Re: Westinghouse L2410NM No Power, No LED
It doesn't look like there're many helpers around. No problem, I'll continue the thread in a hope it can help others in the future.
Since rectifiers under right heatsink shown 0 Ohms btw G and S pins on-board, I kept testing them:
Voltages from the ground:
DS4 G - 5.9V, D - 22.1V, S - 5.9V
DS5 G - 5.9V, D - 0V, S - 5.9V
DS7 G - 5.9V, D - 10.7V, S - 5.9V
Not sure if these values are suitable given 5V, 14.5V and 24V power supply output? I suspect display resolution changes may require changing voltages, since the LCD goes black in btw different resolutions. Suspicious of DS5 D=0V...
I removed the right heatsink and all 3 parts to test off board. It wasn't easy by any means given lack of experience, multiple joints, and no way to reach rectifier screws. The best way probably is to add some solder to each joint, and then carefully remove all solder with cooper wick. Then try removing pins one by one by heating and pressing from bottom out with a screwdriver. I came to this through trial and error, lifted a couple of pads with solder vacuum in the process. Cooper wick absorbs solder much better if there is no pin sticking from the hole. Your iron quality and size makes all the difference. If someone tries this, prevent rectifiers overheating by hooking each to heavy locking plyers. Does lifting these pads make the board DOA?
Once removed, measured rectifiers resistance off board was:
DS4: G-S OL / OL, G-D 1.5 mOhms / OL, D-S OL / 1.5mOhms
DS5: G-S OL / OL, G-D 130 kOhms / OL, D-S OL / 130 kOhms
DS7: G-S 310 kOhms / 300 kOhms, G-D 300 kOhms / 40 kOhms, D-S 40 kOhms / 300 kOhms
Models:
DS4 456 SP10150
DS5 STPS20H100CT GKON7 VW CHN 702
DS7 STPS2045CT CC120V MAR 701
Do the above readings ring the bell - asking mostly myself for now?
More parts info:
The chip to the right of rectifiers looks like voltage regulator marked 4419 BA6515, more info here, but it doesn't feel relevant for me. This seems to be the right part.
I found some issues with very small caps on the board:
CS2 and both non-numbered caps connected in parallel to DS5 G pin measured OL on-board, it looks like they're open. One such cap was lifted with pad and removed. Can someone suggest suitable replacements or at least target part values? Also, what these lines of solder are for all around the board - are these extra cooling surfaces above pads, or to add some capacitance to pads?
I still want to think the board is salvageable since its harder now to find the same replacement. By any means it was great learning experience trying to fix my own electronics from ground zero, and learn in the process what to do, how and why. I will definitely fix the monitor.
It doesn't look like there're many helpers around. No problem, I'll continue the thread in a hope it can help others in the future.
Since rectifiers under right heatsink shown 0 Ohms btw G and S pins on-board, I kept testing them:
Voltages from the ground:
DS4 G - 5.9V, D - 22.1V, S - 5.9V
DS5 G - 5.9V, D - 0V, S - 5.9V
DS7 G - 5.9V, D - 10.7V, S - 5.9V
Not sure if these values are suitable given 5V, 14.5V and 24V power supply output? I suspect display resolution changes may require changing voltages, since the LCD goes black in btw different resolutions. Suspicious of DS5 D=0V...
I removed the right heatsink and all 3 parts to test off board. It wasn't easy by any means given lack of experience, multiple joints, and no way to reach rectifier screws. The best way probably is to add some solder to each joint, and then carefully remove all solder with cooper wick. Then try removing pins one by one by heating and pressing from bottom out with a screwdriver. I came to this through trial and error, lifted a couple of pads with solder vacuum in the process. Cooper wick absorbs solder much better if there is no pin sticking from the hole. Your iron quality and size makes all the difference. If someone tries this, prevent rectifiers overheating by hooking each to heavy locking plyers. Does lifting these pads make the board DOA?
Once removed, measured rectifiers resistance off board was:
DS4: G-S OL / OL, G-D 1.5 mOhms / OL, D-S OL / 1.5mOhms
DS5: G-S OL / OL, G-D 130 kOhms / OL, D-S OL / 130 kOhms
DS7: G-S 310 kOhms / 300 kOhms, G-D 300 kOhms / 40 kOhms, D-S 40 kOhms / 300 kOhms
Models:
DS4 456 SP10150
DS5 STPS20H100CT GKON7 VW CHN 702
DS7 STPS2045CT CC120V MAR 701
Do the above readings ring the bell - asking mostly myself for now?
More parts info:
The chip to the right of rectifiers looks like voltage regulator marked 4419 BA6515, more info here, but it doesn't feel relevant for me. This seems to be the right part.
I found some issues with very small caps on the board:
CS2 and both non-numbered caps connected in parallel to DS5 G pin measured OL on-board, it looks like they're open. One such cap was lifted with pad and removed. Can someone suggest suitable replacements or at least target part values? Also, what these lines of solder are for all around the board - are these extra cooling surfaces above pads, or to add some capacitance to pads?
I still want to think the board is salvageable since its harder now to find the same replacement. By any means it was great learning experience trying to fix my own electronics from ground zero, and learn in the process what to do, how and why. I will definitely fix the monitor.
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