Possible problem with Video Cable for Mac Plus - Need to Establish It's Working or It's Not

butchie52651

New Tinkerer
Sep 22, 2024
1
2
3
I found this link on your site (https://tinkerdifferent.com/threads/mac-plus-with-a-flup-flup-flup-noise-on-boot.1254/), where there was the same "flup, flup, flup" problem as the one I'm having.

The first thing the link suggested doing was checking the continuity of the blue wire within the video cable that runs from the analog board to the logic board to see if there was any. I placed the multimeter testing rods in each of the plugs (one in the plug of the video cable that gets connected to the analog board and the other in the plug of the video cable that gets connected to the logic board) attached to the blue wire pins (i.e., in each case, Pin 6, +5V of each of the two plugs), but there was no showing of continuity.

If you find there's no continuity, they then suggest that you take a look at the fuse that's hidden within the video cable. There are some pictures on the site showing what that fuse looks like.

I did that by moving the band and viewing the fuse. Attached are several pictures, at differing resolutions, showing the fuse in the video cable that I'm dealing with. The problem is that at least I cannot tell from the pictures if that fuse is blown or not.

Can anyone else tell me, after looking at the pics, whether this fuse is blown and whether or not I need to replace it.



Thanks!







 

Attachments

  • Picture1.png
    Picture1.png
    174.2 KB · Views: 18
  • Picture2.png
    Picture2.png
    220.1 KB · Views: 20
  • Picture3.png
    Picture3.png
    218.7 KB · Views: 20
  • +.png
    +.png
    152.5 KB · Views: 19

JDW

Administrator
Staff member
Founder
Sep 2, 2021
1,577
1,373
113
53
Japan
youtube.com
You learn something new every day. Wow. Thank you, @butchie52651 ! I was not aware of a fuse hidden in the Macintosh 128K/512K wire harness! Based on your pics, it would seem to be hidden from view under the large ferrite bead, and the only way to spot it would be to cut off one of the wire ties and move the bead out of the way. Very interesting!

None of your pics show the printing on that green component, which we are assuming is a fuse. So if you could provide that info, that would be great. But it certainly doesn't look cracked or even burned. Knowing the numbers printed on it might allow us to find a datasheet to learn more.
 

wskjinfen

New Tinkerer
Mar 1, 2024
8
3
3
China
If you find no continuity, the fuse is blown. Be sure to check for other short circuit issues that may have caused the fuse to blow before restoring it.