Disclaimer:
DO THIS AT YOUR OWN RISK!
I am not responsible for any damage you might cause to your monitor or yourself by following these instructions. If you open up your monitor case to this point, you will probably void your warranty.
CAUTION: There may be HIGH VOLTAGE present. Disconnect all power during disassembly. Inverters can generate high voltages.
If this repair is too daunting, HP has offered an extended warranty in this HP Support document. Thank you, tsmitty, for this link to HP Support. (Jan. 23, 2009: HP has discontinued this offer)
My HP Pavilion f1703 LCD Monitor suffered the same blackout symptoms as other posters in the CNET forum. After powering on, the display would go black after a few seconds. It was not the power supply in my case – I tried another working power supply with the same result.
It was also not a software problem, e.g., XP SP2, power management, screensavers, etc. In my case, it was a hardware problem, as I tried the monitor on a different machine with the same result: power on, brief display, then black. It also exhibited this behavior with no cable connected to the monitor.
I noticed the screen was faintly visible under bright light and realized that the backlight was not working. It seemed unlikely that the fluorescent tube would fail – I have had my Toshiba Portege 7200CT notebook computer on for 5 years, running SETI@Home.
Since the monitor was out of warranty, I decided to try to repair it myself. This is not a step-by-step procedure, but an general overview of how I solved MY problem with this monitor.
After reading the posts, it seemed that there must have been a loose connection on the circuit board that drives the monitor’s backlight. I especially noted gromit588’s post about disassembly and followed the instructions. gromit588’s experience must have shorted some connection closed to fix the problem. I found that it did not help me, so I looked for bad (cold) solder joints on the backlight inverter board.
After a close inspection of the board, the bad solder joint was obvious. The bad solder joint on my board was on one of the coils – the bare pin on the coil was sticking through from the component side with very little solder on the pad on the circuit board. I resoldered it and that fixed the problem. There may be other cold solder joints at different locations on YOUR board. You just have to inspect each joint carefully.
This is a view of the monitor disassembled from the case:
This is the component side of the backlight inverter board:
This is the solder side of the backlight inverter board with the bad joint circled:
Close-up of the backlight inverter board with the repaired cold solder joint circled. Inspect the board for cold solder joints – they will be fairly obvious. It’s possible that the cold solder joints on YOUR board are in different locations on the board from the one circled here: (Jan. 23, 2009: If the cold joints aren’t obvious, I recommend using a 10x magnifier, or just reheat the solder joints on the components that have white glue holding them to the circuit board, see fig. 2)
Gastropoda
leapingmonkeys
The Onion
Toolmonger
March 1st, 2009 at 2:31 pm
Hello,
I have a Westinghouse 19″ LCD that I bought used (not working…very dim picture) off of Ebay, with the intent that I would just change the backlights on the thing and it would work perfectly. Well, upon tearing the thing apart, I can’t even FIND the backlights, much less replace them. I did, however, find a cold solder joint and resoldered it well. Turned it back on and still same thing….VERY dim picture, can barely see it and only with a flashlight! Any chance that if I resolder ALL the joints on the coils (BTW….what is meant by “coils”?), that it will work, or are the backlights burned out? Can’t find much of anything on Westinghouse monitors or parts, but the board matched up with Viewsonic. Any ideas? Thanks for any help!
March 1st, 2009 at 8:57 pm
Has it been discovered what is wrong with the newer f1703 monitors with the benq boards?
March 17th, 2009 at 7:39 am
Well, thanks to your pictures I know that it is, in face, the Yellow PT 201 and PT 202 are the peices on the board that are broken, not the solder–Thanks!
If you happen to know where to get replacements(this is my first repair), a link would be appreciated.
March 17th, 2009 at 10:01 am
JonelB – PT201 and PT202 are transformers for the inverter. I don’t know the specifications for them. If there are any numbers on them, you can google it or look at Digikey or Mouser, otherwise, you’ll have to find another broken monitor for parts.
March 17th, 2009 at 1:07 pm
Thank you so much, I had no idea what parts they were–They do have numbers on them, and I googled them to death, but I was unsure of what part I was looking for, exactly.
I was thinking that as well–If nothing else, I can buy a trashed monitor and salvage the transformers from it.
March 27th, 2009 at 7:47 pm
Hi Leslie,
I want to thank you for your posting the fix for the HP F1703 LCD Monitor. I work for HP, but not in the computer or monitor segments of the business. An engineer gave me a personally owned F1703 that had the backlight problem. I Googled it and found your page. I fixed the monitor and after a few months the problem reoccured. I had just touched up the solder with a little fresh solder. I went back and totally removed the bad solder and used a little flux on the area to be resoldered and resoldered all of the inductor joints. It’s held up well. I have used the repaired monitor for months. I bought a second “As-Is” F1703 off of EBay for $25, I did the required resoldering and the backlight worked. The Monitor image did not come on. I dug into the monitor and found that the LCD connector above the mainboard had become disengaged. Apparently when the lamp power supply failed the previous owner forcibly struck the top of the monitor, fracturing the hot glue that had been put there to secure it. I rengaged the connector and hotglued it back into place and now I have another fully functional monitor. Thanks for taking the time to document this. I have a nicer monitor in my guest room as a result.
Randy Bray
Corvallis, Oregon.
April 5th, 2009 at 9:54 pm
Hi Leslie,
I acquired another of these monitors, with an additional problem. I wanted to add an addendum, and another fix for this same problem. In addition to the solder joints on the 4 toroids, I looked and found other cold solder joints, dull gray, I completely removed the solder with Solder Wick and resoldered all of those connections. The problem with the backlight persisted. In addition to the Solder Joints, the 4 Driver Transistors (2SC5706) were replaced, THEN the Monitor Worked and has stayed working. These Transistors are about $1(USD) each. I bought them off of ebay. You might want to add this info to your repair blog.
Randy Bray
Corvallis Oregon.
April 20th, 2009 at 2:21 pm
Hi Leslie,
I would like to thank you for posting this fix.
I resoldered all the coils on the blacklight inverter board and the screen works perfectly now.
Jeroen Luchtenberg
Apeldoorn, The Netherlands.
April 21st, 2009 at 4:51 pm
Mr.Wong,
I am sooo not a fixing person. I need a big red arrow to be there when I open things up. I did follow your steps and I noticed your solder is predominately in the middle and mine is on the sides. 2 of the 4 coils have little metal “rings” around the pins (the ones that had the black solder as they go thru to the front of the board. Do you think that might be the connection issue?
Thnx! Jill
May 28th, 2009 at 6:43 am
I implemented the solution and it worked perfectly. It was a bit difficult inspecting the soldered connections. Using two magnifying glasses together it was still difficult to spot the faulty connection. Ultimately I resoldered the 201 connection mentioned in this article. I then followed the Corvallis engineer’s suggestion to inspect all of the cold solder joints, and I touched up the solder on one suspect connection. Then after thoroughly brushing off the board and reassembling the system, the monitor worked great.
Thanks everyone for your input, and for providing the solution. It’s great to have two monitors now.
May 28th, 2009 at 4:46 pm
Thx so much for this im only 16 years old and i opened this up myself, fixed it like u said, and now i can continue playing my XBOX 360 on this monitor. The only reason i had the guts to open it up is cuz i’m in the engineering program at my high school and I desided maybe i’d give it a shot. THANK YOU!!!!
June 26th, 2009 at 12:58 pm
I’ve resoldered the join identified in your article and the monitor worked for a good while. The problem came back again, so I tried the same thing and now the monitor doesn’t power up at all – no light on the power button when plugged in. Have I killed it completely or is there something else I can do. thanks so much for your help. Jono.
June 26th, 2009 at 1:08 pm
@jono
It is not only the joint I circled that could be bad. Any of them could be bad. That’s why I recommend using 10x magnifier to check all the solder joints.
If there is no power, check the solder joints for the jack where the power cord plugs in. Maybe it is shorting. Try flexing it and see if you can see a break in the solder joint. Or just reheat the connections for the jack.
July 2nd, 2009 at 11:48 am
Thanks for posting this. I fixed 2 monitors using your guide. The first I found in the trash. The second I picked up on eBay for $10. They are both side-by-side now on an old Mac Centris 610 (20mhz 68040!) each running at 1152*870 resolution. Lots of pixels per $! Thanks again!
July 5th, 2009 at 7:12 am
Here looking for a solution. My F1703 stays on for about 15 min. gets bright for a secound then shuts down. Haven’t opened it yet but do ya think it might have the same type of solder problems?
July 17th, 2009 at 9:49 am
My Dell monitor Has exactly the same problems as David’s above. Seems to be an overheating problem. Will be fine for hours – then go bright for 5 seconds – then screen goes black. Power light stays green.
I’ve replaced 4 C5707 transistors, and a thermal fuse in there – but problem is exactly the same.
Bad Caps in supply ? or one of the main power transistors on a heatsink that looks a bit hot – P7NK802FP . – This will be my next attempt – all power transistors. Thanks for great article.
July 22nd, 2009 at 10:38 am
Followed the directions, and now it works! Used a $7 5 piece Radio Shack soldering iron set. Only let it stay powered for about 30 seconds to test it because I’m using a 12v/1amp power supply in place of the 12/4 and that would spell trouble down the road … but I’m confident it works fine so I’m happy and will just keep using my Samsung 15″ lcd till I get the right power pack. Just curious though why EVERYONE has a bad solder in the same place? Almost seems like an intentional and concerted effort.
July 22nd, 2009 at 5:49 pm
Like others, I had a problem with my 2-yr-old HP f1703 blacking out or just not ever lighting up when the computer was started or the monitor was plugged in. Sometimes the blue light of the “on-off” switch would flash a couple of times, but nothing else.
Per Mr Wong’s instructions, (with the disassembly recommended by gromit588) I soldered the whited-glued components, plus a few others that looked bad. I now have a monitor that appears to work perfectly again!!
Thank you for your logical and well-explained approach to what should be HP’s problem, but appears to have been abandoned by them. You saved me much time and money, and my sledgehammer is back in the garage where it belongs. Mr Wong, you are a legend! THANK YOU!
August 4th, 2009 at 6:17 am
Something I found while hunting for clues –
Switch Mode power supplies as used in these monitors are susceptable to power spikes or low power situations.
If your monitor blacks out during the same time of day – This can be the cause.
Problem is most likely an overheating fast power transistor that tries to regulate the power required.
Large filter capacitors can dry out – causing excess ripple. Now bad capacitors are definately a “ticking clock” used by manufacturers to scrap older equipment.
This site may help if other repairs don’t do it for you –
http://www.repairfaq.org/sam/smpsfaq.htm
August 7th, 2009 at 5:10 am
- – - – -
I bought a HP f1703 from a man I found on the internet (weird guy..!)
He had the screen connected to a computer, I gave it a quick check and decided to buy it for 40 Euros.
At home installed it on my pc and had it running for one week. Then it started to fail.
The screen kept turning black, after restarting the screen it went back on, and after a few seconds it turned back to black…
+ + + + +
Thanks to this guide for fixing the power board its running for days :D:D
Excellent work !! Thank you ;)
August 9th, 2009 at 11:44 pm
Yes this simple guide make me so happy with my HP Pavilion f1703. I bought this LCD from recycle computer shop at SGD100. It having a flickering after an hour on. With a try following this site I make that flickering gone.
August 14th, 2009 at 1:02 pm
Does anyone know what the value of the inductor at “L101″ is? Mines burned and keeping the monitor (HP f1703) from working…
August 16th, 2009 at 10:58 pm
Thanks to all the people contributing to this issue. The photos were a MAJOR help. I only had to reheat one joint that had become cracked from what seemed to be heat build-up. Picked this monitor up on the curb and now it works great! I also punched a few extra holes in the heat sheild behind the inverter to see if that might releive some of the heat. If it fails then I’ll tear down the old joints and repair them fresh. Thanls to all the contributors to this issue especially whoever put the great photos!!!
August 17th, 2009 at 9:47 am
OOOPS! I was in error. I’m looking for the value of inductor/choke or filter that’s located on “L110″. My pcb number is 715L1091-1-2 so I’m assuming it’s an early model as later models didn’t have this component.
September 25th, 2009 at 2:01 pm
HOLA A TODOS. NECESITO CONSEGUIR LA TARJETA CON NUMERO DE CIRCUITO IMPRESO 715L1091-1-2 DE UN MONITOR HP f1703, YA QUE SE QUEMO, PERO NO SE DONDE CONSEGUIRLA. SERIAN TAN AMABLES DE DARME IMFORMACION DE DONDE LA PUEDO COMPRAR. YO RADICO EN VERACRUZ, MEXICO. AGRADEZCO DE ANTEMANO POR LA ATENCION TOMADA. MI CORREO ELEC ES jc_silvan@hotmail.com ESTARE ESPERANDO SUS RESPUESTAS GRACIAS A TODOS.
October 19th, 2009 at 10:06 pm
Followed your advice, I re-soldered the 4 coils, my HP F1703 is up and running properly again! No more black/dead screen now. I had the same problem with my HP F1903 a few months back, had cold solder joints that took out one of the four display backlighting power transistors. I found them on eBay for $6.00 a set, replaced them all and repaired the cold solder connections. Thank you all for all your advice here!!!
October 22nd, 2009 at 8:01 pm
f1703 heres my issue. Blue LED comes on for anywhere from 3 to 10 seconds, I get a humming noise for a few more seconds then a flash and pop thru speakers blue light again and starts all over. HP said they would send me a new one free of charge a year ago, still haven’t got it yet. I called several more times and was told that it was still in processing. well it cleared up and worked fine doing nothing, so I forgot about it. I called them a few days ago and was told that they are no longer offering replacements. AND this ticks me off the most, they have no record of any contact to them even though I gave them dates & the persons name who I spoke to. A-hole company has lost another customer. I tried resodering the coils and capisters look fine still no luck. Time for a new computer I guess 5 years is a good run the way things are so cheaply made these days
October 29th, 2009 at 4:59 am
Thanks to all,your insight and comments greatly appreciated. Found my monitor in a thrift store for $15.00. My monitor was doing the typical fade to black after about 5 seconds. Found a few questionable solder joints on my board and one overheated and cracked transistor. Repaired joints and replced one transistor, still had same problem. Replaced the other three transistors and problems corrected, works great now. Found transistors on ebay @ $4.99 including shipping.
Leslie; thanks for providing this forum.
November 6th, 2009 at 5:37 am
Hi!
I have an lcd screen hp f1523, and the power board is 715L1034, i know that is not de same, but i think it is simmilary. I dont need to use the backlight of my lcd (it is to build a multitouch), i only need thaht the screen will be recongnized by the computer, and lcd module work.
If i delete the zener (it is burned), and the capacitor (is bigger than normaly), do you think my lcd module only will be work? i dont need backlights.
thank’s for the futures responses, and many sorry for my bad english speaking…
thank’s to all…
Biloo
November 10th, 2009 at 6:10 pm
thanx great fix!!!!! Worked perfect for me.
December 30th, 2009 at 4:31 am
I have a broken f1503 that was given to me by a friend for free, and I was thinking how nice it would be in my car, seeing as it runs on 12v dc natively… but I can’t seem to get it fixed. The caps look fine, no bulging or leakage… The backlight itself works, but it powers down after ~1 second. I tried resoldering the toroids, transformers… but it didn’t seem to fix the issue. I’m running it off a 12v 5A psu, so power is not the issue here. I’m considering wave resoldering the whole board, seeing as none of the joints look cold. There is no visible physical damage to the board itself, ie, burned, discolored marks. I don’t know what to do about this really. What are the possible failures that could cause this problem? I could just replace the whole thing, but where’s the fun in that? I would like to take a look at a working board if at all possible…
January 5th, 2010 at 8:03 am
I also have an f 1503. one of the torroids had a bad joint. reheat + a little fresh solder, backlight works perfectly.
January 16th, 2010 at 1:28 am
To Graham Sheldon post.
Resolder all cold joint is just one small step in troubleshooting,
the cap, resistor, transistor, diode etc need to check with testmeter
in order to confirm it working or not just by looking it may look fine but it doesn’t mean it working.
January 17th, 2010 at 6:38 am
than u very much, i had the same problem now i fixed myself
January 30th, 2010 at 6:05 am
Many thanks I now have four out of six working.
February 8th, 2010 at 4:08 am
Thanks for the useful Guide. I never would have got the HP 1703 apart without it since dismembering the beast is not covered by the HP F1703 Service Manual. These monitors were made by AOC for HP. I fear the one I have is suffering from a little aore than dry joints on the toroidal chokes L102, L103, L201, L202 like your monitor. The 2SC5706 inverter transistors mentioned by Randy Bay are Q209,Q210,Q211,Q212[2SC5706-P-E].
The two inverter transformers [PT201,PT202] are 80LL17T-9-LS and I expect a scrap monitor is the only source of them unless you can get them from AOC. Note that high voltage output is across pins 7 & 9 of these transformers so keep fingers and multimeters clear.
The sequence for testing the inverter board is firstly check CN101 for 12V if no 12v then check the power adapter. Check the on/off signal with a scope. If none check interface board. Check U201 Pin 9 for 12v If none relpace F101. Next check U201 Pin 1 for sawtooth waveform. If none repklace U201. If there’s a sawtooth wave then short C207 and check U201 , pins 7 & 10 for square wave output. If no square wave THEN check Q203 [AO4411 SO-8],Q205 [PMBS3904/PHILIPS-SMT(04],Q207 [PMBS3906/PHILIPS-SMT(06] & Q204,Q206,Q208. if faulty replace. Check that the square wave has a 90% duty cycle minimum. If not check Q209,Q210, PT201, C213 & Q211,Q212, PT 202,C214. If the square wave is OK then check the feedback circuit [R232...........R233]. If No 1.8V, 3.3V, 5V Output, then check CN101, the wiring harness, for 12v If ok start checking U101.
Note – To do this you need a PC, multimeter, oscilloscope and preferably the circuit and board layout diagrams. Some of the devices are surface mount components and you’ll need to have experience ibn dealing with these.
If you are not experienced in servicing don’t attempt to fault find unless you are prepared to send your monitor to the recycling centre. You do this at your own risk as there are high voltages involved.
February 8th, 2010 at 5:17 am
In ans to Buddika, Post 264 – If L103 and the associated P-Channel enhancement mode Field Effect Transistor Q102 [SI4431 OR AO4411, package - SOIC-8 (8 legs surface mount chip)] are heating up the cause is most likely that C113 [470uF 16v} is leaky. Check also D102 mini surface mount schottky barrier rectifier{SR34 PAN JIT check data sheet for voltage }, D104 [BZT52-C3} and C115 (0.1uF +-10% 25V). Note most of these components are surface mounted on the track side of the board and require specialised skills & eqpt to replace.
February 17th, 2010 at 12:37 am
I want to thank you for your advice, I bought a $3 solder pecil, did the work in 10 minutes and my second HP F1703 (dual monitor PC)it’s working better than ever before, tks again!!!
March 11th, 2010 at 9:39 pm
great help for the f1703, but I am having the same problem with the f1730. Now I have fixed the backlite on about 5 diffrent f1703’s and replaced transistors on 2 others. (thats when you get the flashing yellow power lite.) I haved looked and fixed all the bad joints I could find. Now with the f1730 the backlite inverter board is totaly diffrent then my experiences. If some one could point me in the right direction with this one, that would be great.
Thanks
And to all you tech’s out there keep up the good work
Morgan