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Diagnose and repairing a dead 2600 4sw/vader pal


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#1 larryleffaovell OFFLINE  

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Posted Thu Feb 1, 2018 5:37 AM

I bought some further cartridges for my collection. The complete package included a dead 2600 4-switch/vader PAL console. My thought is that this console would be nice opportunity to gain some experience in diagnose and repair (micro-) electronics.

All my cartridges are in good condition. My two light sixer and a junior as well and pimped with a composite/audio out by myself (according to instructions). Soldering skills are quite well. My knowlegde in electronics are very basic - I know nearly all components, but not the "which and when" nor "how does this works" in detail. I don't expect or want a (complete) introduction to electronics and technical details. There are books for that icon_smile.gif - but an "interactive guidiance" would be great. Learning by doing.

 

I'm sure that is nearly impossible to destroy a 2600 completly without a possibility to fix. So I started to diagnose the 2600. As the console arrives as "dead" I setup everything with it's original equipment to the TV at first, but nothing. Power adaptor is ok but I changed it to a stabilized one.

 

So I disassembled the console and checked it's condition. Fairly clean, but I cleaned the mainboard and some doubtful contacts a bit more, looks like new now.

As I can't get a picture from a dead 2600, it is difficult to tune in the correct HF channel, so I modded the console with a composite/audio out. Voila, when powering on the console now the TV turns from blue to black.

 

What I've noticed: When powering on the first time with a cartridge, the screen turnes black. When powering off and on again with the same cartridge, screen turnes black again. But when changing the cartridge and powering on again I can see vertical white bars and either a high frequency noise or a humming sound. Sometimes like this, sometimes like that.

 

I've checked and replaced C243 as the original one shows 1600uF only. The 7805 seems to be in good condition but will be replaced coming weekend. And that's the current situation.

Tools, caps/resistors etc, pinouts, schematics and Field Service Manual are at hand but I need some guidiance now to to go on further.

 

Thanks in advance!

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  • board.jpg


#2 dphirschler OFFLINE  

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Posted Mon Feb 5, 2018 9:09 PM

One of the chips needs replacing most likely.  CPU is most common (middle) followed by TIA (front).  I've seen RIOT (back) go bad too, but only once.  All three had the same looking screen.

 

Darryl



#3 larryleffaovell OFFLINE  

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Posted Tue Feb 6, 2018 6:58 AM

Thanks for this information. Will try this first. Chips ordered - I'll desolder all three ICs and place sockets meanwhile. Stay tuned :)



#4 larryleffaovell OFFLINE  

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Posted Wed Feb 7, 2018 7:51 AM

CPU and RIOT just arrvied. As I have already socketed the board the first test was done quickly. Swapped CPU first. Result: IT LIVES!

Screen is b/w only and unstable for now. Still waiting for TIA.

icon_thumbsup.gif



#5 dphirschler OFFLINE  

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Posted Wed Feb 7, 2018 5:36 PM

Yes!  CPU.  Congrats on socketing the chips.  Not a task for the novice.  I forgot the Vaders were soldered in.

 

TIA could be bad, but not sure about this one.  How is sound? 

 

How's the 7805?  Replaced it yet?  Check the color/bw switch.  dirty?

 

 

Darryl



#6 larryleffaovell OFFLINE  

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Posted Wed Feb 7, 2018 10:51 PM

I've used a soldering iron with integrated pump for that :) Was easy and fast to use and has left a clean board.

7805, the 2200 uF and a 4.7 uF are exchanged for new ones (the PAL has only one 4.7uF). Will add a 820 Ohm to TIA 6+9 and change C241 and C242 then for a 0.1uF Mylar as mentioned there: 

http://forums.atari....cture-on-2600s/ when new TIA arrives.

 

Picture/Animation of the game is ongoing, but very unstable/weak so the (digital-) TV shuts off and on the composite port for a second. But when picture is visible one can see the b/w screen and hear clear audio. 

Good idea to check and clean the color/bw switch. Will try that in addition, maybe I shut down it's function.

 

So keep tuned in here. More fabulous news to come :)

Meanwhile thank you for the support!  icon_thumbsup.gif



#7 dphirschler OFFLINE  

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Posted Thu Feb 8, 2018 5:26 PM

Did that giant heatsink (on the 7805) come on your unit?  I love that!  Also check the coax cable.

 

Darryl



#8 larryleffaovell OFFLINE  

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Posted Thu Feb 8, 2018 10:27 PM

The heatsink was already there and I just leave it there as it's getting warm when the console is powered on. And I recommend to everyone who's modding his 2600 to add one if not there.

The whole HF converter is gone already. As I mentioned in #1 I removed it at the very beginning as tuning a dead console to HF channels is quiete difficult :)

Nothing new for now. TIA is still on it's way...



#9 dphirschler OFFLINE  

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Posted Fri Feb 9, 2018 12:53 PM

Forgot about the composite mod. I am struggling getting a good picture on a composite mod as well. Look up my thread. Someone suggested some different resistor values and it helped but didn't solve it.

Darryl

#10 larryleffaovell OFFLINE  

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Posted Sat Feb 10, 2018 7:13 AM

On which console you're struggling on? I've used the attached circuit from https://www.thefutur...p/2600_comp_mod on a 7800 (good picture), a 2600 jr. (good) and a 2600 Light-Six (noisy) (all PAL consoles). Will try the other suggestions you mentioned as well to see if it helps or solve the noise.

I've used a BC546 instead the 2n3904 as I have dozens ot this type on stock.

Other suggestions that may help you are at http://forums.atari....cture-on-2600s/

Attached Thumbnails

  • circuit.jpg

Edited by larryleffaovell, Sat Feb 10, 2018 7:17 AM.


#11 larryleffaovell OFFLINE  

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Posted Sat Feb 10, 2018 7:54 AM

While still waiting for my new TIA and inspired by your (and other) posts about composite mod, b/w problems etc. I just tried and turned the "what the heck was the R213 (rotary potentiometer) for?"... Guess what: A wonderful and colorful picture comes up - with some ghosting, but stable! Hooray!

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  • rotpot.jpg
  • finally_color.jpg


#12 dphirschler OFFLINE  

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Posted Sun Feb 11, 2018 6:45 PM

Hey!  You don't need a TIA after all!  Congrats!

 

I always thought that pot was for color saturation.  But you give me hope!  I will play with that now after I switch back to the original resistor values.  I notice you have similar ghosting that I encountered.  I wonder what causes that?

 

My console is a 4 switch NTSC model, BTW.

 

Darryl



#13 larryleffaovell OFFLINE  

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Posted Sun Feb 11, 2018 10:47 PM

Hey!  You don't need a TIA after all!

 

Yeah, I know, but as these chips are rare I ordered all three just to be sure to have everything at hand if needed. I've a RIOT and a TIA as a reserve now (or for the next dead console):)

I'm sure that this damn ghosting is a result of https://en.wikipedia...ng_(television) which we should get into the grip when playing with different values for the resistors - and when regulating the whole thing with the pot.

The pot is worth trying. When I turned it around it caused miraculously things, like boosted signal, wrong/other colors, more ghosting ... - but I couldn't got the opposite; there is only a small area that turned the picture b/w and a small step further the signal became too weak for the TV.



#14 dphirschler OFFLINE  

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Posted Mon Feb 12, 2018 5:43 PM

BTW, here is the link to my AV mod issue.  http://atariage.com/...od-whats-wrong/

 

Darryl






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