41 replies to this topic

[dino999]

zylon, on Sun Sep 4, 2011 1:46 PM, said:

That little chip near the power button could be suspect as well. It sends power to the CPU and the video components. It may be sending power to video, but not the CPU functions.

How could I determine if it was working correctly?

[zylon]

dino999, on Tue Sep 6, 2011 11:21 AM, said:

zylon, on Sun Sep 4, 2011 1:46 PM, said:

That little chip near the power button could be suspect as well. It sends power to the CPU and the video components. It may be sending power to video, but not the CPU functions.

How could I determine if it was working correctly?

I usually just swap it with a good one. They can be found cheaply on ebay. There's probably a method in the manual, but file is too big for me to upload here.

http://www.atariage....ost__p__2315709

Edited by zylon, Tue Sep 6, 2011 11:51 AM.

[dino999]

I probably should have mentioned this earlier. Before I replaced the GTIA and ANTIC, I opened up the case and moved two dials (yellow and green circular things) located on the lower right end of the motherboard (pictured in the attachment to this post). I tried to get them into the same orientation, but I don't know if I screwed up something else. Just to clarify: the screen was already solid black when the system was turned on before I did this.

Attached Thumbnails

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Edited by dino999, Wed Sep 7, 2011 2:25 AM.

[Official Ninja]

dino999, on Wed Sep 7, 2011 2:25 AM, said:

I probably should have mentioned this earlier. Before I replaced the GTIA and ANTIC, I opened up the case and moved two dials (yellow and green circular things) located on the lower right end of the motherboard (pictured in the attachment to this post). I tried to get them into the same orientation, but I don't know if I screwed up something else. Just to clarify: the screen was already solid black when the system was turned on before I did this.

The knob on the left is to adjust the pokey. It is used to set the center position for the joysticks.

The knob on the right adjusts the color.

[dino999]

Ha! Ha! That will be fun to fix once I get to the point of seeing stuff onscreen.

[dino999]

Ok, back at this after a month doing work

Anyways. I check the voltage of all ICs and got around 4.9v for most of them. Unfortunately, A7 failed. I also have a bunch of other chip failures reading around 0V; A14 through A25; A27 is good, though. I have no idea how to test A26 since the manual I found on the internet left this one as a mystery.

I was thinking. Might the string of failures from A14 through A25 have something to do with my scratched traces. The one trace I was able to test and continuity was good. The other I am kinda guessing at because it goes to the underside of the board (I think) and I didn't take off the bottom shield.

I included a higher resolution image as well as the original scratch for a side by side comparison.

Attached Thumbnails

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[dino999]

Anyone? Looking for advice on how to proceed. Can it be fixed? Anyone have a similar situation? Really like a working 5200 2-port

[zylon]

A26 is a "spare" and was not even installed on some boards. A7, I believe is the POKEY. Your RAM chips might not be even getting turned on by the system. The 5200 splits power into 2 channels, one for video circuits and the other for logic circuits. I don't believe that scratch is deep enough to affect it but you can try metering either side of the scratch or just clean it up and put a small solder blob there.

[dino999]

Where do I test and how should I test whether power is being sent to either channel? Where is the junction point?

[eightbitter]

Disassemble the console, remove the top RF shield, bottom leave. Remove and reinsert in right positon all chips in sockets. Clean contacts of cartridge, look into cart socket and remove all clips or other metalic intrusions (do not remove gold contacts! ;o). Connect the power supply, RF cable to TV, insert the cartridge and turn on the console. Set the multimeter to 20V DC range and check voltage on pins of chips: for example 74LS139: pin 8 is GND (-), pin 16 is VCC (+) or the RAM 4516 VCC pin 8, pin 16 GND. Next check RF modulator: pin 1 GND, pin 3 VCC. Mulimeter should show ca 5V DC. As GND you can use large metalic track around board.
Next check temperature of chips, should be slightly warm, more warm can be CPU (CO14806) and ANTIC (CO12296). Warm chips of RAM 4516 (CO18082) should be replaced.
Big 40pin chips rarely are damaged.

[dino999]

eightbitter, on Tue Oct 18, 2011 12:01 AM, said:

Remove and reinsert in right positon all chips in sockets.

By "in right position," you mean their correct original position?? I just want clarification on your wording

[eightbitter]

Yes, correct original position. Excuse me for misunderstandig, in some cases I use Google translator, because english is not my native language and I have difficulties in language dezinvoltures and nuances

Edited by eightbitter, Wed Oct 19, 2011 4:59 AM.

[zylon]

dino999, on Mon Oct 17, 2011 11:08 PM, said:

Where do I test and how should I test whether power is being sent to either channel? Where is the junction point?

The junction/split point for the power channels is the small chip near the power switch, but I'd still suspect the ANTIC chip unless it was tested in another working deck. Solid black or green screen is usually a logic circuit failure.

[eightbitter]

Here you are power scheme of the console 5200 2-port. At the bottom you see two squares, the two parts of IC CD4013, which switch on and off the power. Pressing monostable switch S2 causes the transistor Q7 is open or not. When is open - the voltage of 5V is stabilized by the stabilizer VR2 and indicator lights. Now are powered logic circuits (ANTIC, GTIA, CPU and ROM). Cartridge shorts two contacts CI1 and CI2, open transistor Q6 and VR1 stabilizes the voltage. Supplied are POKEY, RAM, TTL, and video circuits. The console starts.
It is sufficient to measure the voltage on modulator (powered by VR2) and any TTL chip (powered by VR1) to make sure that console is powered. You can also check the presence of voltage on the other chips to make sure that there is no interruption in the supply circuit.

Edited by eightbitter, Wed Oct 19, 2011 2:09 PM.

[classics]

Do any of the 5200 diagnostic roms include an option to test the basic system functionality without RAM present?

[Mitch]

classics, on Thu Oct 20, 2011 1:42 AM, said:

Do any of the 5200 diagnostic roms include an option to test the basic system functionality without RAM present?

I don't think so. They need to start up like a regular program to run the diag software.

Mitch

[classics]

Mitch, on Thu Oct 20, 2011 12:16 PM, said:

classics, on Thu Oct 20, 2011 1:42 AM, said:

Do any of the 5200 diagnostic roms include an option to test the basic system functionality without RAM present?

I don't think so. They need to start up like a regular program to run the diag software.

Mitch

Ok, I threw together a RAM tester that will run with bad RAM chips installed (or even no ram chips at all).

I'll post it in a separate thread so people can find it more easily when they are searching for a program to test RAM.

Steve