9 replies to this topic

[The Veg]

This is a C/P of something I recently posted in the 2600 general forum and got no response. I'm hoping you technical guys in this forum might be more helpful. I have also posted a follow-up question in the 2600 forum asking where I may look for an answer if everybody here is stumped.

Here's the dirt:
Hey all,
New guy here, and I have a question. I just unboxed a 2600 that I've had since about 1993 but have not used for about three or four years. I have a problem with the video and audio outputs but before I describe the problem I'll describe what I've done so far:

Dusted everything off
Untangled cords (not very tangled)
Connected all cords to VCS
Plugged in power supply
Connected signal switch to VCR (which functions as my video switching unit what with VCR, DVD, etc.), using 75-300 ohm matching transformer to overcome twin-spade-to-coax connector incompatibility

At this point I turned it on and got nothing, just the blue screen the VCR makes when there is no input. So then I:

Connected signal switch to TV coax input using 75-300 ohm transformer

I turned on the VCS again and I get a picture, but no colour and the sound is mostly static with faint Atari sounds lost in it. The signal switch position was double-checked, and then toggled several times to clear the contacts. Check position again- same results. Check channel position, all connections, rotate RCA connetcor on signal cord, try several carts. After all that the symptom remains the same. I will also point out that the VCS worked perfectly before its storage period and with the same TV set.
So what do you guys think? Don't be afraid to get technical with your answers as I'm a former RF technician.
Thanks in advance!

[CPUWIZ]

Silly question but your switch isn't in the B&W position is it ?

[The Veg]

That's not a silly question. No it's in the colour position, and I checked every switch and threw them several times and rechecked just to be certain nothing was amiss and that all the crud was knocked out everywhere. And as mentioned in the original post all connections were checked, fiddled with, rechecked, etc.
Like I was saying both the video AND the audio seem to be producing weak outputs which makes the former RF tech in me suspect a transistor somewhere but in this case they're all inside the chips, yes?

[Bryan]

Assuming you have a good contact all the way through, it seems like an RF tuning or weak signal problem. Probably time to see if the Modulator has failed or gone out of alignment. Or perhaps a solder joint has gone bad over time.

-Bry

[The Veg]

Quote

Assuming you have a good contact all the way through, it seems like an RF tuning or weak signal problem. Probably time to see if the Modulator has failed or gone out of alignment. Or perhaps a solder joint has gone bad over time.

Hmmm sounds reasonable. I've never seen the inside of a 2600 so how would I go about checking this?

[CPUWIZ]

Which model do you have ? This may also be as easy as pulling and re-seating the chips.

[Bryan]

You'll need to open it up, and poke around. The 4-switch 2600 version is probably a little easier to work with, since it has fewer parts inside. Here's a picture of the 4-switch PCB.

This one's missing the modulator (bottom right corner), but the AV circuits are located under the shield (inside the silver square) on the right side. You can get schematics here:

http://www.atariage....l?SystemID=2600

Sorry, I don't have any pictures from a 6-switch model handy.

-Bry

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[The Veg]

It's a four-switch, and I've just opened and found that chips are soldered so that angle can probably be dismissed. No visually obvious damage to anything, and suprinigly few dead bugs/dertitus.

[The Veg]

Problem solved! Thanks Bry for pointing me in the right direction- it was indeed the modulator alignment. Didn't need much of a tweak- seems like a very comfortable adjustment to make. I used to spend HOURS trying to align obstinate Rx/Tx circuits in old P.O.S. military radios and this was SO much easier!
Now I need to get back in practise- not that I was ever a very good player- and maybe get some more games too (got 18 at present). I'll tell you what I like about the 1600, why I like it better than a truckload of PlayStation2's: because it's simple, and I can sit down and win or lose *right now.* No spending months figuring out a bunch of secrets and tricks. No superhuman manual agility needed. And the games are SO much less expensive!

Sounds great through my 350W/channel stereo too!

[Bryan]

Glad to hear it!

-Bry