White screen, lm1117 is heating

[GeneGenie]

Hi, I have got this product(DSO Shell).
Power it with 9V 600mA power supply.
It works about one week, voltages in test points was alright.

A week later it doesn`t turn on:
- Screen is white all the time
- Led "D1" is blinking twice
- 3 seconds later Lm1117 have a great heating
- STM32F103C8 has a heating too
Voltages at this moment: "V+" = 7.6V; "+3.3V = 3.2V;

Anyone had this problem? What should I do?
Thanks

[jye1]

Did the heat on MCU and LM1117 goes high (like hard to touch) or was it stable at a certain temperature? It is normal the chips are warm.

[GeneGenie]

Did the heat on MCU and LM1117 goes high (like hard to touch) or was it stable at a certain temperature? It is normal the chips are warm.

hard to touch. I have to shut it down, before it is going to melt

[gobo]

Helped me a replacement and programming STM.

[rickseiden]

I'm seeing the exact same thing. White screen and a regulator that is way too hot to even touch. It's even too hot to touch the other side of the board.

I went through the test points and took down all the voltages:

Input: 9.14
3.3v: 2.25
V+: 8.07
AV+: 6.26
V-: -7.22
AV-: -5.84
V1: 0
V2: 0
V3: 0
V4: 1.41
V5: -0.96

I think it's pointing to a bad 3v3 regulator. Can someone confirm that's the issue? Or is it something else?

Thanks
Rick

[swed]

Hmm, I have a new DSOshell coming soon, my first did never function
Maybe time to buy some other brand. Or put better parts on it.

[jye1]

@ rickseiden:

How about U1? Was it hot also?

[rickseiden]

How about U1? Was it hot also?

Yes. Not as hot as u3, but almost too hot to touch.

It was working when I first put it together, but I never actually got to use it in a real world situation.

Then I tried to use it, and the screen was weird. It was like it was having trouble drawing the screen right. I did a factory reset according to the manual, and it worked OK for a little, then had trouble drawing, then just white screen.

Thanks
Rick

[jye1]

What was the power supply voltage? Can you monitor the +3.3V voltage when the problem happen? If LM1117 is bad and we send you a replacement chip would you be able to remove the old one and solder on the new one?

[rickseiden]

What was the power supply voltage? Can you monitor the +3.3V voltage when the problem happen? If LM1117 is bad and we send you a replacement chip would you be able to remove the old one and solder on the new one?

Supply voltage is 9.14 V

3.3V test points read 2.25V

Yes, if you send me a new chip, I'll be able to replace it.

Thank you,
Rick