trying to fix this tv for a friend on the cheap, so no replacing of motherboard or PSU as they are still over 60$ each even though this tv is pretty old
already.
i have psu board number 0500-0407-0700
seen here: http://www.shopjimmy.com/vizio-0500-...upply-unit.htm
voltages im getting at CN201:
pin label voltage
1 5vsb 5.09
2 5vsb 5.09
3 5vsb 5.09
4-7 GND 0
8-10 12v - 12.04v
11 PSON 2.2V
12 INV ON 3.22V
13 LAMP 0V
14 DIM 3.23 at first then drops to 2.91
3 fuses on the mb read fine 5v and 12v
first thing i tried to do was unplug the psu from the main board and used 1k resistors to jump from 5vsb to PSON. no luck. so i jumped also from 5vsb to INV ON. still no luck. just for kicks i tried jumping to lamp from dim, and a few other random combinations. all i was ever able to get was a quick backlight flash, no flash at all, and one time, i swear i got it to stay on but it was flickering like mad. cant remember the combo that got it to do that, but suffice it to say i just couldnt make this psu stay on by itself.
so i plugged it all back in normally with no jumpers and was just trying to test the voltages at the connector, when the backlights came to life. the tv stayed on for over an hour before shutting down again. i started to think maybe it could be a loose wire at cn201? but of course the next day it was back to the same 2seconds to black crap and no ammount of jiggling wires or prodding with the voltmeter probes could get it going again.
so i tried disconnecting inv_on from the mb connector and leaving the mb plugged in and jumping inv_on with 5vsb like before...still nothing.
i started to feel like the problem had something to do with lamp always being 0, so i tried various combinations of jumping it from, pson, inv_on and 5vsb. none of that would work.
but for some crazy reason, when i jumpered from dim to lamp, voila! the backlight stays on solid, the tv functions and everything looks fine!
so LAMP is usually at 0v when the set is in standby or on (amber or white)
and the dimm of course is 0 in amber and 2.91 in white
but when i use the 1k resistor between the 2 of them, they both get around 2v which seems to be the sweet spot.
thing is i do hear a slight whine coming from the inverters. i cant be sure if this is normal. its definitely not something you would hear unless you put your ear to the back of the tv once the case is on. so maybe i dont need to worry about it?
thing im worried about, is can i leave this in place as a permanent solution without possibly causing a fire hazard down the road?
and more importantly, i'd really like to know for sure if this is a PSU problem or a MB problem!
kind of hard to do when theres no service manual for it... (at least i couldnt find it on elektrotanya, is there some better place to look now?)
thank you for all your help so far!
already.
i have psu board number 0500-0407-0700
seen here: http://www.shopjimmy.com/vizio-0500-...upply-unit.htm
voltages im getting at CN201:
pin label voltage
1 5vsb 5.09
2 5vsb 5.09
3 5vsb 5.09
4-7 GND 0
8-10 12v - 12.04v
11 PSON 2.2V
12 INV ON 3.22V
13 LAMP 0V
14 DIM 3.23 at first then drops to 2.91
3 fuses on the mb read fine 5v and 12v
first thing i tried to do was unplug the psu from the main board and used 1k resistors to jump from 5vsb to PSON. no luck. so i jumped also from 5vsb to INV ON. still no luck. just for kicks i tried jumping to lamp from dim, and a few other random combinations. all i was ever able to get was a quick backlight flash, no flash at all, and one time, i swear i got it to stay on but it was flickering like mad. cant remember the combo that got it to do that, but suffice it to say i just couldnt make this psu stay on by itself.
so i plugged it all back in normally with no jumpers and was just trying to test the voltages at the connector, when the backlights came to life. the tv stayed on for over an hour before shutting down again. i started to think maybe it could be a loose wire at cn201? but of course the next day it was back to the same 2seconds to black crap and no ammount of jiggling wires or prodding with the voltmeter probes could get it going again.
so i tried disconnecting inv_on from the mb connector and leaving the mb plugged in and jumping inv_on with 5vsb like before...still nothing.
i started to feel like the problem had something to do with lamp always being 0, so i tried various combinations of jumping it from, pson, inv_on and 5vsb. none of that would work.
but for some crazy reason, when i jumpered from dim to lamp, voila! the backlight stays on solid, the tv functions and everything looks fine!
so LAMP is usually at 0v when the set is in standby or on (amber or white)
and the dimm of course is 0 in amber and 2.91 in white
but when i use the 1k resistor between the 2 of them, they both get around 2v which seems to be the sweet spot.
thing is i do hear a slight whine coming from the inverters. i cant be sure if this is normal. its definitely not something you would hear unless you put your ear to the back of the tv once the case is on. so maybe i dont need to worry about it?
thing im worried about, is can i leave this in place as a permanent solution without possibly causing a fire hazard down the road?
and more importantly, i'd really like to know for sure if this is a PSU problem or a MB problem!
kind of hard to do when theres no service manual for it... (at least i couldnt find it on elektrotanya, is there some better place to look now?)
thank you for all your help so far!
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