Vizio 47 vo47l power supply DPS-433BP

[budm]

Re: Vizio 47 vo47l power supply DPS-433BP

Can we see the picture of this 470uF 50V cap?
What other 35V or 50V cap do you have around?
Something is not adding up here.

[sheen818]

Re: Vizio 47 vo47l power supply DPS-433BP

“24V rail filter caps”, are these C240A-D? if yes, I had replaced in the first time. if not, can you tell me which one? By the way, I had replaced C242, 2.2uf, 50V.

when I replace C241 in second time, I removed these 4 C240A-D caps, and measure esr, all of them are 0.06-0.09, they are ok, then installed them back. my meter is fluke 83, not sure if it is true RMS DMM.

Did you replace the 24V rail filter caps? If you have a true RMS DMM, you could try to measure the AC component on that cap that wants to blow up all the time. If your meter is not true RMS, try to put a series cap on there. Other than that, I am running out of ideas.

[sheen818]

Re: Vizio 47 vo47l power supply DPS-433BP

from top to bottom, first, second, third time. the first and third caps in picture are good, but it is the same as one I used. because I threw the first one, third one is still on the board.

Can we see the picture of this 470uF 50V cap?
What other 35V or 50V cap do you have around?
Something is not adding up here.

[CapLeaker]

Re: Vizio 47 vo47l power supply DPS-433BP

Those shouldn't blow at 24v dc. Something is a miss. What is the power supply board number? Maybe there is a schematic.

[sheen818]

Re: Vizio 47 vo47l power supply DPS-433BP

vizio part number 0500-0510-0340, another part number DPS-433BP A,

Those shouldn't blow at 24v dc. Something is a miss. What is the power supply board number? Maybe there is a schematic.

[sheen818]

Re: Vizio 47 vo47l power supply DPS-433BP

only this C241 bulged, no others, it is no idea why.

[budm]

Re: Vizio 47 vo47l power supply DPS-433BP

I would you to try running the 24V power supply without having the inverter board connected. Unless the caps on the inverter boards are bad, the cap will have to supply large discharged current instead of the caps on the inverter board.
How are the caps on the inverter board?

[sheen818]

Re: Vizio 47 vo47l power supply DPS-433BP

you are absolutely correct. the two caps are bulged in both master and slave inverter boards. after replacing them(680uf, 35v with caps (1000uf, 35v). no problem at all now. Thank you so much.

I would you to try running the 24V power supply without having the inverter board connected. Unless the caps on the inverter boards are bad, the cap will have to supply large discharged current instead of the caps on the inverter board.
How are the caps on the inverter board?

[sheen818]

Re: Vizio 47 vo47l power supply DPS-433BP

capleaker and budm, thanks a lot.

[budm]

Re: Vizio 47 vo47l power supply DPS-433BP

Glad to hear. Any pictures of those caps on the inverter board?

[sheen818]

Re: Vizio 47 vo47l power supply DPS-433BP

capleaker and budm, I have two questions,

(1) I will buy an esr or lcr meter to measure the surface mount components on the lcd panel board or main unit. point is which one is better to measure or test these small components in circus? Can you give me some advice or recommend model and brand?

(2) for OSCILLOSCOPE, it is big useful in repairing job? comparing DIGITAL and Analog, which is better for LCD TV repairing job?

Thanks so much for your help.

[sheen818]

Re: Vizio 47 vo47l power supply DPS-433BP

left one is the third 470uf, others are caps on the both inverter boards.

Glad to hear. Any pictures of those caps on the inverter board?

[CapLeaker]

Re: Vizio 47 vo47l power supply DPS-433BP

juck! Bad caps all right. To answer your question. A 100MHz oscilloscope is all you need, but if you find a used 400 or 500Mhz one for decent money go for it. Doesn't really matter if analog or digital. With an oscilloscope on hand, you could have figured out fast that there is excessive ripple on the cap. Since that cap is kind of in the middle, there were 2 ways to go. The supply caps or caps that are on the other board. Both will have same effect. If the ripple current too high, cap is getting hot, bulged or pops. Same as when one installs the cap backwards, or too low of voltage rating. I use also the scope to check for video on the LVDS cable.

As for the LCR meter... that depends on how much money you want to spend. There are big bench testers and handheld ones. For me I have one made by Agilent or now KeySight. There are other cheap ones too... but may not be accurate specifically with low values, and looking for bad caps in circuit. Everyone their own...

[Shane711]

Re: Vizio 47 vo47l power supply DPS-433BP

Wow, I wish I had sheen818's problem. I first found the 4 bad caps on the inverter boards and bumped up the voltage to 50v. Thought the TV would start right up but no way. Then I found the bad caps on the power board but I had more than just bad caps. Seems the board just about caught fire. Looking around online it seems this is common problem with this power supply.

I plan to change out the 2 coils and all the caps.

I need help identifying the 2 coils. I am not sure what they are called.

[Shane711]

Re: Vizio 47 vo47l power supply DPS-433BP

I think they are magnetic inductors. Still looking for the right one.

[dick_barton]

Re: Vizio 47 vo47l power supply DPS-433BP

Hello Shane,
I think you'll have trouble trying to identify the material the coil is wound on. It's ferrite material which all have individual specific properties to give the coil its inductance.

You could remake the coils by using copper enamled wire of the same outside diameter and wind exactly the same number of turns (or partial turns i.e. it could be 4.5 turns) on the existing ferrite formers.

The board is quite carbonised and to be honest I'm not sure it would be worth the effort.

[Shane711]

Re: Vizio 47 vo47l power supply DPS-433BP

Considering these boards are selling for $100 used I would think my efforts would we worth the trouble. Tomorrow I am going to see if my friend has anything I can use and if not I will rewind it myself as you said. I have been looking all day and can't find anything exact so I have already planed on remaking the coils.

[Shane711]

Re: Vizio 47 vo47l power supply DPS-433BP

Well I decided to repair the inductor coils. They got hot and burnt so I cleaned all the insulated coating off and resprayed them with Rustoleum acrylic spray (Clear Coat). Then I placed them them back on the board and also put a cooling pad under the board to the frame. And I added a cooling fan.

The TV still has a problem, no power going to the backlights so I have to investigate the problem further.

[Shane711]

Re: Vizio 47 vo47l power supply DPS-433BP

Well here is an update. I decided to work on this TV again today because I got another parts TV in with a good Power board. Switched out the power board and I still had the same problem so I decided to look further into the TV.

Turns out I did a good job repairing the Power Supply. I double checked the inverter boards for shorts and blown fuses but couldn't find any and I also checked the fuse on the T-Con board. I checked the main board and all seemed good. After all this I thought maybe the ICs on the inverter boards. So I looked up the datasheet and found pins 1 & 11 to be ground. Checked the Master Inverter and no shorts. Checked the Slave and I found a short on the IC and after looking under my magnifier I found a bubble in the plastic right where the short was. Just so happens I ordered 50PCs (BD9897FS) 6 days ago from China. Can't wait for them to get here because I have 3 TVs that need at least 1 BD9897FS. I will do a follow up after the parts come in.

Here is a picture of the bad IC, as you can see it is barley noticeable.

[budm]

Re: Vizio 47 vo47l power supply DPS-433BP

Yep, that is the typical failure mode, none of the four Power MOSFETS are shorted out?
BTW, the Ferrite slug can be damaged by extreme heat.