Belinea 101715 (help for identifying zener diode)

[srbax]

Happy New Year and very best to all!
I hope I wrote this correctly

On power board of this Belinea 101715 (model 111717) monitor I found shorted mosfet (K2996), bridge rectifier, fuse and one smd zener diode.
Mosfet pdf: http://pdf1.alldatasheet.com/datashe...996-TA3-T.html
I can't find service manual for this Belinea model and I don't know how to determine zener diode specifications.
I need Your help in identifying specifications of zener diode.
Diode was on position Z101. On the same pins were resistor of 0.68 ohms.
Like some other zener diodes on board it has only yellow ring without any other markings.

[UniT3d]

Re: Belinea 101715 (help for identifying zener diode)

Hmmm .....

Service manual attached. I'm not quite sure about Z101 but I believe it should be TZX24B ... Hope that helps.

[budm]

Re: Belinea 101715 (help for identifying zener diode)

Too bad that the service manual does not have the power supply diagram, that Znere Diode is in parallel with the MOSFET Source resistor, it is there to limit the voltage drop on the Source during startup, there is a voltage spike when the power supply is first turn on which can fault triger the Isense signal of the SMPS IC that monitor the current flowing through the Source resistor.
Have to Google the pwoer supply board to find the diagram for it.
When the MOSFET blow up, it will usually take the SMPS IC Gate drive circuit in side the IC and also the Gate drive resistors and Diode. You need to check them all carefully. Otherwise you will blow up your new MOSFET if the Gate drive circuit is stuck with steady High output condition. You can look up the spec of that SMPS IC, sometime they will have application notes showing how the circuits should be made, may be it will show the Zener diode in that app notes.
See example SCH, in this drawing, it is ZD301.
Most companies do not have this Zener in the circuit.

[srbax]

Re: Belinea 101715 (help for identifying zener diode)

Thank You all for Your answers!
Marking on SMPS IC is 203D6 and I found datasheet for NCP1203.
I checked resistor and other diodes and they have correct values.
Do You think that SMPS IC is also have to be replaced?
Is it possible for this power supply to work without that zener?

[budm]

Re: Belinea 101715 (help for identifying zener diode)

OK, lets test the IC resistance reading of all the pins of the IC between pin 4 (Ground) and the other pins to see what you get, make sure to tell us what it shows on the meter so we know for example 1 ohm, 1K Ohm, or 1M ohm.
Then check the resistance between pin 5 (Gate Drive) and pin 6 (VCC) to make sure the internal is not shorted.
The power supply will work without the Zener for now, as you can see in the diagram, they did not have the Zener at the Source of the MOSFET either.

[srbax]

Re: Belinea 101715 (help for identifying zener diode)

pin54=296 Kohm
pin64=216 Kohm
pin74=0L
pin84=367 Kohm
pin14=22.5 Kohm
pin24=41.2 Kohm
pin34=0.54 Mohm
pin56=429 Kohm

[srbax]

Re: Belinea 101715 (help for identifying zener diode)

I was searching for service manual for this monitor and in this post https://www.badcaps.net/forum/showthread.php?t=21185 I saw that Viewsonic VE710b monitor has the same power supply board.
Does anyone have service manual for this monitor?
Model of power supply board is SLV0315A0450-00.

[srbax]

Re: Belinea 101715 (help for identifying zener diode)

I think I found it, but there is no values for components:

[terry]

Re: Belinea 101715 (help for identifying zener diode)

The power board on this monitor might help. http://linfotech.co.uk/schematics/Proview/Preoview 20LCD 20fv926afw.pdf