Repair.IT – Table Tennis Table Support Leg

I was at my local community centre before Easter. They have a number of table tennis tables which get pulled out regularly (almost daily) for people to play table tennis. With all of the use, and sometimes heavy hands, the tables are quite worn and have a few faults. One in particular had a broken support leg, which made it unusable. I had a quick look at it and thought that all it would need is a few brackets to fix the rolling support leg, and it could be as good as new.

I had a look at what Bunnings had to offer and spoke to the community centre about it and offered to fix it for the cost of the parts, which I estimated to be about $30-40. Then it was a matter of getting the parts, then on Thursday last week, I was able to get the leg removed to bring home where I can do the repairs.

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Here is the support leg removed from the table and separated into its various parts, mainly removing the wheels. The top section was welded but this is what had broken.

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A T shaped mending plate was the right size, two of these, one on each side, then a couple of right angle brackets for support. The metal is quite thin on the leg, only 1mm, so I had some 40mm square hollow steel section in my garage, so cut off about 30cm of it. This reinforcing tube which is 2mm thick would fit inside the horizontal leg, but because it is a bit smaller than the inside, would need some spacers to raise it to the top of the leg.

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Then additional spacers for the side, since I wanted to get it more or less in the middle of the hollow leg.

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Here I have fastened the reinforcing tube with four Tek screws. Due to the thickness of the tube, I decided to pre-drill 4mm holes where I would install the Tek screws for the right angle brackets.

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I decided that I should clamp it all together and mark out the holes for the mending plate for both sides. The drilling could then be done easily on my milling machine than with a hand-held drill.

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It was a matter of fastening a lot more Tek screws, and I ended with a leg that is much stronger than the original – maybe a bit of overkill, but not bad for less than $40 in parts. I need to wait until after Anzac Day for the community centre to open before I can install the leg and fasten a couple more screws, and also replace a number of nuts and various bits that were also missing.

If I didn’t help them with this, they would probably have to spend many hundreds of dollars on a new table which is probably not as good as the repaired table. They have some more tables for me to look at too!

Repair.IT – Overheating Presario SR5120AN motherboard

Remember two and a half years ago, approximately, I repaired my Compaq Presario SR5120AN motherboard which had a number of failed capacitors?  Ok, it was some time ago, so here is the link.

https://j0hn88.wordpress.com/2014/12/22/reveal-it-faulty-capacitors-on-presario-sr5120an-motherboard/

At the time, five capacitors had failed, but there were still four others of the same brand and size on the motherboard. I checked them with an ESR meter and they all passed. Fast forward to a month ago – I noticed that my computer cpu fan was getting louder, sometimes normal then suddenly high speed and this kept happening. I ran a utility to check the CPU temperature and it was …  99 degrees, wow! No wonder the fan was on turbos a lot of the time.

I shut down and took the computer apart to reveal the motherboard.

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Two of those same original capacitors were showing the symptoms of failure – see the bulging top and black spots. After some effort, I was able to remove these two capacitors, then replace them with the ones in that little bag – I originally bought ten of these 1800uF 6.3V electrolytic high temperature capacitors. I checked the remaining two on the board and they check out fine.

So, reassemble the computer, and power on – leave it on for a while, and I can see that the CPU temperature is sitting reasonably stable at about 80 degrees. This is still quite hot and would appear to be still abnormal. Since I still have three spares left over, why not just replace the remaining two capacitors and be done with it.

That is what I did – took out the other two capacitors, replaced them with new ones. While I was doing this, I checked the capacitors with my ESR meter, which showed that these two were still ok, but anyway I have new ones in the motherboard now. Once the computer was up and running again, leave it for a while and then it was looking good so I decided to run the Passmark Performance Test, which stresses out the computer.

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This is what the CPU and graphics card temperatures were during the test and then the cooldown period afterwards. The CPU maximum went to about 93 degrees but then back down and sitting stable at 54-60 degrees. This is amazing and shows that even though the ESR meter indicated that the capacitors were ok, replacing them reduced the average temperature dramatically. Why is that – maybe the capacitance has changed? Wait, I can check this!

Just over a year ago, I had bought from eBay, a Mega328 Transistor and component tester. I can connect the parts I have removed and compare with new parts.

These two are the failed capacitors. They appear to be back to back diodes with differing forward voltages.

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Here is a new one – my final remaining capacitor. The value is 1829uF, ESR is good, with Vloss of 2.5%.

Here are the two apparently good ones that I replaced. These also appear to be good as far as the tester is concerned, however replacing these two also brought down my average temperature of the CPU. Why? I don’t really have an answer for this, but maybe someone has.

Right now as I am writing this, my CPU temperature is sitting at around 80 degrees, with CPU load at about 85% since my antivirus scan has been running for some time, but certainly nowhere near the 99 degrees at idle that it was a month ago. It has been a few weeks now, and all seems to be well.

Remake.IT – Raspberry Pi 3 with 7″ Touch Screen and housing

A while ago, I bought a couple of the new Raspberry Pi 3’s and at the same time, bought a 7″ touch screen and a housing (which was on special) for it from element14.

http://au.element14.com/raspberry-pi/raspberrypi-display/raspberry-pi-7inch-touchscreen/dp/2473872

http://au.element14.com/multicomp/cbrpp-ts-blk-wht/raspberry-pi-touchscreen-enclosure/dp/249469102

As usual, there can be a delay between purchase and actually assembly or use, due to other commitments. Anyway, a couple of nights ago, I decided to assemble the Raspberry Pi with the touchscreen. The touchscreen was pre-assembled, so all that I had to do was to attach the screen cable to the Raspberry Pi 3, then connect the four wires to provide power and the data signals to the touchscreen controller board. By the way, the instructions did not say that the SDA and SCL signals had to be connected and showed only connecting the ground and +5V pins.

I also needed to download the latest Raspbian operating system, and copy the image to a micro-SD card which I did the next day. Then finally plugging in the card, and fastening the Raspberry Pi down with four tiny screens. Next was placing all this in the housing. All went together and I connected up a suitable power supply and powered up.

Voila! Hmm, the display is upside down – ok, and the touchscreen wasn’t working. Checking out the FAQ on the appropriate sites indicates a fix for the display – to rotate by 180 degrees in the /boot/config.txt then a check to see if the touchscreen hardware was seen by the OS.  Yes, the drivers are active so what is going on? I decided that it was time to open it up and check the touchscreen cable.

To my surprise the cable was disconnected and sticking up at a right angle – then the penny dropped. Putting the case on, must have disconnected the cable, which was connected, but now is not.

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This is the touchscreen cable, the one that is attached to that black square chip – the cable is a little bent at the edge which meant that something was pressing on it. Turning the back of the case around showed me the problem.

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The cutout for the touchscreen cable has a sharp edge, which was pressing down on the edge of the touchscreen assembly with the chip on it, and since the thinner cable is not that long, pushing down on it would pull that thin cable out. Which is what must have happened. I measured the distance from the edge of the case to that touchscreen assembly, then marked on the case where I needed to remove that sharp edge. I got out my trusty file which happened to be almost the right width at the area I needed to file out, and proceeded to remove some plastic material making that marked area more rounded which would reduce the pressure on that assembly.

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Here is the final result. After careful reassembly and checking of the cable which was can just see through slots in the casing for the HDMI socket, I can confirm that the touchscreen cable is still attached.

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After powering up, I now have touch!

 

Rectify.IT – Fujitsu Lifebook P8110 Scroll Lock flashing

On Saturday, while doing a few things around the house, amongst other things – I was checking to see whether or not I could get a second drive caddy for my Fujitsu Lifebook P8110 notebook.  I was trying to remove the DVD drive and at the same time, decided to take all of the covers off the bottom of the notebook.  One cover hid a mini PCIe socket which I believe is for an optional wireless card – or perhaps even a small SSD.  Another slightly larger cover hid the memory socket, in which was installed a Kingston 4GB DDR3 1333 Sodimm, and of course the much larger cover was for the internal hard disk drive.

In due course, I put everything back together and put it back into my backpack since I use it for work as a Windows 10 machine from time to time.  To my surprise this morning, it failed to power up – well, actually the power light came on, the disk light came on then the Scroll Lock light started blinking.  I could still hear the hard disk drive spinning.  There was no display at all, not even the Bios POST screen came on.  I held the power button to force it to power off.  I did this a few times to confirm that I was not imagining it and eventually put it back into my backpack and went on with my tasks using my work laptop.

After coming home, and watching a short movie, I got my Lifebook back out and tried it again – the same flashing Scroll Lock light.  A quick check on the internet showed no solutions however one site did say that it may be power related.  I eventually got the battery removed, and connected the power adapter and still the same.  One site did suggest memory – and yes, I did remove the memory module on Saturday, so could this be it?

I opened the cover and removed the memory – a 4GB module as described above.  I had the laptop screen down and the main body up – i.e. the laptop was open so that I could reach the power button and see the screen but could also access the memory slot.  I pressed the power button, and the Lifebook came to life, as in the Bios screen came up then proceeded to boot to Windows.  I powered off and went in search for some memory.  I had another Kingston 4GB so tried that – no go.  Then I found two new Kingmax 4GB Sodimm’s and tried one – and yes, it worked.  Afterwards I decided to try the original memory – the first Kingston 4GB and while putting it in, I latched and unlatched it a few times since it could be just a contact problem.

So did it work, I can hear you all asking?

Yes, the notebook booted up!  I shut it down, then put the cover back on, then put it right side up and powered on.  Still working, so it appears that the flashing Scroll Lock light is indicating a memory problem.  The motherboard has 2GB of inbuilt memory, so the notebook will boot from this, and my 4GB brought it up to 6GB – more memory of course, is better for Windows 10.  At least I know what to do if this happens again.

Reheat.IT – Dell XPS M1530 laptop

This is about the Dell XPS M1530 laptop that I had worked on at length back in 2015.  At the time, I had heated the graphics chip to a high temperature in order to get it back in operation.  The laptop had failed again and was not powering up except for a couple of lights – so the same failure condition like last time.

Now, we cannot keep reflowing the graphics chip since the heat used may also damage other components, and if the problem continued to occur, then it meant that eventually, the graphics chip would need replacement. After some further research on this problem, I came across an article that talked about the failure mechanism.  It appears that there is some conjecture about why it fails, and most of the talk that it fails because the contacts where it attaches to the motherboard become disconnected.

Ok, what are we talking about, you might ask?  A typical modern graphics chip is housed in what is called a BGA package.  BGA stands for ball grid array, meaning that the chip instead of having lots of pins sticking out the bottom like a lot of the older CPU’s, has instead, little solder balls on the bottom in an array or matrix.  Most sites say that they need to reball the graphics chip – meaning to remove the GPU from the motherboard, clean off all of the solder balls and then put flux and new solder balls on it and then reheat it so that the balls are melted and firmly attached, then place back on the motherboard and reheat it so that the solder balls melt (flow) and join to the contacts on the motherboard.

How do we get all the tiny solder balls onto the chip?  We use a stencil is how we do this – the stencil is made from stainless steel and looks like this.

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This is one for an ATI 215-0719090 GPU that has 0.5mm ball.  There is a small bottle of 25,000 solder balls and a coin for comparison.  However, the Dell XPS M1530 laptop has a nVidia 6800M graphics chip and I don’t have a stencil for it.

Let’s get back to the failure mechanism – a number of other sites say that reballing the chip doesn’t really fix the problem, since it will happen again.  Some also say that reflowing the chip also doesn’t fix the problem and that the solution is to replace the graphics chip.

Now, a number of sites also talked about wrapping the laptop in a towel and let it run until it overheats and effectively reflowing the chip.  Unfortunately, the temperature would never get high enough to reflow since the battery would have exploded by then, so why does it seem to work and to fix the problem, albeit temporarily.

It seems that further research is required and I may have found some.  If we consider how the graphics chip is put together, lots of actual graphics processors are manufactured on a silicon wafer which is then cut up to individual pieces which is called a die.  This is the part on the top of a chip which is the part that touches the heatsink.  On one side of the die, there are lots of contacts, so there are either small leads attached or we might also have little tiny solder balls.  These solder balls connect to the substrate which is the greenish material and then the die is coated all around with some sort of filler material which is meant to keep the die in place and to help protect it against the sort of thermal and mechanical stress that will occur.  The substrate then is where this reballing happens as mentioned above.  This is of course a very simplified description of the BGA chip and can be very confusing especially when the die is also called a flip chip, since it is upside down, i.e. flipped…

So where were we?  Ok, there is some disagreement about why these chips fail. Either the chip is detached from the motherboard or the die is detached from the substrate.  Any one of these hundreds of connections failing would cause the failure.  If the failure was on the die itself, apparently this could be confirmed by heating the die itself – apparently to about 130-150 degrees Celsius is sufficient to get the connections working again.  Now this temperature is well below the melting point of leaded and non-leaded solder so what does this do?

I thought that I would try it out, since I had nothing to lose – I used a hot air rework station to heat the top of the chip at around 100 degrees for 5 minutes or so, and checked the laptop afterwards.  Nothing happened, so tried the other laptop since I have two of them here.  This time I went to 130 degrees and that laptop after this process did power up enough to show that the screen display was very inconsistent – with a lot of breakage and flickering.

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I went back to the first laptop and this time heated at 140 degrees.  I measure the temperature using a temperature probe.  This time, I had success – the laptop afterwards would power up and I could log in and ran some diagnostics – at the same time as using a monitor program to show the temperature of the graphics chip.  The diagnostics ran fine and the maximum temperature reached with the graphics chip was about 75 degrees – ok, fantastic!

Alas, it was not to be – after shutting down, the laptop would not power up.  Ok, so try again by heating to 150 degrees.  I did this and sure enough the laptop came on as normal, and with a notebook cooler attached – blowing air onto the bottom of the laptop.  It has now been a week, with powering on and leaving it running for a few hours then shutting down and checking again on the next day.  As of today, it is still working, and I think that it could go back to its owner finally.

So, how do we explain this – the temperature is not hot enough to melt solder as such, but maybe by doing this we are equalizing thermal stresses on the die to substrate connections.  This could be explained that some of the connections are not actually properly soldered (we call these dry joints or cold joints), but do get into contact when the die is in the right place.  Meaning of course that the chip is faulty and by heating it up, we get it working again.  So cross your fingers, and hope that the owner is happy and is working again with his laptop for some time to come.

Repair.IT – Asus Taichi 21 Notebook

This follows on from my data recovery of the D: drive of the Asus Taichi 21 notebook.  Actually, it wasn’t really so much data recovery as just copying files and folders from the SSD drive once I had it mounted, but this is about the repair of the notebook.  After I returned the notebook and the data, I was told that the owner would order a replacement motherboard and let me know when it came in so I could then fix the notebook.

In due course (a week and a half later), the motherboard arrived from the US and I got the notebook back. By the way, I didn’t mention about opening the case – there are 10 little Torx screws to be removed and then the two plastic feet near the hinges can be removed to uncover two more Phillips screws.  Then I disconnected and removed the battery, and then removed the heatsink/fan assembly.

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Once the heatsink came off, I could see that the cpu was covered with excessive amounts of thermal interface material – actually only the top of the cpu that contacts the heatsink needs the thermal interface material.  Then it was a matter of disconnecting and removing the wireless card, and the other connectors – then put in the replacement motherboard and reconnect everything.  For the heatsink, I used Arctic Silver thermal material to cover the top of the cpu as a thin film, then put the heatsink on top, jiggled it around a little, then screwed it on firmly.  The last thing was to install and connect the battery.

While powering on, I did notice that occasionally the screen would flicker but it stayed on most of the time, and when I closed the lid, the back screen came on as expected, so that was that – or was it?

The notebook went back to its owner the next day, and all was well – there was the occasion that the screen did not light up but after updating drivers, all appeared to be well.  At least until the owner tried to connect a couple of external monitors and somehow there was no display anymore.

I got the notebook back and I thought it would be strange if the motherboard was faulty again – but it is possible since they might only test it for a short time.  After some examination and reconnecting of the two screen cables, I found that one of the the connectors might have been a little dodgy, so I had to unplug it, then plug it in, unplug it and do this a few times – each time ensuring that it was lined up and would click back in securely.  This seemed to fix it and was able to get a working screen consistently and told the owner what I had done in case it happened again.

That was a couple of weeks ago and nothing has been heard of it since, which I guess is good news.

Recover.IT – Asus Taichi 21 Notebook

I haven’t been writing much lately so it is time to get a few out of the way.  Some weeks ago, I was asked about an Asus Taichi 21 Notebook that had suddenly stopped working.  The notebook is one that has a dual screen, open up normally as a notebook, close the lid and the back screen comes up as a tablet.  Neither screen was operating and it had been sent to Asus to look at.  I suggested that I should be able to get his data off the notebook as Asus would not provide this service.  Eventually a quotation was received which was quite high – you could buy a second hand Asus Taichi 21 on eBay for much less than the quote, so eventually it came to me to look at and get some very important files from it.

On inspection, the notebook as an internal SSD which at first glance looks like a normal mSata or M.2 SSD however on closer inspection – it is quite different.  Further research indicated that there were adapters available that would convert this SSD to standard Sata – and I was fortunate enough to find a local Sydney supplier that had one of these in stock for $20 or so.  I ordered one, and when it was ready – went for a  short drive to pick it up.  Now the adapter looked like it wasn’t the right one, but they assured me that it would work.  The socket is much larger and is not quite the same as the socket on the motherboard, so after some further research, I decided that it should work.  Of course, this can be a risk that could destroy much wanted data – but there were no indications on the internet that these adapters posed a problem.

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This shows the adapter with the SSD installed.  Note the size of the socket.  This adapter is used for the Asus Taichi and UX21/31 notebooks.  See below, for a photo of the motherboard with its socket.

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You can clearly see the difference as the motherboard socket has 6 and 12 pins, but the adapter socket has many more pins.  Anyway, I connected the adapter to my recovery machine, and it was recognized by the Bios and by my Ubuntu operating system.  I went to mount the disk, but it complained that the partition had not been cleanly dismounted.

No real problem, the way to get around this is to mount it as read-only which will ignore the dirty bits as I only want to copy data from it.  After doing an “fdisk -l”  to list the partitions, I eventually used the “mount -t ntfs -o ro” command to mount the partition and then was able to copy the required data to any external usb disk.  The D: drive folders and contents which is what I copied – as this was what was required.

After that, I reassembled the notebook and that was that, or was it?  A quick search of the internet showed that the motherboard “60-NTFMB1102-D07” was available for a few hundred dollars which would likely fix the notebook, but that is another story.