Electronics > Repair
Zenth ZF-171-42 - a new hope err.. problem
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Gen-8bit:
Well, I'm still trying to resurrect my Zenith schlepptop, and have encountered a new problem that can only be traced to tinker error:
I completely neglected to document the position and orientation of all cables and wires that connect to the power board, and while most were self explanatory, one two wire cable has stumped me and senty anxiety sky rocketing fue to the high voltage involved.
You see, the cable in question emerges from the display area and is supposed to supply the lcd backlight. It consists of two wires (black/yellow), terminating in a two pin plug. The only connector it can reach and I remember pulling it from is a three pin, non keyed connector, situated behind a yellow transformer on the right end of the power board.
My dilemma here is Idk which orientation and position I need to plug this wire in, and I don't want to fry the poor thing again!
So anyone with experience in working with and fixing this kind of computer, please help me, thanks!
MathWizard:
I'm looking at some service manual and I've never heard of any LCD screen that uses anything like 308Vpp. So is that what's on connector P3 ?
In the LCD waveform picture, it's at 500Hz, and it's about 109VAC, but on a typical DMM, it would read less, IDK what the voltage roll-off with frequency is, of a typical DMM, but 500Hz isn't that high though. Now if that's really that AC signal on P3, it should be centered around the common/GND, and the polarity shouldn't matter. It would measure about 0 VDC, and maybe 40VAC on some DMM.
But I'd want to see the circuit myself, or at least the schematic, and trace it out, to know for sure.
Have a look at page81,82 of the pdf.
https://www.minuszerodegrees.net/manuals/Zenith%20Data%20Systems/Zenith%20Z-171%20PC%20Series%20-%20Service%20Guide.pdf
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