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1400XL power jack pinout

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I finally got a chance to open up the 1400XL I found at a garage sale. I'm planning to build a power cable for it that will connect to a PC power supply. I used Jerzy Sobola's 1400XL schematic as a guide:

 

http://atariage.com/forums/topic/244786-1400xl-on-ebay/page-5

 

I checked each pin of the power jack against known test points on the board. However, the result seems different than what's on the schematic or what I've seen on the power supply pictures elsewhere in the forum. Here's what I'm getting:

 

post-43315-0-32142700-1488668715_thumb.jpg

 

-5V and +12V appear to be switched on my board from what I've seen elsewhere.

 

I tested my board by checking continuity between +12V on the jack and one end of R140. I also verified that -5V was connected to the other pole of the power switch from +5V. Finally, I verified +5V as connected to the power LED.

 

Am I missing something here? This is one of those things you want to get right on the first try :)

 

Here's a pic of the board in case that helps:

 

post-43315-0-49559700-1488669005_thumb.jpg

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A 1400 at a GARAGE SALE? I need to find sales like that.

 

The Atari gods were smiling down on you that day!

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A 1400 at a GARAGE SALE? I need to find sales like that.

 

The Atari gods were smiling down on you that day!

 

The board itself and at least one of the chips is labeled "1450" ... :-o I need that kind of luck in my life.

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I'm not sure but I think the 1400 board had different power than the 1450 board. Since this is a very early 1450 board, I'd start looking at those folks that built one by hand.

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I finally got a chance to open up the 1400XL I found at a garage sale. I'm planning to build a power cable for it that will connect to a PC power supply. I used Jerzy Sobola's 1400XL schematic as a guide:

 

http://atariage.com/forums/topic/244786-1400xl-on-ebay/page-5

 

I checked each pin of the power jack against known test points on the board. However, the result seems different than what's on the schematic or what I've seen on the power supply pictures elsewhere in the forum. Here's what I'm getting:

 

attachicon.gifIMG_2761.JPG

 

-5V and +12V appear to be switched on my board from what I've seen elsewhere.

 

I tested my board by checking continuity between +12V on the jack and one end of R140. I also verified that -5V was connected to the other pole of the power switch from +5V. Finally, I verified +5V as connected to the power LED.

 

Am I missing something here? This is one of those things you want to get right on the first try :)

 

Here's a pic of the board in case that helps:

 

attachicon.gifIMG_2754.JPG

The correct pin-out for J11 on a 1450 motherboard is:

 

Pin Description

1 - +5V

6 - +5V

2 - -5V

4 - +12V

3,5,7,8 - Ground

 

The switch controls +5v and +12V, the -5V rail is controlled by Q8 - Q9 powered by +5V when switched ON...

 

Check out the 1450 build thread for the PDF Schematic from Atari, it's a bit blurry, but shows the correct wiring for J11.

http://atariage.com/forums/topic/186380-1450-xld-motherboard-build-assorted-questions/page-13?do=findComment&comment=2371407

Edited by AtariGeezer
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The correct pin-out for J11 on a 1450 motherboard is:

 

Pin Description

1 - +5V

6 - +5V

2 - -5V

4 - +12V

3,5,7,8 - Ground

 

The switch controls +5v and +12V, the -5V rail is controlled by Q8 - Q9 powered by +5V when switched ON...

 

Check out the 1450 build thread for the PDF Schematic from Atari, it's a bit blurry, but shows the correct wiring for J11.

http://atariage.com/forums/topic/186380-1450-xld-motherboard-build-assorted-questions/page-13?do=findComment&comment=2371407

 

 

Thanks @AtariGeezer! This pinout makes sense because it means that +12V goes to the SC-01 speech synthesizer chip. Also, that Atari schematic is pretty cool. Here is the correct pinout, including pin numbers (non-intuitive numbering):

 

post-43315-0-79856100-1489379845_thumb.jpg

 

I wired up a cable to connect to my old PC power supply, which thankfully had -5V. I double-checked everything, plugged in the 1400XL, and turned it on, which is probably the first time it's been powered on in 25+ years.

 

post-43315-0-06227100-1489379881_thumb.jpg

 

We have a heartbeat! The color is off, and not too many keys work. At first, the only keys that worked were 9 > = I F2 DEL. I went through and pressed every key 10 times, and a few others came to life: ESC 6 0 < A ; though ; has since stopped working. Besides F2 (which causes the cursor to move down), none of the function keys seem to be working. I popped in a Pitfall cartridge, which worked (looked strange with the reddish hue), but I couldn't start the game.

 

So, I'm unable to test any of the special features at the moment. I was hoping to at least be able to enter self test mode so I could hear it speak, but neither the option key nor the letters B Y E work, so I'm out of luck.

 

Is a 600/800XL keyboard compatible with the 1200XL keyboard? I also got a loose Alps keyboard from the seller. If it's compatible, this would be the easiest way to rig something up in order to test the 1400XL. I'm wary of performing the standard 1200XL keyboard repair since I've never done it before, and I don't want to damage the original keyboard.

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@electronizer:

 

The DIN numbering pattern is odd because it starts with the 3-pin layout, 2 get added for the 5-pin, another 2 for the 7-pin, and finally 1 more for the 8-pin DIN.

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