Chip came off Classic II board and took a pad with it.

[Jon183]

Hi everyone,

I was cleaning the Macintosh Classic II revision 1 logic board with a q-tip soaked in isopropyl alcohol and a chip I was cleaning came off the board, it read 136x 78l08a and I believe it is a texas instruments chip. I looked up the last part and it came up with voltage regulators. Could I find a replacement somewhere (still have original), and what should I do about the missing pad?

 

[Bolle]

You are lucky, pin 4 is NC.

You can use any 78L08 in SO-8 package. Those are still made today so I would just get a new one and not bother with the old one that might be dead due to cap goo anyways.

https://www.digikey.com/product-detail/en/stmicroelectronics/L78L08ACD13TR/497-1189-1-ND/586189 this one should do it.

You might want to check the audio amplifier right next to it as well as the solder points do not look too good on that one as well.

 

[Jon183]

You are lucky, pin 4 is NC.

You can use any 78L08 in SO-8 package. Those are still made today so I would just get a new one and not bother with the old one that might be dead due to cap goo anyways.

https://www.digikey.com/product-detail/en/stmicroelectronics/L78L08ACD13TR/497-1189-1-ND/586189 this one should do it.

You might want to check the audio amplifier right next to it as well as the solder points do not look too good on that one as well.

Thanks, due to shipping costs im going to use element14.

 

[Jon183]

http://au.element14.com/on-semiconductor/mc78l08acdg/ic-v-reg-8-0v-smd-78l08-soic8/dp/1211120

Would this be suitable?

 

[Bolle]

Yes.

 

[jack]

Saw this thread now... makes the other one make sense

 

[Jon183]

The voltage regulator chip came today. I installed it and put the system back together. The analog board has 3 new caps and I have to wait for the rest as element14 takes far longer than RS and charges for shipping too, not sure why. The logic board has been recapped, washed, swabbed with alcohol and q-tips, and has a new voltage regulator for U2. First picture is the final appearance of the logic board.

The system works now, it boots from the HDD. It was set for 110v but it now works with 240v. Thanks for all the help everyone.

View attachment 21290

View attachment 21291

 

[jack]

Congrats! Always exciting to have one more working system!