Mac Plus recap troubleshooting?

[dv-]

Hey,

Based on some advice in another thread I went ahead and did an analog and logic board recap on my Plus.

It booted ok twice, but the third time the screen went blank. No sound from the speaker either. The yoke gives off that amber glow in the dark so I know the crt is getting power.

The board appears to be initializing (holding down the mouse button ejects a floppy disk, although the drive needs servicing). But all I get on the screen is this: (see photo.)

I’ve reseated all the cables as well as reflowing the solder on all the connectors, as well as anywhere on the analog board that looked suspicious. Testing with my multimeter from the backs of the boards, I get continuity on all the pins of the connector between the analog and logic boards.

Looking for troubleshooting tips or other stuff to check. Thanks!

 

[falen5]

you check your voltages after the recap ?

 

[dv-]

you check your voltages after the recap ?

Ack, no, good call thanks.

 

[dv-]

-12.14 on the -12v
5.01 on the 5v
11.81 on the 12v

All measures off the floppy connector. The 12v might be a smidge low but overall those are pretty close to where they ought to be, right?

 

[68kPlus]

Yes those sound fine. Have you consulted the dead mac scrolls? Might be something in there worth looking at.

 

[dv-]

Yes those sound fine. Have you consulted the dead mac scrolls? Might be something in there worth looking at.

I’d never heard of that before. Thank you for the advice; it looks like I have some things to try!

 

[dochilli]

Did you resolder the connectors between LB and AB?

 

[falen5]

if that was a display creation problem on the analog board then that white line you see would be super bright - bit its not - have never seen this problem before

those are pixels in the display buffer by the looks of it with the display 'kinda' looking like its is working - just not the right feed from the board - i think its the logic board is the problem - reseat everything

techknight is the man to talk to

 

[dv-]

Well, I fixed it. Turns out I had a solder bridge between two pins on the analog board. (Pins 9 and 10, 12v+ and GND, of the connector that goes to the logic board.)

Yay!

I also have terrible eyesight. I need some kind of magnifying rig. :-(