Electrocution

For those seasoned electronic repairers you may find this topic as “easy to handle” due to you already exposed to it every single day. That means you already knew all the consequences of when someone got electrocuted. You will take extra careful when dealing with AC supply and know what to do when performing the voltage test on board. Now for those newbieâ€&trade ;s that has just joined this field, I highly recommend you to get an isolation transformer in order to protect yourself from electrocution just in case if anything bad incident happen. I remembered one bad incident happen 10 over years ago where my left hand was slightly burnt due to my hand accidentally touched on the live AC supply. Back then I’ve never heard of what is isolation transformer and my college never emphasis on this subject. I don’t want you to be like me fall into the same bad incident! Treat every AC supply carefully and if you don’t understand, you can always get a repair friend to help you out.

Isolation transformer offer 100% isolation from the AC input line. Even if you are a seasoned electronic repairer, I suggest you to get one too. The isolation transformer shown in the photo has a rating of 1KVA which is equivalent to about 600 Watt and it is a customized isolation transformer. You can easily get a ready made one from your local electronic distributor. For more information about isolation transformer, you can always check from the internet.

Capacitor Discharge

This big filter capacitor (usually rated at 100 uf to 470 uf with 400 to 450 working voltage) in the primary side of power supply is also a potential hazard to electronic repairers. I myself had been discharged by this capacitor before and it really hurt. The mistake that I made was in my mind says that “the voltage will discharge by itself”. Yes it is true only to certain designs and in some designs even though you already switched off the power supply; the charge was still remain in the capacitor. If the start up resistors is open circuit the voltage inside the capacitor can’t be discharged and if possible you have to confirm it with a multimeter. If it reads zero or low voltage then only you begin to work in this area. Due to few times that I made the mistake, I’m now more alert about this area. So newbieâ€&trade ;s you got to be well prepared when troubleshooting this area.

Static Charge A static charge may be built up when two surfaces rub against each other. In our normal activities, we generate static charge all the time. This charge can have a voltage high enough (may be thousands of volts) to create quite a spark. Even though the voltage is high, the current is very low, so only a small amount of power is involved. Static is always a problem when you are repairing and troubleshooting electronic equipment. You must take special precautions whenever you repair any equipment that have CMOS IC’s in it. Before you touch any parts inside the equipment, always ground yourself to remove of any static charge. Many service technicians and engineers wear a wrist strap which is connected to ground through a one mega ohm resistor. This will safely drains off any static electric charges from their body. Look at the photo and you could clearly see a wrist strap attached to his left hand. If you deal with motherboard repair, hard disk, FET components and etc, it is recommended to get a wrist strap before the static charge kills the electronic components.

Tiredness

In doing any repair work one must have the concentration and focus so that the task can be accomplished. If you are tired or weak please take some rest as forcing yourself may invite more problems than you can solve. We as electronic repairers is dealing with electricity and if one mistake (got electrocuted) made we may end up in hospital or even dead. Take a short nap when you are tired. With just 5 to 10 minutes nap, it could refresh your mind and may last you till end of the day. Our mind easily gets tired if we are too concentrating in tackling a problem for a long time. Have a short break and many times during the short break, ideas came and I can easily solve the problem fast.

Transistor/Diode replacement

I believe many of you have come across problem where we could not locate original part number for diodes and transistors. Due to this we used the substitution part number hopefully it will work like the original one. The most common components that have substitution part number are transistors and diodes. For you information, you can get easily get the original value from the market for capacitors, resistors, zener diodes and etc. If you are a TV/Monitor repairer, you must have used substitution part number before for the horizontal output transistor (HOT) and for diodes in the secondary output side.

The mistake made by the electronic repairers was not enough time to run the burn in test for the equipment that used the substitution part number. That means, if you don’t properly test the equipment after installing the substitute part, the customer may complaint again after using the set for few days. What you need to do is to fully test the set before sending the equipment back to customer in order to avoid call back.

If you repair a CRT Monitor and you had replaced the HOT with another part number, the best thing to do next is to run the Monitor on all resolution and make sure the HOT temperature is okay and won’t burn your finger when you touch it. If it extremely hot, then you have to be careful as the set may not last long and may come back again for second repair if you insist to send the set back to customer. Try another part number and if possible get back the original part number for longer lasting operation.

Don’t burn in test any electronic equipment without supervision.

I’m saying it again “Don&a circ;€™t burn in test any electronic equipment without supervisionâ€� �. Why did I mention it two times? It is because if any electronic equipment left unattended (no supervision) for a 24 hours burn in test, if something goes wrong with the electronic circuit, the equipment may caught fire and it can burn down the whole office and etc. I always have some extinguisher standby in my technical department and just in case if there is a fire we can put the fire off in the shortest time. I won’t let the equipment that I have repaired to run without anyone in the technical department. We do not know how reliable and how good an equipment design is (there are so many unreliable or cheap equipment in the market) thus we got to take notice about this matter.

Inform the customer about the repair charges first

If you are in the electronic repairing business, one of the most important things that you need to do is to inform the customer first about the charges of the repair otherwise you may end up quarrelling with the customer over the price charged and lose the customer. Your business may be affected and tarnished if the customer spread around about the nightmare incident in your company. In order to avoid argument, write a black and white letter and sent/fax it to your customer, once they agreed then only proceed to repair the equipment. Although this subject (about charging customers) is a bit subjective, I believe you can sort it out handle it in a professional manner.

Laser warning

If you are dealing with equipment that uses laser diode such as laser jet printer scanner assembly, CD Rom, DVD, VCD, and other laser related equipment, you must abide the warning of the laser in the equipment you are troubleshooting. Ignorance can bring disastrous to your vision especially your bare eyes are directly exposed to laser ray without you knowing it. Study all the safety rules about handling laser equipment and how to avoid your eyes being exposed to the laser ray and at the same time you can perform the troubleshooting and the repairing job.

Not having the right equipment

I came across lots of technicians that only use an analogue meter to do the electronic troubleshooting work. They don’t even have a digital meter! To them an analogue meter is already adequate but in actual fact they have missed out something good in their life. I know that sometimes it is hard to convince these technicians to accept new things in their daily routine work but the changes that the new technology have brought really can make someone to save their troubleshooting time. Example, the time before end of the 90’s, many electronic repairers test electrolytic capacitors either with the help of analogue or from a digital capacitance meter. Do you know that both meters of testing the electrolytic capacitor can mislead you into believing that a bad capacitor is good. Your precious repair times were wasted and at the end you can’t find out the culprit. We need different type of meters to tackle different type of problem or components. By using only one or two meters, you are only limiting yourself to quickly find out the fault fast. If you don’t have any ESR meter and wish to get one you may click here.

Don’t modify the X-ray protection circuit

If you are repairing the CRT TV/Monitor, I’m sure you have come across before the problem where the set shutdown once the power is turned “On&ac irc;€. There must be some reasons or a defective component or circuit that make the equipment to shutdown. Some call it as “High Voltage Shutdown”. The equipment shutdown by itself was due to high voltage (24 KV) suddenly shot up. A bad flyback transformer, increased in B+ voltage, open circuit in holddown/safety capacitor and some other reasons can cause the set to shutdown. The x-ray protection circuit was designed in the TV/Monitor circuit in order to detect any abnormal high voltage present in the equipment. If there is no x-ray protection circuit in the equipment, the high voltage may shoot up to 30 over Kilo Volts and the X-ray produced will be very harmful to the user.

Now your job is to find out the cause of the problem and please do not take any short cut in modifying and defeating the purpose of this sensitive circuit. If not the user will be exposed to X-ray emission without him or her knowing it. A prolong exposure of such dangerous ray could cause cancer in their body. If you can’t repair the problem juts send the set back to the customer or send it to the distributor for repair. Please think of the consequences before you defeat the original purpose of a circuit in any electronic equipment.

I believe there are more than 10 mistakes that you should avoid but with this information, you should by now know how to handle each mistake and be a good and a successful electronic repairer.