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HP MX703 (P9605A) Monitor (Service question)

By betablue
Mar 8, 2007
  1. Hi,
    maybe for some it's a trivial question, but if you know the answer, please post it here.

    How to open the HP MX703 (P9605A) Monitor, without damaging it, so we can access internal electronics for troubleshooting and service?

    I just got this unit for a repair and I removed 3 screws in the base and that's it - it just won't open. It has 4 holes on the side that look like latch holes, but trying to open it there with a screwdriver doesn't work.

    As per pictures, even mild pressure from prying it with a flathead screwdriver leaves marks on the plastic cover.

    Thank you.
     

    Attached Files:

  2. gavinseabrook

    gavinseabrook TS Rookie Posts: 320

    On these types of monitors, they work on clip systems. It is just a matter of finding where all the clips are. When you do find them, take a small flat head (like in eye glass repair kits) and work your way around the grooves to see if you can find these clips. Once you have them all out, you should be able to take off the casing. Good luck.
     
  3. betablue

    betablue TS Rookie Topic Starter

    I used a knife to push the latches in (about 2-inch each) and it worked.

    There are 4 latches: right behind the holes on side of the monitor but have to push them quite deep to release. If U use soething flat (like a knife) you can feel as they spring on you.

    There is one more latch on the top center of the crt housing, but it released it's hold once the other 4 were loose.

    Thank you for the advice - it re-assured me that I was looking in the right areas, just been cautious as I did not want to damage the plastic housing.

    Now, the fun begins...

    This unit came completely dead (no power), so I'll start looking around power supply first.
     
  4. betablue

    betablue TS Rookie Topic Starter

    Based on some other articles found around the net, I think that blown horizontal output transistor might be a good lead.

    Anybody could show me where to look for it?

    I tried to follow HP service manual, but I can't find area T402, they are referring to.


    [​IMG]

    [​IMG]
     
  5. Tmagic650

    Tmagic650 TS Ambassador Posts: 17,244   +234

    The HOT (horizontal output transistor) should be mounted to the metal shield around the flyback (high voltage) transformer. This is the transformer with the heavy wire going to the CRT (cathode ray tube)

    Also,
    be sure to check for cold solder connections on and near the flyback and HOT...
     
  6. betablue

    betablue TS Rookie Topic Starter

    Is it that big TOSHIBA C5386 Transistor as shown on the picture?

    Can I test it in-line (without removing from PCB)? On reverse side it appears to be Q433 with points B,C,E.
    (All solder points on this picture are original factory - I didn't touch anything yet.)

    [​IMG]

    [​IMG]
     
  7. Tmagic650

    Tmagic650 TS Ambassador Posts: 17,244   +234

    Yes,
    the C5386 (2SC5386) is the horizontal output transistor
    D435 next to the 2SC5386 is the damper doide
    T440 is the flyback transformer
    P440 is the horizontal/vertical yoke connector

    You can check the 2SC5386, but you have to pull the leg
    going to T440. If you don't, it will read shorted even if it is good.

    From the look of the board, I suspect that the 2SC5386 is good,
    and although it is always advised to resolder all the high voltage
    power supply connections when servicing a monitor, the solder looks ok.
    T440 is the heart of the hi-volt power supply. With modern monitors, it
    is more likely that the low voltage supply goes first. It is connected
    to the AC house plug
     
  8. gavinseabrook

    gavinseabrook TS Rookie Posts: 320

    Well im glad I told you how to open the monitor, but damn Tmagic. You rock that engineering ****e lol
     
  9. Tmagic650

    Tmagic650 TS Ambassador Posts: 17,244   +234

    Thanks gavinseabrook,
    I've been doing this kind of thing for many years. There is a more obscure fault that keeps some monitors from turning on. It is the video processor. This IC handles color signals to the CRT, but it also sences horizontal timings from the computer. These horizontal timings trigger the monitor to come out of "sleep" mode.

    Betablue hasn't really told us if the monitor is totally "dead" or not...
     
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