Help Identifying SM Diode Acer S231HL LCD LED Monitor

[SgtRock]

Greetings BadCappers:

--Please help me in my ignorance. My Acer S231HL LCD LED refurbished monitor from Geeks.com was dead this morning. The power light was off and it seemed slightly warm in the 19V PS plug area. No complaints, it worked for over a year and was very cheap. My problem is in identifying Diode # 701 on the board that the PS plugs into, see pictures. Below are results of diode and resistance test with my Fluke 87V.
--Diode 701 fails diode test and shows 0 V both directions. It also shows 0.35 Ohms both directions.
--Diode 703, which is marked the same passes diode test with 1.51V in one direction and 0.155V in the other direction. Resistance is infinite in the one direction and 150 Ohms in the other.
--I am assuming the Diode 703 is alright and that Diode 701 is kaput.
--Both Diodes are marked S21F with SM340A directly underneath.
--I would appreciate it if any one could tell me just what Diode 701 is and where to get a replacement.

"He was born ignorant, and has been losing ground ever since."
Fred Allen 1894 - 1956

Best Regards
Clear Ether

[selldoor]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

SM340A is a 3amp 40volt schottky
http://html.alldatasheet.com/html-pd.../1/SM340A.html

Please can you update your profile with country and mains voltage.

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Greetings BadCappers

--Zener Diode 702, see picture, is blown. Fails diode test with zero ohms both ways. It is connected to the negative side of a 220uF 25V Electrolytic Capacitor. It is as SM glass copper zener with a white band covering about 2/3s of the body. Could anybody please tell me what to replace it with or how to go about identifying it. Many thanks to SellDoor for the good information. I have updated my profile.

"Does not squirrel crack nuts on bough of oak tree."
Lao Fu 1410 1620

Best Regards
Clear Ether

[augustboyz21]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

hi...can i ask something what no on U705

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Dear Augustboyz21:

--See attached pictures of Board # 715G3598-M01-0000-004L with close up of U705. I need a camera with a better Macro. U705 is marked MP1584EN, AB804119, MPSB801 and is a High Frequency Step-Down Switching Regulator. It is not obviously blown.

--U101 is a FM24C02A EPROM, and appears to be blown in that pins 1,2,3,4 all go to ground and only pin 4 is supposed to. That being the case I guess it is time to throw in the towel, and declare this board a goner.

--I would still be interested to know, however, what the specs of ZD702 are or what your best guess is.

--I have done quite a bit of research on this project and will gladly provide any information I have. Just Ask.

--This particular board is used in the Acer S231HL and the Philips 191EL2 (in Europe). I did find a Chinese supplier; TaoBao at
http://www.tbcart.com/product/151586...8-M01-000-004L
TaoBao wants $24.52, which is fine, but they also want $17.74 for China Air Shipping, which is not so fine. I am presently trying to contact them to see if they can ship more slowly and cheaply.

--I am awash in Flat Screen Monitors and TVs from the dumpster that I have repaired, so I do not really need to fix this one. But I do have two of them, so I may indeed bite the bullet for the board. I will report further developments. Once again thanks to all.

"I'll have the Alfalfa sandwich, and the smashed yeast"
Woody Allen 1935 -

Best Regards
Clear Ether

[tom66]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Actually U101 is likely OK. I am routing out a board with an EEPROM on now. Pins 1, 2 and 3 are the address lines and four is the real ground pin. They can be grounded or pulled high, depending on if there are other devices on the bus. The most common strategy is to ground all four pins.

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Dear Tom66:

--Damn, Tom, that was quick, insightful and just what I wanted to hear. If I could only figure out the voltage for ZD702, Katy bar the door. I do have a plan B though. I have another unit of the exact same monitor (see pictures of labels) only manufactured in June of 2011 rather than February. So I guess I could take the back off of the working unit and take the voltage at ZD702, yes?

--Inasmuch as I bought the monitor which blew as a "refurbished" from Geeks.com, and had it about a year before the board blew, I am afraid these boards may have been a tad under designed. But, my main monitor stays on 24/7 although it goes to standby after 10 minutes of inactivity, so it does work pretty hard. Thanks again for the good advice on the 50" Panasonic Plasma. A $1200 TV for the cost of a $40 board is a bonus. As a retiree I have plenty of time, and you, as a student you probably have little, so if you are looking for a particular manual, for your manual page, or if you need a data sheet or anything at all, I am your huckleberry. Just PM me and I will try to find the information for you.

"Horse sense is the thing a horse has which keeps it from betting on people."
William Claude Dukenfield, W. C. Fields 1880 - 1946

Best Regards
Clear Ether

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Greetings BadCappers:

--I opened up the working S123HL and found the voltage on ZD701 to be 5 V and have ordered a 5.1 V replacement, along with the 340 A 3 Amp 40 Volt Schlocky, and the two capacitors. I really love the auto "touch" hold on the Fluke 87 V. I will report back. Thanks to every one for all the help.

"Happy for you to desoldering, please."
Wun Hung Lo 1948 -

Best Regards
Clear Ether

[augustboyz21]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

hi SgtRock....i ask u705 couse i have the same thing and it blown and i cant read it for search the part...anyway thankz SgtRock...sorry for my bad english...

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Dear Augustboyz21:

--U705 is a MP1584EN Step-Down Convertor. Data sheet here

ic-igbt.com/uploads/soft/mp1584en.pdf.

--So far the only source I can find is aliexpress at

http://www.aliexpress.com/store/prod...708765578.html

--and they want $17.50 shipping included for 20 pieces.

--I wish you good luck in finding a single chip. Perhaps someone else on this forum has an idea of where to find one.

--If you have any more questions, you had better ask them quickly, because I will, hopefully, be buttoning this one up in a day or two, and putting it back into service.

"He didn't know where he was going. But he knew where he was wasn't it."
Lord Buckley 1906 - 1960

Best Regards
Clear Ether

[augustboyz21]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

dear SgtRock
is it the same for the 715G3603-M01-000-004F cause my board have the hdmi port

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Dear Augustboyz21:

--I am basing all of this on the assumption that you are working on an Acer S231HL which is a later version of the one I am working on. I am working on an Acer S231HL which was manufactured in February 2011, see attached picture of the label, and has driver plate board 715G3598-M01-0000-004L, which has only VGA and DVI outputs, see attached picture.

--You say, I think, you are working on a driver plate board numbered 715G3603-M01-000-004F. And which has the added DVI output. I have searched and have not found that number. I have however found a very similar, and probably later version of this same series of boards, I.E. 715G3603-M02-000-004F, see attached picture. Unfortunately it is not possible to identify U705 definitively from this picture, but it does have exactly the same footprint and pin count, and so is probably the same chip. You may compare this picture with your board and see what you think. This picture is from ShopJimmy and, also unfortunately, is out of stock.

--My educated guess is that, although the board has numerous changes, it probably still uses the same MP1584EN Step-Down Convertor at U705. They would not have changed this chip unless they had to, because they probably had them in stock already. If you can get one of these chips at a reasonable price, I would definitely give it a try.

--I hope all of this helps. Let me know if you need anything else, and please be sure to report your progress.

"I wear suspenders and a belt. I am a security man all the way"
Justin Wilson (The Cajun Cook) 1914 - 2001

Best Regards
Clear Ether

[augustboyz21]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

hi SgtRock
how can i test the step down chip for confirm the chip is faulty

[budm]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

@augustboy: did you check and see if ZD702 is shorted out, and also check and see if the input pin and output pin of U705 does not show really low resistance due to internal MOSFET shorted out.
Here is the diagram: see page 20 for U705
By the way, ZD702 is 6.2V Zener, it is used as crow bar to clamp down the output from going beyond 6.2V or shorted out if U705 failed with short circuit between Input to output (shorted out internal MOSFET) of the U705, which will cause the ZD702 to blow up or shorted out if that happens.
U705 spec:

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Dear Budm:

--What a great find. I will now be able to check more voltages. I replaced all of the parts I mentioned in my previous post. I replaced ZD702 with a 5.1V Zener because I measured 5V on an identical monitor. I now am getting 5V. Both Voltage regulators seem to be working an providing 3.3 and 5 volts. But I still am not getting a blue turn on light. I will take voltages on U705 if I can find them in the schematic and report back. I did not find anything obvious, previously, checking with a multimeter. I would not mind just replacing it if you think that is a good idea. Thanks for all of your good help.

"In the heat of battle, my father wove a tapestry of obscenity that as far as we know, is still hanging in space over Lake Michigan."
Ralphie Parker

Best Regards
Clear Ether

[budm]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

I would change that 5.1 to 6.2 since the output of that circuit is 5V, so if the voltage goes above 5.1, the Zener may conduct heavily and may shorted out, the Zener is not used for regulation, it is used for protection, the circuit will work without the Zener but then it will not have any protection. This is common way of protection.

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Dear Budm:

--Thanks for the prompt response. I will indeed, order the 6.2 Zener just as soon as I figure out what else to order, and report back. I have a new post just up, on a Westinghouse L2210NW. Please have a look if you care to. Thanks again.

"Measure twice. Cut once"
Norm Abram 1950 -

Best Regards
Clear Ether

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Greetings BadCappers:

--I was checking the board out, when I realized that ZD702 was not soldered properly. I re-heated the joints, and now, voila, the board lights up the blue power light and the screen. I shut it back down and have ordered a proper 6.2 V, 500mA Zener to replace the 5.1 V I installed before Budm provided the schematic, which was a big bonus. When the Digikey order arrives, I will install the new diode and do further testing. I will report back if there are any further problems, but I think "She isa fix" as my Italian cousin says. Thanks again to all.

P.S. Augustboy21: Are you having any luck?

"The only relevant test of the validity of a hypothesis is comparison of prediction with experience. "
Milton Friedman 1912 - 2006

Best Regards
Clear Ether

[augustboyz21]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

hi SgtRock
i still didnt test it couse im pretty busy with my job now and didnt have much time :-(

[SgtRock]

Re: Help Identifying SM Diode Acer S231HL LCD LED Monitor

Greetings BadCappers:

--Well I finally put the 6.2V SOD-80 MiniMELF Zener Diode in place of the 5.1V one I was using for ZD702, which was working but was a guesstimate. I am happy to report that both of my Acer S231HL5 monitors are now working properly. One has only a few weeks usage since the factory refurbishment, so it should be good for a while. And the second one I just repaired with good Panasonic, Nichicon, and Rubycon Caps, should be good for a couple of years. The are both just sitting on the shelf, until they are needed.

--I am using a 26" Olevia TV, which I found in the Dumpster, for Comp System #1, and the newly repaired Westinghouse 2210NW for Comp. System #2.

--Without the help of Selldoor, Tom66, and Budm, I doubt I would have gotten either one working. So many thanks to all.

--To Augustboy21: Work hard and make money, and when you get back to your project, please report in, and let us know how it is going.

"The telegraph is a kind of a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Radio operates the same way, except there is no cat."
Albert Einstein 1879 1955

Best Regards
Clear Ether