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jts1957
Joined: 24 Nov 2008
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 Posted: Wed Jan 25, 2012 9:51 pm Post subject: |
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| tofutofu wrote: | OK, the voltage is changing between D701 (pin #2) TO C703 "negative" and going "crazy" when connecting/starting/normal..
(by the way, isn't it the same as the voltage between C703 positive & negative?) |
"Float" either end of L701 and remeasure D701 pin #2 TO C703 "negative".
C703 "negative" is the ground/reference we're using and "positive" is same point as D701 pin #2. (C703 filters this 13 volt supply).
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tofutofu
Joined: 24 Jan 2012
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| Posted: Wed Jan 25, 2012 11:30 pm Post subject: |
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I just found out that the V-INVERTER is stable 14v when not connected to signal (VGA)
BUT when connected to signal (VGA) the V-INVERTER is moving up & down from 13.5V to 12V at frequency that might be same to the LCD blinking (hard to know exactly... ) |
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tofutofu
Joined: 24 Jan 2012
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| Posted: Wed Jan 25, 2012 11:42 pm Post subject: |
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"Float" either end of L701" ??
do you mean connecting between the 2 ends with some wire? |
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jts1957
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| Posted: Wed Jan 25, 2012 11:46 pm Post subject: |
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I mean unsolder one end or the other and letting it float not touching anything while remeasuring at common of Diode.
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tofutofu
Joined: 24 Jan 2012
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| Posted: Thu Jan 26, 2012 12:11 am Post subject: |
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OK 
unsolding one "leg" of L701, gave 18.5V between common of Diode (C703 positive) and ground (C703 negative). |
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tofutofu
Joined: 24 Jan 2012
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| Posted: Thu Jan 26, 2012 12:18 am Post subject: |
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| by the way, C701 & C707 are 2 cap's I replaced as thay looked "puffed" |
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jts1957
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| Posted: Thu Jan 26, 2012 12:26 am Post subject: |
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| tofutofu wrote: | OK
unsolding one "leg" of L701, gave 18.5V between common of Diode (C703 positive) and ground (C703 negative). |
Stayed steady regardless of signal or set being turned on/off?
C701's not even an electrolytic - can you post a pix?
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tofutofu
Joined: 24 Jan 2012
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| Posted: Thu Jan 26, 2012 12:40 am Post subject: |
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your right about C701, that looks OK , I ment C707.. 
19.6v when no signal
~18.5v when off (not steady)
19.4v-19.6v when on/start {going slowly up} (with signal) |
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tofutofu
Joined: 24 Jan 2012
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| Posted: Thu Jan 26, 2012 1:11 am Post subject: |
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a pic of the board:
 |
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jts1957
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| Posted: Thu Jan 26, 2012 2:01 am Post subject: |
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C707 is/was one ... C701 is NOT the other ... That leaves C___ as the 2nd?
The solder connections on the two transformers mentioned earlier are infamous for developing "rings" around one or more pins. As are some of the smaller transistors on that same board.
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