Acer AL1917 giving me hard time

[greggmh123]

Hello!

I have an Acer AL1917 C, version AL1917Cd, model ET.1917B.0DC, built in February 2007. The power board has # 715G1823-2 and the video board has # 715G2227-1-AC.

It will work for several minutes, then turns off. It will not turn back on again unless I disconnect the power cord and reconnect it. It is not just the "2 seconds to black" thing I have read about here. It turns off completely. I can have the monitor cable disconnected and only have power, then let it sit for a while and it will power cycle all by itself. I hear the speakers pop, the green power light comes on, the logo comes on, then it goes back off again. The cycle repeats perhaps five seconds later and keeps doing it until I pull the power cable.

NONE of the caps looked bad: no bulging, no indentation, no leakage, but after Googling and reading about lots of problems being bad caps, I replaced nine caps. I replaced all but the following two...the big Hermei, because it was glued down and I could not see the rating (450V 100uf), and the little 50V 22uf one right next to it, only because I missed it.

I already removed the Hermei 450V 100uf and will buy that one plus the little one.

Given my symptoms, if the two remaining caps don't fix it, what may be another place to look? The board looks physically perfect on both sides.

[Agent24]

Re: Acer AL1917 giving me hard time

Hermei are trash so should be replaced anyway, even if not bulging. If you checked them with an ESR meter you'd probably find they were on the way out.

My first monitor recap, was an AOC with Hermei, I first replaced only the bulging ones but still 2-seconds to black. Replaced the rest and it's been fine since.

What brand did you use for replacements?

If may be you have a problem with the lamps \ lamp wiring \ inverters instead. Bad solder joints on the lamp transformers can cause this sort of problem too.

[retiredcaps]

Re: Acer AL1917 giving me hard time

I already removed the Hermei 450V 100uf and will buy that one plus the little one.

The little one is likely the startup cap typically 47uF 50V. It can be bad without bloating. If it is bad, you will get unstable or fluctuating voltages causing the power supply to be unstable producing some of the symptoms you are describing.

An easy test is to measure the DC voltage with a multimeter.

PS. Are you guys still playing beach volleyball on the beach in mid September?

[tom66]

Re: Acer AL1917 giving me hard time

It could also be a bad voltage regulator as I've had a similar problem (including the clicking speakers) with a small 24" LCD TV.

[Rtech]

Re: Acer AL1917 giving me hard time

The diode that works in conjunction with the start Up Cap can also give you problems as well.

[greggmh123]

Re: Acer AL1917 giving me hard time

Thank you for all of your replies.

The small cap near the big Hermei was a 50V 22uf. I replaced both of them and it has been working fine for 24 hours. I got all my caps at a local store that has a great reputation for selling quality stuff, but I did not look at the brands. I do know they were NOT Hermei or CapXon!

Speaking of testing them, where can I get a decent but not too expensive meter that will test caps? I have a nice Fluke 88 from my days as a Ford tune-up tech, but it will not test caps. I suppose I **could** ask the local store...but they tend to be a bit pricey. Then again, I like to support stores like this one to help them stay in business.

[budm]

Re: Acer AL1917 giving me hard time

You need to get an ESR meter to be able to read the ESR value, regular cap meter will only show the capacitance reading but not ESR, bad cap can show good capacitance reading but it can have high ESR which is bad for switching power supply circuits.
Some people likes Blue ESR meter, there are many out there from $80 and up. But you can always put in new cap that will cost you 20 cents, since you have to take the cap out anyway to do real testing of the cap, you may as well solder in the new caps. And if what you are working on is more than 2 years old, the caps should be replaced with good caps (such as PANSONIC FM/FR/FC series) anyway.
Just think how many caps you can buy with $80. It is good to have tool to analyze the failed cap, but you may not need tool.

[Agent24]

Re: Acer AL1917 giving me hard time

I got all my caps at a local store that has a great reputation for selling quality stuff, but I did not look at the brands. I do know they were NOT Hermei or CapXon!

That doesn't mean much. There are many, many el-cheapo brands.

The store might stock good quality capacitors but they may not be Low ESR, which you typically need.

You really should find datasheets for the old capacitors and the new ones and make sure they match up for ESR and ripple current ratings, otherwise the repair may not last long.

[greggmh123]

Re: Acer AL1917 giving me hard time

budm,

I could buy a lot of caps for $80, but I would always be left wondering WHY something failed. Unfortunately, that kind of stuff really bugs me not to know.

When I was a Ford tune-up tech, I knew their systems inside and out, and could diagnose problems other techs, and sometimes their engineers, could not. I like to know theory of operation, because with that knowledge, I can figure out almost any problem.

Besides, it's a business write-off...and a new toy!

In the case of this monitor, every cap looked physically perfect. The big Hermei tested fine at the local electronics store (93uf). Didn't test the little 50V 22uf guy, but would like to do so just to know. It may also open up a new avenue of making money, or at least impressing the heck out of my clients. I have an old Dell server just begging to be tested!

I will look into that meter you mentioned.

Thank you!

Gregg

[budm]

Re: Acer AL1917 giving me hard time

You can buy the Blue ESR meter in kit form or fully assembled from AMAZON.

[greggmh123]

Re: Acer AL1917 giving me hard time

budm,

I like your "Never stop learning" tag line. It reminded me of my Dad. He had a Masters in Meteorology and a Ph.D in Chemical Engineering. When he was 87, he went to medical school because he "always wanted to have" his MD. He died six months later, and one guy in his class was at the funeral. He told us that they all called him "The World's Oldest Curve Wrecker."

Yep, that was my Dad! He ever stopped going to school and learning. He taught me all about nuclear reactors in one night of intense listening, etc. I got his hairline, but unfortunately, not most of the brains!

[Agent24]

Re: Acer AL1917 giving me hard time

The kit is more fun

But if you don't already have a capacitance meter you might want to get one too, or go for one of the ESR meters that does both. It's good to be able to test both properties, sometimes one goes bad but not the other.

[greggmh123]

Re: Acer AL1917 giving me hard time

Agent24,

I will leave it as is for now (too many other things going), but the next one will get the attention you mention.

Thank you for your input.

[greggmh123]

Re: Acer AL1917 giving me hard time

Heck, I don't even know what "ESR" is yet! I sense another late night coming up!

[Rtech]

Re: Acer AL1917 giving me hard time

Equivalent Series Resistance.......have a good late night.

[greggmh123]

Re: Acer AL1917 giving me hard time

Oh, so much reading. I did find this comparison:

http://www.anatekcorp.com/esr_compare.htm

The assembled price difference between the Blue ESR and the Atlas ESR70 is only $26 US, not counting shipping. In real life LCD and motherboard testing, would the Atlas model's lower ESR max range cause problems?

Any recommendations on other meters, or on the ones above?

Thank you for your help!

[Lumberjack777]

Re: Acer AL1917 giving me hard time

Oh, so much reading. I did find this comparison:

http://www.anatekcorp.com/esr_compare.htm

The assembled price difference between the Blue ESR and the Atlas ESR70 is only $26 US, not counting shipping. In real life LCD and motherboard testing, would the Atlas model's lower ESR max range cause problems?

Any recommendations on other meters, or on the ones above?

Thank you for your help!

I bought that very same Anatek Blue ESR meter a few years ago. It's done me really well. Only had to change the battery once. It's found lots of bad capacitors and never been wrong. I'm very happy with it.

Also, if you assemble it yourself you'll save 46 bucks. I recomended it to a friend. He goes. "what if I can't assemble it right?" I said if he couldn't assemble it; he shouldn't be working on monitors and laptops

[greggmh123]

Re: Acer AL1917 giving me hard time

Thank you for the input!

[greggmh123]

Re: Acer AL1917 giving me hard time

While waiting for my ESR meter to arrive, I took apart the AL1917 again and took some more pictures. Nothing is obviously wrong.

My ESR 70 should be here Friday. If I still cannot fix it, I will hunt down a local repair shop, or throw another $30 at it and get a new power board. If that fails, I'll take a sledge hammer to it.

[Lumberjack777]

Re: Acer AL1917 giving me hard time

While waiting for my ESR meter to arrive, I took apart the AL1917 again and took some more pictures. Nothing is obviously wrong.

My ESR 70 should be here Friday. If I still cannot fix it, I will hunt down a local repair shop, or throw another $30 at it and get a new power board. If that fails, I'll take a sledge hammer to it.

Well at least now you will KNOW what caps are good or not. You can get some broken monitors and fix them up in the future. You'll also need a digital multimeter. Those 2 tools will get you through 99% of diagnostics.

Then with the help of the great minds out here like retiredcaps and budm and the others. You'll be able to track the problem down.

I know that chart on the Blue ESR Meter; but I prefer to use this one. You can print it out if you want. http://www.preher-tech.com/images/esrchar2

Have fun! And if worse comes to worse you can always use that sledge hammer