Hello! jestine,

    Hope you and your family are fine. I had been conducting extensive research on the net on how to test a battery whether it is used or a new one by employing an analogue Ohm- meter. I never could find any amicable solution yet. Could you guide me on this issue. I had bought a few lithium ion batteries and on bringing home and charging it with electricity gives me a discharge life of merely 5 hours compared to one and a half a day that I must receive from the same. It is quite clear that battery is either a used one or it is incapacitated. Is there any method to assess whether the battery is used by detecting through an analogue ohm-meter? Hope my message is quite comprehensive.

Thank you

Alexander

HI Alexander,

Testing a battery without a load is not accurate. Perhaps you need to use a light bulb to see if the battery will sustain the current draw or not. Using ESR meter to check the internal resistance is also a good way but i have not test it on lithium  ion batteries.

Jestine

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Do you know of any technics for soldering replacements on tv  chassis such as Toshiba mod 20AF42 . The printed circuit traces come off the board with the slightest amount of heat making it almost  Impossible to replace a transister or an electrolitic cap or resistor Maybe you may have a book or something. please let me know.

Ken

HI Ken,

Try use external small wire to join it back. I used to repair motherboard and the track came out. By  using the small wire (single core) I’m able to join it back between the circuit track and the ic pin.

Jestine

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HI Selim,

I found out it’s an auto-adjusting SMPS (100-250V). Hence, it worked without any modification.


First i thought you have check and certain that it was only using single ac supply and not auto adjusting. Anyway, good to hear that.

The actual problem wasn’t reaolved though :-(
When I power on the TV the standby light goes on for a second only before going off instantly – same scenario when I unplug the TV (SB light on for a second and then off).

I’m going to check the mainboard this time. The symptoms, which started a month before the TV died were that it didn’t react to remote control nor to buttons on the TV. We always had to unplug it and plug it back in for it to react to remote and on-TV buttons again.

Have you ever run across such a scenario? Any ideas where to look for on the main board?

I suggest that you check the main power supply first and make sure there is supply voltage to the power ic. Standby means there is voltage to the CPU and the CPU will send a signal either to trigger a relay or optoisolator ic circuit. If the CPU itself have problem it will also go into standby mode.

Jestine

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I  dont  know  if you will  help  me, but  I  can ask you.   I  have a  monitor,  and the  screen does not  light up.        having  followed  your  advice on these matters  I  have  carefully   controlled   all  caps  and  resistances,   finally got  round to the   inverter board,   and  have  found  TWO   2sc5707   H/S near too the  small  transfo,   there are  two  transfos   and  two  exits  SO  there are   Four   2sc5707  transistors,   BUT only  TWO  were  dead,  SO  I  have   changed them.   ALSO   checked  every  item on  the  board  resistance    other transistors    and  caps..

pluged in the  monitor  AND  I  had a  great  screen  lite  up  once  more,    BUT  only  for  FOUR  mins   and then  nothing  again.  back to the  board again   AND  the  SAME  two   2sc5707  are  dead  again…

Why………….  is  the  problem  the  relevent  transfo   or  can the  system of  lighting the  screen be  my  problem???

Can you  be of  any  help  please  the  monitor is a  TECO TL 700A

Thanks  for taking the  time to read  this, and I  am  hoping  you  can  help  me.  if  not  its  the  dustbin for this  monitor..

HI,

I suggest that you check the p-channel fet and also for dry joints in the high voltages transformer. Check also for any bad tuning cap that is located nearby the high voltage transformer.

Jestine

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Hi Jestine

I just watched a video today on youtube and if you plug a power supply into a dead motherboard and short out green

and black wires does anything blow on the motherboard.

When I watched the video I did not see smoke comming from motherboard or power supply or here any pops.

Gary

Hi Gary,
Usually power supply will have protection and if it detects any short circuit in the load it will shutdown.

Jestine

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Hi Jestine, I got a small sander to repair. It is not working.
When testing the diode on the circuit with resistance. There is resistance both ways. Why?
I suppose the diodes are o.k visibly as long as they are not burnt.

HI John,

What is the part number of the diode? A good diode should have one reading instead of both ways. For a schottky diode it should have both readings but not shorted readings.

Jestine

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hi jestine am happy and encouraged by your guide. its really helping me on how 2 improve my repair work, but marketing my business is a problem.please advice me

HI Timothy,

Try find yellow pages and fax to the companies telling about how you can solve their problems. Don’t mention how great you are or how big is your company. Give them a decent price and clearly state how your company could help to solve their problem.

Jestine

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Hi, Mr Yong I’ve been reading your blogs and repair guidelines, and they have helped me allot. I am a junior technician and its because of your website why I believe I will be moving up the ranks sooner then I thot.

Do you by any chance have any tips on CRT TV repairing? If so I’d like to take a peak.

Thank you.
B.Z. Chope

Hi Chope,

Try visit this website as i found it to be very good:

http://www.repairfaq.org/samnew/tvfaq.htm

Jestine

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HI Edd,

Am browsing thru your newsletter and I am quite interested in learning more
techniques you talk about. I want to buy ebooks from you. However, with so
many choices, I need you to help me zero-in on the ebook which I can utilize
immediately to repair my two (2) computer CRT monitors. I have electronics
repair background and I still need your help.

Am not asking you to troubleshoot the monitors for me now.. I just need you
to point me to the correct ebook which will help me repair my very old monitors
without too much cost. Cos if the repair cost would be high, I might as well
junk it and buy new LCD ones. (But I won’t learn anything from this.)

I suggest that you get the Testing Electronic components ebook first because you need to know accurately how to test electronic components in order to perform the repair work. Your next book would be LCD Monitor repair.

Here’s my brief problem. There’s no schematics available.
1. IBM 14″. It works, it’s bright and no ‘blooming’ problem. However as it
heats up, it gets out of focus. If I adjust the Screen voltage at the flyback,
it sharpens up (at this temperature). However, if turned on later when it’s
cool, it’s blurry again — until it reaches its normal operating
temperature..It’s
irritating.

This is a flyback problem and need to replace it or you can use a monitor blur buster to solve the problem

2. An AOC 7en. Won’t turn on. I can hear a little ticking sound by the power
FET (FET is good) in the low voltage supply area. Seems like something is
always shutting it down when it attempts to power up. Rectified DC from AC
line is supplied to the power FET. No burnt parts.

So, please recommend which book I have to buy, or what advice you can
give me.

Try this link:

http://www.electronicrepairguide.com/testing-flyback-transformer.html

Jestine

============================

Sir,
I repair a philips DVD smps , first time see the regulator ic is blast. Then i change the ic (TNY176) , TL431, OPTOCUPLER , now connect the AC and secondary voltage is properly show 5V, 12V,-12V.
But when load a 5V motor the regulator ic is blast, i change two time this ic result same. Now how i solve this problem?

Hi,

I suggest that you check all components in the power side and make sure the ic that you have replaced have the same exact part number.

Jestine

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i have purchased some of your e-books and have been very impressed, i have a problem at the moment that you may be able to help with.i have a dell 1545 laptop with a shorted diode on the chargeboard.i cannot locate the part number of the diode.is it possible to just use a standard diode?when looking for replacement diodes what do you look for, is it by voltage or are there other values that need to be checked?

HI Dave,

Thanks for the support. When looking for a replacement diode i will look at the volt, amp and speed. volt and amp has to be same or higher and the speed of the diode (ultra fast recovery diode) should be the same or faster (for example you can replace a 75ns diode with a 50ns diode) . In your case i suggest that you replace the smd diode with UF4007 and test it. let me know the outcome.

Thanks.

Jestine

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Hi Jestine
Thanks for prompt reply, I want  to start learning for testing electronics components & repair. Please guide me how can I start learning, I can purchase books & tools ect. I have lots of old Aircon boards lying unrepair, actually these are not available in India. Without these boards our aircond. is not usable & client also suffers.
Please help me.
Thanks & regards
Manjeet

HI Manjeet,

You can buy the ebook online. As for the tools you need:

analog/digital multimeter
digital capacitance meter
Blue ESR meter
Blue Ring Tester.

Oscilloscope (optional)

If you have other question please do email me again.

Jestine

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Hi Jestine, I have a question:

Why some crystals have 4 legs and some others have only 2 legs?

Thank you

Renie

Hi Reniel,

Three of them are: VCC, GND and Clock OUTPUT.

The last pin is not connected.

Jestine

==========================

Dear Jestine,

 

Just one question, what happens if the CRT video screen is on standby even after the power IC has been changed.  Any hints.

Thanks

Samuelu

HI Samuelu,

It can be the problem of bad CPU, bad eeprom data, abnormal supply dc voltage, bad surrounding components and faulty main power supply.

Jestine

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