Vizio E321VL

[killian6pk]

Re: Vizio E321VL

Well you can officially put me into the dumber than a rock catagory. It was in backwards. Took it out and resoldered it and now I am getting 171.9 volts at the Filter Cap. However I am not able to get the voltage to increase by pushing the on/off button. So I guess now I should check for 5V, 12V and 24V at the cable to the Main Board? Also I gave you wrong info above in post #36 about what that Diode was. I corrected that post in case someone needed that info later.

[budm]

Re: Vizio E321VL

Picture of that D100 as mounted will help also.

[killian6pk]

Re: Vizio E321VL

Ok I will check it and see if it is open or installed backwards. I hope I did not do that. Get back to you in a few minutes.

[budm]

Re: Vizio E321VL

I am still trying to find out why you are not getting the 170vdc on that large cap, as you can see from testing the connection, the traces are OK the only thing that in the path of the + output of the bridge to the + of the large cap (inductor tested OK) is that Diode D100, you can also see it in the diagram I provided, unless that Diode is open (or installed backward), then there is no other reason for not getting any DC on that large cap.

[killian6pk]

Re: Vizio E321VL

OK, you do not have open trace.
How about the D100? That Diode is the one that feed the rectified AC into the large cap.

I don't understand what you mean, what do you want me to do? For information purposes this is one of the Diodes that I took out tested and replaced so it is new. It is a GAMUR460 Ultra Fast Rectifier Diode 4A 600V.

[budm]

Re: Vizio E321VL

OK, you do not have open trace.
How about the D100? That Diode is the one that feed the rectified AC into the large cap.

[killian6pk]

Re: Vizio E321VL

seems like i had one of these in with a bad surface mt diode it was underneath back side of powerboard. near the startup cap, i overlooked it twice and after i let it set for a couple of days i found it. try checking around the area of the cap and see if you find an open sm diode.

The only Diode that I could find was one of those small 3 legged type. I looked for a DataSheet, but could not find one. Number on top of diode looked like either AZW15 or A7W15 the 15 was turned sideways to the letters. I measured ohms between the 3 legs. First leg on bottom of diode, second leg at top and third leg (actually 2nd leg) on bottom.
1-2 = 0.801mohm; 1-3= 1.737kohm; 2-3= 0.767mohm.

[killian6pk]

Re: Vizio E321VL

Please see my redline on the test points and check D100.
Check resistance between:
1 & 2
3 & 4
5 & 6

They should be less than one Ohm.

Checked 1-2 = 0.3; 3-4 = 0.1; 5-6 = 0.1

[budm]

Re: Vizio E321VL

Please see my redline on the test points and check D100.
Check resistance between:
1 & 2
3 & 4
5 & 6

They should be less than one Ohm.

[awyatt2]

Re: Vizio E321VL

seems like i had one of these in with a bad surface mt diode it was underneath back side of powerboard. near the startup cap, i overlooked it twice and after i let it set for a couple of days i found it. try checking around the area of the cap and see if you find an open sm diode.

[awyatt2]

Re: Vizio E321VL

i would try replacing the startup cap and see what happens, what can you loose?

[killian6pk]

Re: Vizio E321VL

Checked several components on both sides +/- and it shows continuity to the next 3 components located on that trace.

[selldoor]

Re: Vizio E321VL

RV is a Varistor
RT is a Thermistor



Edit - just beat me to it but at least we agree.


Before you pull the cap just test for continuity from a leg to the next joint.

[killian6pk]

Re: Vizio E321VL

the rt may be some type of transient device, rv might be a varactor diode. unsure of this a guess only.

I checked Wikapedia and they say RT=Road & Track (no just kidding) it stands for Thermistor

RV stands for Varistor

[killian6pk]

Re: Vizio E321VL

Well I checked the cap again and I got 0.4V DC. Should I pull that cap and check ESR etc? Maybe it was bad even though it was new?

[awyatt2]

Re: Vizio E321VL

the rt may be some type of transient device, rv might be a varactor diode. unsure of this a guess only.

[killian6pk]

Re: Vizio E321VL

If you are getting 174 Vdc at the two pins of the Bridge, that means the big cap does have connections all the way to the bridge output, but I am confused since you have indicated that you are not getting any DC voltage on the Big cap. This power supply has PFC circuits, so when you plug the TV into the outlet, the voltage on the big cap should be around AC input voltage x 1.414, and when you turn the TV on, the DC voltage should go up to around 400Vdc on that big cap.

That makes two of us that are confused. I will recheck the the voltage on the Big Cap and report back in a few minutes.

[killian6pk]

Re: Vizio E321VL

try replacing the startup cap somewhere close to the 8 pin ic. they dont always read bad esr when in circuit.

All of the Electrolytic caps were replaced with good brand low ESR caps before I did anything else. (Power Board only) I sort of make that a rule as they are not expensive and since there is so much crap out there, I think it makes sense.

[budm]

Re: Vizio E321VL

If you are getting 174 Vdc at the two pins of the Bridge, that means the big cap does have connections all the way to the bridge output, but I am confused since you have indicated that you are not getting any DC voltage on the Big cap. This power supply has PFC circuits, so when you plug the TV into the outlet, the voltage on the big cap should be around AC input voltage x 1.414, and when you turn the TV on, the DC voltage should go up to around 400Vdc on that big cap.

[killian6pk]

Re: Vizio E321VL

Inside pair AC In ????
Outside Pair DC out ????/

Is this what you meant: DC- AC AC DC+

If these measurement points are correct then I got: DC= 171.4V AC= 123.7V Does that sound correct?