TechSpot

HP w22 Monitor display disappears after about 2 seconds

By hogwillie
Oct 25, 2009
  1. Make/ Model: HP w22
    Regulatory Model: HSTND-2241-T
    Product Number: RG556AA
    SN: CNT704Z17Q
    Date of Manufacture: January 2007
    Assembly Number: 434000-001
    Rev: CTM003

    Problem: when I turn the monitor on I can see a display for about 2 seconds. The display disappears. If I turn the monitor off, then on, I can see the display for about two seconds, then it disappears again. The cycle continues. The symptom is the same with no signal input, and with input selected for VGA or for DVI.
    If I shine a flashlight into the screen I can see a very faint display. I believe this indicates a backlight issue. I could be wrong.

    Can anyone help me find a service/repair manual for this monitor?
    Can anyone tell me what parts to look at for the backlight power?
    Can anyone tell me what the voltage that drives the backlight might be?

    Thank you all in advance, for your assistance.

    Bill
     
  2. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    Hi Bill,
    this could be an issue with the inverter and not the backlight. LCD monitors are built just like laptop display panels, only bigger. Inverters are not that expensive. The backlights are very delicate, and they either light or they don't. The inverter takes 12 volts DC and turns it into hi-voltage (I don't know the exact rating) It may be AC... Also this could be a primary power supply issue too. I had to learn to repair without schematics. With experience, it becomes easy

    I like this source:
    LCD Parts & Info
     
  3. hogwillie

    hogwillie TS Rookie Topic Starter Posts: 17

    Tmagic650,
    Good to hear from you again. Thank you for the reply.
    I believe that this is an inverter problem, as you suggested. I've removed the power board from the monitor. I see no domed capacitors and no scorch marks, so it seems unlikely that it's a case of “Capacitor Plague” or a shorted diode as was the last monitor that you helped me with.
    The power board has four plugs marked “ High Voltage.” I assume that these are the connections to the back lights , and not to a separate inverter board. The board is labeled with two sections. One section is marked “Isolated” and the other is “Live.” I am assuming that the “Isolated” section is an isolated low voltage power supply and the marked “Live” section is a High Voltage power supply for the back lights. These are assumptions and may have no validity.
    I have limited test equipment. I have a VOM and an “O” Scope.
    Can you suggest some things I might be able to test on this power board?
    Some issues occur to me. In order to test this board I have to power it up. Can I do that with it out of the monitor? I see a pin on an edge connector that says ON/OFF. If I jumper that to ground and the board comes up will it being out of the circuit cause an issue. I have seen such actions blow up boards because of missing load issues.
    I don't know what kind of voltage the “High Voltage” connectors might be supplying to the back lights. I have seen something some where that indicates that the voltage is in the 3000 – 4000 volt range but I can't seem to locate the referent again. Will I need to find a high voltage probe for my VOM in order to measure this? Indeed, can I measure this voltage without the back lights in the circuit?
    I looked at http://www.lcdparts.net/inverter3D.aspx. It looks like a great source. Unfortunately I don't see the PCB-1057-04 Power Board listed.
    If I sound a bit sophomoric please bear with me. It's been some years since I repaired equipment, and even longer since I did component level repair. I'm rather more than as bit rusty.
    Thank you again for your help.

    Bill
     
  4. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    "If I sound a bit sophomoric please bear with me. It's been some years since I repaired equipment, and even longer since I did component level repair. I'm rather more than as bit rusty"...

    I spent over 12 years repairing only computer monitors and non-digital TV's from 1989 to 2001. I started with component-level repair in 1967. I've been "retired" since 2001. I thought you might be either twenty or 30 something, or fifty something in age...

    I use a Fluke 79 True RMS multi meter almost exclusively. I do have a Sencore "O" scope and a Capacitance meter, and other test equipment in a closet, that I haven't used since 2001. Laptop computers and an ocasional TV or computer monitor are my common repairs these days. Since the backlight produces an image even for a few seconds, the problem is in the regulation section of the "live" power supply.
     
  5. Kcircyrd

    Kcircyrd TS Rookie Posts: 316

    If time is worth anything, then monitor repairs are a wasted effort.
    You monitor failure can actually be any of a number of problems.
    There is the time to shop for parts (that are generally not available new) and the shipping, and the discovery that part did not fix the problem.
    We have a stack of about 15 of those HP monitors in the back room awaiting permission to crush them with the caterpillar tracks... their history has been very negative... at least three different components fail.
    Fix this issue, and you will find another with that HP RG566AA.
    When a new monitor can be had for $89 to $139, you are merely getting an engineering lesson.
     
  6. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    If the only issue is making money, you are right Kcircyrd... There are many of us "old" component-level techs that really enjoyed fixing broken things, just for the fun of it, and we still do. EBay has been a great source of "cheap" parts
     
  7. hogwillie

    hogwillie TS Rookie Topic Starter Posts: 17

    We have a bit in common. I too retired in 2001. I started repairing things in 1962. But back then it was Army radios and such. I moved into avionics in 1970 (Civil Service). I worked on F4 Avionics and Fire Control Radar, C5A MADAR (component level), F16 avionics, then moved into writing programs for automated test equipment in the ICBM field. By the time I retired I was a Project Manager and Equipment Specialist in the ICBM field. It's been a while since I worked at component level.
    If I could find a new (or even refurbished) power board for this monitor at a reasonable price I'd probably just buy one. Unfortunately, none of the places on the web that I've found so far even list the PWB-1057-04. I've spent most of two days looking. All the repair videos on YouTube only talk about replacing capacitors. The ones on this board look good to my visual inspection.
    I was thinking that because I get light for a bout 2 seconds, the problem must be in the "Regulation" section of the "Live" section of the power board. I suspect that it has to do with the feedback loop, but without a schematic I am at a loss as to how to isolate it further. I'm glad to see that your advice follows along with my suspicion. It gives me hope that I haven't forgotten everything that I used to know.
    I thank you again for your continued assistance with my issues. It helps greatly.
    Bill
     
  8. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    That's amazing Bill,
    In the early 70's, I worked for a company called Rantec, in Calabasas, California. It was owned by Raytheon. We built and tested RADAR power supplies for Navy fighters like the F15... Have you searched EBay for an entire monitor, working or not?
     
  9. hogwillie

    hogwillie TS Rookie Topic Starter Posts: 17

    Indeed, we do have some similar history. In the early 70's I was working on the F-4 Phantom.
    I have looked on EBay for a w22. All that comes up is two entries for signal cables and a bunch of new equipment ads.
    I also contacted HP. I got the usual BS run around via email. It reminded me of trying to get help from Microsoft. The response was prompt, friendly, polite, and contained absolutely no useful information. I'll call their parts order number later today.
    I guess the only thing I can do is begin removing each part from the "Live" section, and testing each individually. This might find something but without a schematic I'm limited to testing with a VOM. I can probably build a small circuit that will set the gate voltage on a MOSFET even if the "DIODE" setting voltage is too low from my VOM to open the channel. I'll have to check that voltage. Some MOSFETs take up near 4V to open the channel. Most VOM "DIODE" settings are <= 3V.
    I am a bit worried about the testing of the step up transformers for the high voltage. I don't have a "Meger" to test the low resistance of the windings. Any thoughts?
    Thanks again for your help.
    Bill
     
  10. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    Good morning Bill,
    Is this close to what you have:
    HP 2207 EBay

    Many similar models have identical parts. I have an inductance /capacitance meter that I used to repair motherboards before 2001. It was invaluable to me then
     
  11. hogwillie

    hogwillie TS Rookie Topic Starter Posts: 17

    Tmagic650,
    Thank you for the lead.
    I just spent over two hours talking with HP. I started with their parts store, transfered to tech support, then to customer service, then to corporate customer support, then to executive customer relations, then back to senior corporate customer support. The bottom line is that HP will not help.
    They won't sell me the circuit board, point me to an authorized repair facility, sell me tech data, or give me the needed information to find the OEM for this monitor so that I can ask them for the information. They did offer to sell me a new monitor at a discount. That's as far as they'll go.

    The bottom line is that HP refuses to support their own product.

    Behold: I am not amused!

    I've got a tremendous headache now. I'll look at the EBay lead tomorrow.
    Thanks again for the help.
    Bill
     
     
  12. hogwillie

    hogwillie TS Rookie Topic Starter Posts: 17

    Tmagic650,

    Thanks for the lead on the w2207. That's the one that HP offered to sell me as a replacement for the w22. I'd be willing to bet it's the same monitor. I looked at the ones that I could see on Ebay. They are all running over $150.00 or so. A bit pricey for a repair part. I did see three Ebay stores that looked like they might be selling monitors and such. I've emailed them asking for parts and/or data.

    At this point the only thing I can think to do is start replacing capacitors, if that doesn't work, try the diode packs, then the MOFET transistors. That sort of thing. I hate to “shotgun” a repair. I used to be able to analyze a circuit rather handily. Shotgunning a repair offends my sense of order in the universe. But, without schematics and such, I don't see any other option. Even with the shotgun approach many of the parts that I believe to be in the feedback loop are so small that I cant see any numbers on them (even with several stages of magnification). Trying to read them was what was giving me such a headache yesterday. (Well, along with trying to get any useful information from HP). Most are so small that there is no room for ID numbers on them at all. Itsy-bitsy surface mount parts. I don't know what to do about this issue.

    Do you think it possible that one of the CCFL tubes is taking down the circuit? If one of them is beginning to fail would that cause this issue? Is there any way for me to check this without building a mockup to plug the CCFL into?

    I'm thinking of starting up another thread for HP documentation and parts issues. What do you think? Is it worth it?

    Again, I thank you for your continued support.

    Bill
     
  13. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    Bill, you have to consider just what the total value is of the items you repair. I see 2 W2207's up for bids on EBay for $85 and $51. If these monitors are in better condition that the one you are repairing, use them. If they are not, use them for parts. I see that a working HP W2207 is selling for around $400

    Get my point?
     
  14. hogwillie

    hogwillie TS Rookie Topic Starter Posts: 17

    General Hardware > HP w22 Monitor display disappears after about 2 seconds

    Tmagic650,
    Point taken.
    I'll try to contact both sellers today.
    Bill
     
  15. hogwillie

    hogwillie TS Rookie Topic Starter Posts: 17

    HP w22 Monitor display disappears after about 2 seconds Reload this Page Reply to T

    Tmagic650,
    As I said I would, I went to ebay looking for the monitors that you mentioned. I found several. All are advertised as in working condition, and as of 13:53 10/29/09,the prices range from $101.59 to $220.00. There is even one for $433.31. This one is from an ebay store and not an auction. I'm not sure how the model number RK282AA w2207 22ln differs from the others. Perhaps it's considered a “business” model and not a “home consumer” model. I'm guessing that the $85 and $51 offers were bid up and will go higher yet. Alternatively, I may be using a different search criteria than you used in your ebay search. I looked for HP w2207. I got nine results, and three of them are actually w2207.
    With a new from HP price of $299.99 for a w2207, any of these would be an acceptable alternative were I doing this project for pay. Since I'm trying to fix this monitor as a favor to a neighbor, and doing it for free, I'd rather not invest the kind of money that the auctions are getting for these monitors.
    Still, I'd be more than happy to buy up a couple of non-functional w22 or w2207 monitors if I could find some.
    I'm not sure what to do now, but I haven't given up.
    Thanks again for your help.
    Bill
     
  16. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    Well Bill,
    you have to act fast on EBay bids. I see one right now BUY NOW for $169... You can continue trying to repair the one you have, or check with EBay for something comparable at a good price, for a replacement for your neighbor. I repair things for free too, but sometimes replacement is the only solution. Good luck. I got that non-working Compaq monitor for $14. I repaired the customers Compaq using the bad montors parts, for $85 total to the customer
     
  17. hogwillie

    hogwillie TS Rookie Topic Starter Posts: 17

    Tmajic650,
    You are correct. Speed is of the essence (along with a bit of luck) when buying on ebay.
    I'll keep slogging along. Being a stubborn old beast, I don't give up easily.
    Thanks again for all your help.
    Bill
     
  18. BubbaOnWyeMtn

    BubbaOnWyeMtn TS Rookie

    Hp W2207h LCD monitor backlight comes on for two seconds

    Hi there, I see this is a rather old post but I too am venturing into trying
    to whoop this monitor into submission. I have fixed many others but it is
    usually just a cap replacement. This is a 2008 monitor and the boards
    appear as new.

    bubba
     
  19. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    Okay Bubba,
    when you say that the backlight comes on for two seconds, do you see any video/color patterns displayed?
     
  20. BubbaOnWyeMtn

    BubbaOnWyeMtn TS Rookie

    hi Tmagic650,

    My monitor displays the same symptoms as the original poster,
    hogwillie. Yes the display looks normal for about 2 - 3 seconds then
    the backlight goes off. Yes the vga signal is still shown but without
    backlight.

    tnx for your super fast response,

    Bubba

     
  21. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    On the Compaq monitor I worked on, I tried using heat and cold to affect the symptom, but in the end, I had to replace the chroma board and not the power supply board to get the monitor to operate normally. In my case too, the boards looked new. This has to be a design flaw or weakness
     
  22. BubbaOnWyeMtn

    BubbaOnWyeMtn TS Rookie

    Tmagic650,

    This may not be permanent but you can see my monitor guts :)

    Not enough posts yet (djlewis.us/files/hp-w2207h/) to post a link.

    Your reply is less than encouraging ;P

    Bubba
     
  23. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    Yes that looks exaclly like the Comjpaq LCD monitor I am talking about. No bad caps, no bad power supply. The Tsun* IC is the chroma IC. It sends a signal to the power supply to "turn on or off" the backlight. This IC might be the cause of the trouble. i no longer have the equipment "or eyes" to remove or install large surface mount IC's. Very nice pictures by the way...
     
  24. BubbaOnWyeMtn

    BubbaOnWyeMtn TS Rookie

    Tmagic650,
    I did some testing, there is not much in the way of signals between the two boards.
    Power = +5, gnd = gnd, sense + = +5, pwr = +3.3, sense - = 0,
    brightness is the only sig that changes, before power = about 5% pwm,
    during power = 90% pwm, after the 2second on state = 50% pwm.
    So it puzzles me as to how the logic is shutting down the high voltage to the bulbs.
    I may look at it more later in the week..

    Bubba
     
  25. Tmagic650

    Tmagic650 TS Ambassador Posts: 21,067   +169

    You can't really test a logic control IC that way. There are no schematics available either. I only know the problem is with this board because I replaced it and the monitor worked... Replacing the power board had no effect on the symptom. I never heard back from Bill on this
     
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