LisaList2

General Category => LisaList2 => Lisa Troubleshooting and Repair => Topic started by: snua12 on July 08, 2025, 02:52:13 pm

Title: Lisa 2 video issue - vertically duplicated image with diagonal lines
Post by: snua12 on July 08, 2025, 02:52:13 pm

Hi everyone,

I'm working on a Lisa 2/5, likely a converted Lisa 1 (Twiggy version). The power supply is revision 1.2A, and it's running Lisa Office System 2.0.

The machine boots and shows the “Wait” screen, but the video output is distorted – the image is vertically duplicated and there are diagonal lines across the screen. You can see it in the attached photo.

What I’ve done so far:
– Replaced all capacitors in the PSU (1.2A)
– Replaced capacitors on the analog video board
– Checked and reseated all internal connectors

The system seems to boot correctly otherwise, so I suspect a video sync issue, bad video RAM, or maybe something in the analog video circuitry.

Is it possible to adjust the display using the trimpots (potentiometers) on the analog board? Could this be a geometry/sync issue that can be corrected by calibration, or is it more likely a hardware fault?

Any advice or suggestions would be greatly appreciated!


(edit: sigma7 removed em dash from Subject line to see if it fixes blank home page for guests)

Title: Re: Lisa 2 video issue - vertically duplicated image with diagonal lines
Post by: patrick on July 08, 2025, 03:18:33 pm

One of the trimpots is labelled "vertical hold". Try this.

You have to realign the video board after replacing capacitors. Reducing "contrast" on the video board together with "brightness" on the back of the power supply should remove the retrace lines.


(edit: sigma7 removed em dash from Subject line to see if it fixes blank home page for guests)