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hamburgerwalrus

4 switch 2600 snow unless I hold power switch upwards?

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Please forgive me if this is the wrong place to post this, am new to the forum.  I picked up a 4 switch 2600 off Craigslist for a fairly good deal.  The seller had told me that when he tested the console, all he got was snow on the screen but that he also wasn't familiar with the console so it could be a simple issue on his part.  I've owned a 2600 in the past, but my knowledge on issues relating to them is lacking, but I just assumed maybe he had it on the wrong channel, or maybe the switch box was bad, and I have a few of those laying around.

I just attempted to the test the unit and all I saw was snow as well.  I then fiddled with the power switch, and I noticed if I hold the power switch upwards (pushing it towards the top of the console) I get a video signal as well as some audio.  However, the video output is scrolling upwards.  Here is a video I took showing the issue I'm having:


Could it just be the power switch is gunked up and needs to be cleaned out with some contact cleaner, or other solution?  I've had finicky pots on old radios do somewhat similar stuff (albeit with audio, not video) and it was always a dirty pot.  I also read that vertical scrolling is often a symptom of running PAL games on an NTSC TV/system, but I do not think these are PAL games, at least none seem to be. 

Edit:  After fooling around with the power switch, I've managed to get the video signal to display continuously (without needing to hold the switch upwards), but scrolling is still an issue with every game I have tested thus far.  Interestingly enough, all games I've tested scroll upwards, but Combat scrolls downwards.

Edit edit:  Took it apart, somewhat, and used some rubbing alcohol to clean power switch.  Seems to be working fine, but there is still video scrolling constantly on all games.  I haven't removed the RF shield to see what's underneath, but I saw this on the shield itself.  I'm not an electrician, could this corrosion be signs of a blown cap or something?

OOmql0N.jpg

Edited by hamburgerwalrus

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Seems more like the corrosion is due to moisture. There are a few caps in the 2600 yes, but I've not see any that really leak due to them being from the better era of cap manufacturing unless the dreaded cap failures of the 90s.

 

I would remove the RF shield and see what you have hiding under it to see if the corrosion is only superficial or not.

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2 hours ago, -^CrossBow^- said:

Seems more like the corrosion is due to moisture. There are a few caps in the 2600 yes, but I've not see any that really leak due to them being from the better era of cap manufacturing unless the dreaded cap failures of the 90s.

 

I would remove the RF shield and see what you have hiding under it to see if the corrosion is only superficial or not.

I took off the RF shield last night, and it appears the corrosion mostly lies along the rim of the shield, and not so much on the components.  However, I did pull the TIA chip just to see if any corrosion or debris in general was on the socket, and there was some discoloring on maybe 4 or 5 of the little contacts on the socket.  Most of it cleaned off with some iso alcohol and a q-tip.  I randomly found another thread where a guy was having scrolling issues like this and a handful of people suspected the TIA chip. 

Unfortunately in removing the TIA chip, I broke off the green chicklet cap that sits right next to it (C204 I believe).  That'll be easy to replace though.  I just want to know if anyone can confirm that this might very well be a TIA problem before I order a replacement.  The power switch issue seems fixed, but the display output is definitely not right.

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If you have to replace that chiclet cap anyway, might as well just do a complete refresh on it to get that bit out of the way and they aren't that expensive as kits.

 

https://console5.com/store/atari-2600-total-refresh-tune-up-cap-kit-new-capacitors-and-more.html

 

 

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5 minutes ago, -^CrossBow^- said:

If you have to replace that chiclet cap anyway, might as well just do a complete refresh on it to get that bit out of the way and they aren't that expensive as kits.

 

https://console5.com/store/atari-2600-total-refresh-tune-up-cap-kit-new-capacitors-and-more.html

 

 

Good thinking!  Like I said, I'm no expert when it comes to electronics, so for all I know some of the other caps might be problematic as well and I might as well replace them.

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Is it possible that the PAL/NTSC-ness of the system is wrong?  Typical sync issues cause wavy lines, but this looks like the TV is finding sync in the right place but not showing it correctly.  What's the part number of your TIA?

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40 minutes ago, ChildOfCv said:

Is it possible that the PAL/NTSC-ness of the system is wrong?  Typical sync issues cause wavy lines, but this looks like the TV is finding sync in the right place but not showing it correctly.  What's the part number of your TIA?

It could be, I know that PAL/NTSC mixups can cause scrolling like this.  I'm almost positive it's an NTSC system with NTSC carts, but maybe there's another way that these get mixed up?   I don't know lol, bare with me here.

But here is an image of my TIA chip showing the part number. 
X23IiGZ.jpg

 

and just so I know, the green chicklet style cap on the left of the TIA chip should have no polarity right?  I have to replace that, but I know that isn't the culprit of the scrolling issue.

Edited by hamburgerwalrus

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Yeah that's a .1uF capacitor for power filtering.  It's an NTSC TIA, so the board should have only one crystal.

 

Might also be useful to check the spec of the crystal too.  What's the part number on X200?  Also, do you have a meter that can measure at least 3.58MHz frequency?  If so, see what TIA pin 11 shows.

 

Otherwise, try the Atari on other TVs to see if yours is too finicky.

 

 

Wait... just watched the video again.  It seems to show a missing vertical stripe on the pyramid.  That does seem like a graphics problem, though there is always the possibility that it's RAM-related too (ie RIOT).  6532's are still a lot cheaper than TIA's, so I'd suggest swapping that out first.

 

Also, if those are single-wipe sockets, you may want to get out a multimeter and check that the pins make contact where they're supposed to.  Especially data and address.  Test from top of pin to top of pin on another chip.  That will give you an indication of whether or not it's making contact within the socket.

Edited by ChildOfCv

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1 hour ago, ChildOfCv said:

Yeah that's a .1uF capacitor for power filtering.  It's an NTSC TIA, so the board should have only one crystal.

 

Might also be useful to check the spec of the crystal too.  What's the part number on X200?  Also, do you have a meter that can measure at least 3.58MHz frequency?  If so, see what TIA pin 11 shows.

 

Otherwise, try the Atari on other TVs to see if yours is too finicky.

 

 

Wait... just watched the video again.  It seems to show a missing vertical stripe on the pyramid.  That does seem like a graphics problem, though there is always the possibility that it's RAM-related too (ie RIOT).  6532's are still a lot cheaper than TIA's, so I'd suggest swapping that out first.

 

Also, if those are single-wipe sockets, you may want to get out a multimeter and check that the pins make contact where they're supposed to.  Especially data and address.  Test from top of pin to top of pin on another chip.  That will give you an indication of whether or not it's making contact within the socket.

The X200 has the model number "C016010 NDK".  You are right, there is also a missing vertical strip towards the center of the screen.  In hindsight, I wish I had taken a better video showing my entire TV screen before I accidentally broke off that capacitor because now when it powers on it just shows a black screen with some snow. 

I do have a multimeter laying around somewhere if I can find it, but I'm not sure if it can measure frequencies like that.  I'm starting to think that troubleshooting this might be out of my scope of knowledge, and I'm not 100% certain if it's worth buying a new TIA chip and hoping it is the only issue with the system.  I mean these 4 switch systems are pretty inexpensive.  I paid $25 for the whole lot (with 10 boxed games), and the source I found TIA chips online sells them for about that price.  Might be more worth my time to just try to find another system that is tested and working.  I guess I could sell this one off for parts, even though I'm not certain what parts are good or not, but I'd rather someone get some use out of it. 

Or, in the end, it could just be my TV being a pain.  Should have checked it out on another TV while I was at it.  Unfortunately I sold my only CRT when I moved a couple years ago, so I only have modern displays to test it on.  I guess I'll replace that cap and test it on some other TV's, but until I replace it it doesn't want to display much of anything.

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Sorry for the double post, but I'm dumb.  I guess when I took out the TIA chip last night and reseated it, I must have reseated it poorly because I noticed when powering the system on I was getting nothing but a black image with some snow, and the TIA chip wasn't getting warm at all.  So I removed it again and reseated it.  Sure enough I get a very similar display to what was happening before.  Here's a couple quick clips showing Frogger and the, oh so great, 2600 Pac-Man port.  At least the sound seems alright, at least to my ears, someone correct me if they notice audio output issues.

 



There is a very clear vertical line down the screen, as well as the obvious scrolling issue.  Will try out the system on another TV tomorrow just to see if that fixes the scrolling part, but I don't have high hopes.  Think something might very well be wrong with one of the components, whether it's the TIA chip or not.

Oh and I ordered a cap kit from the above link, as well as a new RCA port.

Edit:  Here is an old thread of a user who seems to be having almost the same exact issue.  He never did confirm if he fixed it or exactly what the culprit was unfortunately. https://atariage.com/forums/topic/289357-graphics-issues/

 

Edited by hamburgerwalrus

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Try reseating the RIOT chip too.

 

In the case of a board that I recently fixed, there were about 4 chips that had pins that didn't make contact.  This was after the chips had been reseated.  I ended up replacing their sockets entirely.

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2 hours ago, ChildOfCv said:

Try reseating the RIOT chip too.

 

In the case of a board that I recently fixed, there were about 4 chips that had pins that didn't make contact.  This was after the chips had been reseated.  I ended up replacing their sockets entirely.

I'll try that next.

Could you possibly explain the socket testing method you mentioned a little better?  Or possibly have a link to a guide or video that shows this?  It very well could be that the chips are fine, but maybe the socket itself, or solder connecting the socket to the board is bad.  You had mentioned testing from the top of the pins to the top of the pins on another chip.  So I'd place one probe of the multimeter on say a data pin on the RIOT chip, and then place the other probe on a pin on a completely different chip?  Am I understanding that correctly?  If so, does it matter which other pin I place the second probe on?

I did try one other thing that made no difference.  I ran the 2600 through a VCR thinking maybe it'd solve the scrolling issue or something.  Still had the same issue, in fact I'd say the video quality was worse when doing this, but that could very well be the VCR's fault.  So I'm thinking it's either a chip being bad, or as you said, a socket being bad, or just the connections to the sockets being bad. 

Going to take the riot chip out and clean out the socket a bit with some ISO alcohol and hope for the best.  Should I bother doing this with the CPU at all?  and thank you for the help thus far.  I was weary about trying to fix this, but I am determined now.  At the very least I may learn a thing or two.

Edited by hamburgerwalrus

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What he was stating on testing the sockets is to use your meter in continuity mode. Put one end of the probe on the top of the IC chip leg right where it goes into the plastic and the other end on the bottom of the PCB where the socket pin connected to that leg would be. You should get a beep if the connection is good from A to B there. If the socket has a poor connection, then it wouldn't beep or would seem weak and inconsistent. 

 

 

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2 minutes ago, hamburgerwalrus said:

I'll try that next.

Could you possibly explain the socket testing method you mentioned a little better?  Or possibly have a link to a guide or video that shows this?  It very well could be that the chips are fine, but maybe the socket itself, or solder connecting the socket to the board is bad.  You had mentioned testing from the top of the pins to the top of the pins on another chip.  So I'd place one probe of the multimeter on say a data pin on the RIOT chip, and then place the other probe on a pin on a completely different chip?  Am I understanding that correctly?  If so, does it matter which other pin I place the second probe on?

I did try one other thing that made no difference.  I ran the 2600 through a VCR thinking maybe it'd solve the scrolling issue or something.  Still had the same issue, in fact I'd say the video quality was worse when doing this, but that could very well be the VCR's fault.  So I'm thinking it's either a chip being bad, or as you said, a socket being bad, or just the connections to the chips being bad. 

 

 

You need to get the schematic (there are a couple of one-page versions you can find here at AA).  You'd place one probe on a pin of one chip, and following the schematic, you'd find the appropriate destination pin(s) for that one on other ICs, and check that the continuity is really there, with both probes at the point where the pin enters the chip.  So, for instance, RIOT pin 7 is labeled "A0".  Find A0 on the other ICs (pin 32 on the TIA and pin 5 on the CPU.  Note that not all pins connect to all chips.  Also note that you might have to scratch a little to remove oxidation before you find continuity.

 

Though actually, Crossbow's explanation may be easier to do and doesn't require a schematic.  😜

 

 

2 minutes ago, hamburgerwalrus said:

Going to take the riot chip out and clean out the socket a bit with some ISO alcohol and hope for the best.  Should I bother doing this with the CPU at all? 

It wouldn't hurt.

 

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Haha, thanks, that makes sense.  So one method basically follows a map of where the circuit (might be the wrong term) would travel to, and checks both ends, and one just tests to make sure that the socket itself is actually making good contact with the board.  Forgive my lack of knowledge here, but the latter method seems much more doable with someone with as little experience with electronics as myself.  If I can't find my multimeter, I'll try and see if a neighbor has one I can borrow or something, or I'll just have to purchase one.

I took out the RIOT chip, the socket did seem a bit dirty underneath with what appeared to be white stuff.  It cleaned off real easy and I reseated it, but no dice.  Same issues as before.  Testing each chips will be my next step and should at least help me pinpoint which chip(s) are producing these issues.  

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Correct what I was suggestion was strictly to test the socket connection to the IC chip leg. To put it even easier, one probe tip on the top of the IC chip leg and the other end on the bottom of the PCB where that socket pin is soldered to. Could also possibly follow the traces to the next nearest component and see if you get the beep from that component to the top of the IC leg it goes to. Anything further than swapping chips with known good would require schemes at that point to be looked at. But I do think the issue is in the TIA and or RIOT chips. It also looks like the ghost on pac-man isn't able to move properly and unless it was the video, it looks like some of the details on the lower row of cars on frogger were missing the back end of their graphics?

 

YEAP I just looked again. It is obviously a logic chip issue. The turtles aren't showing their complete right side either and the logs are not supposed to be chopped up like that either. 

 

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So the logic chip would be the TIA chip, correct?  Still plan to test all chips before purchasing any replacements, but if the symptoms I'm showing can pinpoint things down a bit then that is always good. 

Glad I made this post here.  Seems to be a lot of knowledgeable people on this board which is great.  Glad to see so much passion for a system that is 40+ years old.

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That passion is required if we want to keep using and playing games on these 40+ year old systems. 

 

Near as I can follow in the flowchart, it looks like the RIOT might be more to blame on this...

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53 minutes ago, -^CrossBow^- said:

That passion is required if we want to keep using and playing games on these 40+ year old systems. 

 

Near as I can follow in the flowchart, it looks like the RIOT might be more to blame on this...

Well dang, I guess if it is just the RIOT chip being bad I'm in luck since that should be fairly cheap to replace.  I just assumed graphical error = TIA, but I know nothing about how this stuff works. 

Welp as soon as I can source a multimeter somehow I suppose then I'll find out. 

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Just a small update.  I can't find my multimeter but I have some free time tomorrow so I'll go out and buy one.  Hopefully Home Depot has one for fairly cheap that can measure continuity.  I don't think I need an expensive one, I rarely work with electronic components.  I plan to test each pin of each chip to make sure the sockets aren't faulty, or something of that nature.  I also received my recap kit today in the mail, but unfortunately the cap to replace the one I accidentally broke off has too short of leads to fit into that spot on the board.   I've looked up ways to work around this (by essentially extending the leads), but might just be easier to find a cap with the same ratings and hopefully longer leads.  From what I understand, the cap I broke off can cause grainy video, but it might be okay to do without it for the time being if I can fix all the other video problems.

But either way I also need a new soldering iron since mine apparently doesn't want to work anymore, at least it doesn't want to get hot enough to desolder things (could be the soldering tip).  But I plan to use the kit to replace most of the caps, voltage regulator, power jack, and RCA port.  Hopefully the continuity test checks out and it's as simple as ordering a replacement chip or chips. 

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Checked continuity of every pin on all three chips, every single pin checks out.  So I guess that rules out the chip sockets being faulty?  Should I still try and trace each pin of the chip to another pin on another chip?  What would that rule out exactly?  Damaged traces on the board itself?

Also if one of the chips is just faulty and is what is causing this error, the continuity test wouldn't pick up on that right?  Continuity simply just checks to see if a current can flow from point to point?  If so, is there a way to check each chip to see which one might not be working 100%? 

Edited by hamburgerwalrus

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Correct, the continuity is only checking that you have good connection from the chip IC leg to where the socket is soldered to the board. If the logic chip is faulty internally, you won't be able to test that with just a continuity check. That is where O'scopes and logic analyzers come into place. But this is why I keep about a half dozen fully working 2600s along with a half dozen untested and ugly beaten up units on hand as parts donors. Cheaper to pick up used and abused 2600s without any accessories than to purchase the chips from known sources by themselves.

 

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Ahhh okay, wasn't sure if there was a method to test IC's with a multimeter or not.  I guess it's off to ordering a new RIOT chip and keeping my fingers crossed that that is the only problematic IC there is.  Will update with hopefully good news once I replace it. 

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I hate to keep re-upping this thread with random observations, but alas here I am.  I read on another thread where someone said earlier 2600 games (such as Combat) are almost entirely TIA based and barely rely on RAM, so I decided to throw Combat in and see how it behaved.  Same issues as before (scrolling screen, vertical bar in center, etc.), but I noticed a few things.  The vertical line in the center of the screen is not just a graphical glitch, per se, I literally can not drive a tank through it.  When switching to another game mode, such as the helicopter mode, I can fly around the entirety of the screen and do not see the vertical bar, but when firing I see absolutely no pixel showing the projectile exiting my tank/helicopter/whatever.  None of the game modes seem to show any form of a "bullet" exiting the vehicle, but it does playback the sound of it firing.

I also noticed that the opposing vehicles do not react at all to being hit by your bullets.  I mean I can't see the bullets, only hear an indication that I am firing, but there is no reaction coming from other models to indicate that they have been hit.  Also, on the tank mode, I think I remember there being a sound while moving the tank, but on this system there is none.  I only hear the sound of the weapons firing and nothing else.

 

Based on this alone, and with the reading I've done, this seems to say it's the TIA chip at fault.  Putting money for replacement IC's aside, should I start with replacing that first? 

 

Edited by hamburgerwalrus

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The TIA does handle the ball and missile graphics, and it also detects collisions of graphics objects.  So that does point towards bad TIA.

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