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gamer-stu

Incognito Install - double check your CPU board and Antic pinouts!

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Cautionary tale. I was installing the Incognito this evening, following the instructions on Lotharek’s site and FJC’a excellent Youtube videos.
 

When I was about to solder the two wires to the CPU board, I noticed that the circuit board traces didn’t match the picture on the install guide. After investigation, I found that my Antic is on the lift side of the CPU board (when facing the chips), and the notch and 1 pin were pointing down, compared to the pictures on the instructions. Fortunately I was able to orient myself and solder to the correct pins. Apparently there was more than one rev of the CPU boards, with different chip locations. 

 

 

 

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27D0EF17-B4B4-4201-A25A-0DF7A1DD79D6.jpeg

Edited by gamer-stu
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2 hours ago, spspspsp said:

This is important to note. However, I think you have the wrong ANTIC pins selected. Those look like pins 29 and 35.

Holy crap, you’re right. How in the hell does this thing boot up after making a mistake like that? It looks like I soldered to an address and data line. I should count my blessings that I didn’t cause serious damage, but I’m not looking forward to disassembling poor Colleen again to correct it 😱. Cautionary tale indeed. Thank you spspspsp!

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2 hours ago, spspspsp said:

This is important to note. However, I think you have the wrong ANTIC pins selected. Those look like pins 29 and 35.

You have to remember the way IC chips are numbered, and that this is viewed from below the chip. Pin 1 is at bottom left which puts pin 40 at bottom right, counting down from 40 finds the wires are connected to pins 32 and 26.

 

EDIT: I misread the post, and realized afterwards the poster meant the CORRECT pins are 29 and 35.

Edited by BillC

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30 minutes ago, BillC said:

You have to remember the way IC chips are numbered, and that this is viewed from below the chip. Pin 1 is at bottom left which puts pin 40 at bottom right, counting down from 40 finds the wires are connected to pins 32 and 26.

 

EDIT: I misread the post, and realized afterwards the poster meant the CORRECT pins are 29 and 35.

What I’m really after are Antic pin 9 (HALT) and 15 (RDY). I counted from the wrong side

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41 minutes ago, BillC said:

You have to remember the way IC chips are numbered, and that this is viewed from below the chip. Pin 1 is at bottom left which puts pin 40 at bottom right, counting down from 40 finds the wires are connected to pins 32 and 26.

 

EDIT: I misread the post, and realized afterwards the poster meant the CORRECT pins are 29 and 35.

Looking at the chip from the bottom, and facing downward, did a number on my brain. I meant to say that the wires look like they are connected to pins 32 and 26.

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14 minutes ago, gamer-stu said:

What I’m really after are Antic pin 9 (HALT) and 15 (RDY). I counted from the wrong side

You failed to account for the low number pins being mirrored to the left side when viewed from below. When I do mods like this I prefer to solder to vias, cleared of solder first, instead of to pins. I notice that pin 15 has a connected via just to the left of pin 9.

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6 hours ago, BillC said:

You failed to account for the low number pins being mirrored to the left side when viewed from below. When I do mods like this I prefer to solder to vias, cleared of solder first, instead of to pins. I notice that pin 15 has a connected via just to the left of pin 9.

 

Wise advice, indeed.

 

1st option is always nearby soldering pads / points, which will not only be safer, but much cleaner too (no soldering blobs built-up on IC-pins, which will be seen from miles away)

 

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If not an option, then proceeding to hot-pins is the way but, as ClausB said, always removing first the I/C package, if socketed. If not socketed, potential damage is quite possible, one that will show up later on time.

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