Trying to identify a diode...

[sghill99]

I think I have identified this diode as shorted.

I need help in identifying it...

Anybody know what type it is?

It is in the PCB attached to a Viewsonic VX2235WM-3 LCD screen

Where I can find one?

Thanks in advance.
Scott

[PlainBill]

Re: Trying to identify a diode...

I think I have identified this diode as shorted.

I need help in identifying it...

Anybody know what type it is?

It is in the PCB attached to a Viewsonic VX2235WM-3 LCD screen

Where I can find one?

Thanks in advance.
Scott

Given it's proximity to the inductor, it's probably the rectifier for a bucking regulator. That top line looks as much like a logo as a package ID.

1. Measure the dimensions of the package.
2. Determine the package designation. The SMD Codebook could help.
3. Use a parts look-up like Digikey or Mouser has to find a high speed diode in that package. I'm guessing that it is a schottky diode rated at 50 volts and 2 amps.

An additional clue could be obtained from the Maxim IC which appears to be part of the circuit. The application note for it might show the voltage and current rating for the diode.

PlainBill

[sghill99]

Re: Trying to identify a diode...

PlainBill, I think I identified this as a Zener Diode. I don't have a smd readily available, but found four axial Zener Diodes at Fry's. The four I found are:

24V 1W
18V 1W
2.4V 500mW
8.2V 500mW

These axial zener diodes are real, real small. I think I may be able to bend the legs of the diode around and soldier them into the SMD slot on the board.

Any possibility this may work?

Thanks...

[PlainBill]

Re: Trying to identify a diode...

PlainBill, I think I identified this as a Zener Diode. I don't have a smd readily available, but found four axial Zener Diodes at Fry's. The four I found are:

24V 1W
18V 1W
2.4V 500mW
8.2V 500mW

These axial zener diodes are real, real small. I think I may be able to bend the legs of the diode around and soldier them into the SMD slot on the board.

Any possibility this may work?

Thanks...

Why do you think it is a zener diode?

PlainBill

[sghill99]

Re: Trying to identify a diode...

Not knowing there was an SMD Codebook, I just Googled TS and Diode, from there came up with the zener...

I looked over the Codebook, I'm still puzzled... I looked up schottky diode at digikey, and from looking at them, I still can't find anything that looks like this thing looks...

[FIXITNOW]

Re: Trying to identify a diode...

from cook book
A4t = BAV70 Philips B SOT23 dual diode

A4t = BAV70 Philips B SOT363 dual diode

[Toasty]

Re: Trying to identify a diode...

MAXIM MAX1518B datasheet shows a Schottky, 3A @ 30v coming from LX connection, with a 3.0 µH coil on the anode side. Similar to that configuration here, with a 3.3µH coil.

Have you removed the diode and tested it? Schottky's don't test out the same way as "regular" silicon junction diodes do. In circuit, you're likely across another component.

Toast

[Toasty]

Re: Trying to identify a diode...

@ Fixitnow = there's a question from a previous post on what that marking is.
AA tilted?
44 tilted?
A4 or 4A ?

Plus, it's only a 2 connection device, not 3 as the A4T cross indicates.

Oddly looks like the Motorola symbol...?

Toast

[sghill99]

Re: Trying to identify a diode...

Thx for all the help. I have not removed it yet, I tested it in circuit. I'll take it out and have another look if you think that would be helpful... I've contacted Viewsonic and am trying to get the schematic for this PSB.

Thanks

[PlainBill]

Re: Trying to identify a diode...

MAXIM MAX1518B datasheet shows a Schottky, 3A @ 30v coming from LX connection, with a 3.0 µH coil on the anode side. Similar to that configuration here, with a 3.3µH coil.

Have you removed the diode and tested it? Schottky's don't test out the same way as "regular" silicon junction diodes do. In circuit, you're likely across another component.

Toast

Using 'diode + 3A + 30V + Schottky + surface mount + in stock' on Digikey comes up with 41 hits, most of which represent different packaging methods. Knowing the dimensions of the package, it should be easy to find one which will work.

PlainBill

[sghill99]

Re: Trying to identify a diode...

PlainBill felt this was a DIODE SCHOTTKY 3A 30V SMB. I'm not good at figuring out the size of the component so I can order it. I've included another picture of it along with a mm scale.

Can anybody help regarding what size this thing is so I can order it. I can figure out measuring it, I just don't understand the naming conventions regarding size.

Thanks much for your time!!!

[PlainBill]

Re: Trying to identify a diode...

PlainBill felt this was a DIODE SCHOTTKY 3A 30V SMB. I'm not good at figuring out the size of the component so I can order it. I've included another picture of it along with a mm scale.

Can anybody help regarding what size this thing is so I can order it. I can figure out measuring it, I just don't understand the naming conventions regarding size.

Thanks much for your time!!!

It would have helped if you place the scale closer to the diode. I acturally had to mark a piece of paper and slide it down the screen to line up with the scale!! Oh, the inhumanity!!!

That looks to be 4mm long and about 2mm wide. The picture doesn't give me a clue as to thickness. This might be a Rohm PMDT package or the equivalent from another manufacturer. Likely part numbers are RB050LA-30CT-ND (RB050LA-30TR) and RSX301LA-30CT-ND (RSX301LA-30TR). The first numbers are the Digikey stock numbers; the numbers in parentheses are the manufacturer's part numbers.

PlainBill

PS Thanks for giving me something to whine about. Maybe I can find some cheese to go with that whine.

pb

[sghill99]

Re: Trying to identify a diode...

Thanks much PlainBill...........I'll order them today and see what happens...