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Hi, just got back and did a little more testing, unfortunately without success. I've got a 3A adapter that originally came with a PB170.

I read in some other thread that tunnelvision is actually caused by the failing TFT transistors, which have, over the years, been damaged by an unwanted DC offset on their AC supply. This would make sense in that physical pushing and bending doesn't fix tunnel vision symptoms, but heat reverses...

Hi, thank you very much for the follow up! I've tried the steps above and unfortunately there seems to be no change in the behavior. I've removed the grounding strip for this minimal "bench test" (so as to rule out corrosion around/on it), but I have tested the PB fully assembled as well...

This only happens after plugging in to a known good AC adapter, then pressing the power button. The reset button usually rearranges the line pattern (it tends to “move down” a few pixels) and the interrupt button does nothing. I have removed the PRAM battery, as I have read that 180s boot...

So I fixed the 180’s short circuit issue yesterday, but it is still not booting with no sound and only staticky garbage lines on the active matrix screen. (this is after powerring it up in the chassis as well). Any possible causes?

My intuition led me to desolder the D15 diode, which turned out to be blown. I’ve replaced it with a similar looking one from the PB170 board (which died after I fried a MOSFET). Updates when I reassemble the machine, but the board is looking good with a healthy resistance in the megaohm range.

Curiously, the resistance across three adjacent components - C51, D15, C69 by the power jack on the underside of the board - is the same 2.5 ohms I’m getting across the jack. Does anyone have a 180 board to compare this to?

Update: photos. I may have been too dramatic about the corrosion, looking at some other posts here it seems minor.

So I just picked up a new 180 which had quite a bit of battery corrosion inside of it. However, after thorough cleaning, I’m still getting a short circuit on the main DC input jack (with everything unplugged from the motherboard). + to - reads 3 ohms. I’m conparing this to a dead 170 board I...