Powerbook 160 display can only be read off-axis

[DaveW]

I have a PB 160 I picked up that I'm having some display issues with. I recapped the screen's electrolytics with tantalums and replaced the ribbon cable, but the display still seems to have no contrast. Looking at it straight on it looks almost like a blank screen. If I look at it from a sharp angle above I can see the desktop, so it appears to be working.
Hooked up to an external display everything appears normal, so I'm not expecting a problem on the logic board. Is there something else I could look at, or is it possibly just the TFT that has gone bad?

 

[finkmac]

sounds like your contrast is wrong. i assume you've fiddled with the slider?

powerbook 160s don't have TFT panels, they have DTSN panels

 

[DaveW]

The contrast slider seems to work, or at least has an effect. At minimum contrast the image is best, it's just barely visible straight on. Sliding the contrast slider right washes the image out.
From above, the contrast is greatest at the full left contrast position, and goes down when slid to the right.

 

[ObeyDaleks]

Did you also recap the inverter board? If not, that could be your issue.

 

[DaveW]

I hadn't recapped the inverter board; the backlight was good so I didn't think it would be an issue.

I didn't have direct replacements for the 33uF 10V and 47uf 16V caps, but they looked like bulk caps and I could fit a couple 47uF 35V caps in laying down. That does seem to have fixed the issue pretty well. There's still some weird contrast issues, but I think that's just part of the screens from that era.

Thanks for the lead, now I just need to recap the power supply.

 

[ObeyDaleks]

Glad it worked out. Yes, these passive (especially the grayscale) screens have noticeable artifacts that range from bad to horrendous depending on your contrast adjustments. This is normal, and imho part of the charm.

 

[finkmac]

recapping / fiddling with the contrast and brightness usually helps disguise the afterimages.

personally... I prefer my passive matrix powerbooks because they don't develop tunnel vision