Acer LCD monitor which are very dead

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

I had to get the nerve to pull that tiny little chip with out messing up the board both control boards work and both power board work I am going to get that chip and install it before I start using these two monitors

On one of the monitors I have to re-lamp that because one of them broke while I was taking apart

I want to thank every one who has post there suggestions this has help alot and have learn allot in how to repair LCD Monitors

[alexanna]

Re: Acer LCD monitor which are very dead

It come to life after I pull U406 which is a reset controller

Good, jetadm123 suggested that in an earlier post.
So we all know was the reset controller causing the voltage to be low on the front power switch?

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

It come to life after I pull U406 which is a reset controller

Here is the link to a service manal for the controller board

[PlainBill]

Re: Acer LCD monitor which are very dead

I check all of the switches are good
It only the power switch that has no voltage at all

/\/\/\/\/\/\/\/

I will recheck to make sure this is the case

I just do not understand why this switch has no voltage at all unless somthing is bring the voltage down to (0)

DUH!!! Yes, something is probably wrong!!! It's your job to figure out what.

There are several possible explanations. One common design has five inputs of the control chip pulled high by a resistor. Signal lines go from the inputs to one side of five switches. The other side of each switch is grounded. When a switch is pressed, the input is pulled low.

Possible failures include a switch that is shorted or contaminated, a broken wire or trace on the circuit board, a bad connector, open resistor, bad solder joint, bad input on IC, shorted capacitor. An elementary first step is to identify the function of each wire from the signal board to the control panel.

PlainBill

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

I check all of the switches are good
It only the power switch that has no voltage at all

/\/\/\/\/\/\/\/

I will recheck to make sure this is the case

I just do not understand why this switch has no voltage at all unless somthing is bring the voltage down to (0)

[PlainBill]

Re: Acer LCD monitor which are very dead

No the voltage at the ON and OFF switch is 0.00 volts with out switch pushed

And all other switch start at 3.25 and then go to 0.00 volts when switch is pushed

I am a little confused about this that the ON and OFF switch has no voltage at all

I check all what look like to be ether a fuse or a resistors with a marking of

"0000" on it sim chips all have 0 on the meter is a short

That sounds like either you are reading the wrong side of the switch, or the switch itself is defective. It's very simple, actually. I count 12 pins on the connector to the control panel. One or more of those should change voltage when each front panel switch is pushed. There are several ways to troubleshoot this - trace the wires, check each pin while a helper repeatedly pushes each button, etc.

I have never heard of a front panel switch failing like that, but I would be foolish to claim it couldn't happen.

PlainBill

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

No the voltage at the ON and OFF switch is 0.00 volts with out switch pushed

And all other switch start at 3.25 and then go to 0.00 volts when switch is pushed

I am a little confused about this that the ON and OFF switch has no voltage at all

I check all what look like to be ether a fuse or a resistors with a marking of

"0000" on it sim chips all have 0 on the meter is a short

[alexanna]

Re: Acer LCD monitor which are very dead

I also check for power at the ON and OFF switch there is 0 volt but all other switches have 3.25 volts

When you check the front power switch, you should see a voltage toggle as the button is pushed. usually from a high voltage to a low voltage.
Do any of the voltages go low as the front power switch is pushed?

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

Dose any one have any idea on what to check next

I want to use this monitor as a learning tool


On one of these monitor I took the screen apart and saw that the clf tubes on this one are very black on one end and the other end is a little bit black but should keep the power board from even coming ON

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

This is on the control board that there are no burn part on it and it dose not turn on ether and nether board work

Both power board are the same as far as the reading are concern

I have two control boards

Thanks for your help with this monitor

I also check for power at the ON and OFF switch there is 0 volt but all other switches have 3.25 volts

[jetadm123]

Re: Acer LCD monitor which are very dead

Here are the voltage reading at the control board

Black 0.06 volts
Brown 4.48
Red 14.48
Orange 0.00
Yellow 4.94

tie together

Blue 0.00
purble 0.00

It looks like you're getting the 5V and 15V outputs. On your control board, please verify that the burnt transistor is U406. U406 should be stamped on the board itself. If it is U406, then it's probably a reset controller and not a transistor.

Once you have verified it's U406, with the monitor off and unplugged, go ahead and remove U406 and put the boards back together and plug the monitor back in and try turning it on.

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

Here are the voltage reading at the control board

Black 0.06 volts
Brown 4.48
Red 14.48
Orange 0.00
Yellow 4.94

tie together

Blue 0.00
purble 0.00

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

Here is one more photo of the control board

That is the best that this camera can do I am sorry that the photo is not beter

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

Thanks for the info

I will check this later on to day

[jetadm123]

Re: Acer LCD monitor which are very dead

Place your negative (black) probe on a mounting screw. Measure each pin on the wiring harness with your red probe.

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

When check the voltages on the control board is one lead of the meter to " - " and the other lead to each pin or is it " + " to each on the comtrol board is the " - " or " + " off of the supply board

Thank you for your help

[jetadm123]

Re: Acer LCD monitor which are very dead

Your photos are a little on the blurry side and it's impossible to make out the components on the control board. Let's try the following:

1) Connect the boards back together.

2) Set your meter to DC volts. Press the "power on" button on the front panel. Measure the output voltages on the wiring harness of the power board for each pin. If you measured 0 volts for each pin, try pressing the power button again and remeasure the pins.

3) As for the burned out transistor. What is the silkscreen ID on the control board? Is it U406? If yes, then it's probably the reset controller, which if failed, will prevent the monitor from powering on. But you need to verify the output voltages first before going any further.

4) Please provide better focused photos.

[sam_sam_sam]

Re: Acer LCD monitor which are very dead

Thank you for your reply

I will post the cap value later on today or tomorrow

[PCBONEZ]

Re: Acer LCD monitor which are very dead

If you are not familiar with cross-referencing caps then do this.
Make a list.
Show: Make - Series - uF - Volts - Diameter - Length - ESR - Ripple
Use that as a guide to find good replacements. [Helps to post the list sometimes.]
.
When you have the series I'll check if I have the data sheets & upload.
[Current revision of their site does not work.]

[PCBONEZ]

Re: Acer LCD monitor which are very dead

Be patient sam_sam_sam.
The 'monitor guys' are kinda swamped lately but they should find this.
I'm not one of them. [I don't like shipping screens so never got into it much.]
If they don't find this in another day send me a PM and I'll tell you who to PM for help.
-
I can tell you I see Elite brand caps on the yellow/brown board and those HAVE to go.
They are horrible! - 'Replace on sight' kind of thing.
I'm not -sure- if they often fail without bloating but it wouldn't surprise me.
-