Announcement

Collapse
No announcement yet.

User Profile

Collapse

Profile Sidebar

Collapse
Avatar
stroogly
Member
Last Activity: 12-14-2009, 09:48 AM
Joined: 02-24-2009
Location:
  •  
  • Filter
  • Time
  • Show
  • Source
Clear All
new posts

  • Re: Hanns-G HU171D & 171A - Blank (white) screen... both of them.

    >>LVDS is very LOW voltage differntial signal. Swings around .8V or less. The LVDS ICs
    >>if there is, uses 1.7 to 1.8V, not 3.3V.

    Hmmm... That makes sense, so I double checked the datasheet.

    The LVDS transceiver and the AD converters run off 3.3V supplies; the DVI transceiver and the core (microprocessor) run off 1.8V supplies.
    See more | Go to post

    Leave a comment:


  • Re: Hanns-G HU171D & 171A - Blank (white) screen... both of them.

    Is the chip with the sticker on top a Genesis GM5621? Looks like one.

    This chip needs 1.8V for the brains. You have that, otherwise your LED would not change color when you give it a signal.

    It needs 3.3V for the LVDS part of the chip. If this is out it could explain why you have no video.

    If it is in fact a gm5621, this is the whole circuit except for the power supplies!

    I work for a Genesis developer. This is a nice chip. Least it is when it's work...
    See more | Go to post

    Leave a comment:


  • Re: Hanns-G HU171D & 171A - Blank (white) screen... both of them.

    A lot of the newer chipsets (genesis, for example) require 3.3v, which is usually produced right next to the chip. If this PS is out, that could explain your symptom.

    Poke around with your meter and see if you see some biggish caps that don't have any voltage on them.

    Also, once in a while the crystals or crystal oscillators overheat and blow out.

    A pic of the visdo board would be useful.
    See more | Go to post

    Leave a comment:


  • Re: inverters with C5707 benq hp 1940

    The poly caps are .33uf and they look and measure nice. The brown spots are on the opposite side of the PCB from the resistors.

    I'll have to get one of those ringer things. My friend who is an old-school CRT guy told me I need to get one too, so I suppose it is time.

    sofTest: What is the FQU11P06? Is that the FET that drives the C5707s?
    See more | Go to post

    Leave a comment:


  • inverters with C5707 benq hp 1940

    I just found out about badcaps and am amazed at the amount of information here. I have been going through all the old posts and seeing how the experiences of other tech compares with mine.

    One of the subjects I have seen discussed a lot are the inverters based on the C5707. Often these are found in 4 lamp combo inverter / power supplies that have a simple tank circuit with 2 C5707s driving 2 transformers.

    Most often these boards are made by Benq and are found in Dell and HP 17",18" and 19" monitors.

    My experience has been that one C5707...
    See more | Go to post

  • Re: Gateway 900G frustration

    All the electro caps in all the monitors were Samxon GF. I wanted to make sure GF was the series, so I googled "Samxon GF". Can you guess what the first 2 hits were?

    Cheers-

    -Michael
    See more | Go to post

    Leave a comment:


  • Re: Gateway 900G frustration

    All hail eguevarae! And thanks to everyone else.

    There is a 47uf/25v cap next to the switching transistor; I didn't trace it out but it looks like it is part of the network that gets feedback from the optoisolator on the primary side.

    Anyway, replacing it with a 100uf/25v make the circuit magically come to life. The kicker is the one I pulled measures 40uf and holds a charge. That's damn close to what it should be, but apparently not good enough.

    I guess the lesson is you need to be suspicious of ALL electrolytics...
    See more | Go to post

    Leave a comment:


  • Re: HP F1523 - 2 secs display then darkness

    Before you replace any more stuff, you might try plugging in 2 known good backlight lamps and seeing if they stay on. Careful with the high voltage.

    Most inverter circuits have a current sense that turns off the inverter if either lamp is open.

    Also, if you are still having a flash symptom, it is not a fuse so you needn't look for one. If the fuse blows, the inverter won't come on even for a second.

    Hope that helps-

    -Michael
    See more | Go to post

    Leave a comment:


  • Re: Gateway 900G frustration

    Interesting information!

    eguevarae: I did not fiddle with the little electrolytic caps, but I know what your saying! I don't have the board in front of me, but I believe there is only *1* electrolytic that is that small. I'll try your suggestion tomorrow.

    toasty: I tried comparing voltages between the good and bad ones, but all the interesting areas of the circuit on the bad one are bouncing up and down with the ticking like a bunch of drunk kids in a mosh pit! I'll get really meticulous tomorrow with comparing the circuits...
    See more | Go to post

    Leave a comment:


  • Gateway 900G frustration

    Hi All,

    I have about 10 Gateway 900G 19" LCD monitors with the same problem.

    They make a slow ticking and the 5V bounces in time with the ticking.

    If I had a camera here I would take a pic of the guts, but I don't have one so I'll give a description.

    It is a 4 lamp 19" LCD with the power supply (100-240AC in) and inverter on one board. It has your basic 12V 5V switching power supply with 12V going to the inverter section.

    Here's what I know so far:

    It is not caps. I replaced all the electrolytic...
    See more | Go to post
No activity results to display
Show More
Working...
X