[RESOLVED] Trying to fix my Atari 2600 :/

[tthurman]

Congrats Felix!

 

36 minutes ago, ClassicGMR said:

Or - even worse - playing your Atari games on an *GASP* Intellivision!!!

I must have slept through that class!

 

On 8/20/2017 at 9:48 AM, ClassicGMR said:

The geek wearing the black Atari shirt and 80's glasses behind the TV and in the next picture is me.

Nice to be in good company.  Only difference was our TV was hooked to one of these.  Dad isn't a console guy.....

 

 

[stigzler]

On 17/08/2017 at 11:51 PM, stigzler said:

Oh. No doubt you'll do it. Dodgy RF box? (As the vicar said to the milkmaid)

Ahem...

Glad you got it sorted. Is that the heavy sizer at the front? Hard to tell on that photo. For the love of the little baby Jesus' angel hair, don't Piminate that! They needs to be lovingly restored...

[RIP-Felix]

8 hours ago, stigzler said:

Ahem...

Glad you got it sorted. Is that the heavy sizer at the front? Hard to tell on that photo. For the love of the little baby Jesus' angel hair, don't Piminate that! They needs to be lovingly restored...

"Piminate"? Auto-correct gaff or is this a term used across the pond?

     Regardless, the one in front was the Heavy Sixer and I have no intention to modify it. Yes, she is a restoration project. She had a few screws loose and was slightly disassembled in that photo, because she was in the first stage of a loving restoration. To follow is the romance novel synopsis:

Spoiler

I gave her a bath in warm soapy water, I cleaned her crevasses and motherboard with isopropyl alcohol, I gently removed her switches and lubed them with my dielectric silicone grease. We then played doctor and I checked her vitals with my electrical devices (Oscilloscope and Multimeter). She cleared the medical exam with only one hint at her age. She shallowed up 2mV in the 5v +/- 0.1v test. She read 4.88V. However, she hasn't looked this pristine since the day she was born (Dec/31/1980, says the manf. date still taped to her RF shielding)...and now for a quote taken out of context from one of my earlier posts.

On 8/17/2017 at 3:11 PM, RIP-Felix said:

...the tip is a bit long for the female plug on the motherboard. It went in, but didn't bottom out.

...Okay, perhaps I'm enjoying this project a little too much..lol!

     This one looks by far the best. Not just aesthetically, but color depth and pixel accuracy. It's kinda neat to compare them with the same game one after another and see the distinct differences between them. Interesting. They all turn on and play. The oldest and coolest happens to be the best performer. From an untested console off e-bay, Nice! I may have to replace that voltage regulator at some point, since the shallowing voltage can cause problems, but that's an easy fix far down the road.

     While I already tested and verified the Woody four switch is working well, albeit with less color depth and pixel accuracy as the Heavy Sixer, the Vader didn't pass the tests. The vader was guarenteed to work or my money back, it does. It turns on and plays games, yes...but with flickering and RF interference. I figured some cleaning and knocking the rust off the RF cable port would clear the picture up, but it didn't. Here is what I think the reason is:

I'll have to see if I can find the correct cap+resistor to replace and give it a try. It may be that simple. The lack of a reset pulse can cause all kinds of glitches, so it needs to be fixed. I noticed that the layout of the revision 16 Atari motherboard in the Vader is different than the 14 in my woody four switcher. First off the chipset is socketless and therefore not interchangeable without soldering. So they are more difficult to work on:

     While I was checking out the comparative anatomy of my Atari's I took note of pins 12/13 for the NTSC bridge on the Vader four switcher to see what they looked like and confirm their existance:

Good thing I didn't waste my time trying to desolder it.

[hansolo77]

Man congrats on discovering the solution.  I've been silently spying on this thread and am amazed at the technical knowledge and electrical skill you have.  I mean, I wouldn't know where to begin on this stuff.  I'd have tried a different VHF/UHF switch (I have 3 in a box somewhere).  If that didn't work, I would have taken it apart and did my best deep cleaning without the removal of parts (Caps, Resisters, etc) and just hoped cleaning fixed it.  From there I would have just pitched the thing in the trash.  Seeing your most recent post, about using oscilloscopes and stuff is WAY beyond anything I would have tried or even known how to do.  I don't even know how to use a basic multi-meter.  So I think you could probably build your own if you had all the parts.    Good job!

[RIP-Felix]

16 hours ago, hansolo77 said:

Man congrats on discovering the solution.  I've been silently spying on this thread and am amazed at the technical knowledge and electrical skill you have.  I mean, I wouldn't know where to begin on this stuff.  I'd have tried a different VHF/UHF switch (I have 3 in a box somewhere).  If that didn't work, I would have taken it apart and did my best deep cleaning without the removal of parts (Caps, Resisters, etc) and just hoped cleaning fixed it.  From there I would have just pitched the thing in the trash.  Seeing your most recent post, about using oscilloscopes and stuff is WAY beyond anything I would have tried or even known how to do.  I don't even know how to use a basic multi-meter.

    Actually neither did I before I began trying to fix my old consoles and mod stuff. I got a basic multimeter free from Harbor freight with the purchase of some random tool. I've just been using that. It doesn't even have a continuity buzzer, so I just use resistance to check continuity. That plus my $12 soldering iron from Radioshack makeup my ghetto electronics station. I don't even have a tube of Flux ATM! NO FLUX!!!

     Seriously though, I didn't really know what I was doing when I started this project. I learned as I went. Youtube, google, and patience. All I had coming in was comfort working with electronics. Actually, I did know not to start soldering components without checking the circuit schematics. That's why I didn't desolderer the NTSC bridge on TIA pins 12/13 before looking up the pinout diagram. It didn't look right to me, but I didn't want to assume. Turns out that was a good bit of restraint. I figured out a long time ago, you can't break it if it's already broke, unless it ain't broke to begin with. Either you'll fix it or you're back where you started. So why not have a crack at it?

     As for the Oscilloscope, well that's a necessary tool if you're really going to get into fixing old motherboards, especially Arcade games. They can help you locate bad roms, capacitors, diodes, check frequencies, it's the all around tool needed for more serious electronics tinkerers. However, they can be expensive. Since I have access to good ones at work, I went ahead and checked the boards out (Took maybe 15 mins). I rarely need to use a scope, usually a good cleaning is all that's necessary. In this case, I really wanted to get to the bottom of it. And an Oscilloscope turned out to be quite helpful.

17 hours ago, hansolo77 said:

 So I think you could probably build your own if you had all the parts.    Good job!

It would take a lot more reading and tinkering, but probably. Actually the 2600 is a remarkably simple circuit. I was pleasantly surprised how easy it was to understand, but it was mostly that service training video. I'm glad I found that.

[ClassicGMR]

19 hours ago, hansolo77 said:

 So I think you could probably build your own if you had all the parts.    Good job!

This is actually why you could play Atari 2600 games on an Intellivision or ColecoVision. It's also why the Coleco Gemini first hit the market. The 2600 could easily be built using off the shelf parts from any Radio Shack at the time with the exception of the TIA chip. That was the only part that was proprietary and Coleco had Motorola engineers working on their clone that worked on the 2600. It was such a grey area that Atari and Coleco settled out of court because - in my opinion - neither company was on solid ground. Did Coleco infringe on the patent or did Atari build such a simple, basic machine that anyone could put it together by writing their own code to simulate the TIA chip?

All academic as they settled the case, Coleco paid Atari some pittance royalties and both companies made a ton of cash for another year before everything crashed.

Mattel went one step further and designed their own circuits - lawsuits threatened but nothing was even filed by Atari. No leg to stand on - again my opinion.

Quote

Although Atari threatened to sue, Mattel's lawyers concluded that it would be legal to clone 2600s since they contained all off-the-shelf hardware and no copyrightable software (as an Intellivision or Colecovision does). No lawsuit appeared, and clones started appearing from other companies.

 

[RIP-Felix]

Nerdvana. I wonder if that precedent is what made emulation harder. Since console manufacturers had to create innovative (proprietary) technology to prevent knockoffs from under-cutting their business, the complexity consequently made emulation more difficult. Original X-box, for example, is too hard to duplicate and had too few exclusive titles to justify a determined emulation effort. Too much trouble for such a small number of people who would appreciate it.

[RIP-Felix]

     I think I found my answer about the lack of a Reset Pulse on the A2600 Revision 16 "Vader" four switcher. I stumbled across this excellent site which has everything the would be Atari 2600 repairman could need to know about the system. I had a quick read through the service manual and found that the 4 model revisions of Atari 2600 have some important functional differences. My woody four switcher, besides the single motherboard form factor, added some pull up resistors and diodes to the Television Interface Adapter lines (LM1 and Sync). These prevent feedback and ensure +5v on the signal. This change is also present on revision 16 "Vader" motherboards, except they add a Timing Chip (A205) into the Reset Circuit that eliminate problems the reset pulse was necessary for (I assume this is why I don't get the same curve). It's not the result of a faulty reset pulse circuit, but rather a design change that removes this problem entirely. So the lack of a reset pulse I noted earlier on the Vader is a non-issue. It would be a problem on the 2600 and pre-revision 16 2600A motherboards, but they checked out.

     That solves it then. I now have 3 functional Atari 2600s. One "Heavy Sixer" (2600) in pristine condition, one rev. 14 "woody four switcher" (2600A) with a broken Player 1 difficulty slider, and one rev. 16 "Darth Vader" (2600A). They all play games without major issues! If one ever breaks down, now I know how to troubleshoot and fix them (I'll use that service guide's flowchart to diagnose and fix the problem). Actually, from that guide, I now know that the best one of the three to use for daily play is the Vader. It has the best circuit protection and won't have issues with the reset timing. The 2600 should be tucked away for preservation or placed on display, but not used while an alternative exists (Vader/Woody/Emulation).

[ClassicGMR]

Bah... technical blah blah arf woof blah jargon...

PLAY THE HEAVY SIXER. It's the best console ever.

$5.00 to replace that difficulty switch if you're into it.