Electronics > Repair
LCD wrong viewing angle Sony Walkman
<< < (3/4) > >>
dredd:
Scope at R724 bottom (IC702 pin 39). PSU is at 1.30V




Scope at R724 top (IC702 pin 38)



Two together (I'm a scope master now :)



BTW, touching the top of R724 with scope probe changes waveform and lowers oscillator frequency for some reason ...
dredd:
My BM786 multimeter cannot measure the CB701 - the package with four 0.1uF caps in it. It connects to IC702 pins 44-46 and 40.
BM786  fails measuring any of the four caps, just gets stuck showing a dot.

Maybe this is it?

Haenk:
Before dissecting the machine, did you try with another polarizer?
The foils can fail (due to UV light, aka sunlight, but maybe even just age).
Any polarizer (that is not circular) will do, maybe rip it off another LCD display.
dredd:
It is kind of cumbersome opening lcd again, maybe i will.
jzx:
Hello, this is my first post, so be patient, because my english is bad.
I am repliying to this post because once i have seen something similar, not with this model, but with a clock.
Check the capacitors on pins 41, 42 and 43, because this seems part of a voltage doubler. In my case, a capacitor was broken (short) and the lcd worked as if the battery was old, little contrast.
You can use the scope on these capacitors and post the pictures.

The capacitors C8701 are connected to several pins named "VL3", "VL2" etc, posibily decopling the lcd voltages, use the scope to measure the voltage. Check the resistance to see if they are shorted, but is dificult to measure the capacitance in circut, if some voltage is present, the measurement fails.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod