A repair question

[A-T-A-R-I]

Thanks for the help. I am going to give those a try A.J. and post my findings later.

[A-T-A-R-I]

Update

 

I haven't gotten around to checking the caps, but I thought I would try adjusting the rf modulator again. The picture is a lot nicer and brighter now, and while the lines are still appearing on Circus and games with blue backgrounds, I notice that the color is "splotchy" on games with green backgrounds. Take for example, combat. While most of the screen is the normal green, there are a few areas that have patches with lighter shades of green. I will try to get some pics up in the next day.

[A-T-A-R-I]

Here are the new pics. The green you can tell really too much, but it has "lighter green splotches" all over the screen. As you can see on the circus, the problem seems to be getting worse as the lines are getting darker.

[A-T-A-R-I]

I finally got around to trying some of the ideas that were mentioned. I changed the two transistors, and no luck in change. I reheated all solder points and it has cleared up some of the issue, but the blue lines in Circus and other games are still there, and again, when you turn the paddle knobs from left to right, it moves the darker lines up and down on the screen.

 

Also on the green backgrounds like Combat, it looks like the background lighter green "splotches" seems to roll on the screen, kind of a faint horizontal/vertical? hold issue, but the playfield is not affected in the rolling, just the background. I also changed the power regulator and switchboard, no difference.

Edited April 18, 2010 by A-T-A-R-I

[A-T-A-R-I]

Hey everyone,

I pulled the beast back out today and turned it on. The problem is getting worse. It is really showing up now on the light green screens like combat, only it is not just on the left, the shadow bars are clear across the screen.

[A-T-A-R-I]

Ok, so I had some free time on my hands today and started to experiment so see how I can get rid of the shadow lines. I changed out all the following;

The 3 chips

power regulator

line filter caps (c241 & C242)

Q200

C204

X200

and no difference so far. I hate to think about changing the rest of caps & resistors on the board if I don't have to. Anyone else with any ideas on what part may need replaced?

[A.J. Franzman]

My final attempt at remote-diagnosis, considering everything that you've changed already: either the CD4050 buffer (Atari CO10181602), or the +5V filter capacitor nearest to it (0.01 uF, C205, I think -- the schematic in the FSM is very hard to read for this part. It's the one that connects to pins 1 and 8; note that this chip has an odd pinout as 1 and 8 are on opposite ends but the same side of the chip). Of course, if the buffer IC is soldered in, change the capacitor first since that's much easier.

[A-T-A-R-I]

A.j., I tried the cap change and also took a 4050 chip out of one of my other junk units and put it in, no differences made. Maybe the other 4050 is bad, but it was ok before the other unit fizzled out.

[AtariLeaf]

Necro bump. I noticed the same blue lines on the left side of the playfield on Circus Atari as the OP mentioned. I didn't take a picture but they're identical to the ones posted already in this thread. I tried 2 different Circus Atari carts and tried this on both a junior and a heavy sixer and they're present. It seems the OP swapped out about every component with no luck. I don't notice it on other carts at all, just Circus Atari. I use a heavily shielded cable and ferrite beads but it doesn't seem to matter. RF is really clean on all other games. Anyone have any new thoughts on this in the last 9 years since this was brought up

 

EDIT it also happens on a composite modded Vader. Again, just Circus Atari

Edited March 10, 2019 by AtariLeaf

[+save2600]

I've refurbished a handful of various 2600's lately and you know what? I've come to the conclusion that some games just exhibit certain things (like the faint blue line) that aren't worth spending a lifetime trying to "correct". If things like this *really* bug, can always reduce the blue drive on the back of a picture tube a tiny smidgeon, or go into your television's service menu and reduce the RGB guns that way. After replacing caps, regulators, etc. in your 2600 that is. You'll notice less color bleeding too after you've adjusted your TV or monitor this way. Can use the Color Bar Generator cartridge or Harmony with the program to help calibrate, or a few familiar games if you have neither of those. My go-to test games for colors (even after proper dialing) include Ms. Pac-Man, Joust, Jungle Hunt, Space Invaders and regular Pac-Man. After a little fussing, I'm extremely happy with the results across all of my systems, monitors and TV sets.

 

Of course, the regular disclaimers apply; be careful when making such adjustments and fiddling with picture tubes! Watch a few YT vids and read about all the various ways you can tweak a monitor on the web. Tons of great resources out there, especially on the arcade side of things...

[+RichG1972]

Have you tried running the autoscan function of the TV? Sometimes by doing that the TV can get a stronger lock on the 2600's signal

[AtariLeaf]

Have you tried running the autoscan function of the TV? Sometimes by doing that the TV can get a stronger lock on the 2600's signal

 

It's a Commodore 1702 monitor running through a VCR. It's not a TV per se and I don't think has any kind of autoscan function. I don't own any other CRT TV's, just two 1702's.