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Electronic Repair Questions/Answers & Testimonials Part 6

By on July 21, 2008

Hi L,
Here are your questions and answers:

I just wanted to know what does this ebook contain?

Here is the link to the ebook content:

“Would it give the procedures, tips, the way or method to analyse the problem with respect to SMPS,other power supplies, Monitors ( all brands), PC, Printers, any logic & control boards, PC mother board etc;?”

This eBook is more general in testing electronic components. That means if you don’t know how to test electronic components the accurate way then you can’t repair any electronic equipment. If you know the right way to test electronic components you can begin to repair any kind of electronic components. This eBook is not specific to only one type of electronic equipment. If you want to repair pc motherboard, here is a link that can help you out:

Pl. do confirm. Would it be available in India? Suggest please….

Sorry, it is only available online (eBook) and i don’t have a physical book (ordinary book). It is not available in India.

Can you pl. give some tips to solve the problem in PC SMPS?

PC SMPS problem are quite dynamic and it comes with many designs and there is no absolute solution unless you have to test it yourself. The problem could be no power, power cycling, low power, too high power, power shutdown and etc. It still comes back on you how to accurately test the electronic components in the SMPS.


Hi B,

Hope you are not too tired after coming back from fishing.

I’m okay no problem-thanks!

If my budget is very tight to buy an oscilloscope, what is the minimal frequency should I buy for monitor repair? Last time you answer me that I should buy 100Mhz, but I think the price is too high.

Get a 50 Mhz scope

When I read about your article, you always know what is the function of particular component; like s- correction circuit, modulation diode, etc. What do they each function in CRT monitor circuit? How could I gain such a knowledge to know the function name of each component?

Modulation diode is part of the pincushion circuit (controling the east/west display) and s-correction is the resolution circuit (controlling 800 x600, 1027×768 etc). For more information please go to this website:

I know that capacitor when is bad, it could be shorted, high ESR value. Could it also develop open circuit?

Yes, it can go open circuit

If I couldn’t find the smd type of component in lcd monitor circuit, could I just replace it with ordinary type of component with the same rating?

Yes, in fact i do it most of the time.

Hope this helps!


Hi Justine,

I finally got around to downloading your LCD guide yesterday.My problem was that the monitor was flashing on and off.Within 3 hours after reading your guide I had removed and replaced all the electrolytic capacitors on my AOC LM 721A monitor power/inverter board as 3 were leaking badly.

After checking the supplied AC/DC adaptor voltage and amps I found that the voltage was fine but no amps and it failed during that test. I again followed your steps in the guide and replaced the 100uf 400V filter capacitor that was leaking and now my monitor is up and running again.




I got your testing electronics compnents, it quite a hands-on books, thanks for that..



I have read your book.It is nice and covering a lot of details.I really admire u.



Thanks Jestine,. you’ve been a big help and I’ve already learned a great deal from your book. I did just order the blue ring tester so hopefully it will point me in the right direction.



Hi B,

I’ve bought the blue ring tester & DCA55 from anatek, because they ship the goods with USPS and I don’t need to pay for the Import Clearance Reimbursement. Anyway, I have mentioned you who recommend me to buy them.

No problem!

When I read your article, you always use kind of color test pattern to test the monitor. May I know what is the instrument to test them? Because I don’t think I’ll always use my own computer to test the monitor.

It is a monitor test software. You can get many free download by typing in google “free monitor testing program, monitor test program, mnitor testing software”

Yesterday from Malang the town that I live, I went to Surabaya that is the provincial capital of East-Java to buy some parts to prepare being a repairman. I’ve mostly got the ICs used in CRT Monitor, hardly able to find the Power IC, Regulator IC, Inverter IC, the IC that drives the HV transformer, Inverter Powertrench Mosfet, push-pull transistor, smd fuse,smd start-circuit used in LCD Monitor. They even say they don’t sell smd components because they have to purchase big quantity and the buyer is rare. How do you buy these smd components, could you only buy a few? Also, I didn’t manage to buy the p-channel Buck Royer FET, Schottky diode, pico fuse, slow blow fuse, posistor. I would appreciate very much if you could tell me the online store that you used to buy them. I think if they could ship to Malaysia then it could also ship to Indonesia too.

I mainly salvage from used Monitors as many parts i can’t even get from my local suppliers. If i want to buy online i would go to . If you have read my blog you can even try email luca from lavinci it to ask for the parts.

What is the difference ( in terms of appearance ) between slow & fast blow fuse? The parts shops haven’t even heard about the pico fuse and posistor. Could I just use the fast/slow blow fuse to replace the pico fuse or even the smd fuse?

The appearance of slow blow is that the internal tungsten have a coil spring or a dot. The metal end caps at both side have a very clear marking with logo’s, nice printed marking and etc. where else the fast blow have only a thin wire and fading marking at the metal cap. Yes, you can use a fast blow to modify as a pico fuse. I used to do that too!

When I look the BK multimeter catalogue, I don’t understand about their parameter about open circuit voltage when doing the resistance measurement, because one type has 3.2VDC typical, another has -0.45VDC typ, still another has 0.6VDC typ. Could you explain this parameter is all about, and which one should I buy?

This are the voltage measured at the test probe when you switched to ohm test. A semiconductor will conduct when more than 0.6v across it. So if your meter has 0.45vdc that means you can use it to test on resistors onboard even without trigerring the nearby semiconductor. This is the whole basic explanation of why ESR meter can check on board because the voltage produced at the test probes is not more than 0.6 volt-so no semiconductor devices triggered. That means you get what you measured! However, if the resistor is connected parallel, even if you have this meter, the readout would still not be accurate (we call it as back circuit)

What is the title of your next e-book that hasn’t been launched?

Troubleshooting and repairing SMPS. It may comes in a physical book form and no more ebook download. I haven’t decide it yet cause i’m still writing the book. I have completed about 65% and due to many repair courses “on” i have to delay in launching the book. Infact today i’m having a three days course for a participant who in printing machine. The student came quite early and i have no time to write blog in the morning and i could write and reply emails at night. Following few more weeks i have courses “ON” too further delaying in completing my book.

Many thanks for your supportive answer.

No problem!

Best Regards,
Jestine Yong


i am very greatful with your help, Mr Jestine Yong

Ibrahim Oumarou

Recenty I try to service several kind of UPS, I know the basic principle
of UPS is inverter system & charging battery system, also there are two
type : Continuous and Non Continuous UPS system regard to delay time
(switch time from AC on to AC off).

For the 600 VA the repair is more easier way than 1 kVA, that’s my
opinion and look like more simple component inside. My problem is: I
have Merlin Gerlin Pulsar SV9, my customer change the battery 12V 7A 4
pcs by himself. But it can’t work and the buzzer keep buzzing all the
time. He try to change with used battery, suddently it works. And the
problem is next time when he switch on the UPS still dead. ha…..

I try to repair, and find only Tr A1015 damage, I’m not sure the
function because the PCB is double sided/layer, but it near TIP 122 for
charging circuit. I try to change the CMOS 4049, 4093, opamp 339,
74HC393, 4013 but it can’t fix. I feel no hope and the literature is not
enough ,also I have no time to surfing the internet because many
monitor/printer repair at workshop.

So Jestine my friend, maybe you can give me several tip? Would you like
to make article about UPS someday. Thanks for your letter and the
response of my letter! Sorry for my bad English grammar!! See you

Hi B,
Thanks for the full explanation! For your information, at my side here we never repair UPS due to the new unit cost are very cheap thus i did not spend time in analyzing UPS circuit. What we do here was replace the fuse and new batteries and also for APC UPS, after the replacement of the batteries, we have to reprogram the eeprom IC otherwise the BATTERY INDICATOR will still show low even though we had replaced with new batteries. Could it be your case have something to do with the EEPROM data lost too? I wish to help but sorry I can’t give any expertise advice concerning this subject. Have a good day!


Hi A,

After read your reports and some electronic repair tips, found it is excellent, very straight forward, easy to understand and practical.


I am start to repair some simple electronics and electrical equipment since 12 years old, but using just try and error method, successfull rate just 50-50. Although taken the Advanced Diploma in Electrical and Electronics Engineering and pass

the Engineering Council examination but practical skill are not covered, that’s the reason I attend outside course to learn the practical skill like repair VCR, TV, radio and etc.

The EC papers is very tough and not many students could get through-hats off! Your case exactly like mine and worst many electronic repairers out there would not share their secret and this had caused me to practice on my own, buy lots of electronic repairing books from Amazon, visit repair forum and etc.

Now I work at a telecommunication company for 13 years already and seldom due with any repair work because the complexity of the multilayer surface mount PCB. Some time I will try to repair the SMPS module but successfull rate are too low because most of the components are not avalable at Pasar Road, RS Component and Farnell sell it expensive and some need to buy minimum qty of 10. Where can you buy those MF resistor, TVS diode, low ESR cap and special ICs and etc, can you share with me?

In my computer repair field, i bought my parts from local suppliers too (pasar road and etc), salvage from junk boards and sometimes i do order it online.

My company management do think of set up own repair center to reduce cost, currently all module send back to US for repair but most of my engineer do not have electronics knowledge and no interest at all for repair work.

That would be very costly to send the module back to US fro repair. Nowadays many engineers only concentrate in designing and maintaining systems and rarely could perform electronic repair because they are not trained in this repair field. I came across couples of students that had taken up my repair courses because their company wanted to set up their own repair center and wanted them to incharge in the repair. If your company interested to get their staff to be train by me, you may contact me.



Hi Deogracias,

I had a problem that I want to ask you. Do you know how to manually rejuvenent a picture btube without using the pisture tube rejuvenetor,and how about if the G2 of the picture tube is shorted,how do you repair this kind of problem.

You can find the answers here at

and also I had buy from Anatek corporation an Flyback and yoke tester but when I test it with defective horizontal yoke winding and a good horizontal yoke winding i find it no difference in reading both the good and the bad yoke reading are the same 2 LED lit but with the vertical yoke winding its okay it light all the LED in short The Flyback and Yoke Tester Cannot test the Horizontal winding in the yoke. But When I measure it with a Digital Empedance Meter from Altronics I Measure the defective one with a 8.8ohms while the good one mesure 10.5ohms.

Try replace the Blue Ring Tester R7 from 2.2 K to 510 Ohms and it should work fine.


Dear Jestine,

Thanks again for the message. I find your mail very interesting and encouraging.

I am planning to buy your ebook later.

I was wondering if you could tell me the reason why almost all the DVD players work for an year or so without problems and then suddenly one day when you load the DVD Disk you get the message that it canoot read it. The machine looks fine and working but it is unable to read the disk. I tried cleaning the optical lense, sometime it works and on some occassion it does not work. Any tips??

And what is the best way of cleaning the lense??

Thanks for the support on my ebook. As for the DVD player since i don’t repair it due to no profit margin i can’t provide you with a definite answer but one of my repair friend who told me that most dvd/vcd player was caused by a defective laser lens and cleaning won’t solve the problem. One need to replace the head assembly.



Another issue is about my Supersonic DVD player which when I switch it on it just write the word close yet the DVD tray is already closed. It is not able to play Disks. But because it is two in one only the radio is working. As I donot know how to test componets I have failled to know which componet is faulty. If you can do me a favour please. It is the only equipment that entertains my whole family. With great hope in you I look forward to hear your advice and follow it.

With great thanks .

Hi F.W,

As for the question about the DVD player since i don’t repair it due to no profit margin i can’t provide you with a definite answer but one of my repair friend who told me that most dvd/vcd player that can’t play disc was caused by a defective laser lens and cleaning won’t solve the problem. One need to replace the head assembly. Have a good day!


Hi Yerodin,

This week I received my Weller WLC 100 soldering station, and have already downloaded the Weller WLC100, Repair, circuit diagram/pcb, and other info. from the internet .This newer model has a 3 pin receptacle on the side, & can use a 3 pin grounded iron.

However the Weller iron sold with the station uses a 2 pin plug, & is NOT a grounded iron.

Here in Guyana, we don’t have that much of a problem with ESD, however in the articles it was suggested that I can mount a piece of wire and a 1 Mega-ohm resistor between the metal part of the soldering pencil & ground if ESD is a concern.

Research points to similarities between the off-the-shelf ESD wrist strap, & this wire & 1 Meg resistor solution.

It does seem more simple to me to creating a workshop environment with a ESD discharge area, which I touch before doing any soldering work.

What’s your thinking?

Its a good idea as long as it helps in discharging the ESD.


Jestine, using my DMM’s ohm test across the 2 pin plug I discovered:

1. The Weller WLC 100 iron had a resistance of 333 ohms.

2. An old, no brandname iron had a resistance of 554 ohms.

Plugging a regular 40W incandescent light bulb into the SS, & using the front panel knob to vary the brightness value enabled me to discover that I could check the operation of the triac.

I gained a new understanding that triacs are used in in AC applications such as:

1. Light dimming,

2. Motor-speed control, and

3. Temperature control.

If I see the iron as just a big resistor capable of handling 40 watts, and use the power formula:

The power P dissipated by a resistance R carrying a current I with a voltage drop V is:

P = V squared / R

P= VI = I squared R

then at max setting of the triac:

1. The 554 ohm iron is approx. 25 watt iron

2. The 333 ohm iron is approx. 43 watt iron

Does this sound right?

Yes you are absolutely right!

My thinking is to cleanup the old iron that doesn’t use fancy Weller iron tips, & keep it for use with the temperature controlled Station.

A win + win situation.

What do you think?
No bad its another good idea too.

You are just fantastic and you are different from others. Keep up the good works!



One Comment

  1. aaron robert

    October 13, 2010 at 8:23 am

    i found very useful information in this blog..for more information about energy report visit


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