Extremely noisy signal on CRT TV

[walaber]

Hello everyone. I was all excited to get my homebrew game on a cartridge and play on a real 2600, so over the last few months I bought a 2600 off e-bay (it's the light one w/ wood colored paneling, smaller switches for difficulty on the back), as well as an old RCA CRT TV. The kind that's so old you actually screw on the cable with little terminals.

 

I stripped the wire coming out of the Atari and attached it to the VHF terminals, and the picture shows up and is somewhat playable, but there is a LOT of noise, banding, etc.

 

I've tried fiddling with most of the settings on the back of the TV but they only marginally improve the issue.

 

here's what it looks like playing my game:

 

and here's that the various parts of the back of the TV look like:

 

 

 

Is there a resistor or something needed, or a better way to connect a 2600 to a TV like this one that improves the picture quality? the amount of banding and noise changes a bit when I move the TV or console around, but I'ver never seen it completely clear up.

[+iesposta]

First thought. The green "chicklet" capacitor nearest the Voltage Regulator.

Replacing that fixed my 4 switch from a snowy picture to crystal clear.

Experts recommend replacing the Voltage Regultor while you're there. Great inexpensive insurance to install a new regulator.

[walaber]

pretty big improvement!

 

 

I bought a new RCA cable which I opened up and connected to the motherboard, and then connected that through a RCA -> RF converter, and that into one of those "TV BOX" converters that are designed to connect to screw terminals. this has definitely improved the signal quality.

 

the noise starts to show up after playing leaving the Atari on for several minutes though, so perhaps there is some static charge that's slowly building up (maybe a grounding issue?).

[+RichG1972]

Well try this first, depending how long the Atari has gone without use, give it a "burn-in" period, to allow for the signal or the Atari's "blood" to flow thru it's veins, if it doesn't clear up after a while and stabilize, go by process of elimination, that would be what I would consider the best course of action.

 

That's what I do to be sure in certain cases granted it doesn't ALWAYS work but sometimes it does. Because sometimes a system that has been dormant for a given amount of time will have fits in the beginning. Perhaps cleaning the internals MIGHT help. Not saying it will but use some electronics cleaner, preferably a plastic-safe one on the board and what not, and see what happens.

My experiences are with buying secondhand is, it's a roll of the dice, sometimes you roll 2 6's and sometimes ya get "snake eyes"

[+RichG1972]

Another thing you might check is the TV itself because my Atari appeared to have fits on a TV I had and I thought it WAS the Atari when in fact the internals of the channel dial on the TV were dusty, a good way to determine this is when the fuzziness happens, wiggle the dial and see if it clears up, if it does it is the TV and not the Atari

[+RichG1972]

Oh and another thing you might invest in of you have a Walmart near you so you won't need a converter box and it it is more direct is what is called a Matching Transformer, or if you don't feel like paying for one some cable providers will actually GIVE you one for the asking if you are a cable customer, this is the item:

http://comingsoon.radioshack.com/indoor-outdoor-matching-transformer/1501140.html

 

and here as well

http://www.walmart.com/ip/RCA-VH54-LVH54N-RCA-VH54-LVH54N-Indoor-Matching-Transformer/20588615

 

Online only they are out of stock but in the physical store they have them

 

Like I said if you want to avoid having to BUY one, if you are a cable or satellite subscriber they usually have them for the asking. But Walmart sells them RCA branded and Radio Shack sells them as well (yes they are still around), I hope this helps you in your quest

 

Also you might try putting the Atari lower in FRONT of the TV instead of ON it, those joystick cables are not very long and the 2600 wouldn't likely survive a fall, put it on a low table or something, it also makes it so you don't have to get up to change the cartridge

[+iesposta]

If it comes on fine, and gets noisy, it is this green capacitor that need replaced .22uf or .10uf:

[+RichG1972]

If it comes on fine, and gets noisy, it is this green capacitor that need replaced .22uf or .10uf:

I had this problem on THIS television set and what it turned out to be was not the Atari Woody itself but the TV channel dial was dirty inside, so I pulled the dials off and sprayed inside and it corrected the problem, check EVERY avenue that does not involve a soldering iron FIRST and go by process of elimination, because you said you also bought the TV secondhand am I correct? Like I said when you turn the Atari on, the second the picture goes to snow, either wiggle or tap the channel dial, if the picture clears, the problem isn't in the Atari but the TV itself, here is the TV I had the same problem with until I cleaned the station dials and tuning rings, and while at it also cleaned the volume control which was a bit scratchy:

 

 

[Andromeda Stardust]

My first post on AtariAge was on a similar issue Changing the 7805 and the chicklet cap cleared it up.

http://atariage.com/forums/topic/199541-atari-2600-4-switcher-intermittant-fuzzy-reception/

[+RichG1972]

My first post on AtariAge was on a similar issue Changing the 7805 and the chicklet cap cleared it up.

http://atariage.com/forums/topic/199541-atari-2600-4-switcher-intermittant-fuzzy-reception/

Look at my post above yours Stardust, like I advised them, it is best to go by process of elimination FIRST, first make sure the TV ITSELF is not the catalyst, because a dirty channel knob can produce the same result, keep in mind they are using a DIAL TV and the tuning ring can get dirty and produce the noise in much the same way a dirty volume control if you turn it side to side produces a staticky sound over the speakers.

 

So before they go soldering anything in or replacing anything eliminate the TV as the cause FIRST when the noise happens by tapping or wiggling the VHF (2-13) dial first because if they do NOT and they replace the part in the Atari and STILL get the noise in the picture, then they have not only made an unnecessary repair to their 2600, but also they spent money on parts they didn't need that COULD have been spent on more cartridges for the system itself.

 

Better safe than sorry

 

 

[Andromeda Stardust]

For the record, I would imagine the owner has another RF console they could test with the TV in question, or another TV to plug into. But yes, I would recommend also inspecting the cable connecting the equipment as RF cables can and do go bad with age due to oxidation, fatigue, or simply poor manufacturing.

 

I completely stripped out the old cabling replacing with a 1 foot RG6 internal and applied a large RF choke on it, and installed an F jack on the back of my Atari so I could direct connect it VCR style. This did not correct the issue entirely, but the stock RF was immaculate after I replaced the filter cap and regulator.

 

Looking at the OP's pics, he has stripped the 75 ohm RF cord and connected directly to the 300 ohm screw terminals. You need a proper 75-300 ohm transformer for that.

If I wired any of my consoles in this fashion, I would probably get a lot of static too. You can't guetto-connect RF components and expect a clean signal. Now the RF cord needs to be replaced (use a "digital" shielded RCA for RF) and an RCA to F-connector plug to connect the RCA tip to the impedance matching transformer.

 

With proper hookups, you should find a marked improvement in signal.

Edited August 13, 2015 by stardust4ever

[+RichG1972]

I concur, I only had said what I did above about tapping the dial to eliminate the TV as a suspect before going and replacing parts in the 2600, I mean after all is it not generally accepted that things are not always as they might seem? So eliminate the TV as a suspect first when the noise happens by tapping or wiggling the dial back and forth but not enough to change channels. In older TV's like this dust and what not can imapir a tuner dial REAL quick causing it to 'slip'

[BigO]

Looking at the OP's pics, he has stripped the 75 ohm RF cord and connected directly to the 300 ohm screw terminals. You need a proper 75-300 ohm transformer for that.

 

If I wired any of my consoles in this fashion, I would probably get a lot of static too. You can't guetto-connect RF components and expect a clean signal. Now the RF cord needs to be replaced (use a "digital" shielded RCA for RF) and an RCA to F-connector plug to connect the RCA tip to the impedance matching transformer.

 

 

With proper hookups, you should find a marked improvement in signal.

It took a little deciphering, but I believe that this is what the OP says he did in post #3. He just didn't know all of the official terminology like "RCA to F connector" and "75 ohm to 300 ohm impedance matching transformer". But, he appears to have done the right thing.

Troubleshooting image quality is now probably back to the console electronics (or the TV).

Edited August 13, 2015 by BigO

[Andromeda Stardust]

pretty big improvement!

 

IMG_3375.JPG

 

I bought a new RCA cable which I opened up and connected to the motherboard, and then connected that through a RCA -> RF converter, and that into one of those "TV BOX" converters that are designed to connect to screw terminals. this has definitely improved the signal quality.

 

the noise starts to show up after playing leaving the Atari on for several minutes though, so perhaps there is some static charge that's slowly building up (maybe a grounding issue?).

My fault for not reading the entire thread. Yes, the proper hookups created a huge improvement. My 4-switch Atari exhibited similar issues as you are describing, with the fuzzies appearing out of nowhere after leaving my console running for an indeterminate amount of time, typically between 5-20 minutes ballpark. Replacing the green cap and regulator did clear it up. I haven't opened my Atari in the two years since even though I ordered replacement switches from Best but have yet to i stall them (mine exhibit a small amount of noise and contact bounce when toggled but they work okay for the time being). While replacing components with only two or three leads is fairly trivial, I would highly recommend not prodding around on your 2600 if you've never held a soldering iron before. Practice your solder skills on some scrap PCB material or junk electronics first before tackling something you care about. Take care and good luck!