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Se/30 corrosion around cap c7

Forums > Vintage Apple > Macintosh > Compact Macs

iantm
Tinkerer
Michigan
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Joined: Sep 8, 2025
Posts: 73
Likes: 32
Oct 7, 2025 - #1
The good news is I got lucky in that the caps haven't bled all over the board. It was just really dusty.

I'm mostly concerned about what to do about the bluish corrosion around C7. The leads to the chips seem beat up. What can be done about them? I heard a light wash with diluted vinegar and a brush?

Thankfully this looks to me like the worst part of the board.
Attachments:
IMG_6569.jpeg (1.4 MB)
IMG_6564.jpeg (2.4 MB)

Liked by JDW

iantm
Tinkerer
Michigan
--------
Joined: Sep 8, 2025
Posts: 73
Likes: 32
Oct 8, 2025 - #2
Another thought: Are these chips proprietary, or are they just some standard logic gates that I could get from somewhere else and replace freely? i.e these tiny chips in the UA8 bank label " 57F253d - 8914" if you can buy them by the handful and they'll be just as good as what on there, I'm not opposed to replacing these corroded ones.

If anyone knows a place where this is documented... I'm all ears.
Attachments:
Screenshot 2025-10-08 at 15.23.37.png (171.5 KB)

David Cook
Tinkerer
--------
Joined: Jul 20, 2023
Posts: 130
Likes: 172
Oct 8, 2025 - #3
Those are all off the shelf parts.

The numbers like 8914 are dates. That's the 14th week of 1989.

The part numbers are:
UA8: 74F253
UB8: 74F253
UC8: 74F253
UD8: 74F253
UE8: 74LS166
UF8: 74LS393
UG8: 74LS393

Check out the last page of the schematic attached.
Attachments:
BOMARC SE30 Schematics.pdf (3.1 MB)

Liked by cluster_fsckandiantm

iantm
Tinkerer
Michigan
--------
Joined: Sep 8, 2025
Posts: 73
Likes: 32
Oct 9, 2025 - #4
>> David Cook said:
Those are all off the shelf parts. The numbers like 8914 are dates. That's the 14th week of 1989. The part numbers are: UA8: 74F253 UB8: 74F253 UC8: 74F253 UD8: 74F253 UE8: 74LS166 UF8: 74LS393 UG8: 74LS393 Check out the last page of the schematic attached. Click to expand...
Sweet. Thank you!

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