Vizio TV E470VL SMPS Flucuation Output Voltage

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

Fuse 102 was blown. I replaced with a fuseable 2 watt 0.1 ohm resistor FKN200JR-73-0R1. the information for the fuseable resistor replacement was obtain from another Badcaps thread, the person had a similar Power supply and problem with the same fuse. Original fuse attached

[Diah]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

huge different between label F & R ..wrong Info on another threat.. remove the R . u can use normal fuse.

did you find any MOSFET was shorted ( you have 4 ) after this F? if yes and now they are fine no short at them.. just remove the 2 cable you have soldered on the socket and plug the PCB to wall as its out side the tv. and measure only standby on the socket... reference your DMM black probe to any caps leg - on the COLD area ( near to the socket. )

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

Diah, I don't have shorted mosfets that i'm aware of. there is no standby voltage, no 5 volt, no 12 volt, no voltage on caps on cold side, there is no voltage on the cold side of the board.

[dskall]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

I have checked the traces and all 6 ic pins and they are good.
I checked ZD103 with another Voltmeter, it shows 0.579v one way and OL the other. My guess is this voltmeter uses less volts for testing compared to the other VM that showed voltage each way. ZD103 and C109 share the same traces for each of side of their leads which might account for why there is voltage each way on ZD103 with the VM that has a higher voltage. I'm not real good in installing or removing SMD so I would prefer to wait on doing that until all other troubleshooting options are exhausted.
You mentioned that start up voltage is supplied to pin 4 from pin 6, can you help me better understand how it works; Is Pin 4 Feed back and Pin 6 Voltage Start up? Pin 6 has 77.2 volts when the power supply is plugged in. This has been about 2 and 1/2 month project and it gets discouraging at times. I appreciate your help.

Do you have capacitor test on your dvm? You need to remove at least the cap. and check it. Basically only 2 reasons for no voltage at pin 4. Bad IC or shorted components on pin4 circuit. Pin 6 you say has voltage internally feeds pin 4 to build voltage and start things in motion. Then pin 4 gets it's voltage from secondary coil off transformer.

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

I have a LCR Meter. Can I check the cap with a ESR meter in circuit? is the little cap polarized?

[Diah]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

Diah, I don't have shorted mosfets that i'm aware of. there is no standby voltage, no 5 volt, no 12 volt, no voltage on caps on cold side, there is no voltage on the cold side of the board.

then yours issue at hot area... its dangerous parts. advice you

buy replacements boards .. and don't keep swimming in ocean of parts replacements,

at least you will have working boards you can take it as references to check yours and learn from it.

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

what is the best way to trace the Pin 4 circuit?

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

thank you for the reply Diah, I don't think there is a replacement board for this specific power supply.

[dskall]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

You might also unplug and discharge your main cap safely. And check for continuity in diode mode from vcc pin to ground pin. I may have got my pins wrong before. Pin 3 is vcc

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

in continuity mode, placing one lead of my mulitmeter on the negative of a big filter cap and one lead on Pin 3, the reading was .071

[dskall]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

I think that is a problem. Backside pictures are to blurry to trace out. You need to identify components in pin3. Should end up at one pin of transformer.

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

I don’t know what you mean when say, “I think that is the problem.” That Pin 3, Vcc is shows 0 volts? That Vcc is shorted? I don’t know how the power supply works. I will see if I can identify components related to Pin 3 tomorrow. I appreciate your help!!!!

[nomoresonys]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

The first IC I purchased may not have have been an equivalent replacement. Hopefully FSQ0565RQWDTU is. one item that is different from the original is the Continuous Drain Current Max; on the original it is 4.00 on the 565RQ it is 2.8. I don't know how the Continuous drain current works so I ask Do you think having an IC that has lesser rating for this characteristic would have a negative impact on the switch mode power supply? Data sheet attached

If this is your IC, we can put it here, maybe try with only power cord going to powerboard, measure each pin for voltage, neg. probe on neg of main cap, compare it to the datasheet. The datasheet didnt transfer with the quote, it's at post #77.

[nomoresonys]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

.

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

I think that is a problem. Backside pictures are to blurry to trace out. You need to identify components in pin3. Should end up at one pin of transformer.

Zd104 and or c107 appear to be shorted, they read .072 both ways In diode mode. They are both connected to Vcc Pin 3. Should I remove from the board and test further? Picture attached

[nomoresonys]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

Why not, lift a leg of the zener and retest, also test where they connect to see if you still read short and see if the cap still reads short with zener out of circuit. could also test that cap in circuit in ohm mode, it dont look like those should be testing short.

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

What is the best method to desolder one leg? I’m not real good with surface mounted components

[nomoresonys]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

how big is the zener? If the zener isnt tiny I just clip a leg in the middle of it with nail clippers, test it, if its good just put it back together with a bit of solder, other way is just add a little solder to the underside where its soldered in that helps with removal, i use a little flux too, suppose you dont have to have flux but it just makes it a lot easier.

[nomoresonys]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

check youtube for soldering methods, theres a ton of them.

[dholley]

Re: Vizio TV E470VL SMPS Flucuation Output Voltage

I removed ZD104 and C107. ZD104 shows about 0.2 in diode mode each way. I’m assuming that would be a bad zener diode, would someone please confirm. It was not my intention to remove C107 at the same time as ZD104 but I used alloy and the zener and cap are so small and close to each other i inadvertently knocked it off. I think the cap is covered in alloy so I’m trying figure out how to clean it. Some good news I think, with the zener and cap removed there is some output voltage all be it low and fluctuating. Can some please advise of the replacement parts for the zener and capacitor? Thank you!!