PowerBook 180c -- Vertical White Column Lines

[BajaTym]

Greetings,

I’m new to the forum, but I’ve been tinkering with older Macs for several years, mostly compact Macs like the Plus, SE/30, and Classic.

I’m currently working on a recently acquired PowerBook 180c with a bad display and could use some advice on a stubborn issue.

History so far:

• The original display had severe vertical banding consistent with leaking capacitors.
• I replaced it with a recapped Sharp LQ9D01 panel.
• The heavy banding is now gone, but now I’m seeing a different display problem.

Current symptoms:

• During initial power-on, the screen is solid/lit with no visible degradation.
• Once the system begins booting, there’s a visible shift and vertical white lines appear.
• The far-left section of the panel displays perfectly.
• Across the remainder of the screen, the pattern appears to repeat: one correct pixel column followed by one solid white column.
• The pattern remains stable once it appears.

So far I’ve:

• Reseated every cable, including the main display flex and interconnect connections.
• Checked continuity through the display flex cable; it appears good.
• Thoroughly cleaned under the accessible driver flex ribbons with IPA.
• Tried the black multi-position switches on the driver board and returned them to their original positions.
• Inspected the boards and connectors for obvious damage.
• Pressed gently on the driver board/flex connections while the machine was running; this had no effect.

The driver board itself looks clean, and the replacement capacitors are all installed properly.

Has anyone encountered this? At this point I’m wondering whether I’m looking at a panel/column-driver problem, a flex issue, or a problem farther upstream in the 180c’s video circuitry?

I’m happy to post detailed photos of the panel, driver board, interconnect board, flex cable, or the actual screen behavior if they’d help.

Thanks in advance!

James