Benq v2210 Eco - one backlight strip not working

[selldoor]

Re: Benq v2210 Eco - one backlight strip not working

David-p - I am not sure you are following this at all - I believe the mosfets are within the OZ9955A have you looked at the pdf?

OP -I dont know how far you got with the test flow chart - last thing it says to test are the inductors - the coils with the 330 on top - THink you can only test for continuity on the two contacts.

Can you get a better picture of the faulty part of the board - without the flash.

I am also reading the part where budm says
There is OVP pin which will shut down the circuit if the Vout is too high (such as over voltage from the power supply or no LEDs attach so the voltage will rise up high), you should check the OVP of the working and not working IC.
Check the socket and make sure the pins are soldered correctly to the board
and no pins are badly bent or even missing. (it has happened!)

I have assumed so, but can you confirm nothing on the back of the board

[martinlink]

Re: Benq v2210 Eco - one backlight strip not working

I am consulting a more technically skilled person today, let's hope he can figure it out. If not, I'll have more time to mess with it later.

The underside of the small green board can't be really accessed since it is soldered onto the larger board, so I can't check the inductors from the connector, but I will try to test their "legs"...

The ICs are ultra small and checking their pins is nearly impossible without a microscope (which I will have access to in the future, but not at the moment). Also the head on my soldering iron is far too large to resolder them one by one.

[selldoor]

Re: Benq v2210 Eco - one backlight strip not working

Hi - heheh hadnt realised the green board was actually attached !!

The socket and pins (contacts) I meant were the the socket the lamp plugs into
if that is faulty it could give the lamps not connected fault.

And yes inductors test where they are soldered to the board

[martinlink]

Re: Benq v2210 Eco - one backlight strip not working



Red squares around parts I found to be out of spec before handing it over to the "fixer":

R522 - 0 (should be 10K?) - fully shorted out, also small black spot in the middle
R520 - 16,2K (should be 100K)
R530 - 14,2K (should be 30K)

I hope those bits are easy to find and cheap to replace :P
Then again, there might be something else wrong with it as well, didn't go over all the pieces.

[selldoor]

Re: Benq v2210 Eco - one backlight strip not working

They should be easy to find usual problem is not knowing the value having the schematic is a great bonus.
Maybe it is just the burnt out one that is at fault as it is coming up shorted- if you tested in circuit. the others that have a measurable value may be affected by other components they connect to.

Please let us know how it goes.

[martinlink]

Re: Benq v2210 Eco - one backlight strip not working

Yeah, I'll be sure to update if anything new happens.
The reason I had to take it to the tech guy is, I have a couple of exams coming up in the very near future and all my study materials are on the PC, which has no monitor. So there's a bigger chance of getting it working sooner so I can start studying.

If I had a replacement monitor, I wouldn't be in such a rush right now damn this student life without a penny to spare on a new monitor...

[Davi.p]

Re: Benq v2210 Eco - one backlight strip not working

@selldoor, i was referring to the service man. where the mosfet is external.. also there the pinout of the chip seems different from the budm document where pin 1 is SW, in SRV.MAN. there are 2 pins SW1, SW2 where i'm not sure what they does.. anyway it will probably end up with a faulty IC.. but without instrument for soldering...

[budm]

Re: Benq v2210 Eco - one backlight strip not working

Per diagram: R522 is 10 Ohms, it is used as fusible resistor to provide b+ to the IC VIN.
Those resistors are connected in series and parallel with other resistor network, so the reading will not be valid when measured on board.
This will be real hard to repaired due the board is soldered on to the main board that you cannot get access to the bottom side, I am sure there are more parts under the boards.
At this point I am even sure if the SCH actually match the board.

[RethoricalCheese]

Re: Benq v2210 Eco - one backlight strip not working

I can see between those two boards and there are no more parts there.

(I have the monitor at the moment)

Okay, so I started with testing all the resistors on one side and then the other side.

The only difference I found was that R527/528 have 450k/470k accordingly,
the other side has R511/512, which are 175k/180k accordingly.

Other resistors, diodes and coils show same values.


Edit:
By removing C522 and C520, all those 4 resistors had same value. Soo... Just a faulty capacitor?

The problem is.. I don't have a 10uF capacitor sitting around anywhere.

Or how high does the voltage reach there? Found a 10uF 50V only.

[selldoor]

Re: Benq v2210 Eco - one backlight strip not working

I thought C522 was the one that had just been replaced?
Wouldnt have thought both caps could be bad as the lights light on the good half?
Was the resistor R522 burnt out?
I dont know the max voltage - v out only seems to be 17v.
If you have the monitor can you start up the boards and test the voltage
at the cap on the good side?

[RethoricalCheese]

Re: Benq v2210 Eco - one backlight strip not working

Yeah, it had been replaced, just wanted to test without caps.

Soldered them back on like they were - good side has 17V on cap, bad side has between 1 and 2 volts.

[selldoor]

Re: Benq v2210 Eco - one backlight strip not working

Budm had suggested that the resistor R522 was a fuse resistor so if it has burnt out or partially failed might that cause the low voltage on the cap?
Does it have any resistance?

[Davi.p]

Re: Benq v2210 Eco - one backlight strip not working

if the presence of that cap alters the resistors reading why don't you test it in ohms for short?

[RethoricalCheese]

Re: Benq v2210 Eco - one backlight strip not working

R522 is 14 ohms, R507 is 10.7 ohms.

Cap is not shorted, tested already.
And tried to see if the cap caused that low voltage - wasn't the case.

[RethoricalCheese]

Re: Benq v2210 Eco - one backlight strip not working

I found out that bad side coil just had a bad solder. Resoldered it - shows around 17V now. The problem is - no backlight.

I will test voltages on C501/502 later.