Atari 2600 - bad sound !!! (Repost from Atari 2600 forum)

[FireTiger]

Ok, I have a new to me light 6er NTSC with the channel select switch underneath, s.n. 81106688 (in case you know this paticular atari) so I can use my hevy 6er less. The new one has a beautiful picture and the sound plays... everything is clean and the rf cabel seems new so I'm guessing its refurbished.

 

Really nice, all its pins in the controllers all gold contacts clean...dustcover where they should be... perfect switches...

 

The problem is when the tv is not muted the sound it produces to mask the game sound is akin to fingernails on a chalkboard!!!

 

Please Help.

[Max-T]

FireTiger, what you describe is not exactly what happened to me with my Atari, but, if this is any help...

 

I bought a six-switch unit from eBay, and when I got it home and hooked it up, the video was perfect, but the sound output was only white noise. I.e. when the 2600 was turned off, my TVs would auto-mute, but when I turned the Atari's power on, the static sound would come on.

 

So I knew it wasn't the televisions -- it had to be the Atari sending out a bad signal. A couple of people recommended that I replace the RF cable that fed out of the Atari's motherboard... I tried replacing the cable, but there was still the same problem.

 

I ended up sending my system board to an extremely capable Atari fix-it guy who helps to moderate these forums (don't want to give his name out unless he gives the OK), and he told me that my board was simply dead. Bottom line is, even though the 2600 board is simple compared to your newest Pentium/Athlon motherboard, there can still be blown chips or faults in the board itself that can cause problems like you're describing.

 

Best of luck fixing the problem! I'm sure that people smarter and more experienced than I can give you better pointers, but my point is, sometimes an Atari is just dead. I just hope this isn't the case for you.

[madblownaway]

Get an allen key open it up and you'll see on the board, you know i don't even know what to call it so i'll just say looks enough to be a power supply and you'll see this circle thing in it use the allen key and twist it slowwwwwwly see if it gets rid of it.

[tearex]

The problem is when the tv is not muted the sound it produces to mask the game sound is akin to fingernails on a chalkboard!!!

 

Please Help.

 

You could try adjusting the sound subcarrier coil (I guess that's what madblownaway meant). It can be reached through a hole in the metal shielding after you open the plastic casing (so you don't need to open the shielding). It's the hole in center-right if you look at it from above. Instead of some fancy key you can use the back end of a match to turn it. Just don't use anything made of metal as then you have to take it back out every time to see the result. Turn very slowly until the noise is least (it won't go away completely 100%, but almost, in my experience)

 

If you know some electronics guy who's got an oscilloscope you could try to adjust it to exactly the true color subcarrier frequency of your TV norm, but even without that you can usually get it to a nice unnoisy setting.

 

I drillied a small hole into the bottom of my light 6er's plastic casing so I could adjust it without opening the case, since this beast seems to have a tendency to get misadjusted.

[FireTiger]

With a 1/8 inch allen key/wrench I adjusted the coil, the matchsticks didn't work, this is a re-ferb unit as the rf cabel is new and in insides are clean...real real clean.

 

I can't seem to get an real diffrence yet. I have to remove the cart each time I adjust becase of the location of the coil... Can someone give a starting point guess? all the way up or down?

[Whisper]

With me it was more down than up, but be carefull not to screw it in too deeply. I replaced this coil on my Vader system and the new one had to be adjusted. Since I didn't have a plastic wrench, only a metal one, I started with the coil up (well, default like the part came, not all the way up) and just turned the unit on and tested after each turn. If you have a plastic one you can continuously turn and test with a game with sound. It's not that hard, even I succeeded in getting my sound back

[tearex]

I can't seem to get an real diffrence yet. I have to remove the cart each time I adjust becase of the location of the coil... Can someone give a starting point guess? all the way up or down?

 

In my unit the coil is adjustable from below as well (there's a hole in the board), maybe yours too?

 

If not why not just turn on the unit without a cart in it? Just turn it off again if it starts making a funny noise, about half the time it seems to be "silent" when you do this... then you can adjust the sound to actual silence.

 

Or you could plug in just the PCB of some cart, if you have one where the label is damaged anyway (screw visible) you can take it apart and just plug the PCB into the Atari, that should give you enough room to work.

[FireTiger]

After two full spectrem tries to get it to play nicely with my eardrums... She's consigned to "cart tester" she STILL has static, now it's just louder static which is better then the fingernails on chalkboard sound. I'll have her muted and test 'new to me' carts in it.

 

Thanks all.