原创 Updates from Me

Hi, long time no see!

This September will be a different one for me, since I am not a student anymore...

I was busy for my Final Year Project (also known as Graduation Project, or 毕业设计) in the last term. And after finished all the schoolworks in May, I became lazy...

I still remember how happy I was when I got to know logic gates in my first year in University. However, I have not tried all the logic gates that I have yet...

Fig. My DIP IC collection in these 4 years

Now I am working in a technology company as a junior engineer. My main duties include the development of some sensors.

Although the workload in school was heavy, I still do other hands-on works for interest.
Here are just some of the tasks over the past few months..
 

Reuse and repair a LCD from an old notebook computer
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A friend gave me a very old notebook computer. However it could not be turned on...
Since it was too old, I decided not to repair it...

Fig. A very old computer (manuf. in 2000), cannot boot up
 

Fig. Re-use the panel as a monitor with a TV kit, however, the screen is grey

The vendor of the kit said it was due to the bad OP262.
I could not find one on my hand, so I replaced it with a general Op Amp, LM358. Although from the datasheets of OP262 and LM358, LM358 has a much lower performance, it worked.
 

Fig. Replace the OP262 by a LM358

 

Fig. The LCD works fine afterwards

I was surprised that it could show the contents clearly...
 

Fig. The LCD Kit
 

The Li-ion battery of the notebook was taken apart. Then with some 18650 battery cases, they were used for external chargers, which could be used for phones.

 

Fig. The 17670 Li-ion Battery

 

The remaining parts were put to recycle.

 

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Replace a circuit board of a LCD TV
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The power circuit of a LCD TV went out of order. The 5VSB was only 0.x V.
The markers (model number) of the SMPS controller could not be seen clearly. And I could not find the same board online for replacement. So it was replaced with a 'universal' LCD power board. Because the backlight circuit was not compatible with the old one, reusing the old circuit would be good.

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Repair a router
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I like collecting routers and re-distributing to friends. Sometimes I could buy a 2nd-hand router from local street vendors (地摊) for as low as HKD$5 to $10 each.
Then I will check and give out to people who need a router.

Some routers worked fine. While some needed firmware upgreades. And a few were bad. I would try my best to repair and usually my job was successful, but not always.

Fig. Top I like collecting routers; Bottom: MP9141ES replaced by LM2596

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Repair an induction cooker (failed)
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Fig. The induction cooker and the power board

I tried replacing the transistors driving the IGBT and some other components, but still failed.

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Repair a notebook
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The IC in QFN (or DFN) packages were not well soldered (dry joint), making that the notebook out of function. After soldering the ICs, everything was fine then.

Fig. Re-solder the USB3.0 and Ethernet IC in QFN packages
 

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Repair another notebook
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Just to improve the heat conduction.

Fig. Improve the heat conduction by aluminium sheets

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Repair another notebook
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Broken joint for the graphic chip (in BGA package). Hopefully it could run for a long time.

Fig. Heat re-flow on the graphic IC

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Repair another notebook
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The SMPS controller was out of order, causing the notebook could not be started.

Fig. Replacing the notebook's controller IC, MAX1999

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Repair a radio alarm clock
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Bought a radio alarm clock for $20 from street vendors 地摊. The power circuit was burnt and repaired. I changed it to a regulator circuit by MC34063 with input voltage 12V, output 4.5V.

Fig. The alarm clock

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Repair MP3 players
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I bought 5 MP3 players for HKD$10 each. I saw that actually the scratch-protective sheets were not torn - the MP3 players could be brand-new!

However, none of them could be charged no matter how long they were connected to external power. The battery could be over-discharged.

Fig, The MP3 players, and installed dedicated charger IC (left-bottom)
 

I found that there was no Li-ion charge IC inside. The Li-ion battery is connected to the USB port power via a diode and a resistor only. Then the charging current is limited by the PPTC of the battery... Although they were using Samsung's flash, the charging circuit was poor...

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Repair an air dryer
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Replaced the rusted push button of an air dryer.

Fig. The control board of the air dryer

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My on-going projects:
1. A school website (not paid)
2. A PCB for a robot
3. Have fun on Raspberry Pi and Banana Pi

Fig. A Raspberry Pi and Banana Pi, from Taobao

4. Play with Intel Galileo Board

Fig. The Galileo Board, also from Taobao

5. DIY a simple air cleaner
6. DIY a ice box (by Peltier effect panels)

As time went by, I will leave (actually already have left) the University.

I will miss the lovely cats.

Fig. The lovely cats in the University