Vizio VW37 Power Supply PSON working but no 12v or 24v output

[DFH]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

Just checked the main processor board for signs of failed caps and components, negative. The only possible visible finding thus far is a single heat damaged lead off of the large transformer located under the middle heat sink (high power side) of the power supply board. I will try to post photo when I figure out how to do it.

Must stop for the night.

Edit====
Just read your post budm, my power supply is the same as yours DPS-247AP B. My cap seems to be constantly charged and not being switched like yours. I am leaning towards buying a new power supply board.

[DFH]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

budm, I do have the same power supply as you do DPS-247AP B. Looks like my cap is constantly energized and not switched like yours.

Since your power supply board is powered-up can you provide me with comparison DC voltages at each pin of the three DC connectors (5, 12, and 24VDC)?

I am leaning towards replacing the power supply board.

[budm]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

Just plug in without PS_ON signal, the cap read 168vdc, 5VDC at 5Vstb pin, when PS_ON is received, I get 398vdc at the large cap, 12vdc at 12vdc terminal, and 24Vdc at the 24Vdc terminals. When you remove the 24vdc connector from the board so you will not have the inverter loading it down, what do you get at the 24vdc terminals?

[DFH]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

I will have to check tomorrow after work. Thanks for the voltage values.

[budm]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

I hope you do not have two problems: Power supply and Inverter boards.

[tibimakai]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

budm, if there is an issue with the inverter board(s), can blow the power supply?
I still haven't given up on that vx37l, I'm just getting a new PS from China and I wouldn't like to blow it.

[budm]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

The power supply will sense the over current and goes into shutdown.

[DFH]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

Ok, here are my new meter readings from the power supply board.


PSON signal = OFF, zero vdc at PSON connector pin, 450 V 150uF cap reading 150.5vdc (my last reading accidentally had the max hold button pushed on, sorry). The 5vdc pin meter reading is 4.71vdc.

PSON signal = ON, 4.71 vdc at PSON connector pin, 450 V 150uF cap reading 368vdc (so cap is being switched on/off correctly). The 5vdc pin meter reading is 4.71vdc. The 12vdc pin meter reading is 10.8vdc. The 24vdc pin reading is 22.3vdc.


When I removed the 24vdc inverter connectors from the power supply board and turned the TV to ON, i.e. inverter load removed, the 5, 12, 24vdc pin meter readings were the same as above, all lower than expected.

By the way, attached is the photo of the heat damaged transformer lead.

https://picasaweb.google.com/dfherna...eat=directlink

[budm]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

The Main cap voltage, 12v and the 24v sure reading low WITHOUT the load. I just setup the power supply to show how I test it, I use 1157 bulbs testing, and the 12 and the 24 are reading correctly. I would like you to remove that big cap and measure its value., but before you do that, set the meter to AC Volt mode and take the reading on the two legs of the cap again for me with the TV off and the TV. I think that big cap may be bad.

[Datafreedom]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

Hello. In no way do i intend to hijack your thread but a "DSP-247AP power supply was listed above and i very much need your help. I have 2 simple questions. I need the values or resistance "Ω" for resistors "R621A" & "R621B". It would help so much. the pwr sply i have burned both of them completely into. I cleaned off dried liquid that did seem to have enough solids suspended in it to conduct electricity. I have tested most of the rest of the components as best I can. I have no O-Scope so...... . Any input anyone wants to offer will be appreciated greatly. Thanks again (8^) email me direct if you'd like at innovation.dinamix@gmail.com

[budm]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

@datafreedom, your power supply looks like the one I show in the picture? I will look at value of those two resistors for you if you can tell me where they are located at.

[DFH]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

Hey guys, my troubleshooting of this tv will need to go on hold for a day or so do to kid activies. I will be back.

[DFH]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

Well, I am back after spring break. My TV is still in pieces in the garage. I bought a new power supply and it did not fix the problem. I checked all the voltage regulators on the main board (U2, U4, U7, U9 and U33) based on values in other threads and didn't find any major anomallies.

So I started to probe the inverter boards with my meter. All the surface mount fuses were good, and no bad caps. I touched the high power light blue wire connector on the slave inverter that is below the transformer with my lead and the transformer began to buzz and the TV back light came on. Did it several times to confirm. Looks like I have an open circuit (cold solder joint) at this connector.

I will close this thread at this point and open a new thread if problems continue with the inverter boards.

Thanks for the help, and I will be back again.

[selldoor]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

Hello. In no way do i intend to hijack your thread but a "DSP-247AP power supply was listed above and i very much need your help. I have 2 simple questions. I need the values or resistance "Ω" for resistors "R621A" & "R621B". It would help so much. the pwr sply i have burned both of them completely into. I cleaned off dried liquid that did seem to have enough solids suspended in it to conduct electricity. I have tested most of the rest of the components as best I can. I have no O-Scope so...... . Any input anyone wants to offer will be appreciated greatly. Thanks again (8^) email me direct if you'd like at innovation.dinamix@gmail.com

DFH has kindly looked at his boards and has the following information for you : R621A - Covered with heat shrink, unable to view.
R621B - Bands from top to bottom are Red, Red, Silver, Gold. Resistor body is a pink color. If you were to post good clear pictures of both sides of your power supply and a close up of where the caps are/were we might be able to help further. There are no decent pics of this board anywhere so you would be helping people in the future.

[killian6pk]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

If you have an Visio E321VL Service Manual. I would appreciate a copy.

[selldoor]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

If you have an Visio E321VL Service Manual. I would appreciate a copy.

Is there some reason you have bumped an old thread about a VW37 with this request when there is a thread for that model https://www.badcaps.net/forum/showth...ghlight=E321VL

I dont think anyone has or it would have featured.

[killian6pk]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

Someone back early in this thread offered up service manuals for several models of Visio TV's. I stuck this in without thinking about sending him a direct message which I have done. Sorry for upsetting the apple cart.

[kevkevkjkj]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

I fixed this blank screen.

Here's how:

First you need to disconnect the inverter board. only hook up the power supply and the main board. Then check the PSON on the power supply is getting power..about 3.3V. The PSON pin is labeled and located on the right side of the power supply board with all the connectors.

Next, if you have pson at 3.3V then check that there is voltage at the 12V and 24V of the power supply.

If this is ok then you connect the inverter board. Then check the 12V and 24V again. This may change.. which was what the problem was with my TV.

I had to remove one of the big caps to get the TV screen back on. It seems that the TV is working again.. not sure how long this will last though.

[fajardotv]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

Bad t-con makes the tv shutdown.

[NitroRat]

Re: Vizio VW37 Power Supply PSON working but no 12v or 24v output

I received a Vizio with the same problem. After digging around with suggested voltage checks, I found that U33 was defective. These were the symptoms:

Standby VIZIO Logo on : 5 Volts enable
No Power with Remote
Turns On with Side button Power, Backlight is on
No video or no reception (No Signal is not present)

Voltages were present, 5V, 12V and 24V. After I replaced the U33 before the TV works Ok. Now is back with the same problem so I decided to do the same. Unfortunately the part from DigiKey was incorrect. When I replaced the U33 regulator it killed the PSON enable voltage and no 12V or 24V present. I thought something went wrong in the PS. But after checking everything I did not find a reason for a problem.

When I removed the U33 and check voltages, the original problem is back. So, I checked the voltage regulators with a known good one. The readings are half the value, 337 diode check ground to adjustment pin and 327 to emitter. I will get the right part and solve this during this week...I keep you posted.
So the voltage regulator remain the problem and having the wrong part could kill your voltage, PSON and remote operation like a bad PS.

Hope this help somebody!