Try to replace VRAM ics

[CrazyBoss]

Hello

 

I try to fix a NTSC ColecoVision.

 

All VRAM ics are out and now sockets are in place at the mainboard.

 

I checket connection at every socket.

 

I assume I have a few broken traces.

 

PIN 15=CAS, ALL OK

PIN 4=RAS, ALL OK

PIN 3=R/W ALL OK (- U17)

PIN 16=GND ALL OK

PIN 8=+12V ALL OK

PIN 5=A0 ALL OK

PIN 6=A2 ALL OK

PIN 7=A1 ALL OK

PIN 9=5V ALL OK

PIN 10=A5 ALL OK (-U16)

PIN 11=A4 ALL OK

PIN 12=A3 ALL OK

PIN 13=A6 ALL OK

 

Seems like to make a new trace to PIN3 at U17 and a new PIN10 at U16

 

I read somewhere about PIN2 is only connected at U16 to the VDP PIN10 is that right?

 

And I will share my Procedure to desolder the ics:

 

1) Cut the is off by use a small sidecutter.

2) Desolder the pins one by one. (from the component side)

3) heat up the solde, and use a solder pump or sucker, if you dont get a clean hole, apply new solder and try again.

4) If you need to apply new solder, work on another part while it cool down and come back to that later.

5) sometimes you need to try to remove the solder (3) from the solder side or the component side or both.

6) Dont RUSH. It takes time, send the WIFE and KIDS out of the HOUSE