Toshiba 47zv650u no power at all!!

[rmoody]

Re: Toshiba 47zv650u no power at all!!

A Power surge / lightning strike can cause damage at multiple points. You have indicated you obtained the TV in a non-working condition. There is a long tradition of less than ethical 'technicians' (to use the term very loosely) jamming a number of bad parts into a TV and selling it as 'It just quit'.

PlainBill

I'm really hoping that's not the case but you never know.

[rmoody]

Re: Toshiba 47zv650u no power at all!!

As for the resistor on the power board, I swapped the good one from the new board to my board and I was getting power to the panel in some places but was only getting 3.3 volts to the 24v inverter connector.

[rmoody]

Re: Toshiba 47zv650u no power at all!!

Well blow me silly but after taking it apart to get you a pic, i put it back together and now it's working. Not sure how long it will work or if it will even work again after I unplug it. I'm open to all suggestions from you. I know i gotta get it off my wifes counter before I leave for work next week for 5 months. Lol

Oh yeah, Buzzing has gone away for the moment.

[mdbeaster]

Re: Toshiba 47zv650u no power at all!!

I'm just curious, did you ever find out what the issue was? I also have the Toshiba 47ZV650U which stopped functioning after a t-storm one time. I replaced the power supply board with no change. When the power is turned on, a series of three blinks from the power LED as if the TV is trying to start up but can't. I also noticed a faint hum coming from one of the ICs on the main board (one with a heat sink). I'm guessing the main board needs replaced but I wonder if you know of anything to check before taking a $150 plunge. Obviously I've already checked that voltages are present etc. Thanks.

[PlainBill]

Re: Toshiba 47zv650u no power at all!!

I'm just curious, did you ever find out what the issue was? I also have the Toshiba 47ZV650U which stopped functioning after a t-storm one time. I replaced the power supply board with no change. When the power is turned on, a series of three blinks from the power LED as if the TV is trying to start up but can't. I also noticed a faint hum coming from one of the ICs on the main board (one with a heat sink). I'm guessing the main board needs replaced but I wonder if you know of anything to check before taking a $150 plunge. Obviously I've already checked that voltages are present etc. Thanks.

You said the 'words of doom' - lightning strike.

Without schematics, troubleshooting is almost impossible. There are almost certainly a number of voltage regulators on the main board. Check the output voltages for any that are incorrect. Look for any component that seems to be generating a lot of heat.

Other than that, look to see if someone has the same model that suffered 'WII Damage' to the screen.

PlainBill

[mdbeaster]

Re: Toshiba 47zv650u no power at all!!

I did a bit of troubleshooting and I have determined that the buck regulator at IC921 is making a lot of noise and is getting quite warm. When I press down on it, the noise subsides. This appears to be (at least one of) the main power supplying ICs for the board, as it right next to one of the connectors from the PSU. The IC is marked "Z1017AI". What are the chances that this IC is the root cause (as opposed to something else being dead shorted downstream)? Is it worth trying to find this component and replace it before moving on to board replacement?

[PlainBill]

Re: Toshiba 47zv650u no power at all!!

I did a bit of troubleshooting and I have determined that the buck regulator at IC921 is making a lot of noise and is getting quite warm. When I press down on it, the noise subsides. This appears to be (at least one of) the main power supplying ICs for the board, as it right next to one of the connectors from the PSU. The IC is marked "Z1017AI". What are the chances that this IC is the root cause (as opposed to something else being dead shorted downstream)? Is it worth trying to find this component and replace it before moving on to board replacement?

I'd say the chances are slim, but if the IC is available reasonably, or if the voltages out are incorrect, replace it. The odds are the actual noise is from an inductor associated with the buck regulator.

PlainBill

[mdbeaster]

Re: Toshiba 47zv650u no power at all!!

I found the datasheet for this part here:

http://pdf1.alldatasheet.net/datashe...AOZ1017AI.html

On the output is measured 1.5V. It is configurable, but I expected 3.3V or 1.8V. 1.5V seems to be a bit of an oddball to me.

Anyhow, I also just noticed that it is not actually the buck converter but in fact the protection diode on the output that is getting extremely hot (reference D1 on page 1 of that datasheet). Any thoughts on what might turn this diode into a toaster? I'm wondering if the diode itself is bad.

I don't mean to beat a dead horse, just thought I'd try to rule out this sore thumb before I replace the board.

[PlainBill]

Re: Toshiba 47zv650u no power at all!!

I found the datasheet for this part here:

http://pdf1.alldatasheet.net/datashe...AOZ1017AI.html

On the output is measured 1.5V. It is configurable, but I expected 3.3V or 1.8V. 1.5V seems to be a bit of an oddball to me.

Anyhow, I also just noticed that it is not actually the buck converter but in fact the protection diode on the output that is getting extremely hot (reference D1 on page 1 of that datasheet). Any thoughts on what might turn this diode into a toaster? I'm wondering if the diode itself is bad.

I don't mean to beat a dead horse, just thought I'd try to rule out this sore thumb before I replace the board.

Oh, I understand. I've often though my life (and my wife) would be a lot happier if I could accept that some problems aren't worth fixing.

HOWEVER, to me it makes sense to try replacing that diode. Do use an exact replacement; a general purpose diode won't do it. 1.5V IS a standard output voltage, but as far as I know, usually it's a low current supply.

PlainBill

[micahwhalen]

Re: Toshiba 47zv650u no power at all!!

Was the diode the fix? I have the exact same unit with the exact same problem you described, except I don't notice any buzzing and I haven't felt for heat.

[rmoody]

Re: Toshiba 47zv650u no power at all!!

Not sure what the actual problem was, I bought another board because I left town for work and will be gone the rest of the year so I had to get it going. As for the buzzing, that's coming from the inverter transformers, I'll have to replace those when I get home.

[rmoody]

Re: Toshiba 47zv650u no power at all!!

Eventually when I find time, I'm gonna go through the board again and try to identify the problem so I'll have a backup for the future.

[micahwhalen]

Re: Toshiba 47zv650u no power at all!!

Great. Do you mind telling me what the p/n was and where you purchased?

[rmoody]

Re: Toshiba 47zv650u no power at all!!

V28A000962A1 Bought it off of ebay, board had been worked on before but seems to be ok.

[micahwhalen]

Re: Toshiba 47zv650u no power at all!!

V28A000962A1 Bought it off of ebay, board had been worked on before but seems to be ok.

I just realized that my question was actually intended for mdbeaster and not rmoody. Sorry, I should have specified to avoid confusion and my almost buying a PS board that probably is not the fix. mdbeaster, did you buy the board and did it fix?

[Rome]

Re: Toshiba 47zv650u no power at all!!

Yes, that resistor was definitely bad. It bypassed the contacts of the relay to provide standby power which would turn the relay on. Replace it and you will have a spare power supply.

I think you uploaded the wrong video.

You know the drill - pictures of the inverters.

PlainBill

I have the same problem, I change that resistor 1.8 ohms blown again. So I check the mosfet Q820 it's ok & the Schottky diode D872 & D873 are ok. Next I might check the small capacitor c849 I think it's .1 uf

[nicholas1110]

Re: Toshiba 47zv650u no power at all!!

Hi,
The reason why the resistor opens is the contacts of the relay that is next to the resistor are dirty. You either need to clean the contacts inside the relay or replace it. It is the 12v relay. So replace the resistor again and the relay at the same time and you will be good to go. Hope this helps

[Rome]

Re: Toshiba 47zv650u no power at all!!

Hi,
The reason why the resistor opens is the contacts of the relay that is next to the resistor are dirty. You either need to clean the contacts inside the relay or replace it. It is the 12v relay. So replace the resistor again and the relay at the same time and you will be good to go. Hope this helps

I replaced both the resistor & new relay, it didn't work. Thanks