Fujitsu monitor: power is there, but no image from PC

[jvelez]

Hi, seeking for guidance on the following:
I have a Fujitsu Siemens monitor T19-1 (base model is C19-1) that stopped showing any picture, besides the FS logo when it boots.

I'm attaching a picture of the system board with some additional info.
- The monitor recognizes the presence of the VGA signal: the power button switches from amber to blue, and vice-versa when the computer goes sleeping.
- The inverter + CCFL seems to be working fine: the Fujitsu-Siemens logo appears when the monitor is switched on.
- I measured the values in the power regulators:
8050: 1)Vin = 12V 2) SWout 0 = 5V 3)GND = 0 4) Vos = 5V 5)S.start = 2.4V
AIC 1084: 1) 0V 2) 3.25V 3) 5V

Any guidance highly appreciated: I cannot find a Service Manual for this monitor, and my experience with displays is basic.

Thank you in advance,
José

[lotas]

Re: Fujitsu monitor: power is there, but no image from PC

The problem may also be in the W39F010 firmware.

[CapLeaker]

Re: Fujitsu monitor: power is there, but no image from PC

First I would take that square IC in that brown square socket out and reseat it.

[harp]

Re: Fujitsu monitor: power is there, but no image from PC

That may be a "two seconds to off" simptoms, power supply issue common with bad electrolitic caps, or arcing on ccfl lamp.

[jvelez]

Re: Fujitsu monitor: power is there, but no image from PC

Hi, Thank you for the hints!
- I took out and reinstalled the PROM(?) brown socket -> no changes.
- I also checked with the DMM all the FBxxx SMD components, I guess they are fuses ... all seem ok.

Same behavior:
->I see the logo in the screen for one second or so (as it has always done).
--> after that, nothing: neither image from the PC nor menu/OSM when I push the respective buttons...

I will now try to check for the Vcc in all ICs...

[CapLeaker]

Re: Fujitsu monitor: power is there, but no image from PC

Show us a picture of the inverter.

[jvelez]

Re: Fujitsu monitor: power is there, but no image from PC

Some pictures of the inverter (both sides) plus the back of the main (square) board...
Visually, I cannot spot any particular signs of damaged capacitors or similar.

[harp]

Re: Fujitsu monitor: power is there, but no image from PC

Maybe cold solder near R227 on HV transformer pins

[CapLeaker]

Re: Fujitsu monitor: power is there, but no image from PC

Unplug the inverter from everything. Now measure with your DMM in Ohms setting both of the transformers primary and secondary windings and compare them to each other.
The HV windings got to be within 3% of each other.

[R_J]

Re: Fujitsu monitor: power is there, but no image from PC

I agree with harp, re-solder those transformer connections. Those connections are bad so look for similar bad solder connections on the board

[CapLeaker]

Re: Fujitsu monitor: power is there, but no image from PC

Yes there are cold solders on the transformer, good eye! 4th picture.

[jvelez]

Re: Fujitsu monitor: power is there, but no image from PC

Thank you again for the advices!
- I checked both transformers in the inverter, and I have a max of 0.2 ohm in the longest primary coil (0.1 or even zero in the intermediate derivations), and resp. 194 and 199 ohm in both secondaries --> seems ok with the 3% ballpark rule.
- I re-soldered all transformer terminations --> indeed they seemed bad in one of the transformers.
- I checked Vdd/Vss in all ICs in the main board, getting 4.8 or 3.2 volt in all of them...

One thing I noticed: inductor L903 (blue component, please see photo) in the power switching section is extremely hot. Is this normal for an inductor?
Without wanting to be pushy, one more question: what are components CPxxx (e. g. CP401) in the main board?...

[R_J]

Re: Fujitsu monitor: power is there, but no image from PC

The inductor can get quite hot under normal operation, CPxxx are likely capacitor arrays (4 capacitors in one case) similar to the RPxxx which are resistor arrays. Did resoldering the transformers etc. change anything?

[jvelez]

Re: Fujitsu monitor: power is there, but no image from PC

Thank you and sorry, I forgot to mention that the behavior is still the same, the logo pops up and nothing else, no picture or reaction to pushing the menu buttons...

[lotas]

Re: Fujitsu monitor: power is there, but no image from PC

Does the backlight stay on? Do you have a programmer so you can read and program flash?

[jvelez]

Re: Fujitsu monitor: power is there, but no image from PC

Hi Iota, No it doesn't! I just checked in total darkness to be sure, and in fact the CCFLs switch on briefly during the display of the logo, and then switch off.

I can have access to an EEPROM/flash programmer is necessary (I've built one myself, but it only works for the old UV EPROMs...).

[lotas]

Re: Fujitsu monitor: power is there, but no image from PC

Well, just in case, I'll post a dump.

[harp]

Re: Fujitsu monitor: power is there, but no image from PC

In 3 a.m. at night, when is all quiet, dark and still, shut off room light, come close to monitor keep breath and power on monitor. Screen is pointing and rest on table, to not interference in test. Can you hear any fine sounds of sparking, arching or eyespot it on pcb or ccfl connector, like not so bright electrity?

[CapLeaker]

Re: Fujitsu monitor: power is there, but no image from PC

Disconnect the CCFLs backlights and wire a regular twist household CFLs (without the electronic ballast) to the inverter. Turn it on and see what happens.

[jvelez]

Re: Fujitsu monitor: power is there, but no image from PC

Thank you Iotas and Harp!
- After the question posed by Jotas I did exactly that test, and I'm pretty sure there is absolutely no hissing or visible sparkling I could notice.
- I also checked the tensions in the pins of the connector that goes from the main board to the inverter (photo), and I although I don't have the schematic I got reasonable values:
------------------
red wire = 12volt
blue " =12volt
white " = 0 without VGA signal, 3.2 with VGA signal
yellow " = 4.8 volt
black " = 0
black # = 0
-------------------
The repeated questions about the inverter from all more experienced persons than me in this Forum is leading me to conclude that the problem is somewhere in the inverter (something I was ruling out in the beginning...).
As such, I will verify next the elec. capacitors and the 4 MOSFETS in the inverter. There are also a couple of zeners there, maybe it is worthwhile to check them as well... (The transformers are apparently OK)