-
-
Re: Vizio 500I-B1 no standby power
I ran across a video on Youtube that gave a great description of all the parts of a switching mode power supply. The key was that if you're voltages off the dual diodes are low, that usually means that something is happening with the feedback circuit that goes through the optocoupler back to the primary side. I figured it was the opto itself, but it tested good so I started tracing it all the way back to the transformer. Honestly, I should've checked that solder job sooner since the previous person that tried to fix it really messed up everything else, and that's one of the things they tried to fix.
Oh well, here's to learning.Last edited by thezboe; 10-25-2019, 06:29 PM.Comment
-
Re: Vizio 500I-B1 no standby power
You gave a good clue in post #12 you said the previous guy botched up the soldering which should have led me to suggest checking the joints closely, don't know how I missed it.Comment
-
Re: Vizio 500I-B1 no standby power
Well the TV worked for one night and now it's kaput again.
I have standby voltage, and I can turn it on and the light goes solid but no backlights. I am getting like 1.8 volts to both the 12v and 24V(18V?) pins. The transistor labeled IC9103 was the pain point that I fixed that made it started working last time. The solder job is still good so it must be something else.
Let's try this again, shall we?
What do the R/A/K letters mean on the labeling for the terminals of IC9301?Comment
-
Re: Vizio 500I-B1 no standby power
So I'm looking into this set again after a while of just letting it sit. I opened it up and just figured I'd power it up just to see and it powered on fine! Left it going for the night and turned it off a while ago. Tried to turn it back on and it's displaying the same issue. Backlights flicker on real quick and then back off. The sound works fine however. Any ideas what it could be?Comment
-
Re: Vizio 500I-B1 no standby power
Maybe test the powerboard, with cable from powrboard to mainboard UNPLUGGED, use 3 resistors in the 1k range, jump one from PS_ON to +5V, another from on/off to +5v and the other from dim to +5v, plug power into powerboard, see if you get the proper voltages and if backlights come on and stay on.Comment
-
Re: Vizio 500I-B1 no standby power
I will try that tonight.
I also was looking at the output voltages when this is happening. The 5V and 12V rails are good, but the 24V rail is reading something like 15.6V. It seems pretty rock solid at that voltage, so it doesn't seem like a feedback loop issue to me. Maybe a bad cap on the cold side?Comment
-
Re: Vizio 500I-B1 no standby power
That didn't do anything for me. No reaction at all from the power board, only the 5V standby was on. No 12V or reading on the 24V line. so it seems to not be signalling to the power supply to "turn on".
When the board powers up with the cable plugged in, the voltage to PS_ON, ON_OFF both read 3.3V thereabouts. But the DIM pin reads like 0.05V.Comment
-
Re: Vizio 500I-B1 no standby power
If you are getting +12 volts, and no +24 volts, Check all the connections from D9106 & D9103 to the plug. +12v & +24v come from the same transformer.Last edited by R_J; 05-08-2020, 12:20 PM.Comment
-
Re: Vizio 500I-B1 no standby power
Does IC9101 provide the 24V or the 12V rail? I see the sort of "voltage divider" with the transformers. The 12V rail is coming out okay, but the 24V rail is not correct.
Every now and then I can get the TV to power on and work perfectly. When it happened the last time, the 24V rail was reading 15V! So I'm not sure what the difference is when the TV powers up and when it doesn't currently since the power rails seem to be the same in either case.Comment
-
Re: Vizio 500I-B1 no standby power
seems potentially like the other recent thread which now points at a led issue.
try unplugging one of the cables going to the backlights from the inverter. What happens in the start up? Do the same test again, trying the other cable.Comment
-
Re: Vizio 500I-B1 no standby power
I checked a few other threads and I believe the 24v marked on the board is usually around 16~19VDC.
https://www.badcaps.net/forum/showthread.php?t=59528Last edited by R_J; 05-21-2020, 07:16 PM.Comment
-
Hi. I got a Vizio with no power or standby, and won't turn on with remote or button. I checked the voltages on the connector and all read 0.00V or nearly 0(0.050 ON/OFF pin). None of the pins are labeled STB for standby although I do see some 5V pins. Other than the obvious standby led, which isn't coming on, is there a way to check for standby voltage on this PS. I'm trying to see if my problem is the PS or mainboard. Some Vizios I have fixed with no standby led me to think it was the PS but it turned out being the mainboard. Any experience with this set would be greatly appreciated. -
Hi
I am trying to repair an ancient Dell 2209WA Monitor which suddenly shut off with a pop sound. On investigation found that one of the fusible resistors had blown. Further investigation identified multiple components as faulty because of which the fusible resistor blew. Please refer the attached circuit diagram showing the components that were found to be damaged.
1. FR950 - blown fusible resistor - 0.2 Ohm 1W
2. Q950 - shorted Q950 MOSFET - 650V 10A N Channel Mosfet
3. R835 - Blown Resistor - 20KOhm SMD resistor
4. D930 - Shorted Schottkey Diode... -
Have vizio E60u-D3. No standby light. Have searched and read all D??u-D3 posts. posts with same symtoms fixed by new power supply, one guy needed back lights also.
main boards are kinda spendy and, out of stock alot of places. i would like to fix my board.
PS voltages
1 VSNS -2mV
2-5 LED-OUT -2mV
6-10 GND -2mV
11 +16VS 16.29V
12 AC-DET 3.929V
13PS-ON -3mV
14 +16VS 16.29V
15 +16VS 16.29V... -
I have a Vizio E550i-A0 that will not power on. It also does not display the standby light in the corner. I disconnected the main board cable to see if the backlights would light but they did not (maybe this is normal for this set?). I checked the voltages on the plug and they all read in mV or 0, so there's no voltage there. The fuses are ok, and the voltages of the 450v caps read about 160v. I see no visual damage on either the power supply or main board. I have read online that the main board is usually the culprit in this model, but not getting backlights with the main disconnected makes me... -
I am curious if a 0402 resistor could go from 43 ohm to 0. In electronics class and my experience a resistor can degrade and gain resistance all the way up to not being able to conduct at all. I have never heard of a resistor decreasing in resistance and becoming 0 ohm or a dead short… that's not the direction they fail… or so I thought.
I was attempting to remove a wson8 chip on an iMac motherboard and it required a lot of heat, on one side of the chip were 3 0402 resistors that were very close. I popped the chip out unintentionally out of the tweezers and sent those resistors...
Comment