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RF Problems? Poor picture quality.


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#1 Hank Rearden OFFLINE  

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Posted Tue Feb 14, 2017 7:22 AM

I have 2 units and both have picture quality issues. On the first one with the vine there are vertical lines that don't go away. I've tried both channels and different cables and messed with color on TV and the potentiometer. I don't have the right size bit to adjust the RF itself.

On both units it appears I have bad ghosting. Shouldn't the trunks of the trees be solid? I've seen screenshots of really clear pics.

I plan to do a composite mod on the unit with vertical lines. Might that help?

Thoughts and suggestions would be appreciated.

Attached Thumbnails

  • 20170214_080656.jpg
  • 20170214_080410.jpg


#2 mojoatomic OFFLINE  

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Posted Tue Feb 14, 2017 9:27 AM

Pitfall separates the wheat from the chaff on video quality, doesn't it? :-) Nowhere for those pixels to hide behind those trees... 

 

Just as a guess - is the one on the left with the fat trees and two ropes a 4 switch unit? Is the board revision level less than 16? 

 

A few other questions - when you turned R213 (the large white turnpot), did you notice that the trees got thinner, but the color went wonky? 

 

Please perform these tests if you have a multimeter... check the output of A203 7805 voltage regulator and report it's output. Also, check the output of the Atari wallwart power supply and let's see what it's outputting - I'll bet it's higher than 9v

 

If it is a 4 switch and less than ver 16, check to see if there is a  resistor between pin 6 & 9 on the TIA chip (it will be the one closest to the edge on the bottom of the board), if not,  - you'll have to remove the shield to check on the reverse side.

 

I wouldn't touch the RF adjustment at the moment - 



#3 Hank Rearden OFFLINE  

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Posted Tue Feb 14, 2017 9:31 AM

Thanks for the tips. Need a new multimeter. Heading out to get one then will run those tests and report back.

#4 Hank Rearden OFFLINE  

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Posted Tue Feb 14, 2017 1:59 PM

Pitfall separates the wheat from the chaff on video quality, doesn't it? :-) Nowhere for those pixels to hide behind those trees... 

 

Just as a guess - is the one on the left with the fat trees and two ropes a 4 switch unit? Is the board revision level less than 16? 

 

They are both 4 switch units. How do I tell what the revision is?

 

A few other questions - when you turned R213 (the large white turnpot), did you notice that the trees got thinner, but the color went wonky? 

 

Yes...on both units the trees do get thin and actually look good on the trunks but the colors are horrid.

 

Please perform these tests if you have a multimeter... check the output of A203 7805 voltage regulator and report it's output. Also, check the output of the Atari wallwart power supply and let's see what it's outputting - I'll bet it's higher than 9v

 

I'm getting 9.3 volts on the wall adapter. On the unit with the vertical bars problem on A203 I get 5, 0, and 9 readings. I get no readings on the other unit at all! Not sure what my issue is there. If it's bad would it work at all?

 

If it is a 4 switch and less than ver 16, check to see if there is a  resistor between pin 6 & 9 on the TIA chip (it will be the one closest to the edge on the bottom of the board), if not,  - you'll have to remove the shield to check on the reverse side. 

 

I don't see one on either unit. I'll see if I can upload a picture.

 

I wouldn't touch the RF adjustment at the moment - 

 


Edited by Hank Rearden, Tue Feb 14, 2017 2:10 PM.


#5 Hank Rearden OFFLINE  

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Posted Tue Feb 14, 2017 2:06 PM

Apologies for not properly breaking up the quote. I'll see if I can edit it. Here are pics from both units. I don't see resistor between pins 6 and 9.

Attached Thumbnails

  • 20170214_150229.jpg
  • 20170214_150216.jpg


#6 ubersaurus OFFLINE  

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Posted Tue Feb 14, 2017 2:13 PM

The resistor would be on the bottom side of the boards, soldered onto the pins underneath the TIA chip. The board revisions are silkscreened right on the boards themselves in your photos - looks like one is a rev 13 and the other a rev 14.

 

Curious about this too - I have a 4 switch with weird ghosting issues I'm trying to suss out myself.


Edited by ubersaurus, Tue Feb 14, 2017 2:15 PM.


#7 mojoatomic OFFLINE  

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Posted Tue Feb 14, 2017 2:17 PM

OK, on the left one... 

Bars are probably coming from C242 near the A203 voltage regulator & C241 right next to the power input near the rear of the board. Snowy/bright spots in the picture is most likely from C214 (4.7uf cap) & the rolling line in the horizontal is from the big cap, C243 right above the voltage regulator. 

 

To find the revision level, have a look right under the power connector, right joystick port and see if the rev level is printed there in the copper. Also, flip the board over and have a look at the upper right hand side, which will be the underside of the left joystick port. 

 

Just saw your pics - it's rev 13 & 14

 

Pics are talking to us now :-) someone's been in there before, that voltage regulator is not original and there's WAY to much heat sink compound, it won't cool properly when it gets hot. The Nikon cap is original and old, they fail with extremely high ESR values. This is for the rev 13 board. 

 

Rev 14 - caps are original as well - 

 

Looks like you might be in need of a new player 1 difficulty switch.

 

Adding the 820ohm resistor should also help straighten your colors out quite a bit. 


Edited by mojoatomic, Tue Feb 14, 2017 2:27 PM.


#8 mojoatomic OFFLINE  

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Posted Tue Feb 14, 2017 2:31 PM

Can you post pics of the rear side of the boards? 

 

Almost forgot, can you set your meter to the lowest DC range above 9v that's available, or set it to autorange, lowest setting above 9v? Then touch the negative probe to the RF modulator shield, and the positive tip to the 3 legs (one at a time) of the voltage regulator. The voltage reading is critical, including if it's a little higher or lower than 5v. 


Edited by mojoatomic, Tue Feb 14, 2017 2:51 PM.


#9 Hank Rearden OFFLINE  

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Posted Tue Feb 14, 2017 4:35 PM

As requested I'm attaching pics of the board bottoms. Please keep in mind I am very much a novice at this and greatly appreciate the help. I want to get these 2 running optimally and want to learn in the process. That being said, I'm starting to get the hang of the multimeter...at least as far as the A203 Regulator is concerned.  :)

 

Rev 13 board is the one with the vertical line problem. Both boards seem to have ghosting problems.

The A203 regulator reads 4.9 - 0 - 9.1 volts with the setting at 200v and 5.04 - 0 - 9.07 set at 20v on the meter.

 

Rev 14 board

The A203 regulator reads 4.9 - 0 - 9.0 when set at 200v and 5.05 - 0 - 9.15 set at 20v on the meter.

 

Seems like they are either both good of both bad.

 

Thoughts at this point?

 

20170214_165541_zpsip5up1tn.jpg20170214_165741_zpsnsl5f4s2.jpg



#10 Hank Rearden OFFLINE  

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Posted Tue Feb 14, 2017 8:38 PM

Why replace caps that are still on spec?

#11 mojoatomic OFFLINE  

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Posted Tue Feb 14, 2017 11:18 PM

After 40 years, the electrolytic won't be. Since the voltage regulator smoked and was replaced but the snubber caps don't appear to have been, I'd imagine that they opened up and were the root cause of the failure. They've got their coss hairs on the new VR now. What has led you to believe they are still in spec, when all of the evidence suggests otherwise? 


Edited by mojoatomic, Tue Feb 14, 2017 11:21 PM.


#12 Hank Rearden OFFLINE  

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Posted Wed Feb 15, 2017 6:20 AM

After 40 years, the electrolytic won't be. Since the voltage regulator smoked and was replaced but the snubber caps don't appear to have been, I'd imagine that they opened up and were the root cause of the failure. They've got their coss hairs on the new VR now. What has led you to believe they are still in spec, when all of the evidence suggests otherwise? 

I posted the figures for the voltage regulator and they are the same on both units and both units do work but don't output perfect pictures. I may have misspoke by saying they are in spec since I don't know what they are supposed to read.

 

I'm more than willing to dig into replacing the 5 caps and voltage regulator along with adding the resistor as suggested. I'm just trying to understand how/why those items will improve my picture when there are still many other old items on that board. I gather resistors have a longer shelf life?

 

I do eventually want to upgrade at least one of the unit to composite but want to maximize the picture on RF first.  :)



#13 ubersaurus OFFLINE  

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Posted Wed Feb 15, 2017 8:25 AM

My understanding is that electrolytics eventually dry out and go bad, whereas it's much rarer for ceramic components and other "stable" materials to crap out in the same way.



#14 Hank Rearden OFFLINE  

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Posted Wed Feb 15, 2017 10:25 AM

So all of those resistors are likely of no concern regarding my picture quality? Whereas even a capacitor that may appear operable could be causing picture quality problems?

#15 Keatah OFFLINE  

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Posted Wed Feb 15, 2017 10:36 AM

That's about the speed of things..



#16 Hank Rearden OFFLINE  

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Posted Wed Feb 15, 2017 11:00 AM

Well alright then. I will order up a set of new 21st century capacitors and add on the one resistor and hope for the best. I will do some before and after pics and report back.

#17 mojoatomic OFFLINE  

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Posted Wed Feb 15, 2017 12:03 PM

Well alright then. I will order up a set of new 21st century capacitors and add on the one resistor and hope for the best. I will do some before and after pics and report back.

On a personal note... were your parents Ann Rand fans?



#18 Hank Rearden OFFLINE  

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Posted Wed Feb 15, 2017 12:11 PM

Nope! That would be my own doing for online purposes. I know my knowledge does not do this great character justice but I try.

#19 Hank Rearden OFFLINE  

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Posted Tue Feb 21, 2017 8:30 PM

I replaced all the caps and added the resistor on the one board and still have the jail bars. And the picture looks way better on the LCD TV than on the CRT TV. Pitfall is horrible on the CRT but playable on the LCD. Donkey Kong is more or less fine on either but probably because of the black background.

 

I'm going to do the composite upgrade maybe this weekend and eliminate the RF altogether. Hopefully that will do the trick.



#20 Hank Rearden OFFLINE  

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Posted Wed Feb 22, 2017 10:13 PM

Anyone know what the connection is called inside the Atari? It's a short post rca plug but I can't seem to find one in a search. Hoping there's a specific name for it.

#21 ubersaurus OFFLINE  

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Posted Thu Feb 23, 2017 8:11 AM

Far as I know it's just an RCA jack.



#22 Keatah OFFLINE  

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Posted Thu Feb 23, 2017 11:48 AM

He's talking about the plug, the short version.The end of the wire. Not the jack on the motherboard.



#23 Hank Rearden OFFLINE  

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Posted Fri Feb 24, 2017 3:58 PM

That's right. No idea how to search for it. Shitty little RCA plug didn't work. Lol

#24 mojoatomic OFFLINE  

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Posted Fri Feb 24, 2017 4:10 PM

I know of no modern equivalent to the "stubby" RCA that you can currently purchase -  I use a lathe and a parting tool on modern style compression type male RCA connectors to shorten up the end protrusion, and then a tool to break and slightly round the edge.  Mate that to RG6 superflex cable and a compression type F-connector - makes the finest RF cable for the 2600 on the planet. 



#25 DrVenkman ONLINE  

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Posted Fri Feb 24, 2017 6:40 PM

When I replaced the RF cable on my Vader, I just bought a bag of super-cheap L-shaped RF connectors on eBay, cutting pliers to cut the end off the male plug flush with the surrounding barrel, then needlenose pliers to get the plug back into round, and some fine grit sandpaper to remove any tiny burrs. Worked a treat.

 

Sometimes it's useful to remind ourselves that "simple and easy" WILL suffice for a lot of stuff when you just want to play games.






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