuit. I'm going to try to check every different board I can get my hands on so I will know if the others also have too low of an output with the composite mod with included resistor values to be recognized by some televisions. Once I am done I will post results here. EDIT: I believe I mentioned earlier about not being able to see the waveform good and also include the whole waveform on my scope due to the settings. I thought I only had an option of 1V per division or 0.1V per division not thinking about my x1, x2 ans x5 selector switch(I hardly ever use that scope for anything), so I was able to put it on x2 which gives me 200mV per division which allows me to clearly see the waveform and see the whole thing and the flashback is about exactly 1Vp-p as it should be.

Go here http://kickass.ddnss.org/html/library/documents/2600FSM.pdfand you want to go to 4-9 near the bottom of the document for the flow chart to follow. Some of the design may be slightly different with the Jr but it should be roughly same.

I just looked at the schematic, well not for yours but a 2600A model. If the junior is the same in those areas as the schematic I'm looking at the cap to the left of your 6532 shouldn't be an issue because there is a 24k ohm resistor between +5V and the cap so if it were in backwards it wouldn't damage any other components or the voltage regulator.(may still be causing problems however if it is still in backwards but I believe you mentioned you put the old ones back in). The other one though nearest the RF section there is an inductor ferrite bead between +5V and the cap which could have blew open if the cap was in backwards or again also the voltage regulator. I would first look at the +5V supply and if it is good look at the ferrite bead I'm talking about. If you didn't put any caps in backwards my apologies and the only other thing I can think of is static discharge you may have damaged a chip with static electricity.

How do you know for sure your TV is getting a signal? I would check your +5V at the regulator. If you would have accidentally put either of the 4.7k ohm caps in backwards it would have acted as a short and possibly damaged your regulator. Electrolytic caps can blow too if put in backwards. Did you hear any pops in the atari when you powered it on? Either way check for 5 volts first.

I wound up putting a 4.7k in place of 2.2k and I put a 6.8k in place of the 3.3k. You can increase the resistances more and get closer to 1V P-P on the video output but the problem is that you introduce more color bleed(ghosting) when this happens. I have slight color bleeding now but not much. I'm probably going to try another circuit later on with 2 transistors. The symptoms I was experiencing prior to changing from the 2.2k and 3.3k ohm resistors were that I rarely ever got a game to display on one of my TVs because the video signal was too low with this mod. Sometimes a game would load after trying about 10 times in a row and the picture would be shifted and once in a while a game would load okay but when switching to different screen the picture would go back out and I'd be left with sound and a blue screen again. With the two resistors changed out the video output signal is around 600mV P-P and now all my TVs play the Atari fine.

I think Atari could make a comeback and become something better but it would have to start with what games it has left way before thinking about hardware. What they need to do is get with all the STB manufacturers and see about having a subscription based service where people can play all there favorites on those. For example I have a Channel Master DVR+ which is a great OTA DVR and devices like this would be great to play some of those older games on. I used to have dish network and they have dish games where you can play online games from your remote on the receiver. They could get with them about including an Atari section with subscribtion. All of these systems like this can't play modern games like you would find on Xbox One but can play older games just fine. Actually they could just get with TV manufacturers and have an app already installed for playing their games with a small subscription fee. I would have loved to be able to play Asteroids on my Dish network receiver back when i had it. Not sure if that is one that Atari owns but you get the idea.

My bad, I should have researched that first. I never had a sears arcade 2 I just thought it was a remodeled case, I didn't realize it was that different.

I would say it would increase the value, dramatically. I agree with Atari181.

I disagree in that there is no need to mod a Flackback 2. Saying that is like saying there is no need to ever even by a Flashback to start with when instead you can just by a 2600 and then by all the games that would have been included in the Flashback. To me it is completely logical, seeing as you get a great amount of games on the system, that you don't have to fool with changing carts to play, and then modding the console for carts is just a bonus on top of that, and it is only SLIGHTLY incompatible with some games. Another bonus is that it is smaller. And if you ask me the AV picture quality is much better than the AV modded units I've seen with bleeding colors and jailbars. Are you still looking for one. Here is a post of the mod I did on mine here http://atariage.com/forums/topic/264251-my-modded-flashback-2

Did you ever get this working? I think you may have the same problem I had here http://atariage.com/forums/topic/264563-no-picture-composite-mod/

Thank you for the reply. The reason I was wondering was because I thought I might try to sell a few and didn't want to sell them and people come back after me being like WTF is this and say it isn't right and want there money back. I guess I will just make sure I let people know in advance that they will see fine vertical bars on the screen and tell them it is pretty much the norm for these units.

Okay so I decided to go ahead and tinker with it a little tonight. I removed the 2.2k ohm resistor on the mod board and soldered in a 10k ohm pot. The signal looked strongest when I had it right around 5k ohms and higher than that the signal started going back down. I looked for a 4.7k in my stash and couldn't fine one so put two 10k ohms in parallel and soldered them in. Although still not near 1V Pk to Pk as it should be it is much closer. It was slightly over 200mV Pk to Pk last time and as you can see above from my pictures but now it is around 600mV Pk to Pk after changing removing the 2.2k ohm and swapping it for 5k ohms. Now my GPX TV is accepting the picture just fine It looks just like the flashback console on that TV because it only has an 8 inch screen the jailbars aren't visible on it. However my 55 inch TV still shows them after rechecking. I don't think increasing the video signal anymore is going to do anything for those so I don't believe I will bother with that anymore. The main thing I wanted to point out and show how to fix is if you have done the mod and get no picture but sound that it is probably too weak of signal. Hope this helps. Also if anyone else that has done this same mod on their 2600 and also happen to have an oscilloscope handy could you please do the same(not swapping out resistors or anything just checking the output) and post your results here and show pictures of your scope as well so we can be certain if this mod problem may apply to all 2600s. To take the measurement the easiest way(in order to be able to hold a camera and take a picture) if your console isn't apart is to plug in your RCA cables and use a spare RCA jack if you have any left from doing mods and plug it into the other end of the cable and then hook your scope ground and probe to it.

For me the brightness is great and picture was perfect other than fine jailbars and slight ghosting. Sounds like it may be something up with your luma signals, I would trace it back to the TIA. The buffer chip could be bad. But if it was working fine before the mod not really sure. When i get time, probably this weekend, I'm going to work on fixing the output so it is around 1V Pk to Pk like it should be on my console and get back with the results.

I play Battlezone from time to time and I like it but I haven't tried Robot Tank unfortunately.

Here are the clearer pictures.

Yes it is the exact instructions I followed other than the addition of a 75 ohm resistor between the video output and ground which was supplied with my kit.

check for continuity between pin 4 of the joystick port to pin 15 on the riot chip 6532. If there is continuity I would assume the chip is bad.

I spoke too soon. I posted about it here http://atariage.com/forums/topic/264563-no-picture-composite-mod/ Still good TV I just can't use it to test it with Atari 2600s with the common composite mod that's been floating around.

LOL yeah I didn't think I would get an answer anytime soon as I had been looking for a long time and couldn't find anything and the thing I did find wasn't what I even started out asking about(no DVD player) and didn't even have composite input had HDMI instead so I wasn't really clear about what I wanted anyway. I think it may be awhile before i attempt this though because that android STB box is expensive. But I was basically trying to modernize a 2600 console and that would be perfect. Maybe someone that has more money than me that likes this idea too can attempt it before I get a chance to and get back to us. Then that way I'll know for sure if it is doable in a flashback case.

I just got done doing a composite mod on an atari 2600 and thought I would go over some issues incase anyone else experiences the same problem I had. Instead of getting the parts and doing it myself I figured I'd just buy the kit because it came with everything plus has a nice looking PCB and also it was about as cheap as me getting all the parts separately but here is the mod kit I got http://www.ebay.com/itm/Atari-2600-7800-Composite-Video-Mod-Upgrade-Kit-DIY-/311653998049?hash=item4890069de1:g:JV0AAOSwnbZYHzc7 I bought two of them and will be modding another 2600 to compare and post back the results. Well to start off with I bought a GPX KCLD8886DT under cabinet TV to put at my work bench thinking it would make a good TV to test consoles. Well I hooked up my atari flashback in thru AV and everything was fine, it looked perfect. Then I hooked a Vader 2600 to it thru RF and looked normal for RF. I did the mod upgrade with the kit and then I hooked it up to that same TV but this time thru AV since mod was done and sound was perfect but had no picture. I kept checking around the board looking for loose solder joints then wiggled the wires right near the ground, +5V and video signal where the RF board used to plug into. The picture came on and looked fine. I'd turn off the console and start it back and same issue again so then I'm thinking I must have a bad solder joint. I look at it real close both sides of board solder looks fine. I reflow it anyway. Still same problem. So then I check the +5V with my oscilloscope, and video signal and used the ground right there first pin for my ground incase the ground was broke somewhere one the board. Everything looked fine I had a video signal there and +5V. Then I look at the video signal on the output and I had a video signal there but still no picture. After scratching my head for awhile I decided to try the Atari 2600 on another TV. Picture perfect(other than some fine vertical jailbars but looks like all the composite modded consoles I've seen pictures of online have that). Took it back to that GPX TV and still had same issue. I figured by that point the problem is that the signal wasn't amplified enough for the GPX to recognize it as a signal so therefore blue screen, and what was happening was I guess when I was wiggling wires and probably touched the video signal and it caused a signal to go up high enough to trick the TV to display the picture. So I decided to show the comparison of the two video signals incase anyone runs into the same problem. I'm including pictures of two separate video out signals with space invaders plugged in. The stronger of the two is the flashback which plays fine on the GPX. Very disappointing because the sole purpose of me getting this TV was to have something small at my workbench and be able to test consoles on. I guess I'll have to get or build a separate amplifier now to plug consoles in that don't have a strong enough video signal. My appologies for the poor picture quality, I took some too with an Iphone but couldn't find the cord and have no service here so couldn't email them to myself so I had to take them with my junk phone. I might try to upload the higher quality images of the scope tomorrow once I can email the pics to myself. My biggest concern with doing this mod if doing for other people is not knowing who's TVs this will work on and who's it will not so I think I will change some values and try to get it to more closely resemble the amplitude of the flashback unit. I'm going to wait first until I do another mod and make sure the other 2600 also has a weak signal like this one to make sure it isn't anything I overlooked with this console but I don't believe there is. If anyone has any questions or comments about this let me know.

Still probably same issue. Do you have any other pots laying around you could try replacing it with? How do the solder joints look?

If you touched the pot and it worked for a second I'm almost positive it is the pot that is bad. I used to work on DC drives at a repair shop and a lot of times it was flaky pots which is what you are describing. That is actually how we tested them, we would bump them with something and see if it made any difference while running a motor. EDIT: If it isn't the pot it may be a cracked solder joint on one or more of the pot leads which also could have been corrected by you touching pot with screwdriver so check the joints too.

Your last two images show fine verticle bars on the screen. The two images before do not have those. The reason I'm curious is I just finished my first composite mod today and I have the same bars and was wondering if this is normal for the composite mod. My atari flashback I've modded does not show these on the screen. Other than that I like the picture it looks great other than a little ghosting. It almost makes it look like I'm playing on a CRT so I don't know if I should complain or like it.

Okay I think I've found what I've been looking for https://www.aliexpress.com/item/HDMI-in-Geniatech-Enjoy-TV-Dual-Core-MyGica-Amlogic-8726-MX-Android-TV-Box-Google-android/969348073.html?spm=2114.40010308.4.2.9tAHCFand I can use this http://www.ebay.com/itm/Mini-Composite-AV-CVBS-3RCA-to-HDMI-Video-Converter-Adapter-720p-1080p-Upscaler-/361950407767?hash=item5445ecec57:g:RCEAAOSwHoFXtSEL and maybe able to fit all of this into a flashback case if I take these out of there cases.