Repair.IT – Repeller Car Alarm Remote Control

Most recent cars have some sort of remote control, usually to allow central locking and or activate the inbuilt security, engine inhibitor, etc. Cars from more than 10 years ago, might have central locking, but a lot of them didn’t. We have always added an after-market security system, which in the Honda Civic was a Repeller Car Alarm, fitted by the car dealer. These car alarms and keyless entry system usually rely on a key fob remote control that disables the alarm and unlocks the doors. Generally there is a battery inside that needs replacing from time to time. Don’t you just hate it when you try swapping the battery and the key fob still doesn’t work? Usually that is the time to use the spare remote, but what do we do with the one that isn’t working? That is what I had to do, a few weeks ago, to use the spare remote – I didn’t have spare batteries, but at least the spare remote works.

Most of the time, the electronics in the remote control or key fob are very reliable. They have to be, as they are carried in pockets with all sorts of items such as keys and coins. Many times they are dropped on the pavement – how often have you fumbled with the car keys and dropped them in the night time?

So what could go wrong – usually it is the switch that is failing. The simplest way of checking this is to open the key fob or remote control. Generally it is held together by one or two screws, then the housing comes apart. A 12V battery is usually found inside, depending on the car – I know some manufacturers use coin batteries, which don’t last long but is easy to replace. If the battery contacts look a bit green, then the battery has been leaking and the contacts will need cleaning, otherwise they will be covered in an oxide that has a high resistance which can prevent the remote from working. On the small circuit board, there is likely to be at least one switch, quite often two or even three. I didn’t have spare switches as these are surface mount and quite small, 6mm x 3.5mm in size, and 2.5mm tall – I did find them on eBay so ordered some and waited for them to arrive.


The above photo shows the circuit board with the two switches, the red button is what is pressed when you press the rubber knob on the key fob. The white one is one of the replacement switches that arrived this morning. If you press the centre of each switch slowly, you should hear or feel a small click when the switch is activated. On my remote there are two switches, bottom one is to lock or unlock, and the top one is a panic switch – pressing the panic switch sets the alarm off, which is handy if someone is bothering you or trying to steal your car. I don’t think many remotes have this duress switch, but it can be handy at times. The lock/unlock switch doesn’t click which means it has more than likely failed.

If you have a multimeter, you can set it to measure resistance, then touch the probes onto each switch contact and press the switch – it is easy to say, but hard to do in practice. My switch is 6mm long, so after putting the probes on the switch, I need to use a small screwdriver to press the switch button. In my case, the resistance drops briefly but does not stay low, which confirms that the switch has failed. I can get it to stay low by pressing quite hard, but if I relax a little, it goes back high resistance. Ok, so to replace the switch.

I could use my hot air rework station to remove this switch, but I happen to already have a smd rework iron, which has tweezer tips. It is a simple matter of waiting a minute for the iron to heat up, then using the iron, clamp on both switch contacts, wait a few seconds, then lift the switch off the circuit board. Heating the contacts is fine, but when clamping on the switch, it does melt the switch plastic a little. To solder the replacement switch back on, we can do the same – but it is easier to use a conventional soldering iron since I need to hold the switch in place, solder one contact first, then solder the other end.
The replacement switch cost a princely sum of $2 for a packet of 20 – good price. I could have bought one if I could find a local supplier, but it would have cost a few dollars, so now I have 19 spares. Anyone need a switch?


The photo shows it soldered in – yes, I know it is at a slight angle, but it should be fine. I tested it and it is working better than the original switch. However, during testing, the battery started to die. It did unlock and disable the alarm, but I could not get it to lock, unless I waited a few minutes for the battery to recover some charge. But at least the switch replacement is working, so now, I can order a couple of spare batteries – or maybe 5 because 5 costs less than buying 2 – how does that work?

Remove.IT – dust in desktop PC, that is!

Yesterday, a neighbour from down the road knocked on my door. He asked if I could have a look at his PC that wasn’t working properly. I had previously fixed up a laptop for his mum, which is why he came to me. I said, “Sure, bring it over”.

So, he goes back and brings back the PC in his ute. He says he thinks there is a virus or something on it. Now, I remember that his mum had contacted me some time ago about his computer, but he never brought it to me, so it looks like things are worse now.

What I usually do is to open up the computer and have a look inside. When I did this, I noticed a fair amount of dust, so got the vacuum cleaner out and went around the insides with a brush and got most of the dust out. This is when I noticed something about the cpu heatsink, it looked like more dust inside. Fortunately, this heatsink fan, could be popped off by levering a couple of small latches, then pulling off the fan.

What I saw could best be described by thinking of something Crocodile Dundee might have said, if he was a computer repairman – “That isn’t dust, this is dust!”.


I took a photo for you people to look at – it wouldn’t be surprising if the cpu was getting hot and maybe shutting down at times. It would have been worse in summer. I vacuumed all of that dust out, and brushed the fan as well, so now it looks almost like new. There were two hard disk drives in it, a 1TB drive and a 80GB drive. I took both out, and checked them on my test machine – I found a bad sector on the 80GB drive, and some directory problems on the 1TB drive which will have to wait.

Anyway, installing it back together and powering on, showed the screen that Windows tells you if it didn’t start properly, so I chose to go to Safe Mode with Command Prompt. From the command prompt, I did a chkdsk /f of the 80gb drive that had the bad sector – it fixed a few minor errors. Next, I rebooted and let it start up normally. The desktop came up and there were a number of invalid pop-ups which I closed, and left it for a while. The PC was still ok, no signs of sudden crashing, so I decided to do a thorough check of both disks.

chkdsk /R will fix any errors and also check free space for bad sectors. I did this for both drives, except that of course, it cannot lock the drives to do this, so chose to have it run automatically on next startup. Reboot, and let the disk scan run – several hours later, all errors were corrected on both disks, the bad sector was mapped out on the second drive, and all seemed well. So it looks like, this dust was the culprit – how about you check your PC now?

Replace.IT – LCD Screen for Compaq Presario V6002AU

I had this Compaq Presario V6002AU 15.4″ laptop sitting around for a little while – as they do. This laptop had a bad lcd screen, in that the display is dim and doesn’t look like anything is recognizable. I had taken it apart to check the screen. I have a copy of the Maintenance and Service Guide for this laptop. This guide shows how to open and replace parts of the laptop and is a must-have if you are to do this properly without damaging any of the plastics or component boards. Most of the time, these guides are quite accurate – and occasionally they might leave out an instruction or two, like in this case, remove the front panel switch cover requires removing three screws instead of two screws.

Ok, that isn’t the topic of today’s post – but the lcd screen is. The Compaq spare part number for the lcd screen is 431386-001, which is with BrightView, i.e. glossy. I duly went on Google to check whether this panel was available, and found a local supplier on eBay that had this for $81.99 including free postage. Ok, so I ordered it, and when it arrived, I noticed that the backlight cable was a little short. I compared panel part numbers – my original panel is a LG Philips LP154W01 (TL)(AE). The replacement panel is a LP154WX4 so I contacted the seller and we conversed via eBay and email. Anyway after explaining that the backlight cable was too short by about 2cm, I asked whether or not they had a LP154W01 (TL)(AE) in stock.

They came back to me by asking me to cut the backlight cable, and take the old backlight cable and join it to the replacement panel, and that way it should reach. I replied that this is not recommended especially since the backlight voltages are very high, usually from 500 to 900Volts. The wires have silicone insulation and if I do cut it and repair, it can form a leakage point, whereby some of the time, the display becomes dim, due to the backlight not lighting properly. Not to mention voiding the panel warranty if it should fail and then they say that the panel has been tampered with. Anyway, the solution to this eBay panel is that they asked me to send it back and they will refund me.

Now, I could find the required panel, but at a higher price, about $115 – but then it isn’t really worth it. I decided to scrounge around my old broken laptops and eventually came across a Compaq Presario V4000 with the same size screen. Ok, maybe I can use this so proceeded to remove the screen from the laptop. This screen is a LTN154X3-L01 – however the backlight cable is long enough, and the lvds connector is in the right place. I obtained the datasheet for this screen, and confirmed the pin configuration of the lvds connector is the same and the original screen. The resolution is the same, so how about I try it out? I connected this screen temporarily and powered on the laptop and was greeted with a Compaq power up screen, ok – great, so switched off and proceeded to install the screen properly.

After everything was put back in place, I had zero screws left over – always a good feeling. I power up and it wouldn’t power on – now what. Then I realize that maybe the battery is flat. It just happens that one reason I wanted to resurrect this laptop is that it uses the same battery as a HP Pavilion laptop that we had had for many years, which I have a spare battery for. I grabbed the spare battery and put it in and powered on – success, the laptop booted into Windows XP Professional. This laptop only has 1GB of ram and can handle up to 2GB maximum. I think I will use this as my Windows 10 test machine, or perhaps just run Linux on it.

The moral of the story is that quite often lcd screens from different laptops can be compatible as long as the lvds connector is the same and it is located in the right place. This one had a 30 pin lvds connector, but it is always good to compare pin configuration just in case one screen doesn’t use the standard wiring – don’t want to damage a good screen or damage a laptop motherboard.

P.S. No pictures, since a working laptop is … a working laptop.

Repair.IT – Medion Akoya P4020 D All-In-One PC

About a week ago, this Medion Akoya P4020 D All-in-one PC came in with disk problems. This touch-screen PC is distributed by Aldi and was quite popular a number of years ago. It came with a Western Digital Green 1TB hard disk drive, which on examination was not mounted in its original holder. This meant that the disk could flop around a little to the point, that with some vibration, it could possibly lose Sata contact. Anyway, this is meant to sit vertically so it might not be a problem.

The symptoms were that Windows 7 wanted to do repairs, and this could take all day and all night, which was why it came to me. The first thing I usually do, when faced with an unknown disk drive condition, is to make a copy of the data, whatever is readable that is. I connected the disk to my Ubuntu bench test machine and connected a spare 1TB disk as well. I could have copied the WD disk image to my network storage, but would then be faced with copying it back to another 1TB disk if the WD disk was the problem, so decided to short circuit this process by copying to the spare disk.

The WD disk was showing up as /dev/sdb and my spare Hitachi 1TB disk was /dev/sdc. I used the following command to copy the disks:

dd if=/dev/sdb of=/dev/sdc conv=noerror,sync 2>&1 | tee wdcopy.txt

What this command does is to copy from sdb to sdc, i.e. WD to Hitachi, without stopping for errors, but include blank sectors for error sectors, and the last bit 2>&1 is to send the error output to standard output, where tee will display to the screen and write it out to a file “wdcopy.txt”. I do this now because I have found a number of times where I wanted to know how many errors there were.

In due course, this copy finished – because I didn’t specify a block size, it would default to a single sector block size, which will take a longer time. At completion, the last few lines displayed was:

1953512851+12317 records in
1953525168+0 records out
1000204886016 bytes (1.0 TB) copied, 107443 s, 9.3 MB/s

12,317 bad sectors – and took nearly 30 hours. That does not look good for the WD disk drive, so proceeded to boot the Medion PC with my Hitachi disk. After choosing to start Windows normally, I was able to get to a login screen and duly entered the password, or tried to. The password I was provided did not work, so I tried a few combinations of that password, and was able to get in. Suffice to say that it was a different double digit.

Because of all of those bad sectors, once in the operating system, I tried to do a disk check, which it couldn’t do but could schedule it to be done on boot up – which I chose. On restart, an error came up that it could not perform the disk check due to an error. Logging on again, and restarting came up with the same disk check error.


What is going on? It seems that others have encountered this problem, so the resolution was to boot into Advanced Settings, then I went to a command prompt and ran the “chkdsk /r /f D:” from there.


This took a number of hours, but eventually it completed after fixing a number of errors, actually more than a few. As you can see from the photos, one of the complaints about this PC is that the screen is very glossy and we get lots of reflections that is very distracting. I ran the startup repair as well, but no problems were found.  After that a reboot and it was fine, no more disk check on startup.

I contacted the person who brought this machine to me and he said that the customer would be fine with using a second hand disk drive, instead of a new one – so this works for me, as I have a number of spare drives of 1TB capacity sitting around idle. So now this machine is repaired!. I did pad some bubblewrap into the hard disk compartment to stop the disk drive moving around until the owner can find the original mounting frame.

So, what do I do now with the WD disk? Since I have copied the disk already and it is functioning fine in the machine, I decided to run some diagnostics on the disk drive. The WD diags wouldn’t give me anything meaningful, since the quick test that was supposed to take a few minutes kept going and going, so I decided to run the extended test. This completed after many many hours but again didn’t give much result. I decided that the best way was to do a “write zero” to the disk, which is effectively a low level format of the disk using the WD diagnostics. After another many many hours – I don’t stay and look at it, I just come back every few hours to check if it had completed, until it finished.



This is the screen after the diags finished writing. It gives the Smart statistics which shows that the attribute 5, Re-allocated Sector Count normalized value of 75 is below the failure threshold of 140, meaning that the disk is failing. Ok, I decided to actually copy the Hitachi disk back to the WD disk. By doing this, I would also check the raw value of this attribute to see whether this continues to increase. This time, I would speed up the copying by choosing a block size of 10MB:

dd if=/dev/sdc of=/dev/sdb conv=noerror,sync bs=10M 2>&1 | tee hit-to-wd.txt

The raw value of the attribute 5 was 997 – which I obtained from the “smartctl -A /dev/sdb” command.  After about 4 hours, the copying was completed, then I check and see that the attribute 5 raw value is now 1056. This meant that during the copying, a further 59 sectors needed to be relocated to spare sectors. A disk drive does not have an infinite number of spare sectors and eventually these will run out. It also means that this disk drive can no longer be relied upon to keep any data. Also this attribute means that the disk surface where the data is stored is deteriorating. Anyway, if the customer wants his original disk back, he is welcome to it, otherwise I keep it on the shelf in case another WD10EARS disk has failing electronics, which would require a donor disk.