2600a restoration/learning project

[griz]

Hey guys. I am a beginner when it comes to electronics but would like to rebuild an Atari 2600A and hope to learn something along the way. Any help would be appreciated.

 

Voltage Regulator Goo

 

As you can see in the attached photo there is a white paste between the voltage regulator and the motherboard heat-sink area. Is this corrosion or some form of a thermal compound? If I were to replace the voltage Regulator how do you recommend I deal with the white goo?

 

Power Supply

 

While not the original 9 volt 500 ma wall wort that came with my 2600A, I have one from an Atari sx212 modem that claims (in white letters on the case) to be compatible with the 2600. It meters 13.5 volts. Is this a little too much, or nothing to worry about?

 

Wrinkled Mobo

 

I don't know the correct terminology but the green coating over the electrical pathways on the motherboard are wrinkled. Why would this be? Is it a problem?

[shadow460]

The white good is probably thermal compound. If you've got some lying around for a modern CPU/heatsink combo, that will work to replace it. Really, though, I'd just leave it where it is.

 

The power supply could well read 13.5 volts when there's no load, and 9 volts under load from the 2600. If it says it's compatible, it probably is. I've read on here that the 2600 can handle more than 9 volts, but since I'm not the expert, I wouldn't risk running it at over 9 volts with a full load. Later if you want the wireless sticks, you have to worry about frying their receiver with too high a voltage.

[ovalbugmann]

The green coating is put there to protect the curcuit paths, of course, looks like the metal circuit paths underneath the green protective layer are separating from the board itself- since the surrounding areas are still unwrinkled. I wouldn't do anything that will make the electrical paths chip off.

 

Is this 2600 working currently? I would only use the original voltage suppy or an exact replica of whatever it's supposed to have - 9V DC - 500 mA ( 0.5A) Your taking a chance using something else. Are you going to desolder everything (rebuild from the ground up) and put in new components all-around or just try to find any problems it has? If so make sure you have a desoldering wick?, I think it's called. If it's not working, you could just try to find what component is trashed with a multimeter and the specs possibly and replace the offending part.

[wogihao]

the ampage is fine as long as its in excess of the requirement of the unit so anything over 1/2 a amp will be good. That said the voltage will be criticial. if its out I doubt that the atari was robust enough to take a wide voltage range. so sticking to 9v would be key here.

[BigO]

That's not an unusual appearance, the wrinkled look. I've never investigated whether it's a result of the solder/tinning on the traces or the coating or what, but I've never had it cause me any problems. It's not exclusive to old 2600's.

 

If I had the pieces in front of me that the original poster has, I'd hook it up, plug it in and play (unless of course it's broken in which case I'd enjoy the challenge of fixing it more than actually playing it anyway).

Edited January 7, 2008 by BigO

[A.J. Franzman]

Hey guys. I am a beginner when it comes to electronics but would like to rebuild an Atari 2600A and hope to learn something along the way. Any help would be appreciated.

Rebuild it, why? What's wrong with it? If it ain't broke...

 

 

Voltage Regulator Goo

 

As you can see in the attached photo there is a white paste between the voltage regulator and the motherboard heat-sink area. Is this corrosion or some form of a thermal compound? If I were to replace the voltage Regulator how do you recommend I deal with the white goo?

This is standard silicone and zinc oxide heatsink compound. If you need to replace the regulator, you will need to clean off the old compound and replace it. Don't bother using any of the new silver-based compounds that cost like $20 and up for a couple of grams -- it's a complete waste of money. Just get more of the white stuff from Radio Shack, Fry's, or your favorite electronic components vendor.

 

But, do you actually need to replace the regulator? The VCS chips require a supply of 5.0 volts, +/- 5%. This gives a range from 4.75 to 5.25 volts. Most 7805 regulators run slightly below 5 volts, this is normal. Measure the output on the middle (ground) and lower (output) pins as shown in your photo, and if it's in that range, you don't need to replace it.

 

 

Power Supply

 

While not the original 9 volt 500 ma wall wort that came with my 2600A, I have one from an Atari sx212 modem that claims (in white letters on the case) to be compatible with the 2600. It meters 13.5 volts. Is this a little too much, or nothing to worry about?

Don't worry about it. For one thing, the voltage should be measured under load; and for another, the 2600 can take at least 16 volts as input -- the main limiting factor is the voltage rating of the large black filter capacitor, a little above the regulator in your image. This is usually 16 volts, but sometimes 25 volts. You can even use an AC adapter with a voltage as low as 7.5 volts or so, if you happen to have one. Lower voltage will let the console run a bit cooler.

 

 

Wrinkled Mobo

 

I don't know the correct terminology but the green coating over the electrical pathways on the motherboard are wrinkled. Why would this be? Is it a problem?

The green coating is called solder mask, and it is very common for it to wrinkle or even flake off. It already served its purpose when the console was assembled and makes no difference now if it's smooth, wrinkled, or gone. Edited January 6, 2008 by A.J. Franzman

[griz]

Later if you want the wireless sticks, you have to worry about frying their receiver with too high a voltage.

 

What is too high for the wireless sticks?

 

Is this 2600 working currently?

 

No. It worked about a year ago but produced horizontal lines of static on the TV. Now when I power it up I don't get a picture but I notice an initial flicker in the static when it's turned on.

 

Are you going to desolder everything...

 

No, I intend to just get it working and replace parts as needed.

 

unless of course it's broken in which case I'd enjoy the challenge of fixing it more than actually playing it anyway

 

It's broken and yes that's what I'd like to do.

 

This is standard silicone and zinc oxide heatsink compound.

 

Thanks for confirming.

 

Measure the output on the middle (ground) and lower (output) pins as shown in your photo, and if it's in that range, you don't need to replace it.

 

I get a steady 4.96 volts. From the top pin I am getting 9.8 to 10.5 volts. Power supply and voltage regulator are fine then?

 

The green coating is called solder mask, and it is very common for it to wrinkle or even flake off. It already served its purpose when the console was assembled and makes no difference now if it's smooth, wrinkled, or gone.

 

Solder mask - good to know, thanks.

 

Power on/off and color/bw switches

 

As you can see in the photo the color/bw switch is completely missing. Would this cause the 2600 to not display a picture? I have new switches on the way. The foil tape that connects the switches is no longer in stock at Best electronics. Can I get this from somewhere else or possibly solder some wire between the switches and the rf shield?

[A.J. Franzman]

Is this 2600 working currently?

No. It worked about a year ago but produced horizontal lines of static on the TV. Now when I power it up I don't get a picture but I notice an initial flicker in the static when it's turned on.

This sounds like it will probably be beyond your capability to diagnose, but you may get lucky with the "shotgun" approach (replace a bunch of parts and maybe you get to the right one{s} eventually). The two different descriptions of the image are worrisome -- this console probably now has multiple failures.

 

 

Are you going to desolder everything...

No, I intend to just get it working and replace parts as needed.

Well, that's good; there may be hope for you yet!

 

Can you help us out by describing your level of electronics knowledge/skill, and telling us what diagnostic equipment you have available and know how to use?

 

 

Measure the output on the middle (ground) and lower (output) pins as shown in your photo, and if it's in that range, you don't need to replace it.

I get a steady 4.96 volts. From the top pin I am getting 9.8 to 10.5 volts. Power supply and voltage regulator are fine then?

Apparently so. The 4.96 volts output is a little unusual; in my experience it's usually between 4.8 and 4.9 volts. Your higher voltage could just mean that your console has a voltage regulator that's closer than most to the "correct" output value, or it could mean that one or more of the chips is so totally blown that it isn't drawing any power at all. Another possibility is that the crystal oscillator circuit isn't working -- the VCS's NMOS chips draw less power in the steady-state (as they would be if there are no clock pulses) than when active.

 

 

Power on/off and color/bw switches

 

As you can see in the photo the color/bw switch is completely missing. Would this cause the 2600 to not display a picture? I have new switches on the way. The foil tape that connects the switches is no longer in stock at Best electronics. Can I get this from somewhere else or possibly solder some wire between the switches and the rf shield?

No, it isn't totally missing... just the slider part and everything attached to it (probably also the top of the casing, though it's hard to tell from your image.) Anyway, the switch being in this condition would only cause the unit to remain in "color" mode, or possibly B&W mode if the foil tape is touching one of the middle or upper contacts.

 

Your suggestion to solder some wire in place of the fancy die-cut foil tape may work, though it will make working on the board more difficult in the future. But it may take so much heat to solder to the switches that you melt the plastic sliders. The foil doesn't need to be custom-shaped like that anyway; if the ones in your console are no longer sticky or no longer in one piece (note that they almost always get torn across the top because of the way the console goes together, but if the bottom part is still solid and stuck, they're OK) you can replace them with any plain metal tape you can find (try auto parts stores). Just cut about a 1/8 inch wide strip and run it along the lower part of the switch bodies to the shielding, folding under a bit at each end and on top of the difficulty switches to make good contact. I have no idea why penny-pinching Atari went to the trouble of having these custom die-cut foil pieces made.

Edited January 8, 2008 by A.J. Franzman

[griz]

This sounds like it will probably be beyond your capability to diagnose, but you may get lucky with the "shotgun" approach (replace a bunch of parts and maybe you get to the right one{s} eventually).

 

I agree it may very well be beyond my capability. I thought I would try some of the more common repairs and hope they work ("shotgun" approach).

 

Can you help us out by describing your level of electronics knowledge/skill, and telling us what diagnostic equipment you have available and know how to use?

 

I would describe my level of electronics knowledge and experience as a little more than beginner at best. I do not own a scope but have a multimeter and can solder/desolder components. I'm attempting this if for no other reason than to learn a little along the way.

 

Apparently so. The 4.96 volts output is a little unusual; in my experience it's usually between 4.8 and 4.9 volts. Your higher voltage could just mean that your console has a voltage regulator that's closer than most to the "correct" output value, or it could mean that one or more of the chips is so totally blown that it isn't drawing any power at all. Another possibility is that the crystal oscillator circuit isn't working -- the VCS's NMOS chips draw less power in the steady-state (as they would be if there are no clock pulses) than when active.

 

Is there a way to confirm any of the above given the limited equipment and skills I currently have?

 

Good to know regarding the color/bw switch and the foil tape. Thanks for your time Mr Franzman.

[A.J. Franzman]

The 4.96 volts output is a little unusual; in my experience it's usually between 4.8 and 4.9 volts. Your higher voltage could just mean that your console has a voltage regulator that's closer than most to the "correct" output value, or it could mean that one or more of the chips is so totally blown that it isn't drawing any power at all. Another possibility is that the crystal oscillator circuit isn't working -- the VCS's NMOS chips draw less power in the steady-state (as they would be if there are no clock pulses) than when active.

Is there a way to confirm any of the above given the limited equipment and skills I currently have?

If I suspect a nonfunctional oscillator circuit, I usually check it with a logic probe. If your multimeter has a frequency counter built-in (which is not very common and more often found in expensive multimeters), that may work. You'd need to check from ground to pin 11 of the TIA chip (the 40-pin chip furthest from the cartridge port; 11th pin from the lower left) for a signal of about 3.58 MHz.

 

Other than this, chip-swapping is about all you can do at this time.

 

You're welcome!

Edited January 10, 2008 by A.J. Franzman

[griz]

If your multimeter has a frequency counter built-in (which is not very common and more often found in expensive multimeters), that may work.

 

Unfortunately no it doesn't.

 

Other than this, chip-swapping is about all you can do at this time.

 

Just to bolster my shotgun approach I have ordered the following parts :

 

- tia chip

- cpu chip

- i/o chip

- 7805 voltage regulator

- .22uF mylar capacitor

- large axial 2200uF capacitor (C243)

- new rf cable and switchbox

- new switches (all 4)

- new factory power supply

 

With luck and some help from you guys I'm hoping to be able to bring this 2600A back to life. I realize it would be less expensive to just purchase another unit, but this was my first Atari and I'd like to learn some things along the way.

[A.J. Franzman]

Just to bolster my shotgun approach I have ordered the following parts :

 

- tia chip

- cpu chip

- i/o chip

- 7805 voltage regulator

- .22uF mylar capacitor

- large axial 2200uF capacitor (C243)

- new rf cable and switchbox

- new switches (all 4)

- new factory power supply

In that case, I hope your unit doesn't have a bad RF modulator. I've had a few "no picture" units that I fixed by replacing the modulator, or the CO10174 (CA3086) IC inside it.

[elliott]

In that case, I hope your unit doesn't have a bad RF modulator. I've had a few "no picture" units that I fixed by replacing the modulator, or the CO10174 (CA3086) IC inside it.

Perfect opportunity to A/V mod it.

[griz]

Hi guys,

 

Just quick update on where I'm at with my 2600A. I soldered in new switches (all 4), replaced the rf cable, tv switchbox and wall wort power supply. Without changing anything else the unit is now functional to my surprise! Thanks for your help and suggestions. I found some aluminium foil tape at my local hardware store and used that for the static strips as suggested (thanks Mr. Franzman). See the pictures below. Note that I also have foil tape between the switches and the rf shield in the finished version.

 

Perfect opportunity to A/V mod it.

 

Exactly!

[A.J. Franzman]

I found some aluminium foil tape at my local hardware store and used that for the static strips as suggested (thanks Mr. Franzman). See the pictures below. Note that I also have foil tape between the switches and the rf shield in the finished version.

Looks good! You should also fold the tape under a little bit at each item (switch or shield) to be sure the non-sticky side makes contact with the metal. I turn under one corner at each end, and cut a small slit to do the same at the switch(es) in the middle.