Solved No Power Problem In HP L1706 (PX849A) LCD Monitor
This Monitor came in with no power problem and found the main fuse 3.15 amp open circuited. As usual one has to find out whether other components have short circuit or not before you put a new fuse and retest the set. After scanning all of the primary and some of the major components in the secondary side of power supply i could not locate any shorted components. Placing a 100 watt bulb across the fuse and noticed that the bulb dims down and the big filter capacitor voltage did not drop even though the power jack already been removed.
Since the start up resistors are going to the power IC SG5841SZ (SMD IC) I suspect that this IC could be faulty causing the filter cap voltage remain high. Finding from my spare part compartment could not locate such part number thus i use SG6841SZ SMD IC as replacement to try it out. Before i put in the new IC, i did search from the internet and compare both spec and found that both of the IC’s were not much different from each other.
So the result was the LCD Monitor power came back a life after the replacement of the SG6841SZ IC and a fuse. This HP L1706 Monitor use some of the part numbers such as :
BIT3713 (INVERTER IC), 40P03GJ (FET), 2761I (Power FET), 817B (Optoisolator IC), 1506 (Voltage regulator IC) and AZ431 (Adjustable Precision Shunt Regulator IC). Please jot down in your diary book that the SG5841SZ can be replace with SG6841SZ.
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sako
November 6, 2008 at 4:52 am
plese help me
admin
November 6, 2008 at 11:03 pm
Hi Sako,
What is the fault?
Jestine
salameh yaseen salameh
June 4, 2009 at 5:05 pm
i have a monitor al 1706 ,,this monitor light goes off after 5 minetes ..some times more than five minets.. bus still data is appearing on the lcd with no inverter light
no dry joints are found may be one of the lamps is defected (far)
or inverter transormers(most common) i need your advice
waiting for your kind reply
saameh
admin
June 8, 2009 at 5:15 pm
Hi Salameh,
Yes it could be the lamp that have flickering intermittent problem. Check also for bad e-caps too in inverter board and smps area.
Jestine
Craig
July 19, 2009 at 3:20 am
Can you help me?
I have 9 HP 1706 monitors that I hope to repair.
They all work but shut off after 3 - 5 seconds.
I have replaced most of all of the usual suspect caps on 2 of the monitors - and resoldered some cold solder joints. No Change.
I have fixed other types of monitors in the past.
Thanks.
admin
July 19, 2009 at 11:34 pm
HI Craig,
Have you try changing the lamp?
Jestine
Kumar
July 20, 2009 at 1:31 pm
Hi Jestine
I tried opening up the HP L1706 Monitor. I removed all the screws but still cant open up. Could you please give me some tips. I am new to this but have amountless interest in repairing electronics. Thanks in advance.
Kumar
admin
July 20, 2009 at 7:48 pm
Hi Kumar,
Have you removed the stand (base) as in some model the screws are located behind the stand.
Jestine
STEVO
August 5, 2009 at 9:46 pm
I have A TSSI TS-19SVb. This monitor will show a power light for a second after plugging it in, then nothing. previously worked perfectly. Can you please HElP me?
admin
August 5, 2009 at 11:18 pm
HI Stevo,
After shutdown does the smps still have output voltages or not? If yes then suspect a bad mainboard and if no then you need to check on if there is any components shorted at the inverter board that had cause the power supply to shutdown.
Jestine
koon
August 6, 2009 at 3:08 pm
I want service manual LCD hp model l1706
admin
August 6, 2009 at 8:53 pm
HI Koon,
Sorry i do not have the schematic diagram.
jestine
Mohamed Bagrudeen
August 26, 2009 at 3:21 am
Hi Jestine,
I have Display problem in L1706 (PX849A). I have power LED blinking Green and shut OFF and again ON but no display. When I check in dark room, i can see the dim display image and cut OFF due to the power Blinking. Can i know what would be the problem.
admin
August 26, 2009 at 8:55 pm
HI Mohammed,
First you need to make sure the output voltages are good/stable. Check also on the inverter board to see if there is any shorted semiconductor that had cause the power to blink. If the output voltages from the smps are stable then it could be the mainboard faulty.
Jestine
ken
August 29, 2009 at 1:11 am
i can't seem to find the IC SG5841SZ at the motherboard, may i know where it is
admin
August 29, 2009 at 5:52 pm
Hi KEN,
I'm not sure whether this model has the same version. Sometimes the power IC is located behind the power board.
Jestine
ken
August 30, 2009 at 11:14 pm
ya, there are a few ic behind the board, but i can't figure out which one is IC SG5841SZ .
admin
August 31, 2009 at 3:45 pm
Hi Ken,
May i know what are the part numbers of the ICs? Particularly look for the one behind the power board and not the inverter board.
Jestine
Carlo
September 2, 2009 at 10:02 pm
Hi Jestine.
Thank you for the tip to change the SG5841SZ with the SG6841SZ on the L1706. It worked for about 3 hours and then the video goes black again.
The Green led continue flashing as before.
In the beginning i have to chenge three CAPS (25V 470uF) that were blown.
Have you any other idea please ?
I replace the SG6841SZ with another one i found but this time did't help.
Thanks.
admin
September 4, 2009 at 12:02 am
HI Carlo,
I guess you may need to recheck all the components again in the power section. As for me the replacement works well and so far no return.
Jestine
Craig
September 10, 2009 at 7:45 am
Thanks for getting back to me.
The 9 HP l1706 LCD monitors all have burned out lamps.
Removing the bulbs proved to be quite a bit of work.
Since there are 2 Lamps in each top / bottom, at $11.99 ea
I am taking these to the recycling center.
I also found the lamps burned out in a Plantronics 17 inch LCD.
I had to practically destroy the monitor to get at the lamps - they have wires at both ends of the 2 lamps.
Thanks again and keep up the good work,
Craig
ken
September 10, 2009 at 10:53 pm
Mr yong, can you help, i really want to fix my pc, but somehow i do not have deep experience on electronic, i learnt electronics during one of my modules during my poly days. now i am not even sure it is the capacitors fault as there is a very very slight bulge of those 3 caps, and i could not even find the IC SG5841SZ in the main board, may i know many pins in this IC and where is it located near? thank you very much. as i have financialy tight, therefore i cannot afford to spend any more money on a new one. i hope you could help me.
admin
September 11, 2009 at 9:36 pm
HI Craig,
You mean all the four lamps have problem?
Jestine
admin
September 11, 2009 at 9:37 pm
HI ken,
If the caps are slightly bulge then direct replace it. As for the IC, it could locate at the back of the power supply board.
Jestine
Francesco
September 17, 2009 at 4:03 am
Hello Mr. Yong
I'Francesco and i have problem winth HP L1706 lcd monitor, i found in the power board card (bottom of the lcd) 3 caps 1000 micro 10 volt damage: they are slightly bulge, do you know why this append... the monitor is connected to a ups and the voltage is ok. Do you think the problem are only the caps or the damage is more big...
Tanks
Francesco
admin
September 17, 2009 at 7:29 am
Hi Francesco,
It can be only the cap or other problem. I guess you may need to check the corresponding components. The cap problem could be due to bad quality, too hot in the LCD Monitor and bad corresponding circuit.
Jestine
Pierre
October 8, 2009 at 10:26 pm
Hello
You often need to replace the 3 1000µf/10V capacitors.
They are under scaled for what they have to do; replace by 1000µf/25V and it will work fine. The rule is: minimum 3 to 4 times the requested voltage. In this case, they have to regulate 5V => 25V is ok.
admin
October 9, 2009 at 8:20 pm
HI Pierre,
Thanks for sharing!
Jestine
pitigoi
October 19, 2009 at 10:31 pm
Mr YONG vaq respectfully ask datimi some details on MOSFET transistors 9960gh not find anything on the web about what they can thank his inlocuiesc.va anticipat.specific that are ROMANIA
admin
October 20, 2009 at 7:36 pm
Hi Pitigoi,
Sorry no information on that components.
Jestine
Altaf
November 5, 2009 at 2:23 pm
dear jestine
i have 17" crt monitor (studio works 710E(K). it had problem that monitor was shutdown automatically after 20-25 minutes. Then i read ur comments that desold the B+ fet and cheak. But when i desold fet and ON monitor by series bulb there was no any action means no any power no any display. so i again resold the fet. But now monitor is not picking power and power LED also not blinks. But big filter recieving voltages but not droping voltages autmatically. Sir i cant understand what is the problem so kindly help me.
i will be thankfull of u Respected jestine
admin
November 5, 2009 at 11:41 pm
HI Altaf,
Try isolate the problem using the method below:
http://www.scribd.com/doc/2957819/TT204-Identifying-television-SMPS-problems
Is there any voltages measured at the SMPS output?
Jestine
cheap computers
November 10, 2009 at 9:43 pm
i did search from the internet and compare both spec and found that both of the IC’s were not much different from each other.
ashok kumar
November 13, 2009 at 11:47 pm
i am using HP L1706 model monitor...after switching on the power ...the power lamp goes on blinking for about 30 to 40 min..after that the display is appearing....so please help with a solution for this
admin
November 14, 2009 at 9:52 pm
HI Ashok,
Try check all the filter cap for high ESR. Check also for dry joints in the power/inverter area.
Jestine
ashok kumar
November 15, 2009 at 12:30 am
Jestine really thankful to u for replying me...but i am not an hardware expert...i am just one of the customer of HP....what should i do now...take it to HP service center or buy a new one?
admin
November 15, 2009 at 5:23 pm
Hi Ashok,
You need to check with the HP center to see how much it cost to repair the LCD. Then compare the price with a new one. If the price is not much different then i suggest that you get a new Monitor.
Jestine
Altaf
November 16, 2009 at 6:12 pm
i have 15" philips monitor it is showing just only white screen. please help me and tell me its solution
thanku
ur student Altaf
admin
November 16, 2009 at 8:00 pm
Hi Altaf,
Replace the LCD panel.
Jestine
Altaf
November 18, 2009 at 4:00 pm
Brother Jestine Young
i have 15" crt monitor its foucus is to bad. and not showing picture because of bad docus. i have also set it through flyback nobs but effect. can u tell me its solution
ur student
altaf
admin
November 18, 2009 at 9:43 pm
HI Altaf,
If the display is blur even after adjust flyback then replace the flyback transformer.
Jestine
Adriel
December 2, 2009 at 2:38 am
I lift my hat to you sir for taking the time to post this info online. It was greatly appreciated.
Simone
December 7, 2009 at 7:56 pm
Hi Jestine , I have a HP L 1706 monitor . It has been working but today as I tried to switch it on I just see a "no output signal" on the screen and then "Monitor going to sleep". I am not an expert. EWhat do you think the problem might be?
Thanks Simone
Simone
December 7, 2009 at 8:16 pm
Hi again.
Sorry the mesage is "no input signal"
admin
December 7, 2009 at 9:30 pm
HI Simone,
Have you check the internal cable of the H/v signal from the vga connector to the mainboard?
Jestine
John Lorenz
December 15, 2009 at 2:43 pm
Hi Jestine,
Interesting items in your blog. I have 70 LCD monitors where I work and it seems like no two manufactures use similar circuits. I had two in the same week exhibit the same symptom- Upon power up, they work for a few seconds, then the screen becomes "dark". A common symptom, some I have fixed – bad caps. However, on an HP1706 and a Syncmaster 203B, if I leave the monitor on for a few minutes, then power cycle it, both monitors work perfectly, until turned off for a time. Repeat the warm up and they work again. I did touch up the solder joints on the HP and noted the board around the 40P03GJ and 40T03GJ darkened from over heating. I had not looked at the capacitors specifically for bulging, but nothing caught my eye. Very odd symptom. Ideas?
admin
December 16, 2009 at 9:39 pm
HI John,
Suspect one of the backlight have problem. A slight/mild flicker in one of the backlight could cause the display to shutdown.
Jestine
leong cheong fatt
December 17, 2009 at 11:48 pm
Dear Sir:
I got similar product same model without power on but fuse is working without blown out,whay I have discovered the circuit board got 5VDC output to board (sorry don't sure what it call "VGA board")before to panel suiz and 35VDC(if not mistaken),Do you have this circuit for share with me?or have you experiance this issues,thanks you read and feedback.
admin
December 22, 2009 at 11:21 am
HI Leong,
Sorry i do not have the schematic diagram and have not come across such problem before.
Jestine
Charlie
December 24, 2009 at 11:19 pm
Here is a potentially related problem, for a Samsung 203B 20" monitor. This unit has started requiring ridiculously long "warmup" times. I use it in a dual-monitor configuration. When the computer is turned on, one monitor comes up immediately, the other stays black. If I physically turn it off and then on again after about 5", a dim image comes up and then quickly returns to black screen. It only comes up brightly and permanently after about an hour. Can anything be done?