Toshiba 46SV670U

[Mr Bill]

Re: Toshiba 46SV670U

This tv has some hard to find parts that for sure. Did you try Mad Professors suggestion disconnecting the tcon to see if the backlights come on?

[mike123333]

Re: Toshiba 46SV670U

Yes I did try that with no success. I just repeated disconnecting it again and same thing no backlight or picture. I am wondering whether that dimmer is the root cause of this issue. $150+ is a lot of gamble.

[Mr Bill]

Re: Toshiba 46SV670U

I don't think i could stomach a $150 guess either.

[mike123333]

Re: Toshiba 46SV670U

I located one at shop jimmy's but its for the 55" not the 46" for $50.. I put in an inquiry with them whether I would be able to utilize that board in the 46" That part number is 75015786 dimmer board. There is not much to this board.

[mike123333]

Re: Toshiba 46SV670U

I did purchase a dimmer board for under $50 and that did not fix the problem. I assume now teh focus should be on the TCON. which is another rare commodity at a cheap price.

[mike123333]

Re: Toshiba 46SV670U

I found a small IC on the TCON that I am trying to identify what it is. The device ID is 58A0..The 0 looks more like a backward C so I am unsure whether it is a 0.. it has 6 legs.I am wondering whether it a voltage regulator or mosfet.The upper right leg has a voltag of 12v but Icannot probe around with my meter since the leg are so small I may short circuit the IC. But there are no voltages going to the caps and diode next to the inductor.

I circled the chip in red.

[mike123333]

Re: Toshiba 46SV670U

I cam across this device while searching the component ID. I am wondering this is the device I am searching for. The device ID is 0.58A . Any thoughts?

[mike123333]

Re: Toshiba 46SV670U

I need an experts opinion on some voltage data readings I took on the IC for the LCD which is the TPS65167 I included a TDS. I am interested in knowing whether potentially the IC is damaged or an external source is causing it to malfunction. If its the IC chip I am willing with experimentting with removing an replacing it with a new one. So far I have been unable to get the one with the Surface with extended pins not like the one in the tech sheet.

Here are my voltages with everything hooked up.

Vin = 12v
Boot = 11.06v
SWB = 3.3v
Vlogic = 3.3v
REGOUT = 4.872
REF = 1.21V
FBN = 1.04
SUPN = 12.16
TEMP = 1.67
VGH = 0V
VGL=0V
GD = 12V this pin goes to the gate of the mosfet I eluded to in an earlier post. the source is 12v which is keeping the drain open. I have 0v on the drain.

AVIN = 12V
FBLDO = 4.87v
Base = 0.648v

All other pins are at or near 0.0v..

I did not measure directly off the chip as there was no way of doing that given its dimension. I traced each pin to its specific location or safe measurement.

Based on what I am seeing in voltages especially with the critical output I think the IC is malfunctioning.

[mike123333]

Re: Toshiba 46SV670U

Anyone have an idea or opinion?

[tom66]

Re: Toshiba 46SV670U

The IC appears to work except VGH and VGL... do those change when the panel ribbons are disconnected?

[mike123333]

Re: Toshiba 46SV670U

The voltages remain the same with the removal of the ribbons VGL and VGH both measure 0.000V

Would this mean something is going on with the main processor?

[mike123333]

Re: Toshiba 46SV670U

I was studying the schematic for the iC chip. Inorder for the chip to have VS and VGH the positiv charge pump must be enabled and that get sits voltage from the external drain of the mosfet. pin36 which is the gate drive for the external mosfet. When I measure the voltages of the external mosfet I get 12v at the gate and 12v at the source. So the IC chip is delivering the gate drive of 12v. Having said that and the mosfet bein a P-channel that would mean that the mosfet drain will never contact the source to allow the flow of electrons and voltage.

What that mean the IC chip is disabling the source to drain or the mosfet is malfucntioning. Nothing is shorted on the mosfet as best I can measure in circuit.

[tom66]

Re: Toshiba 46SV670U

Is the FET in series with power? If so, it is a P-channel fet and 12V on gate and 12V on source means it is not turned on, possibly a problem somewhere else on the t-con...

[mike123333]

Re: Toshiba 46SV670U

Yes the source of the FET is in series with the power right off the fuse.The gate is driven from the IC chip as mentioned above. Which is pin 36 of the IC chip. That is why I thought maybe something is faulty with the IC. It is P channel Mosfet I included the specs on that FET in an earlier post of this thread.

[mike123333]

Re: Toshiba 46SV670U

Tom66 - you think its worth the the effort to try and swap that 40 pin IC? The EN pin on that chip is the one that enables the boost converter,VS, negative and positive charge pumps.. the only problem I have is tracing the pin and where it get its voltage from. the pin goes from the iC to bottom of the board and that's it. Without a schematic its nearly impossible.

[tom66]

Re: Toshiba 46SV670U

It may be worth it - however, have you considered that a signal is not coming from the main PCB to the T-con telling the IC to switch the voltage on?

[mike123333]

Re: Toshiba 46SV670U

that is a good point I assumed based on getting the voltage coming into the board that the Main has enabled the signal. The TCON board goes through the dimmer board. Iwill do soem voltage checking on the dimmer input/output. is the voltage usually a 3.3V?

[tom66]

Re: Toshiba 46SV670U

Typically but could be anything more than 2V. Likely <=5V.

[mike123333]

Re: Toshiba 46SV670U

I was reconnecting the TCON back to the set. I went to perform some measurement on the main board and dimmer board. An odd thing I seen was the presence of the voltages on the VGH and VGL on the TCON board. I still had no picture. I turned off the unit for about 15min and turned it back on and the voltages went back to 0. Now I am wondering whether the issues is in the main board or TCON. I did replace the Dimmer with a known good one and that had no affect on the issue.

[tom66]

Re: Toshiba 46SV670U

Could be a loose connection? Try flexing cables lightly.