On the bench for refurb/overhaul

[Shawn]

You are joking, right? Look right above the "A" - see that charred hole? - it's cracked through to the rear of the IC.

 

Didn't see that as a hole sorry. The pics didn't lend to that for me.

[mojoatomic]

 

Didn't see that as a hole sorry. The pics didn't lend to that for me.

 

No worries - I really kind of figured you were making a joke and breaking my balls :-)

[+xucaen]

Every electrolytic can on these boards is bad. Period. Electrolytic caps have a useful lifespan of around 10 years... beyond that, the electrolytic degrades and the ESR of the cap goes through the roof.

 

Are there just 3 - the big one and the 2 small ones?

[mojoatomic]

 

Are there just 3 - the big one and the 2 small ones?

That's it for the electrolytic caps

[kb3wmh]

 

You mean isopropyl? That's what rubbing alcohol usually is. Is there another type called isopropanol?

 

Edit:

I guess I could have googled first. Isopropanol is just another name for isopropyl?

Isopropyl alcohol is the common name, IUPAC calls it isopropanol, so yep, they're the same .

 

Sent from my Nexus 6P using Tapatalk

[Andromeda Stardust]

Isopropyl alcohol is the common name, IUPAC calls it isopropanol, so yep, they're the same .

 

Sent from my Nexus 6P using Tapatalk

Yes exactly the same thing. Isopropanol has the hydroxyl ion on the middle carbon instead of one of the ends, making it ever so slightly more polar than propanol.

[mojoatomic]

I haven't received the parts for the original machine posted about yet, but I did receive parts for other new ones on the bench :-) Onto the show - running out of room, they're sitting on the laser cutter.

 

All cases washed, polished and shining like new money.

 

Top left - caps, voltage regulator and replaced female cart connector (too far gone to be reliably repaired). Original symptom was blank screen, issue was RIOT, replaced. After that it didn't like Activision, so cart connector replaced with new OEM connector. It's ready for another 30 years now.

 

Bottom left - caps, voltage regulator good, replaced left joystick port, reflowed dry IC joints, made RF adjustment. This is a version 8 board - my favorite of all the 4 switch units.

 

Top right - caps, voltage regulator, TIA showed bad on burn in after 10 minutes (wavy rainbows, then blank) replaced. Replaced channel switch, reflowed high stress joints and all IC joints.

 

Bottom right - caps, voltage regulator, both joystick ports, reflowed switches and IC joints, replaced jack

 

 

 

 

Here's the version 8 ready to go -

 

Edited February 5, 2017 by mojoatomic

[Tombstone]

And the game from 1982 looks better than ever! Well done. I am taking notes. I've got maybe 100 consoles in my garage that, some day soon, will be given the attention they deserve. I have a break in a couple of weeks and another in March and plan to see what I can do to get those beauties back to their intended glory. Thanks for the inspiration!

[mojoatomic]

And the game from 1982 looks better than ever! Well done. I am taking notes. I've got maybe 100 consoles in my garage that, some day soon, will be given the attention they deserve. I have a break in a couple of weeks and another in March and plan to see what I can do to get those beauties back to their intended glory. Thanks for the inspiration!

 

Most welcome! It can take a bit of effort to get them running correctly for sure. Your gonna need an assembly line for 100 :-)

[mojoatomic]

Got a light sixer on the bench -

 

Replaced caps, VR was good, reflowed IC's - they had some really bad cold joints, caused an issue that looked like a bad RIOT, but just cold solder joints. Installed an 820ohm resistor per factory bulletin - look at how vivid it makes the colors. Small RF adjustment and there we have it. The old man still knows how to fix 'em after all these years :-)

 

Someone just sent a PM for clarification; yes, that's RF, not composite :-)

 

Edited February 5, 2017 by mojoatomic

[Andromeda Stardust]

Got a light sixer on the bench -

 

Replaced caps, VR was good, reflowed IC's - they had some really bad cold joints, caused an issue that looked like a bad RIOT, but just cold solder joints. Installed an 820ohm resistor per factory bulletin - look at how vivid it makes the colors. Small RF adjustment and there we have it. The old man still knows how to fix 'em after all these years :-)

 

Someone just sent a PM for clarification; yes, that's RF, not composite :-)

 

I replaced the 7805 and "Chicklet" capacitor in my 4-switch Atari woodgrain and stripped out the RCA in favor of Coax. There's a 1 foot internal RF cable mounted to a right angle RCA plug to an F-coupler on the back of the unit. Large RF brick over the internal cable too. I hook it up same as you would a VCR, NTSC channel 2. Couldn't be prettier, and yes, I did do the 820 ohm mod in 2015 and it really makes the colors a lot warmer and overall improve the saturation. I couldn't ask for a cleaner snow-free picture over RF. There is about a half pixel width of chroma bleed due to the lack of pre-emphasis filtering, but this makes the sprites look more natural and less jaggy. I will not be installing AV-mod on it.

[+DrVenkman]

Got a light sixer on the bench -

 

[sNIP]

 

Installed an 820ohm resistor per factory bulletin - look at how vivid it makes the colors.

 

The Service Bulletin is for pre-Rev 16 4-switch units.

[Andromeda Stardust]

 

The Service Bulletin is for pre-Rev 16 4-switch units.

Or make the already bright and vivid 6-switch even more bright and vivid. I wonder what effect different values of resistance would have, ie lowering the resistance value might brighten the colors to a point, until the output becomes garish. That Ms Pacman screenshot does appear somewhat unnaturally saturated.

 

On a side note, the output from my 4-switch woody RF was almost exactly the same as my AV 7800 through composite on the same TV. When I added the 820 ohm resistor, it really made the colors on the 4-switch pop. Too bad there is not a similar mod for the 7800.

[+DrVenkman]

Or make the already bright and vivid 6-switch even more bright and vivid. I wonder what effect different values of resistance would have, ie lowering the resistance value might brighten the colors to a point, until the output becomes garish. That Ms Pacman screenshot does appear somewhat unnaturally saturated.

 

On a side note, the output from my 4-switch woody RF was almost exactly the same as my AV 7800 through composite on the same TV. When I added the 820 ohm resistor, it really made the colors on the 4-switch pop. Too bad there is not a similar mod for the 7800.

 

Oh, I know it CAN be done on any 2600-type machine. I'm just pointing out that the Tech Tip is specifically for pre-Rev 16 2600A 4-switch units. I've performed it myself.

 

And for what it's worth, you can do the very same mod to a 7800 but personally I didn't see much difference. *shrug*

[Tombstone]

Most welcome! It can take a bit of effort to get them running correctly for sure. Your gonna need an assembly line for 100 :-)

 

Yes, an assembly line may be in order. These have accumulated over many many years and maybe 10 of them are used for donor parts. This has become my favorite thread on AA.

[mojoatomic]

 

The Service Bulletin is for pre-Rev 16 4-switch units.

 

Please have a look at your schematic for the light 6 2600 - you'll find that r213 is a 680ohm resistor running between pin 6 & 9 on the TIA. On some 2600's this resistor was inexplicably a 1/8w part, and it should have been 1/4w. Also notice the following circuitry on the pins is identical. See that 5v downstream? It's an issue and can cause a dry joint over time, and the color gets screwy. You can without harm replace it with a 820ohm 1/4w and enjoy richer color saturation, or put the original value part at the correct wattage in its place. To my knowledge, there was never a bulletin addressing this; I don't remember seeing one anyway and I don't have one in my old files. Hence the need for old guys who know to look for it :-)

 

You are correct that the bulletin addresses the 2600A board, but it also works for the light six as well, better than original actually - that's why they made the change from 680ohm to 820ohm on the 2600A.

[Andromeda Stardust]

Please have a look at your schematic for the light 6 2600 - you'll find that r213 is a 680ohm resistor running between pin 6 & 9 on the TIA. On some 2600's this resistor was inexplicably a 1/8w part, and it should have been 1/4w. Also notice the following circuitry on the pins is identical. See that 5v downstream? It's an issue and can cause a dry joint over time, and the color gets screwy. You can without harm replace it with a 820ohm 1/4w and enjoy richer color saturation, or put the original value part at the correct wattage in its place. To my knowledge, there was never a bulletin addressing this; I don't remember seeing one anyway and I don't have one in my old files. Hence the need for old guys who know to look for it :-)

 

You are correct that the bulletin addresses the 2600A board, but it also works for the light six as well, better than original actually - that's why they made the change from 680Ω to 820Ω on the 2600A.

So they went from 680Ω in the light sixer to 820Ω in the 2600A? Why then is it necessary to add it in if it was already there?Would that not bring the effective resistance down to 410Ω?

 

Also it shouldn't matter if the resistor is 1/8 or 1/4 watt. No voltage potential inside the Atari is greater than 5V. 5V across a 680Ω resistor is about 7mA. 7mA * 5V is only 35 milliwatts so even a tiny 1/16w resistor would be well within the component tolerance, and 1/32 being barely exceeded. The higher value 820Ω resistor has an even lower wattage at 5V so I'm not sure why it matters what the maximum power rating the resistor is.

 

So I am wondering, was the 820Ω omitted fromthe 2600A schematic? Or was a too-high resistor value used, and the 820Ω parallel resistance brings it down to 680Ω?

 

Confused.

[mojoatomic]

Im not sure that I understand the first part of the question - you can remove the 680 and replace it with a 820 on the light 6 if you want to, but on 2600A boards it was simply omitted from the circuit (from the factory) completely up till 2600A rev 16 boards.

 

You wouldn't think it would make a difference, but it does for whatever reason, as only the undervalued resistors ever have an issue, and not all of them do at that. Here's another weird thing... All of the ones that have an issue measure quite a bit lower than they are marked. No idea why. It's just weird and one of those things I guess.

 

The best reason I can think of as to why it was omitted up till rev 16 2600A boards is that it saved 1/100 of a cent per board, or something like that. The color is better with it, and I think that's why the bulletin was worded in a "If you want to" tone. Basically it says, "This will make it look better, but we're not gonna pay for it. You can provide the resistor and charge your customer a few bucks to install it if you want to."

 

Which reminds me of something I haven't thought of in a long time... I seem to remember later on Atari added the resistor to the reimbursement schedule. I need to find my original NARDA forms that Atari reimbursed us off of and see if I ever made a claim for installing these resistors...

 

There was a booklet that they gave to factory authorized repair centers, and I can't find mine - but they had the repair reimbursement schedule in them. If I can find it I'll research this and post. I guess it doesn't really matter, other than being an interesting bit of what us now ancient history.

[mojoatomic]

Well, I haven't found the paperwork I was looking for..yet - but man oh man oh man look what I did find!!

 

several boxes of these!

 

[Andromeda Stardust]

Holy sweets; foam washers!

 

Didn't Best run out of these? My Atari fortunately had all four still intact.

 

Aye, if I read you right, Atari used a 680 resistor in the 6-switch, then omitted them all but the latest the 4-switch models, then recommended adding back in the 820 which improved color but had a lesser impact than 680. What effect does too small a resistance have on the circuit? Do colors become over-saturated? If I had an Atari for tinkering, a pot in series with a 330 ohm resistor (or value sufficient so as not to burn up if the pot is shorted) would yield an interesting effect. tweak it up and down, then you have a saturation pot in addition to the hue pot.

 

Kinda like my pitch bending Pitfall II circuit.

[mojoatomic]

Back to the original 2600A from this post - got a few parts in the mail today, so on with the repair -

 

Everything else has been repaired... except for the RF. You could buy the module and slap it in :-) or... you could make it like new for a few pennies instead. Unrepairable? Pish posh. There's no magic to it.

 

 

Remove as much solder from the 2 joints on the side as you can, and then use desoldering braid for the rest - after that, just pull the board out.. like so -

 

 

 

 

Make a few tests - it's a bad IC this time, just a transistor array. DON'T install an IC socket for this repair... I know what I said before, but it doesn't count for RF :-)

 

 

New IC installed, ready to go.

[AtariLeaf]

Very interesting thread. I wonder if bad caps would cause that jailbar effect a couple of us have been having.

[mojoatomic]

Very interesting thread. I wonder if bad caps would cause that jailbar effect a couple of us have been having.

Anythings possible. In troubleshooting a issue like this, it helps to have an absolutely minimal setup for testing - 2600>F connector>TV. I noticed you said " I get the same effect on multiple consoles with multiple rf cords and multiple power supplies." Do you have a UPS with a battery lying around, or can you borrow one? If you unplug it and run in UPS mode, that will get you a divorce from any issues with line power being the culprit. Plug in the Atari and TV, and that's it.

 

On another note... the caps are 40 years old, they're suspect right off jump street - I would change them prophylactically.

[AtariLeaf]

Anythings possible. In troubleshooting a issue like this, it helps to have an absolutely minimal setup for testing - 2600>F connector>TV. I noticed you said " I get the same effect on multiple consoles with multiple rf cords and multiple power supplies." Do you have a UPS with a battery lying around, or can you borrow one? If you unplug it and run in UPS mode, that will get you a divorce from any issues with line power being the culprit. Plug in the Atari and TV, and that's it.

 

On another note... the caps are 40 years old, they're suspect right off jump street - I would change them prophylactically.

 

Thanks, no I don't have a UPS, just a surge suppressor. Not a cheap one but a higher end one that I actually bought with my HDTV. It has been recommended to me that I do get a proper UPS just need hobby funds.

 

As for the caps, is there a reliable online source to purchase the ones I'd need for my 2600's? I'm not a techie and if I do replace the caps it would be a local game store owner who does fix consoles so I'd have to buy the parts and bring them to him.

[mojoatomic]

 

Thanks, no I don't have a UPS, just a surge suppressor. Not a cheap one but a higher end one that I actually bought with my HDTV. It has been recommended to me that I do get a proper UPS just need hobby funds.

 

As for the caps, is there a reliable online source to purchase the ones I'd need for my 2600's? I'm not a techie and if I do replace the caps it would be a local game store owner who does fix consoles so I'd have to buy the parts and bring them to him.

 

I'll send you a set, PM me