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Early Mac LC proto?

North Hedge Ned

Well-known member
So, I got around to troubleshooting the one of my two LC protos that powers on, but only gives a strange video on screen.  The battery had blown up on the board, and fried one of the ROM chips - at least the pins are affected!  Figures - one of the 4 pictured below - can you tell which one?  The dirtiest, 3rd from the left.  So, I pulled the ROM chip - carefully, and 1 pins remained in the socket, and 2 simply fell off.  They were corroded.  I have thoroughly cleaned the board, dried it well with air, and had a thought.  Before the though,... the report:  one pin is half there, one pin still has a bit of metal coming out of the chip, and the third is almost flush to the ceramic.  I have prepared (almost) the pin that is flush by carefully grinding the top down to expose more metal.  

My question is this: I want to somehow reconnect this to the socket.  Do I have these options?  

1) solder on fine wire (like 20 or 22 gauge) to the missing pins on the chip, and wire-wrap around to the corresponding socket pins underneath the board? or,

2) use single strand copper wire (rigid) to solder on new make-shift pins to the chip and put the chip down into the socket as far as possible, or

3) a combo of both where new pins can go into the socket and wire-wrap on those that have a pin stuck inside

For the pins in option 2 or 3, can I use paperclip or do I have to source out single copper wire?

In wire-wrapping a chip to the underside of the socket pins, as in option 1 or 3, is there some set of rules to be aware of in regards to resistance and distance?  Gotta think that if wire wrapped, the ROM would have 3 connections that would be far, far longer than the rest of the chip to the board.

Thanks in advance.

IMG_6361.JPG

 

North Hedge Ned

Well-known member
1) solder on fine wire (like 20 or 22 gauge) to the missing pins on the chip, and wire-wrap around to the corresponding socket pins underneath the board? or,

2) use single strand copper wire (rigid) to solder on new make-shift pins to the chip and put the chip down into the socket as far as possible, or

3) a combo of both where new pins can go into the socket and wire-wrap on those that have a pin stuck inside

For the pins in option 2 or 3, can I use paperclip or do I have to source out single copper wire?

In wire-wrapping a chip to the underside of the socket pins, as in option 1 or 3, is there some set of rules to be aware of in regards to resistance and distance?  Gotta think that if wire wrapped, the ROM would have 3 connections that would be far, far longer than the rest of the chip to the board.

CORRECTION OF TERMS - when I said wire-wrapping I did not mean it in the proper sense.  What I mean is, instead of pins, can I solder a short wire lead from the chip to the socket pin on the underside of the board.  Forgive my improper use of term...

 

denodster

Active member
I've got one of these. It has the Apple Confidential stickers on the roms, and the big cap. The caps were leaking so had them replaced and the big cap is now a different big cap.

IMG_20191116_215157121.jpg

 
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