BELINEA 10 20 05 no picture, confused

[dvorav]

Greetings everyone!

I have got Belinea 10 20 05 20" LCD monitor recently. It's not functional. When you plug it in (without signal cable) and turn it on, it doesn't display anything (not logo nor missing signal table, which is commonly displayed when you plug monitor without signal cable) but power LED is green. After a while (usually around half minute) power LED goes amber.

Thus I opened it finding 3 swollen caps (on fig 3 marked by red arrows). Photos of untraditional 3 board agraggate are attached. After recapping, nothing changed; monitor is not working at all .

Maybe servicing manual would be helpful, but internet seems dry.

I address everyone, please, post your hints, ideas, recommendations what to do. I'm clueless I'll be really grateful for any advice.

dvorav

[PlainBill]

Re: BELINEA 10 20 05 no picture, confused

Greetings everyone!

I have got Belinea 10 20 05 20" LCD monitor recently. It's not functional. When you plug it in (without signal cable) and turn it on, it doesn't display anything (not logo nor missing signal table, which is commonly displayed when you plug monitor without signal cable) but power LED is green. After a while (usually around half minute) power LED goes amber.

Thus I opened it finding 3 swollen caps (on fig 3 marked by red arrows). Photos of untraditional 3 board agraggate are attached. After recapping, nothing changed; monitor is not working at all .

Maybe servicing manual would be helpful, but internet seems dry.

I address everyone, please, post your hints, ideas, recommendations what to do. I'm clueless I'll be really grateful for any advice.

dvorav

OK, this is an older design with separate power supply, inverter, and logic cards. Nothing earthshaking there.

First step: With power off take your VOM (DVM) and measure the resistance of F1 and F2 on the inverter board. (They are just to the left of CN1 (the black connector) on the first picture.) If they measure 0 ohms, you may have found the problem.

Next step: Hook the boards up and apply power (observe all normal precautions for working around high voltage). Measure the voltages on the connector in the upper right corner of the power supply. The legend is just below it.

Last step, you indicated you "recapped". Which ones, and what brand, values, and series did you use. If you didn't replace them all, which did you replace.

PlainBill

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

First of all, thank you for posting your reply.

First step: With power off take your VOM (DVM) and measure the resistance of F1 and F2 on the inverter board. (They are just to the left of CN1 (the black connector) on the first picture.) If they measure 0 ohms, you may have found the problem.
PlainBill

You mean F1 - the main fuse? If yes then it has 0.1 Ohm. Maybe I'm blind but I can't find it. There are another two fuses F501 and F503, both having 0.1 Ohm. I think they work fine.

Next step: Hook the boards up and apply power (observe all normal precautions for working around high voltage). Measure the voltages on the connector in the upper right corner of the power supply. The legend is just below it.
PlainBill

I have measured that connector:

Bright. (37 mV*) | GND (0 V) | VO (12 V) | VO (12 V)
-------------------------------------------------
ON/OFF (4,15 V) | GND (0 V) | GND (0 V) | VO (12 V)

Bright. 37mV with disconnected LCD panel. ON/OFF (4,15 V) with monitor turned on (green LED shining).

Last step, you indicated you "recapped". Which ones, and what brand, values, and series did you use. If you didn't replace them all, which did you replace.
PlainBill

I have recapped 3 pieces of swollen 16V@100uF LUXON with 25V@100uF Jamicon. They are located on signal board (picture 3.jpg, 2nd in attached pictures – sorry for confusing you). The caps are marked by red arrows. All other capps are looking “fine” with naked eye.

Any other ideas what to do?

DvoraV

[PlainBill]

Re: BELINEA 10 20 05 no picture, confused

First of all, thank you for posting your reply.

You mean F1 - the main fuse? If yes then it has 0.1 Ohm. Maybe I'm blind but I can't find it. There are another two fuses F501 and F503, both having 0.1 Ohm. I think they work fine.

DvoraV

Wrong board. The inverter board. I've circled them. (Excuse the penmanship).

PlainBill

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

I have measured those components F1 and F2. Are they really fuses? If yes, they are blown open (DVM showing open circuit, of course I have removed isolating resin film) despite they do not have any obvious marks of being fried. What it a cause of opened fuses?

F1 is the upper one from view of the inverter.jpg. Component F2 is the lower one. They both are bearing number 63. I don't know what for type of fuse is it.

What next?

[PlainBill]

Re: BELINEA 10 20 05 no picture, confused

I have measured those components F1 and F2. Are they really fuses? If yes, they are blown open (DVM showing open circuit, of course I have removed isolating resin film) despite they do not have any obvious marks of being fried. What it a cause of opened fuses?

F1 is the upper one from view of the inverter.jpg. Component F2 is the lower one. They both are bearing number 63. I don't know what for type of fuse is it.

What next?

They appear to by typical SMD fuses, but the marking does confuse the issue. The fact that BOTH are open is unusual. I have seen a similar arrangement on the inverter in a Viewsonic 21" monitor.

C11, C12 and C13, C14 are obviously the filter caps for the inverter supply. I suggest two approaches. The quick approach is to apply power and measure the voltage from ground to the right side of F1 and F2; then measure the voltage from ground to the left side of each fuse. If they are both open you should see something like 12-18 volts on the right side and 0 volts on the left side. (Left and right are as in the original picture. Left is the side of the board with the CCFL connectors; right is the side with the connector to the power supply.)

A more cautious approach would be to check the resistance from the left sides of the two fuses to ground. If there is a very low resistance it becomes a matter of finding the shorted component.

If you require further assistance, a good picture of only the inverter would be appreciated. You did a superb job of taking a picture which includes all three boards, but better detail on the inverter board would be helpful.

PlainBill

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

Hi Bill, thanks a lot for advising.

They appear to by typical SMD fuses, but the marking does confuse the issue. The fact that BOTH are open is unusual. I have seen a similar arrangement on the inverter in a Viewsonic 21" monitor.
C11, C12 and C13, C14 are obviously the filter caps for the inverter supply. I suggest two approaches. The quick approach is to apply power and measure the voltage from ground to the right side of F1 and F2; then measure the voltage from ground to the left side of each fuse. If they are both open you should see something like 12-18 volts on the right side and 0 volts on the left side. (Left and right are as in the original picture. Left is the side of the board with the CCFL connectors; right is the side with the connector to the power supply.)
A more cautious approach would be to check the resistance from the left sides of the two fuses to ground. If there is a very low resistance it becomes a matter of finding the shorted component.
PlainBill

I tried both approaches; precisely according to your definition. Here are the acquired data.
The first one (measuring voltage from both sides to ground) gave following readings.
F1 – left side to ground – 0 Volts
F1 – right side to ground – 12 Volts
F2 – left side to ground – 0 Volts
F2 – right side to ground – 12 Volts
The second one – measuring resistance from left sides to ground showed that circuit is open. (Neglecting the phenomena of increasing resistance to infinity due to charging up the filter caps).

Your prediction was right. It seems that both fuses are open. More serious question is the cause of them being open? Shorted transformers? Or some surge?

If you require further assistance, a good picture of only the inverter would be appreciated. You did a superb job of taking a picture which includes all three boards, but better detail on the inverter board would be helpful.
PlainBill

I'll be glad for further assistance, since that monitor is not easily repairable as I originally thought. I hope that attached pictures of inverter board will be useful.

[PlainBill]

Re: BELINEA 10 20 05 no picture, confused

Hi Bill, thanks a lot for advising.

I tried both approaches; precisely according to your definition. Here are the acquired data.
The first one (measuring voltage from both sides to ground) gave following readings.
F1 – left side to ground – 0 Volts
F1 – right side to ground – 12 Volts
F2 – left side to ground – 0 Volts
F2 – right side to ground – 12 Volts
The second one – measuring resistance from left sides to ground showed that circuit is open. (Neglecting the phenomena of increasing resistance to infinity due to charging up the filter caps).

Your prediction was right. It seems that both fuses are open. More serious question is the cause of them being open? Shorted transformers? Or some surge?

I'll be glad for further assistance, since that monitor is not easily repairable as I originally thought. I hope that attached pictures of inverter board will be useful.

Both fuses blown really bothers me. With a standard design, either fuse blowing would have shut down both sides of the inverter. Since neither side is shorted, I would have expected at least one fuse to be intact. By the way, an application note for the controller is here.

A further problem is identifying the value of the fuses. Well, I can think of three approaches for further testing.

The BEST way is to hook a variable power supply to the left side of both fuses and increase the voltage while monitoring the current. This would have to be done while the monitor was receiving a signal and the rest of the boards wer powered up. If you are lucky you will have working backlights, and will have enough information to choose the proper fuse size. Of course, most normal people don't have access to a 12 Volt 4 Amp variable power supply.

The next choice is to pick up a package of 2 Amp fast blow pigtail fuses and use two of them to jumper the open fuses. (The app note suggests 1 Amp for 1 CCFL, I'm doubling it for two.) Turn the monitor on while hoping the fuse won't blow.

The last choice is a little more exotic. Simply bridging the fuses won't work, the fuse on the power supply would go open if too much current is drawn. The better choice would be to jumper F1 and F2 with 12 volt automotive lamps rated for 2-3 Amps at 12 Volts. This would limit the current while providing a visual clue of how much power is being drawn. IF the backlights work perfectly, then measure the current drawn on each side and choose fuses rated for about 50% more.

PlainBill

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

Both fuses blown really bothers me. With a standard design, either fuse blowing would have shut down both sides of the inverter. Since neither side is shorted, I would have expected at least one fuse to be intact. By the way, an application note for the controller is here.
PlainBill

Nice material, that's for sure. Some things are clearer after reading this.

A further problem is identifying the value of the fuses. Well, I can think of three approaches for further testing.
PlainBill

Yes, the value of fuses will be challenge. But as a clue, I think, can be used max current specifications on power board (central board). There are some specifications next to the black connector.

Model A (ticked)
VO1: 12V/1.8A
VO2: 12V/2.8A

Right side of fuses is powered by 2 VO's , thus at worst we have 2*2.8A. Probable value of fuses can be over 3A. But I agree, for first its safer to try only 2A fuses.

The BEST way is to hook a variable power supply to the left side of both fuses and increase the voltage while monitoring the current. This would have to be done while the monitor was receiving a signal and the rest of the boards wer powered up. If you are lucky you will have working backlights, and will have enough information to choose the proper fuse size. Of course, most normal people don't have access to a 12 Volt 4 Amp variable power supply.

The next choice is to pick up a package of 2 Amp fast blow pigtail fuses and use two of them to jumper the open fuses. (The app note suggests 1 Amp for 1 CCFL, I'm doubling it for two.) Turn the monitor on while hoping the fuse won't blow.

The last choice is a little more exotic. Simply bridging the fuses won't work, the fuse on the power supply would go open if too much current is drawn. The better choice would be to jumper F1 and F2 with 12 volt automotive lamps rated for 2-3 Amps at 12 Volts. This would limit the current while providing a visual clue of how much power is being drawn. IF the backlights work perfectly, then measure the current drawn on each side and choose fuses rated for about 50% more.
PlainBill

Hopefully I have access to the university dormitory lab, where is such a power supply located. So I can try the first approach. But this will be happening on Monday at earliest since I'm at home.

After that I'll send a conclusion.

Have a nice weekend!

DvoraV

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

Hi community!

Here are the promised result from the measurement.

I desoldered both fuses and soldered a pair of wires instead. I have used a variable power supply with maximal current of 6 A. Firstly I tried to slowly increase the voltage to 12 V and to monitor the current at the same time. The voltage was set up to approx. 8 V with current 4 A. When increasing the voltage the current rose over 5A. The lamps went on for short while (picture was ok, signal board is all right), then they went off, but at the same time one of the transistors TPC8401 started smoking . (almost fried TPC8401 is marked at the attached picture)The voltage has dropped to about 3 V. I quickly turned off the supply.

Next experiment used the power supply with preset voltage 12V and max current 5A. When the display has been turned on, the lamps quickly blinked. Peak current was about 1,6 A. (the TPC8401 still holding but it is little coocked)

Here is datasheet of transistor TPC8401: http://www.datasheetcatalog.com/data.../TPC8401.shtml

It seems that something is overloading the TPC8401. Any clues? Any ideas for further testing?

DvoraV

[PlainBill]

Re: BELINEA 10 20 05 no picture, confused

Hi community!

Here are the promised result from the measurement.

I desoldered both fuses and soldered a pair of wires instead. I have used a variable power supply with maximal current of 6 A. Firstly I tried to slowly increase the voltage to 12 V and to monitor the current at the same time. The voltage was set up to approx. 8 V with current 4 A. When increasing the voltage the current rose over 5A. The lamps went on for short while (picture was ok, signal board is all right), then they went off, but at the same time one of the transistors TPC8401 started smoking . (almost fried TPC8401 is marked at the attached picture)The voltage has dropped to about 3 V. I quickly turned off the supply.

Next experiment used the power supply with preset voltage 12V and max current 5A. When the display has been turned on, the lamps quickly blinked. Peak current was about 1,6 A. (the TPC8401 still holding but it is little coocked)

Here is datasheet of transistor TPC8401: http://www.datasheetcatalog.com/data.../TPC8401.shtml

It seems that something is overloading the TPC8401. Any clues? Any ideas for further testing?

DvoraV

I'm not sure what you mean by "the lamps quickly blinked". Do you mean they blinked on and stayed on, or they blinked on, then off?

Blinking on, then off is a sign the OZ960G controller is detecting a problem. Some common causes are a bad CCFL, a shorted (or open) turn in a transformer, possibly even a bad cap. One trick that has been mentioned is trying this in the dark. Any arcing on a transformer will be easier to see.

PlainBill

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

I'm not sure what you mean by "the lamps quickly blinked". Do you mean they blinked on and stayed on, or they blinked on, then off?

Blinking on, then off is a sign the OZ960G controller is detecting a problem. Some common causes are a bad CCFL, a shorted (or open) turn in a transformer, possibly even a bad cap. One trick that has been mentioned is trying this in the dark. Any arcing on a transformer will be easier to see.

PlainBill

They blinked on, then off. Is any procedure to measure bad transformer? Yesterday I have measured resistance between legs of both transformer primary circuits. They had both the same values about 0.2 Ohm. There should be some noise when the transformer is arcing, am I right?

May I try to unplug the branch of CCFL, where the transistor is frying and to test the current drain?

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

Hi to everyone,

after some time I carried out some tests with CCFLs. I disconnected one branch (with frying transistor) and then I turned it on (with external variable power supply). Remaining CCFL blinked on and off. No activity after that. Surprisingly the same result. CCFL blinked on and off. If both CCFL are bad, why would be only one transistor frying?
Any ideas what to check next?

dvorav

[PlainBill]

Re: BELINEA 10 20 05 no picture, confused

Hi to everyone,

after some time I carried out some tests with CCFLs. I disconnected one branch (with frying transistor) and then I turned it on (with external variable power supply). Remaining CCFL blinked on and off. No activity after that. Surprisingly the same result. CCFL blinked on and off. If both CCFL are bad, why would be only one transistor frying?
Any ideas what to check next?

dvorav

Looking at the board, it would appear ther are 6 CCFLs. The usual safety circuits will trigger a shutdown (blink on, then blink off) of any one of them draws too much or too little current. It will also shut down if the output voltage from any transformer gets too high.

PlainBill

[EGuevarae]

Re: BELINEA 10 20 05 no picture, confused

Looking at the board, it would appear ther are 6 CCFLs. The usual safety circuits will trigger a shutdown (blink on, then blink off) of any one of them draws too much or too little current. It will also shut down if the output voltage from any transformer gets too high.

PlainBill

If it is a 4/6 CCFLs inverter and even one is missing or bad, the inverter will shutdown : all the lamps must be connected and good or else the inverter will shutdown.

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

If it is a 4/6 CCFLs inverter and even one is missing or bad, the inverter will shutdown : all the lamps must be connected and good or else the inverter will shutdown.

Hi.

A strange thing is that inverter will shut down after protecting paint around mosfet starts smoking due to extensive overheating of that part. I mean if any lamp is defective I suppose that the inverter should shut down immediately, not after the overheating the mosfet. (I don't know how long it takes to inverter shut down due to CCFL defect.)

As well as I don't know what to do with protective circuits, which were mentioned two posts before. I haven't worked with them before.

I'm still confused what to do next. What should be done to localize potential defect?

Thanks for any clues.

Dvorav

[EGuevarae]

Re: BELINEA 10 20 05 no picture, confused

I don't know how long it takes to inverter shut down due to CCFL defect.

Just one or two seconds at most.

A strange thing is that inverter will shut down after protecting paint around mosfet starts smoking due to extensive overheating of that part. I mean if any lamp is defective I suppose that the inverter should shut down immediately, not after the overheating the MOSFET.

I'm no expert either, but I would check the voltage coming in to the MOSFET, and the MOSFET itself.
The caps in the inverter are good?

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

Just one or two seconds at most.

In fact it took around 2 sec, as you mentioned. Thus protection is obviously working.

I'm no expert either, but I would check the voltage coming in to the MOSFET, and the MOSFET itself.
The caps in the inverter are good?

Well, according to the pictures of inverter board, caps (all 4 of them) seem all right.
When you mentioned MOSFET... i have realized that presumption of working mosfet (which is always overheating after several secs) can be wrong. I'll try to measure the voltage and maybe even to measure the MOSFET to see if it isn't shorted. Then I'll give the report.

Thanks

[EGuevarae]

Re: BELINEA 10 20 05 no picture, confused

Well, according to the pictures of inverter board, caps (all 4 of them) seem all right.

Caps can go south without visual indication. What brand/series/capacitance are those?

Also, what voltages are reaching the inverter? Have you measured the 12v line coming out of the PSU?

[dvorav]

Re: BELINEA 10 20 05 no picture, confused

Caps can go south without visual indication. What brand/series/capacitance are those?

Also, what voltages are reaching the inverter? Have you measured the 12v line coming out of the PSU?

Those caps on inverter board are:

4 pieces of NICON, 56 uF, 25 V, 105°, F204C EVL, green

Few posts before I have written this about voltages on PSU output (to inverter board):

Connector:

Bright. (37 mV*) | GND (0 V) | VO (12 V) | VO (12 V)
-------------------------------------------------
ON/OFF (4,15 V) | GND (0 V) | GND (0 V) | VO (12 V)

Bright. 37mV with disconnected LCD panel. ON/OFF (4,15 V) with monitor turned on (green LED shining).

About PSU board caps:

2 pieces of Ltec 1000 uF, 16 V, 105 °C, 4806D
1 piece of Ltec 680 uF, 16 V, green
2 pieces of Ltec 470 uF, 16 V, 105 °C, 4903D
1 piece of Taicon 47 uF 50 V, it is near main cap filter.

but with stable output voltages, I don't think that the PSU caps are bad.

One note - the monitor is manufactured in 2005.