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tripled79

Repair the VCS?

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I just bought a used Atari that was listed as parts only.

I took it apart, cleaned the board, soldered fresh capacitors, switches, power jack, etc. The Power supply seems okay under no load.

 

I'm wondering if there is a source of info or schematics so i can poke around and troubleshoot the unit before I write this thing off.

Any ideas?

 

Thanks.

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On 8/14/2021 at 10:19 AM, DrVenkman said:

The Field Service Manual is on Atarimania. It’s got schematics, parts lists and a very complete set of troubleshooting flowcharts.

 

http://www.atarimania.com/documents/Atari_2600_2600_A_VCS_Domestic_Field_Service_Manual.pdf

This will be most helpful. Now if only my clogged printer heads would produce a decent piece of paper worth reading...

 

Thanks.

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On 8/14/2021 at 10:19 AM, DrVenkman said:

The Field Service Manual is on Atarimania. It’s got schematics, parts lists and a very complete set of troubleshooting flowcharts.

 

http://www.atarimania.com/documents/Atari_2600_2600_A_VCS_Domestic_Field_Service_Manual.pdf

After giving the book a little bit of a read, I guess the next question is, how I can get a DTC (Diagnostic Test Cartridge)?

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19 hours ago, tripled79 said:

After giving the book a little bit of a read, I guess the next question is, how I can get a DTC (Diagnostic Test Cartridge)?

To fully utilize the diagnostic cart, you'd need to track down a vintage test harness or wire one up yourself. To be honest, I have never bothered with that. By and large, you really don't need it for the majority (maybe any) of the common issues that affect 2600's. If you follow the troubleshooting flowcharts, can read a schematic, know how to use a multimeter, and have at least one working 2-player four-way joystick game (like Pac-Man) and one working paddle game (like Breakout), you can basically fix any 2600 problems. 

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On 8/14/2021 at 10:49 AM, tripled79 said:

I just bought a used Atari that was listed as parts only.

I took it apart, cleaned the board, soldered fresh capacitors, switches, power jack, etc. The Power supply seems okay under no load.

 

I'm wondering if there is a source of info or schematics so i can poke around and troubleshoot the unit before I write this thing off.

Any ideas?

 

Thanks.

 

Check the voltage regulator if that was not already done when you replaced the other supporting population. The TIA, RIOT and 6507 would be the next things that you should have a look at. I've seen more than enough 2600's over the years and all that was wrong was a dead voltage regulator.

 

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On 8/16/2021 at 9:07 PM, Shawn said:

 

Check the voltage regulator if that was not already done when you replaced the other supporting population. The TIA, RIOT and 6507 would be the next things that you should have a look at. I've seen more than enough 2600's over the years and all that was wrong was a dead voltage regulator.

 

Thanks,

I replaced the voltage regulator. When I test the system, nothing happens. I might have to check the power flow. Hmm... maybe the power switch itself.

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On 8/16/2021 at 4:36 PM, DrVenkman said:

To fully utilize the diagnostic cart, you'd need to track down a vintage test harness or wire one up yourself. To be honest, I have never bothered with that. By and large, you really don't need it for the majority (maybe any) of the common issues that affect 2600's. If you follow the troubleshooting flowcharts, can read a schematic, know how to use a multimeter, and have at least one working 2-player four-way joystick game (like Pac-Man) and one working paddle game (like Breakout), you can basically fix any 2600 problems. 

Thanks for the input.

I haven't read far into the troubleshooting flowcharts yet, but the ones that I read ask about the image quality, etc. I can't get any picture on screen. Must be a power issue.

I might have to get my hands on a second working console in order to effectively narrow the problem in this one down.

 

Thanks again.

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2 minutes ago, tripled79 said:

I can't get any picture on screen. Must be a power issue.

 

Maybe, maybe not. There are plenty of reasons why a system may not work even if you have good power. First of all, let's be clear: are you testing with a known good, working cartridge? If so, then go to the next steps.

 

Plug in a working cartridge and power on the system. Get out your multimeter. Measure the voltage from the power supply input jack to pin 1 of the voltage regulator. Check the output of the VR on pin 3. If you're getting at or very close 5VDC, then check the 5V and GND pins on each of the three main chips. If you're getting good power and ground at all three main chips, then you may have to get hold of a spare system to try swapping chips. 

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On 8/21/2021 at 12:54 AM, tripled79 said:

I can't get any picture on screen.

Are you getting snow/static of black screen?

If the latter then if the voltages DrVenkman mentioned check out I suggest checking that the voltage on the RES (Reset) pins of the 6507 (pin 1) and the RIOT (pin 34) are 5V. 

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On 8/20/2021 at 7:10 PM, DrVenkman said:

 

Maybe, maybe not. There are plenty of reasons why a system may not work even if you have good power. First of all, let's be clear: are you testing with a known good, working cartridge? If so, then go to the next steps.

 

Plug in a working cartridge and power on the system. Get out your multimeter. Measure the voltage from the power supply input jack to pin 1 of the voltage regulator. Check the output of the VR on pin 3. If you're getting at or very close 5VDC, then check the 5V and GND pins on each of the three main chips. If you're getting good power and ground at all three main chips, then you may have to get hold of a spare system to try swapping chips. 

I'm not quite sure which pins on the Voltage regulator are 1,2, or 3, but I'm only getting 3.5VDC on one, 0 on the middle, and like 0.2 V on the last one. 

Bad power supply? With no load on the power supply, I'm getting 14VDC. Not sure where all the voltage is getting dropped...

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I replaced the power jack recently, so I'll start looking for a new power switch...

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19 hours ago, tripled79 said:

I replaced the power jack recently, so I'll start looking for a new power switch...

Looks like Best electronics sells replacement power switches... Stand By...

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On 8/22/2021 at 10:11 PM, tripled79 said:

I'm not quite sure which pins on the Voltage regulator are 1,2, or 3, but I'm only getting 3.5VDC on one, 0 on the middle, and like 0.2 V on the last one. 

With the pins nearest to you and the tab furthest from you left to right is Input, GND, Output. For the voltage regulator to output 5V it needs an input of 8V or more, as the input voltage drops below 5V the output voltage is generally the same as the input.

Therefore if you have 3.2V in and 0.2V out that suggests to me that you might have a short Circuit somewhere. I would suggest desoldering the output pin of the regulator and when certain there is no connection between it and the rest of power rail switch on and measure the output voltage, if is it 5V then your problem is after the regulator, if still at 0.2V then it is at or before the regulator.

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18 hours ago, Stephen Moss said:

With the pins nearest to you and the tab furthest from you left to right is Input, GND, Output. For the voltage regulator to output 5V it needs an input of 8V or more, as the input voltage drops below 5V the output voltage is generally the same as the input.

Therefore if you have 3.2V in and 0.2V out that suggests to me that you might have a short Circuit somewhere. I would suggest desoldering the output pin of the regulator and when certain there is no connection between it and the rest of power rail switch on and measure the output voltage, if is it 5V then your problem is after the regulator, if still at 0.2V then it is at or before the regulator.

Sound plan.

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Sorry for the delayed response. One thing I left out is that I recently bought a Composite/S-video mod kit from Winz_mod. I've been chatting with the group on discord. It seems that one of their latest boards that they've been selling recently shorts out and results with the issues I am having.

The troubleshooting method that Stephen recommended would have worked to eventually point the finger at the mod board.

I hooked up the Atari with RF and the system still works, thankfully.

Thanks for all the input, guys.

Hopefully I can successfully mod this system with nicer outputs, but until then I'll have to play Atari today in full "retro mode".

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