Old Compaq TFT5030 Monitor - won't turn on

[Rolin]

I have an old Compaq TFT5030 LCD that won't turn on. Dead when hitting the button.

Heres what I have found. You'll notice in the pic 2 red circles and a blue line between them. The lower red circle is a fuse - it's blown. The blue line follows a trace up to a regulator numbered SK 8033JD (data sheet http://pdf1.alldatasheet.com/datashe...SI-8033JD.html ).

The 8033JD pins measure as follows 12.33V, 6.94V, 0, 6.88V, 2.428V

According to the data sheet, the output should be 3.3V, not over 6V.

Let me know if I'm correct on this, but it appears this regulator is double the output it should be and it blew the small fuse.

If I'm right, where can I find this regulator? I can't find a cross at digikey. If I'm wrong, let me know where I went wrong! And what should I do next!

Thanks as always!!

Rolin

(This is such an old 15" monitor, don't know why I just don't toss it! But I can't help myself, I just have to fix the darn thing! What's wrong with me....)

[retiredcaps]

Re: Old Compaq TFT5030 Monitor - won't turn on

The 8033JD pins measure as follows 12.33V, 6.94V, 0, 6.88V, 2.428V

According to the data sheet, the output should be 3.3V, not over 6V.

Let me know if I'm correct on this, but it appears this regulator is double the output it should be and it blew the small fuse.

Yes, when something outputs close to double the correct voltage there will be some collateral damage.

Here is how I did the search in digikey.com

1) From the SI-8000JD datasheet, I see the words "step down switching mode regulator".

2) Then I click on "in stock".

3) Then I narrow down the search by selecting output type = fixed.

4) voltage-output = 3.3V

5) supplier device package = to263-5 (from datasheet)

6) click apply filters and I have 14 choices

7) I choose this one (1A output current) and lowest price

http://search.digikey.com/us/en/prod...NOPB-ND/363645

because that part number is sort of fresh in my mind from 2 days due to this thread ...

https://www.badcaps.net/forum/showthread.php?p=220909

8) Double check the original and replacement datasheet to make sure the parameters are correct.

9) You might be able to find this IC on an old junk motherboard as 3.3V is commonly used.

(This is such an old 15" monitor, don't know why I just don't toss it! But I can't help myself, I just have to fix the darn thing! What's wrong with me....)

Nothing. I have a few items here that are beyond economic repair when you factor in materials and my time, but I like the challenge and enjoy fixing them.

[Rolin]

Re: Old Compaq TFT5030 Monitor - won't turn on

UPDATE: I replaced 8033JD with LM2575S-3.3/NOPB from DigiKey, and also the blown fuse. It powers up and it works great! Thanks for the help!

[retiredcaps]

Re: Old Compaq TFT5030 Monitor - won't turn on

UPDATE: I replaced 8033JD with LM2575S-3.3/NOPB from DigiKey, and also the blown fuse. It powers up and it works great!

Whew, 1/1 on recommending substitute parts this year. I thinkI will quit while I'm ahead.

Just wish it was cheaper than $2.70.

[Rolin]

Re: Old Compaq TFT5030 Monitor - won't turn on

I'll help you improve that score, so don't quit yet! I have a few more LCD's to go!