Atari 2600 fuzzy screen. Repair tips?

[dymus9]

Hey Guys

Trying to get this Atari 2600 going. I have a fuzzy screen. I can see the game but I'd like to get rid of the fuzz.

 

I tried 2 different rf cables, I tried 2 different rf adapters, I cleaned both ends of the rf cable and inputs with rubbing alcohol and still fuzzy.

 

Is there a component on the mother board I can change out to fix this?

 

Thanks, Mike

[Thomas Jentzsch]

Have you tried a really good shielded cable?

 

Also, if you search on AtariAge, there are numerous discussions about your problem.

[dymus9]

I tried another thicker cable and there is no change. I also tried many search terms in the forum search and was not able to find any other similar topics.

 

 

[dymus9]

I found some posts. Reading now

[zylon]

Try a good cleaning of the channel select switch.

[Keatah]

Has anyone tried doing decoupling caps? Or looking for ringing logic?

[MaximRecoil]

Hey Guys

Trying to get this Atari 2600 going. I have a fuzzy screen. I can see the game but I'd like to get rid of the fuzz.

 

I tried 2 different rf cables, I tried 2 different rf adapters, I cleaned both ends of the rf cable and inputs with rubbing alcohol and still fuzzy.

 

Is there a component on the mother board I can change out to fix this?

 

Thanks, Mike

 

By "RF adapter", are you talking about those "TV/Game switch" boxes that originally came with old consoles, like this?

 

 

If so, there's a good chance that's your problem. Try connecting it directly to your TV's F connector (RF input jack) by using an RCA-to-F adapter, like this:

 

 

https://atariage.com/store/index.php?l=product_detail&p=42

[dymus9]

 

By "RF adapter", are you talking about those "TV/Game switch" boxes that originally came with old consoles, like this?

 

 

If so, there's a good chance that's your problem. Try connecting it directly to your TV's F connector (RF input jack) by using an RCA-to-F adapter, like this:

 

 

https://atariage.com/store/index.php?l=product_detail&p=42

I'm using RCA-to-F adapter

[Wyluli Wolf]

Make sure you are not getting interference from any other nearby equipment. Having your power supply close to the RF cable can cause issues let alone Microwaves and other electronics.

You might try reading through the Atari Field Service Manual for more tips.

http://www.atariguide.com/pdfs/atari_2600_vcs_domestic_field_service_manual.pdf

 

 

[MaximRecoil]

I'm using RCA-to-F adapter

 

Do you have another Atari to try on the same TV, or any other video device with RF output, such as another old console or VCR? Also, do you have another TV that you can try your Atari on?

Edited December 1, 2016 by MaximRecoil

[R.Cade]

Note that switchboxes contain a ferrite ring to reduce interference. The direct F-type cable does not... You may need one.

[Keatah]

Switchboxes also match impedance, the F-adapter does not.

[MaximRecoil]

Note that switchboxes contain a ferrite ring to reduce interference. The direct F-type cable does not... You may need one.

 

I've never seen one make a bit of a difference compared to an RCA-to-F adapter, except to sometimes make things worse. In best case scenarios there is no perceptible change whatsoever. The best ones are the automatic switching types like came with the NES and other consoles of that era (they won't work with an Atari though, because it doesn't send a signal down the coaxial cable to trigger the switching function). The NES one had a weak point, but it had nothing to do with the circuitry in the box. It used stranded wire as the center conductor in the coaxial cable, with an F connector that had a built-in center pin. That center pin wasn't soldered nor crimped to the stranded wire in the center conductor; it just relied on a "pressed together" contact, and with a lot of use, they start to separate from each other. I've fixed one before by replacing the original coaxial cable with a solid core one which has the same type of F connector crimped on that cable companies use. By the way, the NES RF switch has no ferrite in it whatsoever:

 

 

The reason they work so well is because there are no moving parts, whereas the manual slide switch on the older style ones would get dirty, resulting in a poor connection, and poor picture.

 

Switchboxes also match impedance, the F-adapter does not.

 

An RCA connector is 75 ohms and so is an F connector. The only impedance matching that was ever done was in the case of the original RF switch boxes that came with Atari 2600s, because those had 300 ohm twin-lead cable which connected to a pair of screws on the back of the TV. In the '70s, most TVs didn't have a 75 ohm F connector, they only had the 300 ohm twin-lead screw terminals. So those RF switch boxes served the function of matching the 75 ohm RCA connector on the end of the Atari's coaxial cable to the 300 ohm input of the TV. When connecting to a 75 ohm F connector input on a TV, there's no mismatch to begin with.

Edited December 1, 2016 by MaximRecoil

[Keatah]

An RCA connector is 75 ohms and so is an F connector. The only impedance matching that was ever done was in the case of the original RF switch boxes that came with Atari 2600s, because those had 300 ohm twin-lead cable which connected to a pair of screws on the back of the TV. In the '70s, most TVs didn't have a 75 ohm F connector, they only had the 300 ohm twin-lead screw terminals. So those RF switch boxes served the function of matching the 75 ohm RCA connector on the end of the Atari's coaxial cable to the 300 ohm input of the TV. When connecting to a 75 ohm F connector input on a TV, there's no mismatch to begin with.

 

Yes of course my bad.

[dymus9]

What I can say is that I have had many different Atari 2600 systems set up to this tv via the same method and this system is the only one that has had this issue. I also tried more than one RF adapter and the pic does not get any better. It leads me to believe it is the system/mother board.