Which one's right!?!? (Atari 2600 Schematics)

Electric Rain · Post by **Electric Rain** » Tue Mar 29, 2005 12:41 pm

Hello,

I'm building an Atari 2600 portable, and I need schematics. I've found three different schematics in my searching.

Kevin's: http://www.tripoint.org/kevtris/2600/2600schemo.html

Dan's: http://atarihq.com/danb/a2600.shtml

AtariAge's: http://www.atariage.com/2600/archives/s ... _High.html

Problem is, none of them are the same. I started on the power section. I haven't compared other sections very much yet, because I've been baffled at the power section.

I want to use Kevin's schematics because they're the simplest. Can someone tell me what (if anything) is WRONG with Kevin's schematics?

1. It looks like Kevin screwed up the placing of that 4.7K resistor. It's after the diodes, but on the other two, it's before the diodes.

2. On Dan's schematics, that power filter cap is only 220uF. However, on the other two it's 2200uF. (I think the correct value is 2200uF...)

3. There is also some confusion on those caps near the "end" of the power section. It seems as though Dan and AtariAge have them the same way, but Kevin cut some out. Is this because he cut out the modulator and therefore doesn't need them?

4. Also, Dan and AtariAge's reset generator is the same, but Kevin's couldn't look much different. I see he used one of the sections leftover from the 4050 he used in his video mod. Why is this, and will it still work right?

I'm sure there are other differences as well. So, basically what I'm asking is, can someone tell me if there's anything in Kevin's schematics that needs to change? Thank you.

Rain

P.S. Do I need that last schematic on Kevin's page? The one labeled 2600 IF? Or can I cut it out since I won't be using RF? I don't see what other purpose it serves...

P.P.S. I can't afford to kill Stella! She's expensive!

Lucretius · Post by **Lucretius** » Tue Mar 29, 2005 12:46 pm

Is it possible that they are reffering to different modles. The 6-Switch, 4-swith, etc. There were 26 models made...

Post by **gannon** » Tue Mar 29, 2005 12:53 pm

Kevin Horton's are the schematics for the 2600 Jr.

Electric Rain · Post by **Electric Rain** » Tue Mar 29, 2005 1:59 pm

That's what I thought... so this means that Kevin's are 100% correct? Also, can I cut out all of those filter caps on the joystick lines? Or should I keep them there? What purpose do they serve?

JackFrost22 · Post by **JackFrost22** » Tue Mar 29, 2005 2:24 pm

for paddles

Electric Rain · Post by **Electric Rain** » Tue Mar 29, 2005 2:49 pm

Whoa whoa whoa! Kill Firefox!? What's wrong with Firefox?!?! Well... I guess that's just your opinion. Can't be helped.

But anyway, what about the paddles? Why do they need those caps?

HK-47 · Post by **HK-47** » Tue Mar 29, 2005 3:03 pm

The paddles require the .068uf caps.

Also what model are you using? jr, 4 switch, or 6 switch?

Electric Rain · Post by **Electric Rain** » Tue Mar 29, 2005 3:15 pm

HK-47 wrote:The paddles require the .068uf caps.
Also what model are you using? jr, 4 switch, or 6 switch?

Model? Well... let's just put it this way. I've never owned an Atari, and I still don't. But I still love it, and it's a classic, so I want to make it portable.

So I'm building one from scratch and I'm getting my chips from http://www.best-electronics-ca.com/.

Oh, and also... do I REALLY need that ferret bead in the power schematic OR the entire last schematic on Kevin's page? What do they do? Thanks.

Rain

HK-47 · Post by **HK-47** » Tue Mar 29, 2005 3:20 pm

Buy your chips from here: http://www.vintagefunworld.com/items.asp?ID=31
There cheaper.

Electric Rain · Post by **Electric Rain** » Tue Mar 29, 2005 3:38 pm

Wow... not bad. Not bad at all. Very nice prices, though they aren't new. I can only assume they are more of a surplus type of place. They run out of things and have a very low quantity of USED parts. Best Electronics claims to have new chips, however. (However they can get their hands on those...) But, I may still go with Vintage Fun World. Those prices are hard to ignore.

Post by **gannon** » Tue Mar 29, 2005 4:38 pm

It's kinda impossible to get new TIA chips

The ram and processor chips are standard though so pretty easy to find new.

Electric Rain · Post by **Electric Rain** » Thu Mar 31, 2005 11:41 pm

Yeah, well, I'm just going by what I saw...

Anyway, about that ferret bead in the power schematic and the last schematic on Kevin's page, do I need them? If so, what do they do? I only intend to use composite video and audio, so I don't see what purpose the bottom schematic serves.

FBs are for interference, right? So if I'm not using RF... do I really need it?

Rain

Electric Rain · Post by **Electric Rain** » Fri Apr 01, 2005 5:27 pm

Aw, come on now. Just two more questions.

I'm in the middle of designing the PCB. But I need that info. Can someone answer those for me? Thanks.

Rain

Post by **gannon** » Fri Apr 01, 2005 6:12 pm

They probably aren't needed. I think they just clean up the signal.
Also, check out http://benheck.com/v-web/bulletin/bb/vi ... php?t=1452

and http://www.atariage.com/forums/viewtopic.php?t=63578

Electric Rain · Post by **Electric Rain** » Fri Apr 01, 2005 11:30 pm

Thanks gannon. Also, quick question... can I use 1/8 watt resistors for Kevin's CD4050 video mod? There's a lot of them in that schematic, and I need to have them be as small as possible. Thanks.

Rain