Two 800XL's No Color On Channel 3

[thegamezmaster]

I have two that on power up there is no color on channel 3. But if I switch it to ch 2 that has color. Then I switch back to ch 3 and the color comes back. Have tried taking apart one switch and cleaned and relubed with dielectric grease, didn't help. Have tried the solid brick power suppy and the white and brown vented power supply with same results. Can anyone please help me with this problem? I'm stuck and don't know what to do. Thanks for any help with this.

[fujidude]

Sounds like the RF modulator circuitry is getting flaky. Typical things that go bad with age in electronics are oxidizing contacts and capacitors with electolyte drying out. In this case I doubt it's the switch so maybe some caps? If yer handy with a soldering iron and can source and replace the caps that might be cheap depending. You can look for obvious signs of bad caps but not all bad or marginal caps will be obvious by looking. Testing caps requires more than a multimeter also.

[thegamezmaster]

Sounds like the RF modulator circuitry is getting flaky. Typical things that go bad with age in electronics are oxidizing contacts and capacitors with electolyte drying out. In this case I doubt it's the switch so maybe some caps? If yer handy with a soldering iron and can source and replace the caps that might be cheap depending. You can look for obvious signs of bad caps but not all bad or marginal caps will be obvious by looking. Testing caps requires more than a multimeter also.

 

 

Thanks for the reply. Do you mean check the caps in the RF Modular? Or something more specific? Thanks.

Edited December 16, 2014 by thegamezmaster

[ApolloBoy]

Why not just use an AV cable instead of RF?

[thegamezmaster]

Why not just use an AV cable instead of RF?

 

Don't have one and don't know what else is compatible.

[fujidude]

 

 

Thanks for the reply. Do you mean check the caps in the RF Modular? Or something more specific? Thanks.

Yes, I mean check the caps in the RF modulator part of the machine. The only checking you can do (without more specialized equipment that I doubt you own) is to visually inspect the caps. Look for any bulges or opened ones. If you see any like that, obtain replacements (of the correct specs). The desolder the bad one(s) and solder in the new one(s). Then see where you are at. If still failing, repleace the rest of the caps even if they look okay. They can be too far out of spec and still visually seem okay. I'm guessing the caps would not be very expensive. But whatever you do, don't buy chincy gincy ones. The good ones (at least in these variety of caps) are probably not a lot more. Use a reputable electronic supply house that sells quality parts.

 

If are not handy with an iron, makes friends with someone who is, or practice on some similar old vintage (through hole) circuit boards until you do get good enough that you dont risk borking up your equipment.

 

Good luck.

[fujidude]

 

Don't have one and don't know what else is compatible.

 

I think C64 monitor cables (5 pin DIN variety?) are compatible with the Atari port. You need to make sure though that you use the correct RCA connector that goes to the composite video on the Atari. I would not assume that the pin-outs on the port on the Atari and C64 are the same. I would look up the pin-out.

Edited December 18, 2014 by fujidude

[thegamezmaster]

Thanks for the info. I'll check it out.

[thegamezmaster]

Checked inside the RF modulator and there are no Electrolytic caps in there. Just the brown round ones. Do those go bad? Or which ones did you mean? There are two by the channel select switch. Thanks

[fujidude]

Checked inside the RF modulator and there are no Electrolytic caps in there. Just the brown round ones. Do those go bad? Or which ones did you mean? There are two by the channel select switch. Thanks

I'm afraid the limit of my "expertise" has been rached as far as knowing what bad parts to look test for then at this point. I just know that in the absense of a overvoltage or short, it's usually caps and oxidizing that cause problems after time. Since you described an intermittent problem, I ruled out anything blown outright in the circuit and thought it sounds like something is slowly deteriorating and is becoming marginal and thus intermittent. Sorry I can't offer more. Perhaps there are some experienced electronic buffs in here who can pick up here...?

[thegamezmaster]

I'm afraid the limit of my "expertise" has been rached as far as knowing what bad parts to look test for then at this point. I just know that in the absense of a overvoltage or short, it's usually caps and oxidizing that cause problems after time. Since you described an intermittent problem, I ruled out anything blown outright in the circuit and thought it sounds like something is slowly deteriorating and is becoming marginal and thus intermittent. Sorry I can't offer more. Perhaps there are some experienced electronic buffs in here who can pick up here...?

 

I've reached mine too but I appreciate the help. Thank you very much! What's weird is I've got two that do the same thing. Any thoughts as to why? Can anyone confirm the 5 pin C64 composite cable works? Or some other cable? Thank again for everyone's input!

Edited December 19, 2014 by thegamezmaster

[thegamezmaster]

Did confirm a 5 pin C64 cable works. Just need some help with the RF Circuit, please!

[fujidude]

Did confirm a 5 pin C64 cable works. Just need some help with the RF Circuit, please!

Hey no problem. I like to help (to the extent that I can). Good news though, I did find confirmation of the compatability of the monitor plug between the Atari8 and the C64. Looks like the pinouts of the ports are even the same for the composite video and audio out (pins 3 & 4). If you have chroma/luma upgraded 800XLs, then you use the leads that come from pins 1 & 5 instead. I did that to my 800XL long long ago, and it was a great improvement over regular composite, which in turn is improved over RF modulated TV signal). Of course to take advantage you have to have a monitor that can use it. S-Video is the same thing as chroma luma. I bet if the signals were fed into an S-video input port on a TV (assuming it has any), it would work a treat. That would require a bit of hacking together a custom cable though. But anyway I'm blathering on. Your composite video outputs on pin 4 of the monitor port.

 

http://www.hardwarebook.info/Atari_8-bit_Monitor

http://www.hardwarebook.info/C64_Audio/Video

Edited December 19, 2014 by fujidude

[thegamezmaster]

Hey no problem. I like to help (to the extent that I can). Good news though, I did find confirmation of the compatability of the monitor plug between the Atari8 and the C64. Looks like the pinouts of the ports are even the same for the composite video and audio out (pins 3 & 4). If you have chroma/luma upgraded 800XLs, then you use the leads that come from pins 1 & 5 instead. I did that to my 800XL long long ago, and it was a great improvement over regular composite, which in turn is improved over RF modulated TV signal). Of course to take advantage you have to have a monitor that can use it. S-Video is the same thing as chroma luma. I bet if the signals were fed into an S-video input port on a TV (assuming it has any), it would work a treat. That would require a bit of hacking together a custom cable though. But anyway I'm blathering on. Your composite video outputs on pin 4 of the monitor port.

 

http://www.hardwarebook.info/Atari_8-bit_Monitor

http://www.hardwarebook.info/C64_Audio/Video

Thanks for your help. Don't know or understand the upgraded chroma/luma though.

[fujidude]

Thanks for your help. Don't know or understand the upgraded chroma/luma though.

I could get into it a little, but there is plenty on the net already (Google is your friend). You can search for chroma/luma or also for s-video. S-video is just a marketing term and connector specification for the chroma/luma signal type. You can find mod instructions for the 800XL to add those signals. The mod (the one I remember doing back in like '85) does not take away the fully composite signal so no worries if you want to retain flexability to use monitors of either kind. The 800 had the signals, and the 800XL has the support circuitry, but I suppose Atari didn't hook it all up for cost savings or some marketing plan they might have had. Dunno. It is a pretty SIMPLE mod. It doesn't involve much. Search for it or ask around here on Atari Age, I'm sure the dox are available.

 

But first.... just get a cable and make sure your composite signal isn't red also. Now that I think about it, I almost remember a guy I know back in the 80s telling me about red screen XL having a flunky GTIA in it or something. But if that were the case for you, it seems less likely that it would be okay on channel 2 rather than just red all around.

Edited December 20, 2014 by fujidude

[thegamezmaster]

I could get into it a little, but there is plenty on the net already (Google is your friend). You can search for chroma/luma or also for s-video. S-video is just a marketing term and connector specification for the chroma/luma signal type. You can find mod instructions for the 800XL to add those signals. The mod (the one I remember doing back in like '85) does not take away the fully composite signal so no worries if you want to retain flexability to use monitors of either kind. The 800 had the signals, and the 800XL has the support circuitry, but I suppose Atari didn't hook it all up for cost savings or some marketing plan they might have had. Dunno. It is a pretty SIMPLE mod. It doesn't involve much. Search for it or ask around here on Atari Age, I'm sure the dox are available.

 

But first.... just get a cable and make sure your composite signal isn't red also. Now that I think about it, I almost remember a guy I know back in the 80s telling me about red screen XL having a flunky GTIA in it or something. But if that were the case for you, it seems less likely that it would be okay on channel 2 rather than just red all around.

 

Not sure what you mean by composite signal being red? What I did was found a 5 pin din plug C64 A/V cable and tried all the rca male ends and one had color video that looked good and one had audio.

 

Does anyone know the cheapest place to get just an Atari composite A/V cable? Ebay seems a little high priced. Or anyone got a couple to sell? Thanks again to all!

[fujidude]

 

Not sure what you mean by composite signal being red? What I did was found a 5 pin din plug C64 A/V cable and tried all the rca male ends and one had color video that looked good and one had audio.

 

Does anyone know the cheapest place to get just an Atari composite A/V cable? Ebay seems a little high priced. Or anyone got a couple to sell? Thanks again to all!

What I meant by composite being red, was the same as you meant by RF modulated channel 3 output being red. I wanted you to make sure that the "redness" was confined to a faulty RF mdulator circuit rather than due to a problem further back in the video chain. The reason I suggested you verify that, was so that you didn't go to the trouble of moding your computer for the enhanced chroma/luma capability in case the computer had an unrepairable problem. That would be a waste of time. I'm glad to hear now that the trouble is confined to the RF modulator section. That means if you were so inclined, you could improve upon the plain old composite video you got working now. Like I said though, you need a display device that can take advantage.

 

Questions?

 

Since the C64 and Atari monitor cables are the same, do you mean the cheapest place to get a C64 (or Atrari) monitor cable?

Edited December 21, 2014 by fujidude

[thegamezmaster]

What I meant by composite being red, was the same as you meant by RF modulated channel 3 output being red. I wanted you to make sure that the "redness" was confined to a faulty RF mdulator circuit rather than due to a problem further back in the video chain. The reason I suggested you verify that, was so that you didn't go to the trouble of moding your computer for the enhanced chroma/luma capability in case the computer had an unrepairable problem. That would be a waste of time. I'm glad to hear now that the trouble is confined to the RF modulator section. That means if you were so inclined, you could improve upon the plain old composite video you got working now. Like I said though, you need a display device that can take advantage.

 

Questions?

 

Since the C64 and Atari monitor cables are the same, do you mean the cheapest place to get a C64 (or Atrari) monitor cable?

Thanks for the reply. I guess since the cable works with either it doesn't really matter. Or does it?

[fujidude]

Thanks for the reply. I guess since the cable works with either it doesn't really matter. Or does it?

No, it does not matter. The cables are the same, and the cables don't "know" which machine you will use it on.

[thegamezmaster]

No, it does not matter. The cables are the same, and the cables don't "know" which machine you will use it

 

 

 

Need a few for my Atari computers since I only have 1 for my C64.

[thegamezmaster]

Has anyone had an Atari 800XL had a problem with RF out being black and white on channel 3? But if I switch it to 2 it's fine and is in color and then if I switch it to 3 then it shows color. Monitor out shows color fine, no problem with that. Can really use some help with this please. anyone? Thanks!