Vizio E321VL

[killian6pk]

Re: Vizio E321VL

The minimum voltage difference between pin 3 (input pin) and pin 2 (output pin) needs to be at least 1.3V for the regulator to regulate, for example, if you want to have 2.5V output, the input voltage must be at least 3.8V if it is less than that, the output will not be able to maintain 2.5V output. This is applied to both Fixed and Adjustable.
The adjustable regulator, the voltage between pin 1 (adj pin) and the output pin 2 will always be 1.25 (this 1.25V precision voltage reference is inside the IC). For example, if you have adjustable regulator with the resistors between pin 1 and ground, and second resistor between pin1 and pin2 to set the out put voltage to be at 3.5V. The voltage reading between pin 1 and pin 2 must always be 1.25V (if the precision ref voltage circuit is working), then the voltage reading between pin 1 and ground should be = 3.5 - 1.25 = 2.25V. At the same time, the input voltage has to be at least 3.5 + 1.3V = 4.8V minimum.

The fixed regulator has the resistor network inside the IC, so you can only verify the input and out voltages only, you cannot get access to the 1.25V precision voltage reference circuits inside.

I've got a family member in the hospital who is seriously ill. I will try and digest what you have said here and get back as soon as possible. Thanks for your help so far.

[selldoor]

Re: Vizio E321VL

Thanks for letting us know - family and health come first on here, just re activate the thread when you are ready.

[budm]

Re: Vizio E321VL

I hope he/she will recover well and soon.

[killian6pk]

Re: Vizio E321VL

I hope he/she will recover well and soon.

Well things did not go well at the hospital. This was my wife's cousin and he passed away.

I have done some reading in the other threads on Vizio's as I have had time over the last few days. According to one post you wanted the values of the two resistors under the legs of the U4 LDO AMC1117 to help calculate the Vout and Vin. The two readings I got were:
R1 = 179.9ohms R2 = 109.8ohms. However, that only appeared to be applicable to the Adjustable regulators.

Another formula I found in the data sheet was Vin = Vout + 2V using the voltage readings I took on U4 Vout is 3.3V so Vin is 5.3V. Is this correct?

In another thread I read that there should be continuity between the first leg of the regulator and ground. I get continuity on the first leg of U8 and U5, but I don't get it on U4. Does this indicate that U4 needs to be replaced and if so is the 3.3V fixed version the correct regulator to use? None of these 3 regulators have anything printed on them but 1117. The U8 & U5 I believe to be adjustable regulators since that is printed on the board. Just for info's sake the readings I got on U4 are Pin1 = 2.04v; Pin2 = 3.29v and Pin 3 = 5.23v. Reading left to right with tab at top. U8 was Pin 1 = 0.00, Pin 2 = 1.24 and Pin 3 = 3.32v. U5 was Pin 1 = 0.549, Pin 2 = 1.79 and Pin 3 = 3.32v.

[budm]

Re: Vizio E321VL

Very sorry to hear the bad news.

This is applied to adjustable regulator 1117 series:
Voltage between pin 1 and pin 2 should always be 1.25V. There will always have one resistor between pin1 and circuit ground, and there should be a resistor between pin 1 and pin2. If you do not get 1.25V between pin 1 and pin 2, the the regulator is bad.

Fixed output 1117 regulator:
There is no external resistors since they are inside the regulator.
Pin 1 will always be connected to the circuit ground, the output pin 2 should put out the regulated voltage as printed on the body of the regulator and should be within 3%.

The "Vin = Vout + 2V" means that Vin must be at least 2V higher than the out put voltage that you want to regulated, it can be +3, +5, etc.

[killian6pk]

Re: Vizio E321VL

Very sorry to hear the bad news.

This is applied to adjustable regulator 1117 series:
Voltage between pin 1 and pin 2 should always be 1.25V. There will always have one resistor between pin1 and circuit ground, and there should be a resistor between pin 1 and pin2. If you do not get 1.25V between pin 1 and pin 2, the the regulator is bad.

Fixed output 1117 regulator:
There is no external resistors since they are inside the regulator.
Pin 1 will always be connected to the circuit ground, the output pin 2 should put out the regulated voltage as printed on the body of the regulator and should be within 3%.

The "Vin = Vout + 2V" means that Vin must be at least 2V higher than the out put voltage that you want to regulated, it can be +3, +5, etc.

This is where I am running into problems. Since there is nothing printed on the regulator except 1117 I have know way to determine the voltage output. Also I am not even sure that this regulator is connected to ground since I can't get a continuity beep on Pin 1 of the U4 regulator. Can I take a voltage reading on Pin 3 and subtract 2.0V and safely call that the output voltage? Currently Pin 3 is reading 5.23v.

[tom66]

Re: Vizio E321VL

No, unfortunately it doesn't work like that. Measure the output - adjust voltage. Let's say it is 0.5V. It should be 1.25V. Let's say the output is 1.33V. The output voltage should be: 1.33V * (1.25V / 0.5V).

If you have a faulty adjustable regulator, you should replace it with an adjustable regulator.

[killian6pk]

Re: Vizio E321VL

No, unfortunately it doesn't work like that. Measure the output - adjust voltage. Let's say it is 0.5V. It should be 1.25V. Let's say the output is 1.33V. The output voltage should be: 1.33V * (1.25V / 0.5V).

If you have a faulty adjustable regulator, you should replace it with an adjustable regulator.

I am pretty sure that the regulator that I am talking about is fixed. The numbers on all the regulators only say 1117 not 1117-XX, however on the other two regulators U8 & U5, silk screened on the board at pin 1 it says (adj.). Pin 2 says (out) and Pin 3 says (in) . That is not printed on U4. If in fact U4 is fixed like I think it is then I have to determine the output so that I can get the correct regulator and install it. I may be totally wet thinking that this regulator is bad, but everything I have read so far about Vizio's they have had at least one bad regulator. The two adjustable reg. seem to be ok from what I am reading in the data sheet Bud supplied.

Since on U4 I am getting a voltage reading on Pin 1 (2.05v) and no continuity to ground on that pin it makes me think that it is faulty. From the looks of the board U4 Pin 1 should go to ground and not have a voltage to my way of thinking at least. I hope this makes sense.

Again I have been wrong before and am sure I will be wrong many more times. Being corrected won't bother me at all. I wish I could get a Service Manual for this model, but have not been able to find one.

[budm]

Re: Vizio E321VL

If you are getting 2.05 on pin 1 of u4, then it is not FIXED output regulator since pin 1 is not at ground potential.
What voltage do you get when you put the probes on PiN 1 & 2 of U4. It should be 1.25V.

[killian6pk]

Re: Vizio E321VL

If you are getting 2.05 on pin 1 of u4, then it is not FIXED output regulator since pin 1 is not at ground potential.
What voltage do you get when you put the probes on PiN 1 & 2 of U4. It should be 1.25V.

I am getting 1.243v between Pin 1 & Pin 2. I wonder why they would print the adj. on the board on the other two regulators and not on this one? So if U4 is adjustable then are all three regulators operating correctly?

Reading left to right with tab on top
U4 = 2.05 3.29 5.23
U5 = 0.549 1.79 3.32
U8 = 0.0 1.24 3.32

On the connector between the power board and main board on Pin 1-3 I am reading 5.24v as is printed on the label for that connector. The only other pin that I get any reading from is #13 which reads 0.430v the rest of the pins I get some kind of negative reading in the MV range.

[budm]

Re: Vizio E321VL

They do not always print everything on the PCB.
So U4 PIN 1 is 2.05V, pin 2 is 3.29V, PIN 1 and PIN 2 is 1.243V
then 2.05V + 1.243V = 3.293V, so it is OK.
The key point for checking the Adjustable regulator is to measure pin 1 and pin 2 voltage, it should ALWAYS be 1.25V (+/-3%), if not, then it is bad. Then you add this 1.25V reading to the pin 1 reading, that will become your output voltage at pin 2.

U5 looks like Adjustable also and the voltage looks OK if PIN1 and PIN 2 reads 1.25V, then 1.25V + 0.549V = 1.799V. U5 is good.

U8 it looks like it is a fixed regulator, pin 1 should read less than 1 Ohm to Ground, and the number as printed on the body should be some thing like 1117-1.25. Post the picture of this U8 so I can see how it is hooked up.

[killian6pk]

Re: Vizio E321VL

They do not always print everything on the PCB.
So U4 PIN 1 is 2.05V, pin 2 is 3.29V, PIN 1 and PIN 2 is 1.243V
then 2.05V + 1.243V = 3.293V, so it is OK.
The key point for checking the Adjustable regulator is to measure pin 1 and pin 2 voltage, it should ALWAYS be 1.25V (+/-3%), if not, then it is bad. Then you add this 1.25V reading to the pin 1 reading, that will become your output voltage at pin 2.

U5 looks like Adjustable also and the voltage looks OK if PIN1 and PIN 2 reads 1.25V, then 1.25V + 0.549V = 1.799V. U5 is good.

U8 it looks like it is a fixed regulator, pin 1 should read less than 1 Ohm to Ground, and the number as printed on the body should be some thing like 1117-1.25. Post the picture of this U8 so I can see how it is hooked up.

I checked the voltage between pin 1 & pin 2 for U8 and U5 and both are 1.24v. Also I checked the ohms between pin 1 and ground for u8 and it is 2.01ohms. On all three regulators there is nothing but 1117 written on the regulator.

[budm]

Re: Vizio E321VL

U8 is fine, it is Adjustable to put out very low limit of the regulator, 1.25V.

[killian6pk]

Re: Vizio E321VL

U8 is fine, it is Adjustable to put out very low limit of the regulator, 1.25V.

Well if all the regulators are good then what is causing the lack of 12v back to the power board to turn everything on? I have checked the fuses, and the two on the main board and the one on the power board read 0.1ohms. There are two smd fuses on the inverter board. The large one reads 0.1ohms, but the small one (0.75amp) reads 0.9ohms.

If I understand correctly there is a small voltage signal constantly from the power board to the main board, then the main board sends back a signal for the power board to send out the 12 and 24volt to the inverter and LCD control board.

I have not done anything other than measurements on the main board or the inverter board. Checking for voltage across the two fuses on the inverter board there is a 0 voltage reading so it does not appear that board is getting any power from the power board.

[budm]

Re: Vizio E321VL

There is 5V standby voltage to run the processor, when power switch is activated, the processor will send out PS_ON signal to turn on the Main power supply 12V/24V section.
We will need the diagram of the main board to find out where the PS_ON is at which IC.
I wrote this for FIXYA years ago:

LCD Flat panel TV troubleshooting guide
http://www.fixya.com/support/r509388...shooting_guide

[killian6pk]

Re: Vizio E321VL

There is 5V standby voltage to run the processor, when power switch is activated, the processor will send out PS_ON signal to turn on the Main power supply 12V/24V section.
We will need the diagram of the main board to find out where the PS_ON is at which IC.
I wrote this for FIXYA years ago:

LCD Flat panel TV troubleshooting guide
http://www.fixya.com/support/r509388...shooting_guide

Ok I will read this and ponder on it. I have not been able to find anything printed on this particular model like a service manual or schematics etc. I will get back to you tomorrow. I read in another thread a guy said that he had a lot of service manuals on Vizio's. I sent him a private message, but have not heard back from him. Thanks for all the help Bud. My head is rather thick so pounding on it really hard helps to get me to understand.

[budm]

Re: Vizio E321VL

I am sure you are not the only that has this TV with this symptom, may some one in this forum had worked on this model.

[selldoor]

Re: Vizio E321VL

Can we have a close up picture of the two areas where I thought the traces were broken.

[killian6pk]

Re: Vizio E321VL

Can we have a close up picture of the two areas where I thought the traces were broken.

This is the best picture I can get tonight. I hope it is good enough for what you need. I looked these areas over pretty good and did the continuity test you suggested and could not find any broken traces.

[killian6pk]

Re: Vizio E321VL

I am sure you are not the only that has this TV with this symptom, may some one in this forum had worked on this model.

There are several threads on this model which I have read thoroughly. I will go back and reread them again.