Mac 128k help needed!

[KenB123]

Hello everyone! I have a bit of a problem with my new Mac 128. Everything is beautiful on the inside and out but the issue with it is I'm getting that error code. Can someone help me pinpoint the trouble ram chip? I am experienced in soldering and I have sockets for new a new ram chip but the issue would be for me to get the chip and finding the one that's bad.

I am 17 and have quite a collection. So far I have 5 128k computers. A Lisa2 and multiple other se's plusses etc... And I fixed nearly all of them so I have a very good amount of knowledge on this kind of stuff.

I am also very happy this has the original logic board in it and 400k floppy which I wrestled to get working with parts from swore parts 400k drives.

Any help would be appreciated.

 

[unity]

G11

This helps a lot:

http://support.apple.com/kb/TA46376?viewlocale=en_US&locale=en_US

 

[KenB123]

Alright thanks so much for the help! I really appreciate it! Would you know off hand what location that is on the motherboard?

Thanks again for your help

 

[unity]

Ya... G... 11....

The board is marked. Just like playing Battleship!

 

[KenB123]

Oh haha I see it now I didn't know there was letters on the side like that.

Thanks so much for your help! I really appreciate you taking the time to help me out!

 

[KenB123]

Here's a pic of the board. There isn't any visual defects with it. I guess it needs to be replaced. Does the ram chip have to be the same brand as all the others? I am pretty sure that type of thing is important on some computers.

Now I'm wondering where I am going to find a replacement chip.

I will have to talk to my friend and see if he has a spare one.

 

[unity]

Does not have to be the same brand, just the same type. While I have not experienced it myself, others report that the Apple-Logoed RAM chips seem to fail at a pretty high rate. If I recall, you can still buy new RAM chips for pretty cheap from electronic parts distributors.

 

[KenB123]

Yes I remember reading about that also. And probably if I replace this one I heard that it has the possibility of giving me another error code from another bad chip that the test wasn't even able to get to yet. I will let you know what I am able to find once it is replaced.

Thanks again for your help this is fun and interesting to solve this problem!

 

[TheWhiteFalcon]

Best to buy a small handful just in case that happens.

 

[Elfen]

MT is the manufacturer for Apple who I forget who that is; their RAM Chip is the 4264; which is pretty generic of the 4164 Dynamic RAM Chip. You should be able to use 4164s in its place. Get as many as you can of them, preferable all 16. Take your time soldering them as they are sensitive to heat and static. And the traces are delicate in this area, so take your time and take it easy doing this. Many would replace the chips with sockets and then put the RAM Chips into the sockets.

If you like or are daring, you can upgrade at this point by using 41256 Dynamic RAM chips and it will boost your board to become a 512K Mac, its a direct chip drop in and no need to cut or add wires to the board. But that is on you, if you do, you need to replace all 16 RAM Chips.

 

[KenB123]

Wow thanks for everyone helping me on this! I didn't realize I would get this kind of support from people. I looked on eBay and saw they are $6 a piece :-/ http://pages.ebay.com/link/?nav=item.view&alt=web&id=381024802658

I have removed the ram on these before but I used hot air and small screwdrivers to pry them out. I guess a solder sucker would be better to use although all I have is wick.

Another problem I worry about is getting solder to the other side of the motherboard connecting it to the top half. With a socket I can't reach the top traces to get connected to the legs.

I would like to keep it original 128k ram. I can't believe that they are $6 a piece.

 

[techknight]

Uniserver has the RAM to redo 128K and 512K machines. Send him a PM. 

Since its a 4-layer board, using a heatgun and solder wick would be a nightmare with enormous risk, but doable nonetheless. 

 

[Elfen]

If you are using hot air, you should be using solder paste instead of solder on a roll. Simply done, fill the hole with solder paste and put the chip in and apply heat with a 15 watt iron and then inspect it. Clean up with acetone and alcohol when you're done.

There is a metal grommet in the hole that connects to traces on both sides of the board, but you should clean up the holes before soldering in the chips. A 15 watt iron, some flux and solder wick should clean the hole throughly. A clean hole will make the solder flow evenly to both sides. Add a bit of flux to the hole and solder from the bottom pin side and not the top chip side and let gravity and capillary action pull the solder down.

In my day, 4164s used to be $35 a piece and that price did not go down until after 1994!

 

[KenB123]

Alright with a socket I wouldn't be able to solder from the chip side anyway.

It am going to need to find a good way to remove these without damaging the traces. I have a good iron and flux but I can borrow things from my uncle. What do you think is the best tool to remove these chips with?

 

[KenB123]

i am going to be a little delayed on Replies I am helped cover the pool.

 

[KenB123]

I am going to be a little delayed on Replies I am helping cover the pool now.

 

[Macdrone]

Just fyi my 128 showed ram issue code but ram has not proven to be the issue.

 

[KenB123]

Oh god.

I inspected the motherboard and I don't see any visual bad spots.

I am done helping cover the pool so I can talk again.

I am going to try and re-seat the rom chips and see if there is a change.

 

[KenB123]

Ok reseating the Rom chip didn't help.

The startup bong doesn't sound healthy which makes me think the only source could be ram.

I have these 16 pin sockets which I can use on it.