10 Mistakes That Every Electronic Repairers Should Avoid

If you are in the electronic repairing field, I guess there is some important information that

you should and need to know. The information that I’m going to share to you is about the

mistakes that many electronic repairers have ignored and never put into practice. These

mistakes sometimes can be fatal and you need to take extra precaution when dealing with it.

Here are the mistakes:

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 newbie’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 newbie’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

 

Take a short nap or rest if you are tired

 

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

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”. 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. Take care my friend!