Monitor 15" GOLD L-151

[badrianiulian]

I have a problem with a monitor Model L-151, Type: L5AK6 with input 12V, 4A
It had a power supply problem at first so I replaced the power brick (12V, 4A)
Checked the inside and found a blown mini coil (L) and a circuit AIC1578CS
The coil goes to the invertor and the circuit gives 5V to the main board as I figured after replacing the circuit
Now my problem is that even after replacing the burned parts, the monitor still doesn't light up ... no power led - green or orange
Checked the backlights and they are working (with a inverter that i keep just for testing). The inverter has no blown fuse and the 4 transistors are working.
I need some guidance. Here's a photo:



L015 was the coil
U003 is AIC1578CS
U004 is a mosfet that I replaced at first (works as it gives 5V to the main board)
I even reconnected all the connectors

[selldoor]

Re: Monitor 15" GOLD L-151

Any components on the backs of the boards - can we have pictures and also pictures of the other boards.

Perhaps a closer picture of just the main board and a separate one of the "Audio" board.

Can you list the volatages on each of the 3 main connectors on the "audio " Board .
Is there any indication on the board of what the pins should be.

[badrianiulian]

Re: Monitor 15" GOLD L-151

Here are some board pictures, and there aren't any components on the back of the boards
Didn't bother on the left part of the audio board since there were no fried parts there and if I reseat the speakers connectors while powered, I hear some noise







On the connector that goes to the inverter the connections are: black and brown =12V, red and yellow are GND, and the last two connect the inverter to the mainboard through the second connector that has 5V (green and brown) GND (white and yellow) and the inverter control pins
Forgot to mention that I even checked the power button ... even if the leds aren't showing any signs of activity

[selldoor]

Re: Monitor 15" GOLD L-151

Do you actually get 12v and 5v

[retiredcaps]

Re: Monitor 15" GOLD L-151

The main/logic board usually controls the power LED going on/off. If there is no power LED at all, look at the main board.

I see 4 voltage regulators on the main board. See my sig file below on how to test them.

PS. Your pictures are excellent. I only wish the other 90% of people who post here would take the time and effort to even try.

[badrianiulian]

Re: Monitor 15" GOLD L-151

So I checked the regulators on the mainboard
U1=U2=U5(H16A) give out 3,29V on the multimeter and U6(1117M3) gives 2,5V ... all inputs are 5V

Here's something interesting: I checked the voltage on the power led and here are the results:
pin 1=green, pin 2=GND, pin 3=yellow in IMG4 near power button (corner down left) from top to bottom
Plugin power: pin 1 and 2 = 0V, pin 3 and 2 = 0,16V
Press power button: pin 1 and 2 = 0,16V, pin 3 and 2 = 0,16V

I even checked the capacitors (with a capacimeter) on the "Audio" board ... they all have the value they're supposed to have

[selldoor]

Re: Monitor 15" GOLD L-151

Again - do you get 12v and 5v on the connectors or is that just what they should be?

[badrianiulian]

Re: Monitor 15" GOLD L-151

Do not have any voltages written on the PCB but here are some readings:







The two wires in IMG5 and IMG6 that read 0V and 0,16V are one and the same since they are connected through the "Audio" board
Sorry for the late info processing ... I work on this LCD as I have time ... I'm a stay at home dad taking care of my 11 months baby

[selldoor]

Re: Monitor 15" GOLD L-151

Ok - 5volts on the board but no 12v - yes?

Can you test the voltage on each side of D008 Meter on 20vdc Black lead on a ground screw probe each end of the diode with red lead.

EDIT Just looked again - you do get 12 volts on the inverter connector?

IF so I have just spotted a white component just at the right side of the connector on the inverter board.
Is this a fuse is it labelled. ?

[badrianiulian]

Re: Monitor 15" GOLD L-151

12V is flowing towards the inverter. The voltages in the images are readings with the monitor powered on/off.
On the D008 marking end I have 5V. The other end is GND.
Yes it is a fuse... checked it too ... it's in working condition (even when powered 12V at both ends). Also no shorts on the transistors in the inverter.

[selldoor]

Re: Monitor 15" GOLD L-151

Good - so do the lights not flash even for a second or even half a second when you
turn it on. Is there a number on the inverter transformers.

[badrianiulian]

Re: Monitor 15" GOLD L-151

No they do not flash at all
Markings on the transformers: 06A000041E K

[selldoor]

Re: Monitor 15" GOLD L-151

That is bad news - the only hit I get on that number is for this thread!!.

I was going to try and find where the secondary winding terminals are.
Can you do that? If not can you post a picture of the bottom of the
inverter board.

[Rtech]

Re: Monitor 15" GOLD L-151

Does the Power led come on if you take the Inverter board away ???? The problem seems to be no Power on led,there is obviously no Bl_on signal, therefore No output from monitor, 12v to inverter board just about eliminates that from being the cause,UNLESS taking it away brings the Power led on.If you have the correct voltage to the main board, would suggest that is the problem,and you will probably have to replace it IF you can get one !!.

[selldoor]

Re: Monitor 15" GOLD L-151

Hi Rtech - Doubt if there is much chance of a board anywhere. My plan was to go through and establish what was good and what was not. I always think it is easier to test inverter transformers and bulbs first as if they are not good its probably not worth continuing on a board this size.

I am not happy with the test on U6 OP is getting 2.5v but from the part No
1117M3 I think it should be 3v - what do you think?. Next question ,is that due to the U6 being faulty or perhaps the caps connected to it. I think he will have to take it off the board to verify.

[Rtech]

Re: Monitor 15" GOLD L-151

Selldoor,if he wants to check for the 0.5 volt that is missing,then the thing to do would be to replace the regulator and hope,as trying to find the missing 0.5v, if it is essential for the monitor to work properly,anywhere else but the regulator ,would be like looking for a needle in a haystack.

[budm]

Re: Monitor 15" GOLD L-151

The brand of this monitor is 'GOLD'?

[badrianiulian]

Re: Monitor 15" GOLD L-151

Been a busy day today
Got around to check without the inverter board if the monitor does start: no activity whatsoever.
Yes the monitor is branded GOLD ... trying to fix it so I can hook up a RCA to Monitor adapter ... the general intent is to use it as a separate system to use with a Playstation console (the bonus is that it has speakers integrated) since I have a fast growing todler

Next I'l remove the caps near U6 and measure them... maybe I'll get lucky

[retiredcaps]

Re: Monitor 15" GOLD L-151

I am not happy with the test on U6 OP is getting 2.5v but from the part No
1117M3 I think it should be 3v - what do you think?.

If the OP had provided the information in my preferred easy to read format, you will see that U6's part number line #2 is 250249 implying it is a 2.5V regulator.

[selldoor]

Re: Monitor 15" GOLD L-151

Thanks retiredcaps I actually looked at that on the part
Perhaps I was just hoping too much that it was a 3v running low!

Badrianiulian ( hope I dont have to type that often)

I meant for you to check the voltage on them in position unless you have an esr meter taking them off wont show much.