2600 (Darth Vader) with static sound and no color.

[TonySoprano]

I have a 2600 that is just static and the color is well off, there is a hint of color when you power it on, but it fades to dull b&w like color. There is no sound at all, it is all static. I've tried Channel 2 - 3, and different power supplies and RF switch boxes. Anything I can check inside the machine? I have no problem desoldering/soldering any chips etc. as long as I know what I'm looking for.

[TonySoprano]

I fixed the color by adjusting the pot, now it looks great but I don't have any sound (still static) what controls the sound output?

[Zeus]

Though I don't know what the exact problem is, I have the same static sound problem on one of my Jr.'s

[TonySoprano]

http://www.atariage.com/2600/archives/sche...2600A_High.html

 

There is a schematic there and I found the Sound Adjustment, but I don't have a proper allen key to adjust it yet.. Dunno if that will work

[BeerGnome]

http://www.atariage.com/2600/archives/schematics/Schematic_2600A_High.html

 

There is a schematic there and I found the Sound Adjustment' date=' but I don't have a proper allen key to adjust it yet.. Dunno if that will work[/quote']

 

baring the allen key.. you can probably just use a tiny little electonics terminating skrew driver to work that pot.

you might want to squirt soem contact cleaner in there as well.. in fact.. clean the entire board.. it can only help

[TonySoprano]

Thanks, the system is really clean and the board looks brand new. Does anyone know which parts on the board are specifically related to the sound output?

[+-^CrossBow^-]

There aren't really any specific adjustments for just the sound. what you can adjust is the RF tuner. That is most likely what is causing your static like sound and could have been part of the color problem as well. I had a CV that would only do BW and had nothing but static. I little turn clockwise I believe on the RF bar and boom...Sound is crystal clear. Didn't fix the BW problem though. I ended up having to basically resolder almost all the points I could find on that CV. At some point something I did worked, because I have color again on my CV.

 

Anyway, I would adjust that RF tower and see if you can get the sound back.

 

[TonySoprano]

Thanks, I've tried adjusting the "sound" tower but nothing changed. There is also a pot on the RF mod, but that didn't seem to make any difference either.

[CPUWIZ]

I have a bag full of those if you want to try to replace it.

[TonySoprano]

Yes that would be great, but I would only need 1 :-)

Maybe we can make a deal with those 7800 carts you have?

[CPUWIZ]

Yes that would be great' date=' but I would only need 1 :-)

Maybe we can make a deal with those 7800 carts you have?[/quote']

 

Oh crap, I forgot about those, I'll check them and PM you.

[TonySoprano]

Good news!!

 

I did some more experimenting tonight and I managed to fix it by just reheating each of the pins on the TIA chip. I guess there may have been a loose contact somewhere...i also checked the schematic and resoldered any of the parts specific to the Pin 13 on the TIA. Seemed to work as now I have sound...

 

I changed the pots around again with the sound working, and nothing seemed to change at all. What do those pots actually adjust???

[cwilkson]

I changed the pots around again with the sound working' date=' and nothing seemed to change at all. What do those pots actually adjust???[/quote']

 

I'm only aware of one pot on the 2600...it adjusts the chroma delay for the video. There is also a variable inductor near the RF section. It adjusts the RF carrier frequency, ie the VHF broadcast frequency of the 2600. What you should do here is make sure your tv is fine tuned properly (while watching a broadcast show) and then switch to the atari and adjust its RF inductor until you get the best picture. I've never needed to adjust the audio inductor. But part of what the RF section is doing is mixing (in the signal processing sense...ie multiplying or modulating) the audio into the RF signal, creating the required audio sideband. When demodulating the signal, the receiver expects the audio sideband to be at a specific frequency relative to the RF carrier. The audio inductor adjusts the distance (in frequency) between the carrier and the audio sideband.

 

Long answer to a short question.

 

-Chris

 

PS. Be sure to use a PLASTIC tool when adjusting those 2 inductors. If you use metal tools, they'll interfere with the inductor's magnetic field and it'll be really tough to get the inductor adjusted to where you want it.