Re: Vizio vx42l hdtv10a Bad 5VSB Circuit
Guys, break out the confetti, I think I got it working again. I went and ordered the works, two replacement ICs, the startup transistor(Q901), and a triode for the 5v line.
Replaced the transistor, tested, didn't work, replace the triode(D951) Moar volts!
I lost a voltage regulator I pulled from the main board (U33) so I can't do a power on test yet, but I'm confident....
Whats strange is I tested that triode, it measured 300 ohms on each post, and in the correct directions, so I assumed it was OK
jonpad01
Member
Last Activity: 09-22-2015, 01:17 PM
Joined: 05-20-2015
Location: Oregon City OR
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Last edited by jonpad01; 06-12-2015, 10:41 PM. -
Re: Vizio vx42l hdtv10a Bad 5VSB Circuit
[url]https://www.youtube.com/watch?v=DmlGSE6Akf0&feature=youtu.be[/url]
My phone is clearly really bad quality, or I just don't know how to focus, but basically at the beginning the max voltage is 1 volt, and half way through I disconnected the resistor, it eventually reached 7 volts at the end.
Also, I can buy a 47 Ohm 1W resistor if the ones I'm using aren't correct for testing loads.Re: Vizio vx42l hdtv10a Bad 5VSB Cir...youtu.be[/url]Last edited by jonpad01; 06-06-2015, 03:42 PM.Leave a comment:
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Re: Vizio vx42l hdtv10a Bad 5VSB Circuit
Okay I gave it a try, I put a resistor between 5VSB and SGND, hopefully that is correct.
33 ohm 1/2 watt Ressitor - between 0 and 1 volt
150 ohm 1 watt Resistor - between 0 and 2 volts
2x 150 ohm resistor - 0 and 1 volt
2x 33 ohm resistor - 0 and .5 volt
nothing connected - 7 - 7.75 volt
All of this was done on my analogue meter, I am going to upload a video of what its doing, because it's hard to explain.Leave a comment:
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Re: Vizio vx42l hdtv10a Bad 5VSB Circuit
So I'm back at it. I decided to measure the output on the transformer output, and got nothing, I only get voltage after the diode.
What was interesting tho was when I busted out my analogue meter, it showed that 5v output was hitting 6 volts, and jumping to 7 volts every 2-3 seconds. But I still couldn't get anything off the transformer with it, even when I connected it back up to the mainboard.
Note here, this definitely is the 5v transformer, it was also receiving about 160v from the primary side. Is there any...Last edited by jonpad01; 06-04-2015, 05:36 PM.Leave a comment:
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Re: Vizio vx42l hdtv10a Bad 5VSB Circuit
Well, after installing all new electrolytic caps, I still have the exact same problem. I am reaching the end of my diagnostic ability for power supplies. At this point I'm just guessing at what to replace, does anyone else have any ideas?Leave a comment:
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Re: Vizio vx42l hdtv10a Bad 5VSB Circuit
Just ordered a round of new caps. I went with Panasonic FM/FC series, they seem to be reputable for low impedance capacitors.
After researching a bit, I realized that capacitor impedance ratings vary depending on what temperature they are at, it's all starting to make sense.Leave a comment:
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Re: Vizio vx42l hdtv10a Bad 5VSB Circuit
Well I tried the hot air gun(don't have a hair dryer) and got it to go up to about 3.5v, it seemed to be the area around the 2 electrolytic caps for the 5v line.
Just so I understand whats going on here, is the heating a test for bad capacitors? Or does it test for other components as well.Leave a comment:
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Re: Vizio vx42l hdtv10a Bad 5VSB Circuit
Yes sir I did, it was good according to my capacitance meter. I think tomorrow I am going to pull all of the heat sinks back off and check the resistors / diodes.
I should probably mention that all of this testing has been done off the TV with nothing else connected to the power supply. I noticed when I connected it to the mainboard the 5v line dropped down to 1 volt.
I might also replace all of the electrolytics just because, would there be any reason to think they are bad? I honestly sounds like a capacitor problem...Last edited by jonpad01; 05-22-2015, 11:21 AM.Leave a comment:
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Vizio vx42l hdtv10a Bad 5VSB Circuit
Part # on the board is DPS-283BP B Rev S0
I got this tv recently and have been doing a bit of troubleshooting, but not much luck. I figured I'd make a post here to confirm my theory and to see if anything jumps out that I don't know about.
Here are the symptoms:
-No power, no orange light
-Power button does nothing
-5VSB circuit reads 1.2v initially then slowly climbs to 3 volts, all the while fluctuating +/- 0.25v
-All of the capacitors on the secondary, including the 5v line read at or slightly above their... -
Re: New Members - please post your introductions here
Hello I am trying to fix a vizio tv (vx42l) and thought id try here, power supply is only reading 3v on the 5v standby circuit, and i'm about to pull my hair out and buy a new power board! I think I have to make a post here before starting a new thread, so here it is
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