Acer AL1715 briefly works then goes black

[SonicSteve]

Re: Acer AL1715 briefly works then goes black

In that first picture the cap next to that large one is way crooked. Is it just badly soldered, if so that is sort of odd because all of the others are soldered properly flush to the board.

If you think that one is crooked take a look at the cap on the top left of that same pic. Notice that you see the top of the cap and very little of the sides!
I could show you an emachines board full of caps just like those two.
Anyhow before I derail my own thread,
I could really use
I have far too many questions to go on.
I looked at other threads, it seems that the first pic is the CCFL inverter. I need someone to confirm or deny this. I also need someone to help me with all the questions I asked in previous posts. I'm sorry I've asked so many.

[Darkside]

Re: Acer AL1715 briefly works then goes black

Hi Steve,

I don't know if you have tried this or not but my first suggestion would be to unplug the display completely (signal cable and CCFL cables) then use a CCFL (can get these at most electronics stores) to test if it turns off after a few seconds(don't forget to check all 4 outputs). I say this as I recently worked on a Dell LCD which would also turn off after a few seconds caps tested ok. Turned out that there was nothing wrong with the circuit but the screen was damaged due to someone dropping it, once the screen was removed the inverter stayed on and the electronics tested fine with another screen.

[SonicSteve]

Re: Acer AL1715 briefly works then goes black

Hi Steve,

I don't know if you have tried this or not but my first suggestion would be to unplug the display completely (signal cable and CCFL cables) then use a CCFL (can get these at most electronics stores) to test if it turns off after a few seconds(don't forget to check all 4 outputs). I say this as I recently worked on a Dell LCD which would also turn off after a few seconds caps tested ok. Turned out that there was nothing wrong with the circuit but the screen was damaged due to someone dropping it, once the screen was removed the inverter stayed on and the electronics tested fine with another screen.

Ok I'll give it a try, thanks.
Any advice on the discharging of the capacitor? No one seems to want to answer this.

[shadow]

Re: Acer AL1715 briefly works then goes black

The reluctance to answer this questions seems to be because people do not want to be responsible for any accidents.
Well it was for me.

I have never done this before so I do not know for sure, however what I would do is use a screwdriver and short the capacitor....make sure u hold onto the plastic part of the screwdriver!

I you see sparks or any signs of high voltage flow, take the screwdriver away and let the pull down resistors do their job some more.

Alternatively, you could get a high power rated resistor and touch one lead of the resistor onto one lead of the capacitor and do the same thing for the other lead. If you have voltage flow, the resistor should be converting that energy into heat. This should accelerate the job of the pull down resistors. I would use pliers or something to hold the resistor just to eliminate the possibility of touching the resistor leads while the capacitor is discharging and if the resistor gets hot.

A third possibility is to get proper high voltage discharge probes. I have no idea where to get them thou.

Hope that helps you!
Good luck!

[SonicSteve]

Re: Acer AL1715 briefly works then goes black

waiver of responsibility in this matter.
I sonicsteve hereby declare that I will not hold anyone responsible for any damage to myself or to my property for any advice given.

Trust me I understand that in the end my actions are my own. Surely someone here has done this kind of thing before and knows of a way that is mostly safe and mostly sure to get the job done.

My materials.
I don't have any resistors that I can use without going out and buying some. So if anyone recommends this please be specific in what I will need.
A basic multimeter that is most automatic claims that it can withstand voltage up to 450v
Screw drivers
capacitors
Large insulated rubber glove
general household items


There you have it friends, I won't be suing you if things don't work out as intended, I just would like some advice from those who know.

[Darkside]

Re: Acer AL1715 briefly works then goes black

I generally don't bother to discharge caps before working on them (high voltage isn't that bad ) but my suggestion is to try to power up the monitor without the power cord plugged in. In my experience this will discharge the cap through the internal circuitry and seems to work for most electronics, however if you want to be really safe I would suggest to follow this page http://www.gallawa.com/microtech/cap_test.html (if it works for microwave caps im sure it will provide you more then enough protection from the cap your worried about)

[SonicSteve]

Re: Acer AL1715 briefly works then goes black

I generally don't bother to discharge caps before working on them (high voltage isn't that bad ) but my suggestion is to try to power up the monitor without the power cord plugged in. In my experience this will discharge the cap through the internal circuitry and seems to work for most electronics, however if you want to be really safe I would suggest to follow this page http://www.gallawa.com/microtech/cap_test.html (if it works for microwave caps im sure it will provide you more then enough protection from the cap your worried about)

Thanks I just got back from vacation yesterday, I'll give it a try later on.

[SonicSteve]

Re: Acer AL1715 briefly works then goes black

OK so one more bit of help.....I should just say like it is. Man do I need help!!

I bought a 5w 5ohm resistor.
Do I just put one end of the resistor on one side of the capacitor and the other on the other side?

[Per Hansson]

Re: Acer AL1715 briefly works then goes black

Yup

half a minute or so should more than suffice

[starfury1]

Re: Acer AL1715 briefly works then goes black

You are right to be concern about getting belted or killed from that section

Its just a matter of taking care and following the instructions out lined in the links above
The cap will most likely discharge
If in doubt wack a meter on a HIGH DC range across it and check it is discharged.
(if it has 1000 VDC use that depends on what you multimeter is top range is )

They will give you a nasty bite but not likely to kill you if no power is applied to the main PCB.

Discharging with a Resistor is ok but again follow the instructions in the links
they give value (or values in the sci faq)
(they say 2K 25W well you not going to get a 25W easy
so you are better to parallel up 4 X 10K 5 Watts
(wattage seems to be a bit over kill but anyway)

If you not sure what I mean by parallel look for "parallel and series resistors"
on the net, basic electronics


If you read the FAQ Here
You will notice they mention screwdriver AFTER you discharge it with a resistor

Reasons to use a resistor and not a screwdriver to discharge capacitors:

1. It will not destroy screwdrivers and capacitor terminals.

2. It will not damage the capacitor (due to the current pulse).

3. It will reduce your spouse's stress level in not having to hear those
scary snaps and crackles.

That cream PCB has a double duty
it is the Main SMPSU and the INVERTER on one PCB

From the many posts around here on SMPSU and Inverters
you should be able to get an idea of whats what on the PCB

I don't have an answer on what the fault is
but others have given you advice on what to check which is a good starting point.
(and hoping for you end point)

As I said there maybe a common issue with these I don't know

Just for clarity
and this is only working from the photo
(I would have expected more on the inverter side maybe under the PCB?)
here is roughly what I think are the area's

[jfriends24]

Re: Acer AL1715 briefly works then goes black

@sonicsteve
what is the result of your troubleshooting? i know its been a long time but can someone tell me what is the problem with this symptoms?

[lurker]

Re: Acer AL1715 briefly works then goes black

I inherited two these monitors that have images but no light. Figuring that they were the caps I replaced both of the inverter boards with new caps. Much to my dismay both monitors still didn't light up. I was able to "try" the inverter board with the replacement caps on another identical monitor and to my amazement it worked! Used a ccfl power supply from a PC case mod that I had and powered up the light tubes one by one. There was one light from each monitor that was pinkish red in color. I may try to scavange one tube to make one good monitor. If that works I may eventually buy two more tubes to fix the second monitor. The price is right.

[retiredcaps]

Re: Acer AL1715 briefly works then goes black

There was one light from each monitor that was pinkish red in color.

Pinkish/red hue indicates that the ccfl is dying. As it dies, it draws more power possibly causing "2 seconds to black".

ccflwarehouse.com and ccfldirect.com sell replacements that come in a variety of options (with housing, with cables, without, etc).

I believe a few members here have positive experiences with ccflwarehouse.com. I can't speak for either since I have never done business with them.

[retiredcaps]

Re: Acer AL1715 briefly works then goes black

PS. Good "Lamp Soldering Tutorial" with pictures at

http://ccflwarehouse.com/lasotu.html

[lurker]

Re: Acer AL1715 briefly works then goes black

Thanks guys.

[meanderer]

Re: Acer AL1715 briefly works then goes black

1 way to discharge high voltage caps is to use a incandescent lightbulb with a socket, and connect the 2 ends across the cap. if it discharges it will light up a bit to tell you that you just saved yourself from a nasty shock. use a 100W bulb.

This is taken from a blog entry by Justine Yong, someone who has posted his ebook about LCD repairs everywhere on the net.

[romansroad]

Re: Acer AL1715 briefly works then goes black

ccflwarehouse.com and ccfldirect.com sell replacements that come in a variety of options (with housing, with cables, without, etc).

I believe a few members here have positive experiences with ccflwarehouse.com. I can't speak for either since I have never done business with them.

I have bought multiple items from CCFLwarehouse. Super fast shipping and stout packaging. It comes in a triangular carton, wrapped up and finally inside a long poly tube with vinyl endcaps. Nice!

[lurker]

Re: Acer AL1715 briefly works then goes black

I was able to get one of the two 1715s working, I'm using it right now. I swapped out the bad light tubes from one to repair the other. Even if they were the same models the wired ends were different, even the wire routing and containment was somewhat different. After completely taking one monitor apart I realized the I only needed to remove one screw and the light tubes slide out with it's carrier. Not sure if I'll put the second one back together. Knowing me I probably contaminated the layers of the lcd and plexiglass with dust.

I have another monitor to look at in the next couple of months. It's a DCLCD. I replaced the caps, all four CCFLs work, but the monitor goes dim after a coupible of seconds. I tried manually lighting up one of the tubes and I can see the message "No Video Signal" floating around. As soon as I plug in the VGA cable the monitor goes black. Maybe someday it'll get fixed.

The information I found here was responsible for me being able to repair this Acer.

Thanks again.