AtariAwesomeness! Posted April 7, 2016 Share Posted April 7, 2016 Hi all I'm new here. I apologize if this is posted wrong. I recently did best electronics composite video mod. Also replaces on/off, reset , select, pause, difficulty switches, controller ports, and the crystal oscillater. I have video and sound but there's color lines that appear randomly . Also if you tap case or shake it glitches and freezes up. The board has expansion slot. I would appreciate any help greatly? I'll include a picture. Thanks in advance Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted April 7, 2016 Share Posted April 7, 2016 I am not sure what the video mod entails but your problem sounds like you may have a bad/intermittent contact somewhere either on a solder joint, push fit connection or a connector/IC that has been badly inserted into an IC socket - sometimes the legs get folded under the connector/IC during insertion into an IC socket so it looks ok on a casual glance but is actually making little or no contact with the socket. 1 Quote Link to comment Share on other sites More sharing options...
tdididit Posted April 7, 2016 Share Posted April 7, 2016 rework custom chips, but why you were changing oscillator ? If you didnt use original Atari oscillator but cheap chineese it can cause the problem Maria needs special selected oscillator, ask about it at Best Electronics 1 Quote Link to comment Share on other sites More sharing options...
AtariAwesomeness! Posted April 7, 2016 Author Share Posted April 7, 2016 Thank you Stephen and tdididit for your replys. I will recheck solder joints. Tbh, I randomly decided to replace crystal oscillater . I purchased it from best electronics. I just rechecked the ic chips. They all have good connections. Was thinking of swapping back to the old crystal. Quote Link to comment Share on other sites More sharing options...
AtariAwesomeness! Posted April 7, 2016 Author Share Posted April 7, 2016 It appears connections may be bridged but I'm not sure Quote Link to comment Share on other sites More sharing options...
tdididit Posted April 7, 2016 Share Posted April 7, 2016 (edited) you should solder this bad soldered chip in the middle of your picture 74ls08 Edited April 7, 2016 by tdididit 1 Quote Link to comment Share on other sites More sharing options...
AtariAwesomeness! Posted April 7, 2016 Author Share Posted April 7, 2016 Sorry tdididit . I forgot to mention I replaced that chip. The issue occurred before I replaced it. I extremely grateful for your response Quote Link to comment Share on other sites More sharing options...
tdididit Posted April 7, 2016 Share Posted April 7, 2016 (edited) video mod you installed on top of 74ls32 or you got it on cables ? in my 7800 machines I was replacing only first 2200uF capacitor ... and PSU check is no shortcut - bottom-left part of your picture and fill joins of LS08 you can post component side picture too Edited April 7, 2016 by tdididit 1 Quote Link to comment Share on other sites More sharing options...
tep392 Posted April 7, 2016 Share Posted April 7, 2016 The circled joint looks cold to me. Make sure you are heating both the wire and pad with the tip of the iron when you solder. Also check for solder bridges on both sides of the board. I've seen little strings of solder connect two pins under an IC when too much solder is used. 2 Quote Link to comment Share on other sites More sharing options...
AtariAwesomeness! Posted April 7, 2016 Author Share Posted April 7, 2016 Thanks tep and tdi. I checked and fixed all the solder joints. Doesn't glitch now when tapping motherboard. Still the weird lines on display. Scratching my head now. I really appreciate everyone's suggestions. I'm posting a pic of screen and motherboard . Thank you all again. Quote Link to comment Share on other sites More sharing options...
alortegac Posted April 12, 2016 Share Posted April 12, 2016 1.- Have you tried a different set of RCA cables? different game? do you have the same issue 2600 vs. 7800 game? 2.- Perhaps, you would want to use a piece PCB to set all the components down and then connect them with individual cables to the points in mother board. From the pic, they seem a bit loose, in time this could create connectivity issues due to movement and vibration. 3.- Retrace your steps,maybe you are connecting one of the resistors of the mod to an incorrect one on the board. (it has happened to me ) 4.- Check the mother board, cartridge slot and game for debris, a bit of soldering, a piece of cut resistor, etc. Does it do the same with and without the bottom metal shield on? I had a situation where the shield was making contact with 2 pins, and the screen showed lines.... These are my ideas, hope they help you.....and hopefully you find solution to your problem. 1 Quote Link to comment Share on other sites More sharing options...
Osgeld Posted April 14, 2016 Share Posted April 14, 2016 rework custom chips, but why you were changing oscillator ? If you didnt use original Atari oscillator but cheap chineese it can cause the problem Maria needs special selected oscillator, ask about it at Best Electronics I'm sure Atari had custom crystals cut by some master gemsmith when making a toy ... In china Quote Link to comment Share on other sites More sharing options...
AtariAwesomeness! Posted April 14, 2016 Author Share Posted April 14, 2016 Thank you Alortegac. I will try your suggestions. Tried several games 2600&7800 acts the same. I appreciate your help Quote Link to comment Share on other sites More sharing options...
+Stephen Moss Posted April 14, 2016 Share Posted April 14, 2016 Thanks tep and tdi. I checked and fixed all the solder joints. I hope that includes those at the bottom of the image that appear to have something in them but little or no solder. It looks like you are connected to a modern flat screen display, do you have access to an older CRT display you can try it on to determine if the problem is with the 7800 or the display? Many modern displays/TV's run at 100Hz (possibly 120 for USA) or more and are progressive scan rather than interlaced, if your display is one of these then it has to detect the 50/60Hz source and manipulate it as necessary for it to be able to display it. Consequently it is possible that the random colour lines are just artifacts produced and a result of all that manipulation hence my query about trying it on an older display. Some modern units actually have a gaming mode they can be switched to improve the display/response although I doubt they had systems as old as the 7800 in mind when developing the gaming mode. 1 Quote Link to comment Share on other sites More sharing options...
alortegac Posted April 15, 2016 Share Posted April 15, 2016 (edited) It looks like the IC's are socketed. Push them down with your thumb to make sure they making good contact. Edited April 15, 2016 by alortegac 1 Quote Link to comment Share on other sites More sharing options...
AtariAwesomeness! Posted May 1, 2016 Author Share Posted May 1, 2016 I managed to fix the glitching. Ended up being the bottom ref shield. Still getting the weird color lines. It only does it with 7800 games. 2600 games work fine. It can't be the 7800 carts as they work great in my other 7800. I'm scratching my head as to what the issue is now. Thank you all in advance for your help. Quote Link to comment Share on other sites More sharing options...
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