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Atari 2600 Heavy Sixer paddles not working on left port

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I was doing a thorough cleaning on a Heavy Sixer I just picked up and I know I tested paddles and joysticks in both ports previously but I can't remember exactly what I'd done between it working and it not working. I originally tested the paddles on both ports using Warlords and they worked fine. I'd already cleaned it so if I opened it up and put it back together I'm can't remember why. I then proceeded to clean the new paddles that came with it and when I put them all back together the paddles wouldn't work on the left port. When plugged into the left port neither paddle causes any motion when moved, the fire button for player 1 works and the fire button for player 2 seems permanently engaged. I tried the paddles in my Vader and they worked fine and a known good set of paddles showed the same behavior on the heavy. I tried swapping the RIOT and TIA chips one at a time between this unit and an as of yet untested unit but one of them exhibited the same behavior and one of them just gave me a black screen (unfortunately it was late last night and I can't remember which). I also tried checking the port itself and I can't see any visible issue where its soldered to the board, no pins look loose, I don't see any cracked solder and there doesn't seem to be any play when I attempt to wiggle it. The only obvious issue is that the ribbon cable going between the two boards is starting to separate but it still seems to be working and I wouldn't think that would cause this issue since the joystick ports and main guts of the unit are on the same board.

 

Any thoughts? Anybody seen this before? Any suggestions on how to go about tracking down the problem? I two Sears heavys, a Vader and a 4 switch woody available for testing or swaps as needed.

 

Thanks!

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Thank you for the response. I'm looking at my pictures and I can't tell, is that normally a socketed chip or will I have to de-solder/solder it? I guess its only 16 pins so not as bad as some of the larger chips and the spacing isn't too tight. How confident are you that its the fix? Thanks!

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Well that didn't work and maybe made it worse. I bought a new 4050 chip and swapped it. I won't discount the possibility of me having screwed something up during the removal or having a bad solder. The original behavior remains and now the right joystick port repeatedly fires.

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I keep meaning to come back and update this thread. I was finally able to fix it. I went back and cleaned up my solder on the 4050 chip and tested all the connections for continuity using my working board as a guide. I also re-soldered the voltage regulator which was loose. This got me back to where I was initially with everything working except the paddles on the left port. Even though they looked rock solid I checked the continuity of all the pins on the port and sure enough one of them wasn't making good connection. I re-flowed the solder on that pin and suddenly everything worked!

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a bad buffer can also damage the TIA which handles the paddle and trigger lines, so it is good that you have a new one now. Glad it worked out. :)

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Ok, I can't believe I've come back to this problem again. I haven't done any work on this unit until recently. Shortly after declaring it fixed it put it on auction along with a sears heavy as a "buyers choice". Fortunately it was won by a local AA'er who came to pick it up and test it before leaving. When we tested this unit it was fine at first but then after swapping carts the video started showing funny lines. He ended up taking the Sears Heavy (I gave him the option to back out) and I put this one aside to work on it. I first fixed the video issue which appeared to be a loose cart port. The carts weren't making good connection. Then when I put it all back together, player two would act as if the fire button was always pushed. I removed the right joystick port and it still acted as if the fire button was pushed. Assuming that maybe I had fouled the hex buffer I then removed the hex buffer I'd already replaced, soldered in a socket (can't believe I didn't do that before) and installed a new hex buffer. I also replaced the large 2200uf filter cap on the switch board for good measure while I was at it. So that seemed to correct the fire button, but when doing a full check out I discovered that I'm not back to square one and the paddles don't work on the player 1 port. The buttons on the paddles work but the paddles themselves don't. Player two works fine. What the heck is going on here and how do I diagnose it? I've seen several people point to the service guide, but the the steps there seem to require a test plug and an oscilloscope or waveform generator. Are there any easily diagnosable or replaceable components I could try first or any other suggestions on what to check? Is there a particular pin on the hex buffer that would be responsible for this? Oh, I also tried swapping RIOT, CPU, and TIA chips with a 4 switcher and that didn't seem to fix the issue either.

 

Any help would be appreciated. Thanks!

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I don't have a schematic that shows the hex buffer, but it really wouldn't make sense for the paddle input lines to pass through there.

 

Conceptually, what happens is that the 5v line on pin 7 of the port is fed to the potentiometer in the paddle controllers then loops back to the console through the paddle pot to either pin 5 or 9 (player 1 or 2, don't remember which is which), subsequently charging a capacitor that is connected to a TIA input/output pin.

(The TIA pin, under the control of the game software goes to a 0 level temporarily and discharges the capacitor then turns back into an input and looks for a logic 1 level voltage. The time it takes to recharge tells the game logic what the paddle position is. The variable resistance of the pot varies the amount of current available to charge the capacitor, thus varying the time it takes the cap to charge.)

http://atariage.com/2600/archives/schematics/Schematic_2600A_Low.html

 

So, thinking of that as the circuit, it could be broken in a number of places:

  • The controller could have a broken wire.
  • The potentiometer could be bad.
  • The controller plug could be failing to connect to that specific pin in the port.
  • The port pin could have a bad solder joint at the main board.
  • The port pin could be bent.
  • The capacitor could be bad or have bad solder joints (especially if it's physically in the vicinity of where you were soldering, it could be shorted).
  • The input function of the correlated TIA pin could be broken (bad TIA).

I'd first try a different set of paddle controllers if you have them.

If not, I'd rig up a connection to the port and use a, say, 10K ohm resistor to connect between pins 7 and 9, 7 and 5 to see if the on-screen player responds.

Then I'd check the solder connections on the caps to make sure they're not shorted or open.

Then I'd double check the hex buffer work to make sure there are no solder bridges in that area.

Then I'd swap the socketed TIA.

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Thank you very much for the response!


Best I can figure the only things that haven't already been tried or ruled out from your list are:


1. Capacitor issue (bad or lack of connection to)

2. Issue with my hex buffer work

3. Possible continuity to the correlating TIA pin? (can anybody confirm which pin it is?)


I tried to check my hex buffer work and best I could tell it seemed good. I was able to get continuity from the pin on the chip to another destination on the board for every chip except 14. I just assumed I wasn't finding an appropriate test point for 14 and I couldn't find any evidence that it was involved with the paddle.


I tried to check the caps but to be honest, I'm not 100% sure which ones they are. From my reading I was led to believe they were one or more of the 4 green caps under the cart port. I tried testing them but I couldn't find a way that seemed to work. I don't have a cap setting on my multimeter. I read where you could use a high ohms setting and it should show a reading and then go to infinity but I couldn't get a consistent behaviour out of any of them so I assumed I was doing it wrong (do they have to be removed to test?).


The reasons I think the other possiblities are ruled out:


I have two sets of known good paddles. Both work on the right port and neither work on the left.


I've checked continutity on all the controller port pins and even reflowed them for good measure. No change.


I've swapped the TIA chip. I haven't used the unit it came from so I could put it back together and rule out the possibility of having 2 bad TIA chips.


I've also swapped both the CPU and RIOT chips.

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I don't have a board here in front of me to tell you where the caps are and, honestly, I have only done a couple of repairs on 2600's. But, there are 4 identical caps. According to the schematic I looked at they were .068 microfarad.

 

http://atariage.com/2600/archives/schematics/Schematic_2600_Low.html(not 100% matching your board, but should work fine for this exercise).

 

I don't remember which pin is which, but with the help of the schematic and an ohmmeter, I could pretty quickly trace them out on a board sitting in front of me. If I were in your position, I'd sit there looking at the board and the schematic, probing around with an ohmmeter (disconnect power to the Atari board) until I had identified the capacitors and then find the specific one that correlates to the controller that's not working.

 

Should be pretty easy to trace down to two capacitors for that one port pretty quickly. Start at the controller port and work your way toward the TIA from there. You'll see on the schematic which TIA pins the caps are connected to. You could also start at that end and work your way back.

 

In 15 minutes, you'll have located those caps.

 

Personally, I happen to have an oscilloscope so could check out what's going on directly while the board was up and running and possibly be able to tell if the I/O pin was functioning at the same time.

 

Without that advantage, I'd swap places with the two capacitors for that controller port and see if the problem moves to the other paddle controller. If it doesn't move with the capacitor, then the capacitor component itself isn't the source of the failure.

 

If the cost of replacement caps is low enough, a "shotgun" approach of replacing all of the caps to see if you happen to hit the target isn't elegant, but can be effective.

 

Your thought on verifying the TIA functionality in the other unit is a good one. Though it might be odd to have the same exact failure on two units, it's possible. It's also possible that they've both been damaged by being in the faulty unit. Go with that. Verify that the TIA is functional in the other unit. It's all about eliminating variables.

 

Figuring out what the problem isn't, is almost as good as figuring out what it is. :)

Edited by BigO

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Thanks for the assist! I'll do some work and report back!

 

Anyone else with info feel free to chime in even if I haven't finished my tests yet.

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BTW - can you clarify exactly what the failure is? When you're plugged into the first/"normal" port, are both player 1 and player 2 failing in the same way? Or is just one of them failing?

 

Which game are you testing with? With the buttons working, you should be able to test both player 1 and player 2 in Circus. If the paddle control fails on both players, I'd check to see if +5v is present between pins 7 and 8 on the controller port. (I've been thinking that it's only one paddle that's failing. Something got me wondering if that was correct.)

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I found this in the field service manual which might be worth checking, since yours is an Heavy Sixer, so it probably uses an early rev board:

TECH TIP #6

Left Paddle Failure

Early production 2600 mother boards (Rev 8 and lower) had an artwork
error which was corrected by placing a dot over the trace. This
insulates the trace from the casting and should always be on the board.
The dot is located under the J200 upper left corner, and the trace should
be completely covered.


post-10599-0-77093300-1446123626_thumb.jpg
If the "dot" is missing, use some tape to insulate that area from the alluminium shield.

If you have an Harmony cart or other means to run roms on real hardware, then try the TestCart to quickly check the controllers.

Not all the test with the Atari diagnostic cartridge require an oscilloscope, so it's worth trying that too. The shorting plugs are easy to build and only made of a few components: 2 standard female db9 connectors, 6 resistors, 2 leds and 2 diodes:
http://atariage.com/forums/topic/34973-for-those-hunting-for-a-diagnostic-cart/page-2?do=findComment&comment=1247004

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I found this in the field service manual which might be worth checking, since yours is an Heavy Sixer, so it probably uses an early rev board:

 

attachicon.gifh6_pcb_fix.jpg

If the "dot" is missing, use some tape to insulate that area from the alluminium shield.

 

If you have an Harmony cart or other means to run roms on real hardware, then try the TestCart to quickly check the controllers.

 

Not all the test with the Atari diagnostic cartridge require an oscilloscope, so it's worth trying that too. The shorting plugs are easy to build and only made of a few components: 2 standard female db9 connectors, 6 resistors, 2 leds and 2 diodes:

http://atariage.com/forums/topic/34973-for-those-hunting-for-a-diagnostic-cart/page-2?do=findComment&comment=1247004

Nice find. Seems plausible. Sounds like running without the shielding would tell the tale, too. That'd be frustrating: to have it work during a bench test then not work when assembled.

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BTW - can you clarify exactly what the failure is? When you're plugged into the first/"normal" port, are both player 1 and player 2 failing in the same way? Or is just one of them failing?

 

Which game are you testing with? With the buttons working, you should be able to test both player 1 and player 2 in Circus. If the paddle control fails on both players, I'd check to see if +5v is present between pins 7 and 8 on the controller port. (I've been thinking that it's only one paddle that's failing. Something got me wondering if that was correct.)

 

The failure is no response to paddle movement on Player 1 & 2 (left port). Player 3 & 4 (right port) work normally. Paddle fire as well as all joystick functions seem to work fine. I haven't tested Keypads since I got stuck focusing on this problem. I've verified this with two sets of paddles in both ports. I've also swapped TIA, RIOT and CPU with a 4 switcher and verified that it doesn't exhibit this behavior.

 

Last night I swapped the related caps last night. They don't seem to be the problem. Swapping the caps between the two ports didn't fix the problem. I tried new caps (they only had .068 630V caps but they told me they would work. Is that true?) as well but they didn't fix it. One very interesting note though. After putting in the new caps when I turned on the atari with the harmony cart plugged in and the paddles connected to the left port, the menu was repeatedly moving as if the paddles were turned. For a second I thought it was fixed but when I moved the paddles the movement stopped and didn't work at all after that.

 

I found this in the field service manual which might be worth checking, since yours is an Heavy Sixer, so it probably uses an early rev board:

 

attachicon.gifh6_pcb_fix.jpg

If the "dot" is missing, use some tape to insulate that area from the alluminium shield.

 

If you have an Harmony cart or other means to run roms on real hardware, then try the TestCart to quickly check the controllers.

 

Not all the test with the Atari diagnostic cartridge require an oscilloscope, so it's worth trying that too. The shorting plugs are easy to build and only made of a few components: 2 standard female db9 connectors, 6 resistors, 2 leds and 2 diodes:

http://atariage.com/forums/topic/34973-for-those-hunting-for-a-diagnostic-cart/page-2?do=findComment&comment=1247004

 

Oh thanks for that info on the dot! I bet it is missing. I looked at the pictures I took when I first opened this board and it was there. I washed this board at some point though and I wonder if it got removed.
Thanks for the pointer to the info about the test plug. I had no idea how to make one. I might make a run on my parts place at lunch and grab the stuff to make a set. I see now that there are indeed some tests I can to without an oscilloscope or waveform generator. I hadn't seen those yet (maybe I just need to read the entire service manual huh?). I used to have an oscilloscope at work but I excessed it long ago because I don't do the sort of stuff that needs it and I needed the rack space for other gear. Wish I hadn't now.

Nice find. Seems plausible. Sounds like running without the shielding would tell the tale, too. That'd be frustrating: to have it work during a bench test then not work when assembled.

 

Well crap, so the dot missing would only be an issue with the shield on? I've been testing with no shielding so I guess that isn't the problem.

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Well crap, so the dot missing would only be an issue with the shield on? I've been testing with no shielding so I guess that isn't the problem.

That's my assumption. Don't see how it could matter otherwise.

 

You're closer to the solution. You now know one more thing it isn't (the caps).

 

If the problem is in the console or the port connection, the keypad controllers should also have a problem. They use the two paddle lines as part of their scan matrix.

Plugging in the keypad controller with a paddle game running should act like the paddles are cranked far to the right.

Plugging in a keypad would essentially do the test I mentioned earlier: putting a resistor across pins 7 & 5, 7 & 9.

 

Not sure what you're using to test, but with nothing plugged in the "player" should sit all the way to the left in Circus or Super Breakout. Plugging in the keypad would make the player jump to the right (both player 1 and player 2).

 

If it's stuck to the right, the caps are never discharging.

If it's stuck to the left, the caps are never charging (or the TIA isn't reading the input pins).

 

I assume you have inspected the controller port to make sure the pins are all where they should be.

 

Next steps I'd take:

  • Verify that you're running a known good TIA.
  • Carefully measure the voltage between pins 7 & 8 on the bad controller port with the console powered up (7= +5v, 8=Gnd). Should be 5 volts there.

That 5 volt supply on pin 7 is the simplest thing to test that could cause both player 1 and player 2 to fail.

I imagine that's a pretty robust signal path up to pin 7. Should be a direct path to system power. Unless there's a bad solder joint on pin 7 or you broke a trace on the board somewhere, I'd expect to see 5v there.

If you see 5v there, find a way to probe the same points with the paddle controller plugged in. Should still be 5v.

Edited by BigO

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Ok, so I think I fixed it but I'll test some more to make sure since I've been fooled before. I did a test on the pins and as it turns out in wasn't getting 5V. I tested on the solder side and it was there so somewhere in the port there must have been a break. I also noticed while looking closely that Pin 9 was not well soldered. I replaced the port and that seems to have fixed the problem. One of my sets of paddles was flakey but I think it's their connector. I also put a bit of electrical tape over the spot indicated the service manual so thanks for that! Hopefully is all fixed but I'll report back if I find out otherwise.

 

Thanks again!

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Summary:

 

Symptom: both paddle controllers non-responsive on a controller port. Fire buttons normal. On-screen player positioned as if no controller is plugged in.
Cause: +5v not present on pin 7 of controller port.

Test: measure voltage between controller port pins 7 and 8.

Remedy: Replace controller port

Note: could also be caused in some cases by faulty solder joint on main board at controller port pin 7.

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Here's an interesting little tidbit. The dot that was originally on my motherboard doesn't seem to be in the same place indicated on the drawing above. The drawing seems to put it on the exposed spot right at the edge of the cart port plastic (where there is indeed an exposed contact point) but mine was to the left of the caps/resistors just behind the controller port. I went ahead and covered both areas with one piece of tape.

post-42103-0-67113500-1446475100_thumb.jpg

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Thanks so much for this. I bought a Sears Light sixer (Taiwan) last year, and I love it to death. But I just tried Warlords and NO POT ACTION for player 2. I reflowed the solder joints and everything works GREAT NOW!!!

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