light sixer recap, now worse

[lowlytech]

I picked up a light sixer last month and the guy showed me it played a game before I took it home.  The picture was full of snow and lines, but nontheless it did work and you could play the game.  He also mentioned it would freeze after being on for 20 or so minutes, but I figured a new VR and caps would take care of these minor issues.  So I got the refresh kit from console5 yesterday, installed all the caps, voltage regulator, along with the protection diodes, etc. 

 

Well now when I turn on the machine I am greeted with snow and static kinda like the RF isn't hooked up at all, it occasionally will get to be a darker type of snow and you can see some variation when power is toggled on and off, but for the most part it appears dead.  I tried channel 3 and 4 with no change.  I tested my crt tv and switchbox with my 7800 unit and it works well, so I can safely say I did something to the 2600 during the refresh.

 

I will get it opened back up and check the voltages at the regulator, any other suggestions on what to look for?

 

Thanks again for the help.

[+DrVenkman]

Did you replace the green polystyrene “chiclet” caps on the switchboard? Those are typically one cause of snow and static, though they won’t make the picture freeze. Definitely check the output of the 7805 - to be honest, you really should have checked that as the first step of any refurb, even before recapping. Fuzzy picture can also be caused by the RF modulator going bad - if that’s the case, although some people try to adjust the modulator coil, I’d personally consider the system a candidate for an AV mod.

 

Freezing, if not caused by the processor crashing due to low voltage, could also be caused by any of the IC’s being bad or having bad connections with the sockets. Remove and reseat each one, checking for corrosion or damage on the pins of each one and each socket. If that doesn’t help, and if the system shows good voltages at each chip, then you might try swapping chips. Start with the CPU and RIOT, TIA last (since they are getting rather expensive).

 

Another good idea in general is to go to AtariMania and download the Atari Domestic VCS Field Service Manual - it has full schematics and layouts for 6- and 4-switch units, troubleshooting flowcharts, and parts lists.

[Cmherndon79]

9 hours ago, lowlytech said:

Well now when I turn on the machine I am greeted with snow and static kinda like the RF isn't hooked up at all, it occasionally will get to be a darker type of snow and you can see some variation when power is toggled on and off, but for the most part it appears dead.  I tried channel 3 and 4 with no change. 

Try channel 2 as well.  The RF modulator on Atari 2600s uses 2 or 3 vs 3 or 4 like many other systems.  You might have just knocked the switch into the channel 2 position when you were reworking the board.

[lowlytech]

Yes, console 5 sent another cap to replace the chicklet cap and i installed it.

I also managed to take the console apart and I test 10.5 volts DC on the incoming leg of the regulator and 5.00 on the out.  Now I have pretty clean video and didn't do anything but take the console apart.  However i have no sound and I highly suspect it is the wires connecting the two circuit boards together as I tap on those cables and the behavior changes with video.  These cables are extremely stiff and as we speak i just get color bars or other random stuff now on the screen when i try a cart.  I figure there is no ribbon cable upgrade available anymore?

 

My plan is to reflow some points and see if that makes things more consistent.

[lowlytech]

After messing with the connector that connects the switchboard to the motherboard several of the wire connections broke off on the motherboard end.  Ended up using an old floppy cable from a pc to repair this.  However this didn't change the behavior.  I still get random horizontal bars, or a few times will get a green or red screen with bars. Not sure what happened as i had a good looking picture without sound a few times before. Seems like i can't get this machine to be consistent.  Downloaded the service manual and will try to get some time to try a few additional things.

[lowlytech]

Reseated all the ic's and cleaned the legs/sockets with deoxit except a203 which is not in a socket.  You think this could be a bad RF modualtor?  I don't mind doing the composite mod, but don't like the idea of not being able to go back to RF if i wanted to.  

[Cmherndon79]

If you've swapped out all of those components from the Console5 kit and from the photos, it appears you have and tried new RCA cables, tried different or checked the RCA to coax or coax/switchbox/rca connections and still have problems with RF, yeah, it's probably a bad RF modulator.  I've got over 100 RF modulators I've pulled off boards when converting them to composite.  If you want one I can send a pair (just in case) for the cost of shipping.  DM me if you're interested.

 

If you want to convert it to support composite (with S-Video available as well) you can install the UAV mod instead of the more inexpensive composite mod made up of a transistor and a pair of resistors that has you pull the RF modulator from the board.  UAV mod just has you solder a socket on top of that 4050 hex buffer on the board draw in +5v and color off the board to the UAV, leaving the RF as is.

[Cmherndon79]

Just happened to be doing one of those UAV mods tonight. Looks like this once done.  RF is left and can still be used.

[lowlytech]

That UAV mod looks pretty slick and clean.  I already ordered a composite mod unfortunately off ebay that uses the single transistor method. I guess that UAV will give you s-video? I like the idea of keeping rf, albeit inferior. The TV i plan to use is a sony trinitron with only composite and rf connectors.

 

 I will report back once i get the kit to confirm if the modulator was the fault.