Olevia 747-b11 power on, screen dark

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

OK, finally moved the piece and removed the covers from the side boards.

Photos:
- right board
- left board
- zoom in on right board of one of 4 seemingly identical blocks
- zoom in on the middle part of right board
- markings on the right board (I guess the left board is the same)

I am not seeing anything that looks obviously damaged or burned. What should I check next? Thx

[cliff_hootarski]

Re: Olevia 747-b11 power on, screen dark

Your 4th picture of the power connector going to the inverter has a burn mark.

[D.T.]

Re: Olevia 747-b11 power on, screen dark

I agree.

Anyway, I went to the rat shack and they only had 3 of the capacitors I was looking for. So I de-soldered the bad caps I had to replace (4 of 9) and just wanted to see if it would work.

Wa La! I'm back in action! Sound and video works great!

Thanks to this site.

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

Your 4th picture of the power connector going to the inverter has a burn mark.

quote from earlier in the thread:

That's what I feared but it's not too bad. You just shorted it to ground (the case..) Unplug power for a minute and try again. The PSU would have gone into a protection mode, no damage should occur.

After you complete repair I'd clean up that spot with a bit of 99% isoprop alcohol l and a q-tip.

You should be getting readings around 24V so make sure your meter is on volt DC.

So whether or not this has done any additional damage, I am still trying to figure out what the original problem was.

[budm]

Re: Olevia 747-b11 power on, screen dark

OK, put all the screws that you removed back into the board mounting holes so the boards will be properly grounded (shields still remove), also seat all the connectors back in place properly.
Did you check all the fuses on both boards?
The master inverter has yellow and blue wire, they are for BL_ON and Dimming control signals. Take the DC voltage readings of those two pins when TV is off and when TV is ON, chassis as the ground ref. point.
Notes: I cannot read the labels for the Yellow and Blue wire to figure out what the pins names are. Closed up pictures on the connector needed.

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

OK, put all the screws that you removed back into the board mounting holes so the boards will be properly grounded (shields still remove), also seat all the connectors back in place properly.
Did you check all the fuses on both boards?
The master inverter has yellow and blue wire, they are for BL_ON and Dimming control signals. Take the DC voltage readings of those two pins when TV is off and when TV is ON, chassis as the ground ref. point.
Notes: I cannot read the labels for the Yellow and Blue wire to figure out what the pins names are. Closed up pictures on the connector needed.

Right board conn labels:
Red X 5 = VBL
Black X 5 = GND
no wire X 2 = NC

Left board:
Red X 5 = VBL
Black X 5 = GND
Black = VSEL
No wire = E_PWM
Yellow = I_PWM
Blue = BLON

I am having trouble uploading additional photos (maybe uploaded too many already). On previous ones, can you tell me where the fuses are? And do I do a connectivity test on them with a multimeter? Thx

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

The master inverter has yellow and blue wire, they are for BL_ON and Dimming control signals. Take the DC voltage readings of those two pins when TV is off and when TV is ON, chassis as the ground ref. point.

OK, put the screws back in. Now want to make sure I am measuring right.

I plugged in the TV but did not turn it on. Is that the 1st measurement? Do I measure between the blue and the yellow, or between the blue and GND and the yellow and GND?

And then for the 2nd measurement, do I repeat the same with the TV turned on?

BTW, my multimeter is fairly old and what I noticed when I measure is that the reading jumps around. I tested it by measuring an AAA battery and it shows the right voltage but still jumps around that value a bit. Is this normal or do I need to a new meter? Thx

[tom66]

Re: Olevia 747-b11 power on, screen dark

Both blue/yellow measurements to be taken when the set is off and on.
You may need to clean your meter probes if the reading jumps.

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

Both blue/yellow measurements to be taken when the set is off and on.
You may need to clean your meter probes if the reading jumps.

Between yellow and blue:
TV OFF: 0
ON: 11.6 mV

[tom66]

Re: Olevia 747-b11 power on, screen dark

The measurements should be one between yellow and chassis (red on yellow, black on chassis), and one between blue and chassis. For both ON and OFF states.

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

The measurements should be one between yellow and chassis (red on yellow, black on chassis), and one between blue and chassis. For both ON and OFF states.

OFF: Blue 51.4 mV, Yellow 51.3 mV
ON: Blue 37.0 mV, Yellow 48.6 mV

[budm]

Re: Olevia 747-b11 power on, screen dark

OK, all the boards are connected? If that is the case, the main board is not sending either BLON (Backlights ON), or Dimming signal. The meter is set to DC?

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

OK, all the boards are connected?

The two side boards are connected with the black/red/blue/yellow wires. I don't see any cables/connectors that are obviously disconnected.

By "main board" do you mean the power board in the middle?

The meter is set to DC?

Yes

[budm]

Re: Olevia 747-b11 power on, screen dark

The main board is the one with the input jacks, ant connector, HDMI, VGA, ETC.
The two signals from the main board are routed through the power supply board for clean wiring, the power supply board is used as the junction point.

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

The main board is the one with the input jacks, ant connector, HDMI, VGA, ETC.
The two signals from the main board are routed through the power supply board for clean wiring, the power supply board is used as the junction point.

What Blue/Yellow voltage is normal for OFF and ON?

[budm]

Re: Olevia 747-b11 power on, screen dark

BL_ON > 2V (it can also may be >3V depends on circuit design) = ON, <1V = OFF
I_PWM is the VARIABLE PULSE-WIDTH SIGNAL @around 200Hz.
The main board has many 3-pin voltage regulators ICs that you can start testing the the voltages, see the link below on how to test them and report the readings in easy to read format.
http://www.shopjimmy.com/olevia-sc0-...main-board.htm

https://www.badcaps.net/forum/showth...999#post300999

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

BL_ON > 2V (it can also may be >3V depends on circuit design) = ON, <1V = OFF
I_PWM is the VARIABLE PULSE-WIDTH SIGNAL @around 200Hz.
The main board has many 3-pin voltage regulators ICs that you can start testing the the voltages, see the link below on how to test them and report the readings in easy to read format.
http://www.shopjimmy.com/olevia-sc0-...main-board.htm

https://www.badcaps.net/forum/showth...999#post300999

Ok, will do, but if any of them, or any other parts of the main board, are bad, can they be replaced, or will I need to replace the whole board? Found a few more links to the board online (besides yours above) and they all say "out of stock". Thx

[mmartell]

Re: Olevia 747-b11 power on, screen dark

Some parts can be replaced but depending on the problem troubleshooting the Main board can be much tougher due to its complex signal processing.

[ilyaz]

Re: Olevia 747-b11 power on, screen dark

BL_ON > 2V (it can also may be >3V depends on circuit design) = ON, <1V = OFF
I_PWM is the VARIABLE PULSE-WIDTH SIGNAL @around 200Hz.
The main board has many 3-pin voltage regulators ICs that you can start testing the the voltages, see the link below on how to test them and report the readings in easy to read format.
http://www.shopjimmy.com/olevia-sc0-...main-board.htm

https://www.badcaps.net/forum/showth...999#post300999

I found only two 3-pin regulators, they are shown with white arrows on one of the attached photos. By the way, when the unit was ON, there were 8 green and 2 red lights on; when OFF, one red light. Does it mean anything in terms of what's working and what's broken?

Both regulators are marked "1084-33 0707HL". I measured voltage between pins of both regulators in both OFF and ON. Here's what I got:

ON:
- top reg
Vin-GND 5v
Vin-Vout 1.69v
Vout-Gnd 3.3v

- bottom reg
Vin-Gnd 4.96v
Vin-Vout 1.67v
Vout-Gnd 3.295v


OFF:
- top reg
Vin-GND 77.6 mV
Vin-Vout 77.3 mV
Vout-Gnd 0

- bottom reg
Vin-Gnd 77.8 mV
Vin-Vout 23.5 mV
Vout-Gnd 54.8 mV

[TCB]

Re: Olevia 747-b11 power on, screen dark

Hello - I see this is an old post as I searched for 747-B11

I recently was given an Olevia 747-b11 47" LCD TV (very heavy object)

Symptoms: When powered up has dark screen, no sound.
Am told problem originally occurred when TV was operated one day for many hours in very high ambient temperature (Florida, summer, A/C broke down)

Details:
When Plugged in and main power switch on, blue pilot light appears.
When TV is POWERED UP, Blue pilot light goes out, a click is heard, a brief 'chirp' is (sometimes) heard coming from inside the TV, no activity, dark screen, no sound.

Observations:
Main PCB has many GREEN LEDs,
2 RED LEDs (D1, D2 RED)
and 1 LED comes on briefly as GREEN (D96) then goes dark, sometimes with a high pitched chirp sound coming from main PBC in this area (bad horizontal oscillator circuit?)

24VDC observed at both TCON boards with VM.

Fuses (8 on each) TCON board test ok (tested in circuit with ohmmeter)

Shielding removed to reveal TCON boards, Main PCB, Power supply PCB.
No visibly bad caps on any of the above PCBs.

PCB IDs / numbers:

MAIN PCB
DigiMedia Technology
SDA1 R0.9
PCB P/N EPC-P508201G000
STICKER P/N sc0-p5028201-s10 NS1
STICKER S/N CSHN7B01202355

POWER SUPPLY PCB
Delta
DPS-408AP B
Rev S3-F
S/N A16W0742049708

TCON PCB - left
CMO S
4H.V1838.351 / E2
VK8A183L02 0735TD-S11172
27-D005130 1470H1-24-V01-D1H0 REV 1H

TCON PCB right
All numbers exactly same as above EXCEPT is M11172 instead of S11172

Help?