[SOLVED]A1398 820-3662 No image after screen repair

Status
Not open for further replies.

Tony Tone

Member
I was changing the screen and think something with the screen was wrong. I witnessed L8300 turn bright red and blow. I changed it and watched it blow again. I did this about 3 times (it was pretty cool).
I have tried multiple know good screens (brand new) and don't get any image.

Looks like the only voltage I get is 1.5V on pin 12.
I get 5V on pins 2&3 on U8300 but that is it.
 

Tony Tone

Member
When I put in a different LCD I get voltages. I have 3 new (still in packaging) LCD's never used. Can't believe all 3 of them are bad.
 

dukefawks

Administrator
Don't use comments I don't see them.

If there is 5V on both sides and there is an image it must work. I doubt it will cause video garbage, but anything is possible.
 

Tony Tone

Member
OK. I changed L8300. Out of the several screens that I was testing with, the one that had a distorted image is actually good when I used the good L8300.
You can close this mystery out ! A bad L8300 can cause a distorted image. I thought L8300 was good because it had continuity. L8300 is an inductor? Like a coil?

I didn't know that you couldn't see comments, that is weird. I will post them below.
Comments:
FL8300-FL8303 have continuity. L8300 good. Caps C8320 & look good and present.
So it can have continuity and still be bad?
Would a bad L8300 cause a distorted image on the screen?
Or would it not allow the screen to be "seen?"
Thank you Duke
 

Tony Tone

Member
So I am trying to order some more of these from Digikey. But I can't figure out the values of what is needed. The schematics say its an inductor L, ferr makes me believe its a ferrite bead? But the 220-OHM is confusing.
 

dukefawks

Administrator
Looks like it to me. Why all the effort to get this when you should just get a pile of donor boards, or just put a wire in place.
 

jadao

Member
This is absolutely not needed for board repair, but let's make it more confusing:)

Equivalent circuit of ferrite inductor is a resistor and a coil in series. R in series with L.
The symbol used in the industry is L wether it s a coil, a filter, a ferrite bead, inductor...
220 ohm mentioned in schematic for L8300 is not a resistor value it is an impedance value.
Impedance is a complex number that contains two parts: the resistance (R in ohms) is the real part and the reactance (X in ohms, X=2PifL) is the imaginary part.

Usually industry uses only impedance and dc current range for ferrite.
 

G.Beard

New member
This is absolutely not needed for board repair, but let's make it more confusing:)

Equivalent circuit of ferrite inductor is a resistor and a coil in series. R in series with L.
The symbol used in the industry is L wether it s a coil, a filter, a ferrite bead, inductor...
220 ohm mentioned in schematic for L8300 is not a resistor value it is an impedance value.
Impedance is a complex number that contains two parts: the resistance (R in ohms) is the real part and the reactance (X in ohms, X=2PifL) is the imaginary part.

Usually industry uses only impedance and dc current range for ferrite.

Basically it's not a DC resistance and you can't throw a resistor in it's place.

Donor boards here:

https://www.aliexpress.com/store/pr...tina-15-A1398-repair/1596219_32611298760.html
 
Status
Not open for further replies.
Top