Short on Digital board

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JayisGreat
Posts: 1
Joined: Thu Oct 11, 2018 11:01 pm

Short on Digital board

Post by JayisGreat »

Short on Digital board.
DSO Shell 15001K (SMD pre soldered), User Manual Rev.08

Step 1. I connected a 9 volt 500ma regulated supply. The display would blink white for a moment then go out. I checked the power supply voltage while it was disconnected, 9.1v, when connected, 2v pulsing when connected. With the power supply disconnected I checked for an input short, none found.

Next I connected a 9v battery (for more current). The display lit white for a few moments longer (nothing on the display, just white), the 3.3v regulator started getting hot.

I disconnected power and checked the 3.3v regulator for a short. It appeared shorted. I removed the regulator and tested it, it tested good (3.3v). With the regulator removed, I checked 3.3v pads to ground, there is a 1 ohm short.
I checked the non vcc/vdd pins to ground on all IC’s, no problems. I removed several capacitors (and L1), that connect to ground, still shorted. Checked all visible traces (under magnification), no shorts.

I hate to remove the processor and the eeprom (all pins other than vcc/vdd check “not shorted”) to check.
Do you have a diagram showing where the traces go.
I know it is cheaper to buy a new kit than it is to send it back or to repair it. I just want to know what’s wrong.
jye1
Posts: 1221
Joined: Wed Feb 20, 2013 4:58 pm

Re: Short on Digital board

Post by jye1 »

Please see attachment.
150PCB_clip.jpg
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