Problems with video after installing Composite modification

[timsit]

I installed a composite mod kit from Vintage gaming and more and now have a video issue I don't know how to fix. The colors are not together or broken looking for lack of a better way to describe it (See Pictures).

 

I've gone through and reflowed all the solder joints I made. Checked for bridged connections. Verified the ground connections are good.

 

Anybody have some suggestions for where to start troubleshooting? This is a Rev A board with the expansion plug.

Edited March 14, 2016 by timsit

[alortegac]

I am assuming your unit was working fine before the mod. Could you take a close up pic of the actual board and the mod small board? Do you have sound? With this mod is easy to confuse the 3.3k OHM resistor with the 2.2k OHM resistor, check the color bands on each resistor. The one with orange is the 3.3K one compare against the install guide. Also, make sure the bottom of the mod board is not in contact with other surface of the mother board by using the double sided tape provided in your kit. Also, another possibility is you might have missed to cut out resistor #5 or #3 off the mother board.

Edited March 14, 2016 by alortegac

[timsit]

Yes I have sound, The mod board is floating above the board and not attached with the double sided tape right now.

I verified the correct resistors were removed and the mod kit resistors are in the correct positions.

 

I attached some pictures.

 

Edited March 16, 2016 by timsit

[alortegac]

Both things look ok. Let us explore other options then. It looks like something is creating interference of some sort or maybe while working on the mod something moved a bit out position or is not making good contact. It may be something minor that we must be missing. With your fingertips push down gently the large IC's, specially if they are socketed they may have moved a bit loosing good contact. If you can, please take a picture of board (view) so that I can help you visually inspecting it and comparing it to my own 7800 mod's. Also a pic of the RCA jack wiring, if you can.

If you took the board out of the metallic cover to work the mod, please do it again and take a look at the bottom of the board, I have had situations where small bits of soldering (your soldering) stick to the board ...not fully causing a short but creating similar effects. Check also that the metallic bottom is not touching or smashing the wires going to the jacks.

 

Does it do the same with a 7800 and a 2600 game? without a game?

 

another point, how did you splice the wire for 2 audio inputs? (Internal wire + c10 wire)

 

Did you clean the board with a brush or something? I noticed some debris in one of your picture. A good way is with bottled of air to remove dust, also inside the cartridge slot.

 

I forgot to mention, as it may sound trivial. Have you checked your RCA cables? Are they new/good? and have your tried it in more than 1 TV?

 

If these actions do not help, we are facing a more difficult problem and the solution will require a more in depth trouble shooting with equipment. It could be a component not making good contact (cold joint), a cap, resistor, rust, bad IC, etc. Maybe will need re-doing the mod altogether to rule out a bad transistor.

Edited March 17, 2016 by alortegac

[Barakandl]

Looks similar to what I am getting with the same mod and atari 7800 with expansion slot. The seller said every atari is different and recommended trying trim pots to fine tune the resistance. I have some trim pots in the appropriate range on hand, but i haven't tried it yet. Using a darlington transistor instead of the one included helped some. So did using a nicer quality rca connector/cord.

 

Here is a picture of froggie on a LED monitor. Red text is always really blurry. You can see how the blue color blurs as well.

 

 

I can't say mine looked any better with the RF. My atari sat for years and years not played until recently. Never tried the RF...

Edited March 18, 2016 by Barakandl

[alortegac]

What I see from TIMSIT is out the norm in my opinion, static and scrambled video is not what I have seen before in a composite video working mod. I agree it is not HDMI quality, I think some level of color bleeding is kind of normal (you can see some in NES or DVD composite output too), but it should be way, way, way better than RF. I am not sure expansion slot has any effect on the video quality. I have never needed to use trim pots or transistors, but I will try it, perhaps it is much better picture .....so thanks for the info!

I had a situation like this one once in a ATARI 2600, had left the ends of 1 filter cap untrimmed and making contact with few pins of the TIA IC Once I removed those ends...it looked great!

 

I agree on the cables, using good quality cables improve picture and reduce noise (if any).

Edited March 18, 2016 by alortegac

[78001987]

did you disconnect the pins connecting the RF unit to the board? that looks similar to how it would look if the RF unit was never removed.

[alortegac]

I agree, looks like a resistor or something is creating this statics/. Let us know.,