belinea 101750, lights led once

[senndogg]

hello friends!
i must excuse for the quality of photos first.
i have this old monitor with the following problem. it lights only once the green led, when attached the AC plug, and then no more signs of life. i searched the forum and i saw sth about a 3.3V output from the PSU. this PSU has a steady 12V, 5V but no 3.3V. instead it has a 2.2V. normal?

photos:

[selldoor]

Re: belinea 101750, lights led once

YES! Your pictures are quite bad.
What are the caps - samXon??
I have attached part of a picture. Is the item circled red and yellow a cap?
Cant even tell.
Of the other two the top one looks as though it has leaked- has it?
The lower one looks bad but it may just be the picture. is it?
I think you should consider a full re cap except for the BIG Cap
May be a good idea to list the caps and manufacturer and series.

Can you test the backlights on another monitor?

If what I can see looks this bad its a worry what I cant see.

[senndogg]

Re: belinea 101750, lights led once

yes, the caps are samXon. that was what i thought, a full recap. today im gonna shop for them, what do you recommend me?
i dont think its backlight related as the green indicator led lights only once when the display is connected to the mains, and then it is all dead. i am worried about the 2.3V output, im convinced it should be 3.3V. thanx anyway.

[selldoor]

Re: belinea 101750, lights led once

Im sure you must have read what low esr caps are recommended but you may be limited by what you can get.- where do you normally get caps from? Do get them locally or ebay or mail order. Best thing would be to make a list of the ones on your board and then a list of what you can get and post it for more advice. I was suggesting you test the ccfls as if they are ok you can then test the inverter transformers as these are usually the expensive parts to replace.
It would be good if you could actually answer questions.
We still dont know if both the caps I mentioned a have leaked or if the yellow ringed
item is a cap? You may think- what does it matter if they are all being replaced but it
does give us an idea of the general condition which we cannot see fully from the pics.
Poor pics = more commentary required.
The low voltage may be due to the caps or faulty regulator. If the caps are really as bad as I think they look I am surprised it comes on at all.

Have you tried to find the schematic? I think I found one on a Polish site but had to register to get it so didnt bother as my polish isnt up to it (non existant)

[senndogg]

Re: belinea 101750, lights led once

thanks selldoor, you are right. time for some answers.
i tried to get the schematic and after googling for 30min i gave up.
the yelllow ringed component IS NOT a capacitor.
the CCFLs are ok, just tested.
the board is not in good conditions, as it is almost 7 years old and has been repaired before.
the existing caps are: samxon: 470-25v, 680-25v, 470-10v, 220-25v and the one i replaced 1000-16v the brand i dont know, it has a C with a crown on it.
now i have in my hands a bunch of new capacitors but they are cheapo ones, and mostly fake, at the local dealer i almost jumped when i saw sth like "rubycon" but it was a bad chinese imitation called "robicon". shame.
as i have no time for ebay, at the moment im gonna recap it with what i have, and later will tell you.

[selldoor]

Re: belinea 101750, lights led once

Ok - personally I think you may be wasting your time - replacing bad with worse!
At least check them for shorts before you put them in.( or check them properly if you have an esr meter) Any idea what the yellow ringed item is? does it have a board designation. Cwith a crown is WC - another poor unknown brand.

This is the forum that mentions a schematic if you want to register and try and get it.
http://www.elektroda.pl/rtvforum/topic1639236.html

[senndogg]

Re: belinea 101750, lights led once

this service manual seems very poor to me.
i followed the instructions, the 5V was there but the fault was very general following this manual :the U2, a big chip in the middle of the logic board.
the logic board is a Hyundai Imagequest L70D/P.
ps.: the yellow ringed is not a component at all in fact, its just a dusty piece of glue on a resistor

[senndogg]

Re: belinea 101750, lights led once

after several times trying to upload the schematic which i downloaded from the polish site, i have to blame my internet connection and try tomorrow. thanks anyway.

[senndogg]

Re: belinea 101750, lights led once

the repair manual.
thank you for your time.

[selldoor]

Re: belinea 101750, lights led once

Ok - manual is better than some and certainly better than none. Its hard to navigate though as "Find" doesnt work
When you have put the replacement caps in do the voltages change.
Clean the glue off the Resistor it may have gone conductive.
There is also a rectangular splodge on the back of the power board near where you measured the voltages can you clean that off. Can you try and measure the 3.3v expected at Pin 4 of U6. What is the value of the cap at C15 according to the manual it should be 47uf 50v, which is a common value for the "Start Up" Cap but you do not mention that value in your list. and there are other caps that should be 50v.
Perhaps you can check other components against the parts list to try and determine if the schematic is good for your board. Another possibility is that someone has just put in what caps they had got without even bothering about size/voltage.
We could really do with some decent photos of both your boards is that possible or not?

[senndogg]

Re: belinea 101750, lights led once

the voltage do not change, that makes me think more about a logic board failure.
the glue is now cleaned, also some parts of the board.
i am afraid too this schematic does not suit my monitor, but it is similar.
this monitor was repaired before and for a cap was changed but a 10V was used. it had exploded btw. it was in the 12V rail so i thought a 1000uf/16V would suit.
the 4 pin of U6 is NOT 3.3V, it is 5V.
and finally, i cleaned my phone lens, now looks better.

[senndogg]

Re: belinea 101750, lights led once

the cap section

[selldoor]

Re: belinea 101750, lights led once

Wow! cant believe the improvement in pics. Thank you
What values do the caps at c118 & C121 have.

[selldoor]

Re: belinea 101750, lights led once

Wow! cant believe the improvement in pics. Thank you
What values do the caps at c118 & C121 have.

Sorry may not be 118 its the one on the other side of the ic from C121

[senndogg]

Re: belinea 101750, lights led once

it is c110 and it is not replaced: 47uf/25V. C121: 1uF/50v.

[RJARRRPCGP]

Re: belinea 101750, lights led once

One of the brown ones is a Jackcon.

[selldoor]

Re: belinea 101750, lights led once

One of the brown ones is a Jackcon.

And your point is?

[senndogg]

Re: belinea 101750, lights led once

yes, i confirm.
but can i think more of a logic board failure? the voltages did not change (the 5V and the 12V) when changing the caps. looks like it has no effect on the power board, would you recommend me to measure anything near the MCU?

[selldoor]

Re: belinea 101750, lights led once

When you are testing the voltages is the main board attached?
Can you test it with and without it attached and report any changes.
I still think one of those small caps is the start up cap and if they are not
working correctly it will never start.

[senndogg]

Re: belinea 101750, lights led once

i have measured the voltages with and without the main board connected and no changes. still 12V and 5V.
i downloaded a schematic for another similar monitor Hyundai L70S, and this solves the mystery of the 2 extra pins at the power plug.
they are for the backlight.
but remember, this is not a backlight problem. the monitor is dead. the green led lights only once and then no signs. the voltage at the power microswitch in the control board is 5V.
selldoor can you tell me more about this start up cap? the C15 is a brown SMC cap near the inverter. can this have such a big effect?