Pac/Ms Pac Issues After RAM Socket Replace

Michael Roma

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I am trying to get my 4n1 v3 Pac board running but have an issue.

I modded a working Pac board to the Souzilla 4n1 v3. It worked but I needed to replace the IC sockets at 4K and 4N with dual swipe sockets to use the NVRAM adapter.

In my haste (which is never good when doing board work) I lifted 3 traces on 4K (pin 2, 11, and 14 ) which I decided to just jumper on the solder side. I jumpered pin 11 on 4K to pin 9 on 4H and pin 14 on 4K to pin 6 on 4H.

4K
Pin 2 to pin 2 on 4L
Pin 11 to pin 9 on 4H
Pin 14 to pin 6 on 4H

I compared continuity on another working board I had.

Now when I power it up without the NVRAM adapt. and just the RAMs that are in their originally I get the following.

4n1_ram_socketissues.jpg


Here is the back of the board where I jumpered.

pac4n1ICsocketPCB.jpg


I tested the RAM at 4K and 4N in another board so I know they are good. I also tested continuity between RAMs and 4H and confirmed with another working board.

Any suggestions?
 
Check for solder bridges on 4K and 4N, you could have shorted out 2 neighboring pins accidentally?
 
Or you lifted another trace you overlooked.
What kind of desoldering tool are you using? Get yourself a good desoldering station and you wont have these problems anymore.
On the original pac sockets I always remove the plastic housing before desoldering the pins. It makes it much easier to get them out and much less chance to pull a trace.
 
After the plastic housing is removed, I heat them individually from the top of the board and gently pull each one out using a curved dental pick while the solder is melted. Also make sure all of the pins are straight on the solder side of the board so they pull right through easily before you start. Then cleaning the solder out of the through holes is a breeze.

Bill

Or you lifted another trace you overlooked.
What kind of desoldering tool are you using? Get yourself a good desoldering station and you wont have these problems anymore.
On the original pac sockets I always remove the plastic housing before desoldering the pins. It makes it much easier to get them out and much less chance to pull a trace.
 
After the plastic housing is removed, I heat them individually from the top of the board and gently pull each one out using a curved dental pick while the solder is melted. Also make sure all of the pins are straight on the solder side of the board so they pull right through easily before you start. Then cleaning the solder out of the through holes is a breeze.

Bill

I just desolder the pins and when I have done them all I run my finger over them and they will all fall out. If the pins are straight they will fall out on their own usually. Then I lightly hit the pads with a fiberglass pen which will clean the pads and remove any solder smear that could short traces. If you clean the pads on the topside of the board it helps the solder flow to the top.


Roma, are you going to the event in a couple weeks? If so I will bring you a FG pen if you dont already have one. Let me know if you need anything else.
 
I ended up cutting the socket in half, then removing it and then removing the pins one at a time. I was just a little to aggressive on several of the pins on 4K. I do not have a desoldering station. I just heat up the pins and use a solder sucker.

I don't see any solder splash on the solder side of the board but will check continuity on the parts side to see if I have any pin shorted to another one in the same socket.

Riptor, what event are you referring to?

- Mike
 
I would turn the heat down a little on your soldering iron... 9 times out of 10 that is why the pads get lifted
 
SUCCESS!!!

I had shorts between pin 2 and 17 on 4K and pin 9 and 10 on 4N. I ultimately pulled both sockets, cleaned around the solder pads on both sides of the board and replaced the sockets. I tested for shorts and I am all good getting the 4n1 menu screen.

Now it is just a matter of physics getting the NVRAM adapter in place. It is getting in the way of the VRAM addresser board. I tried to double up the sockets of the VRAM but it seems to not have a snug connection.

- Mike
 
I just desolder the pins and when I have done them all I run my finger over them and they will all fall out. If the pins are straight they will fall out on their own usually. Then I lightly hit the pads with a fiberglass pen which will clean the pads and remove any solder smear that could short traces. If you clean the pads on the topside of the board it helps the solder flow to the top.


Roma, are you going to the event in a couple weeks? If so I will bring you a FG pen if you dont already have one. Let me know if you need anything else.

I'm a little impatient when I remove sockets like that... I'll remove the housing then get the el-cheapo radioshack type desoldering iron out (the one with the bulb on it). Instead of try'ng to suck up the solder, I heat each of the pins, then quickly sqeeze the bulb. It just shoots them out onto the table and leaves the holes perfectly clear. I know there's a slight chance of "back splash" on the parts side of the board, but I give everything a quick look over and I haven't found any splashes yet.
 
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