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Some Of The Real Life Technical Support Questions/Answers From Buyers And
Testimonials
Hi Jestine,
I must tell you that i all your Ebooks and am surprised to find so much
knowledge about electronics repairs things i would never known without your program and now am fixing all types of
monitors and making good money.
many thanks.
God bless you.
Johnie J.
===============================
Hi Jestine,
Thank you very much for the additional free
information,its very interesting and useful!
I purchased your book on testing electronic components,
and I´m learning a lot!
Thanks again!
Best Regards,
Victor V
=================================
HI Mr JESTINE .Your repairing tips have helped me a lot in
my repairing of electrcal appliances , keep up your good work . Thank you . I Feel Very Happy .
james h.
GRENADA
=================================
Hello Jestine
thank you very much for your email, it is always a pleasure to receive I do look forward to it each month,it is so
informative and educational in every way,I feel sometimes that you are looking over my shoulder whenever I have a
problem with something .In using your commonsense approach it soon leads me to the problem,even without expensive
equipment. Your knowledge of your world around you is an inspiration to us all, we have a saying in England ," A
problem shared is a problem halved", but with you it reads, "A problem shared is a problem solved
".
Thank you once again, yours faithfully Albert.
=================================
Hi Jestine,
Thanks! I was curious though how did you know from what i told you that by measuring the voltages at the MCU and
EEPROM that it was the main board that was bad?
Thanks again for your help!
David
HI David,
This came from repair experience. By right, if the MCU got the right voltage (assuming the vga signal cable is
connected to CPU) it should output a signal to the green LED. Since now the LED is blinking and the LED signal is
coming from the MCU then chances is very high the MCU or the EEPROM have problem. I do come across other brand of
Monitor that have blinking problem and when the mainboard was replaced the picture came back to normal with steady
green LED.
Jestine
============================
HI Nuno,
I have bought your books, and I'm reading them with a lot of interest.
I have started by Testing Electronic Components.
In there you say that to test a lot of components you use an analogue
multimeter. I have bought a digital one. Can't I do all of the testings? Should I
buy an analogue?
In fact you can do the testing with digital meter but for some components like testing diodes, transistors and
etc an analog meter is far more accurate then digital meter. I came across those components tested good with
digital meter but fail when test with analog meter. Analog meter is very cheap nowadays. A Sunwa meter cost about
USD10.00 and you should invest one.
One other question:
How can I know whe I have a simple transistor or a FET or a power
regulator? They look very similar..
By looking at the part number and search for the data spec and you will know it belongs to which
component.
Jestine
=============================
Hi,
Good Day!
I would like to ask some kind of advise if what is the
best brand of cheap, reliable BGA Soldering Station in the market.
I am pretty sure you have one in your work
station.
Best Regards
Viany
HI Viany,
So far my place here did not sell those cheap BGA machine. All of them are the high end type. At current moment I'm
only using the normal rework station but of course it can't be used to extract the BGA IC. Try search from youtube
for BGA machine and i believe there may have some for sale.
Have a good day!
Jestine
=================================
MR JESTINE what would cause a SMPS a humming noise
.
Hi Rich,
It could be the transformer itself have problem or cause by problem in the corresponding components.
Jestine
============================
Hi Jestine,
its a long time since we communicated. i have a problem with a sharp television. the problem is a grey
screen and some horizantal lines. could you tell me whwer to start. Are they retrace lines.
I did not get a march issue of your report.
HI Patrick,
Grey screen means no signal is reaching the CRT cathode. You may need a scope to trace backward from the RGB points
in the CRT and see at where the signal had lost. It could be the color IC have problem or missing supply voltage to
the color IC.
Jestine
==================================
hi mr yong.
there are some letters after main part number of some electronic components. what does these letters mean?
for example:bc107c or bc107a
can i replace bc107c with bc107a or vice versa?
thanks a lot.
HI Saaed,
Those are version. It depends on the part number, generally it can be used for all part number regardless the
version. However, if you have doubt the best is to find back the original number.
Jestine
=========================
HI Alex,
I come across a FET J370, May I know where I can get it's data sheet or information.
According to my databook the replacement number is
2SJ236,2SJ293, 2SJ321 and 2SJ390. You may have to check this from your local electronic store.
Have a good day!
Jestine
===========================
HI Bailing,
Yesterday a customer sent me this local product CRT monitor. The problem is while contrast at its lowest minimum,
the monitor still have a quite bright raster, causing all the colors to be chaotic.
I took voltage measurement at the CRT pin, found the G is 58V, while R&B is about 50V. G1 is -48V, G2 is 440V.
Also I found that the Posistor is quite hot, causing its outer case color to be somewhat grey, not clear black
anymore, is this normal?
Posistor will usually run hot but if there is color patches and the monitor can't be degaussed
then there is problem with the posistor. G2 voltage seems to be very high and you may need to lower it
down. In some monitors, the RGB voltage may have some variation and not necessary have to
be all the same.
This CRT board is using LM1282N Video Amplifier System. I have checked there are no bad capacitor on the CRT board,
G1 resistor is also OK. Do you think I have to replace this IC?
If after the adjustment of the G2 did not help you may need to replace this IC.
Jestine
========================
Hi Sir Jestine,
My questions are:
1. Base on the picture, the black with round shape, Is it
considered an IC?
2. Is it prone to damage? If it is, Is it
repairable?
Thanks and more power.
I will be waiting for your reply
soon
randy
HI Randy,
Yes it is an IC and it can't be repaired.
Jestine
===========================
HI Liviu,
Thank you for the ESR tester.
You are welcome.
After I had to fix the first dot (LED was A with K swapped) I could use it. I just want to ask your opinion
over the values read measuring the capacitors on the main board:
Tantal: 4.7u/16V ESR: 1.1
4.7 0.68
4.7 0.77
4.7 0.86
4.7 1.0
4.7 0.63
4.7 0.91
4.7 0.79
10u/16V 1.1
10 0.22
22u/16V 0.54
22 0.56
1u/25V 0.25
1 2.6
1 2.9
1 3.6
1 1.7
1u/35V 0.28
Aluminium 100u/25V 0.16
100 0.15
100 0.15
Please let me know what do you think about the values
measured. I still have not measured the SMD capacitors (which are over 1 uF) as I couldn-t identify them. The
main problem was that the LCD display was freezing the image and now I'm looking for bad
caps.
I couldn't understand why in your table for ESD values you
put 1uF/16v max value is 5. Shouldn't be much smaller?
Actually i did not put that value. It was from the ESR meter designer Mr Bob
Parker. The chart is just for reference purposes/guidance.
About the value that you have checked on the mainboard, since you checked it it on board,
there may be some connected parallel thus lowering the ESR value. I suggest that you take out one of the cap
and check the original ESR value and then compare the value of the cap that you want to check on board. Any
big differences in the value may indicate problem in the cap but then again to double confirm it, remove the
suspected cap and recheck it again.
Jestine
=============================
hello sir
when i power up the tv appear horizontal line in the middle of screen red and green tin color only.no rastar but
the sound is ok...last night i try to replace the vertical and horizontal ic LA7625 but the problem cannot
solve...at now when i power the unit the relay click but the lights from the crt neck is gone and the sound dis
appears....
Hi Jayron,
I guess there must be something that had wrongly done otherwise the TV should have the high voltage. When you said
you heard a click only that means the flyback is not energizing. I suggest that you double check again or even put
all components back to original and retest it. One horizontal line could be due to missing supply voltage to the
vertical IC.
Jestine
==========================
Hi Jestine,
Good day sir, i downloaded the ebooks from the link you gave me and i have been reading them, the material
inside are very rich. I am a repairer but what i discover in your book is amazing, i am encouraging you for the
hard job you are doing God Bless you and your Family.
Thanks Emmanuel
========================
HI SHAUN,
Hope you don't mind me asking another question..
No problem.
I have a psu that i have taken apart as i have had an intermittent fault with it..So i decided to test most of the
components in it either by soldering out one lead or completely removing it and testing..
Now i came a cross some schotty diodes attached to the psu heat sinks ..3 on one side and 2 on the other..
There is 3 bigger schotty's and 2 smaller ones..now i did your testing method from the schotty pdf i got from
you..
Used analogue meter ( exact same one you have) at X 10K red probe on middle leg(cathode) and i touch black probe on
both outer legs (anode) and get the right reading pointer full deflection ! then i reverse the black probe to
centre leg and red probe to outer legs ..pointer moves up just a bit ..so this is a good schotty diode right ?
You are right. It is good.
Now when i tried to take a reading as above on the smaller size schotty diode ( marking on diode is STPS20H100CT
)
I get the pointer swing full deflection when red probe touches middle leg (cathode) and black probe on each outer
leg ..but when i reverse it by putting the black probe on middle leg (cathode) and red probe on each outer leg i am
not sure that the pointer moves because it is so small a movement i don't know if my eyes are playing tricks lol..
If my eyes are not playing tricks then the pointer movement is less than a mm if that .. hope you can understand
what i am saying only it is hard to express it in an email..
So my trouble is now ,is this a good schotty if it did move by a hairs width ? Have you come across this yourself
when testing ?
They are good schottky diodes even though it moved a little. If it swing full scale when black on the middle pin
and the red on the other pins then it is shorted.
Now the psu problem is intermittent like i said it will power and start up my pc then when i turn the pc off and
try to restart it will sometime work normal and other times it won't boot the pc..
It may be the problem of a start up resistor and sometimes a bad POWER IC may cause such problem.
I am in the process of changing out all the caps apart from the 2 big main filter caps so i thought i would learn
to test while i have it apart and put use the great ebooks that i got from you..I have never studied electronics as
stated before so i am learning every day thanks to your ebooks that guide me.
You are welcome!
Just one more question if it no trouble ..when testing smd components like caps,resistors and diodes (this psu has
some smd on the pcb) do they also have to be soldered out when testing .
Yes you need to if possible.
Thanks once again Jestine for all your help as it is much appreciated.
You are welcome
Jestine
========================
I have this question for you. I am working on a ITT dvd
player..one of the expensive one actually. I found a dead short in the power supply and one of the shorted part
is a mosfet 900 volts 9amp. I got a new one in 600 volts but 20amp mosfet. it is a brand new but but strangly
when I get the whole circiut with the lopt/FBT with the mosfet on, it gives me only four bars... but when I take
out of the circuit, it gives me a full bar? I find that really strange since it is a good and brand new one..any
ideas?thank
Hi Waleed,
Thanks. Have you check all the components in the primary side? In some SMPS design, the tester may act this way. If
you have confirm that all the components in the primary and secondary tested good then go ahead to on it.
Jestine
==========================
hello
I have just sent you an email before this one, I have CoolerMaster SMPS product no : RS-350-PCAR-I3 350 276W it
stops and dead it's fuse is good and I tested the outputs and all is good expect the +12V nothing with it no 12V,
may I start troubleshoot with the primary part or the second part ?
thanks
--
Issam S.
HI Issam,
If all output are good and only the 12 volt line have problem then you should check problem only in this line. It
could be dry joints, bad filer caps, bad output diodes and etc.
Jestine
==========================
Hi Jestine
I have fixed an HP D5060a lcd monitor
The symptom was flickering
So I checked the inverter board for dry joints and found an inverter transformer was dry jointed
I re soldered all transformers .
It is working good now.
BTW a tip for ERG members
when I fix LCD 's I always re solder the transformers as it is high tension get quite warm & solder goes
dull.
HI Lee,
Thanks for the email. Yes i agree with you that one has to resolder the high voltage area as i came a lot of LCD
Monitor with this kind of fault.
Jestine
===========================
Hi jestine
I have a problem with crt color tv LG 21"model CF-21S32EX,the voltage
G2 of television increase and decrease frequently the light of tube of
picture increase and decrease consequently the light of picture that
saw of tv too,also the color of picture increase and decrease or or
sometimes total screen blue for instant again picture return,I was
tested parts of power supply ,b+,fixed and not changing also I varied
behind high voltage trans potentiometer(screen and focus)when varied
the potentiometer of screen the picture of tv bad and again problem
exist I replaced ic number tda8842 but again problem exist,i am
sending low resoulation film (3gp format) about this problem please
help
me immedietly
thanks
HI Hadi,
Try remove the G2 wire and test to see if it stable or not. If the B+ voltage
to the flyback is stable and the G2 wire output is not stable then suspect a bad flyback divider. You may need to
replace the flyback transformer. If the G2 voltage is stable then most probably along the G2 line there is
components that may have problem especially the high voltage ceramic capacitor. You may need to direct replace the
capacitor because the normal digital capacitance meter can't really test if it is good or bad. By the way, sorry i
could not open the video.
Jestine
=============================
Hi Jestine,
Finished your monitor teaching course? Like to ask 1
Question. Any substitution for transistor A2039, Can U check for me please.
Thanks Jestine for your help & God
bless
Hi Bernard,
Just completed few hours ago. The substitution for A2039 is 2SA1244, 2SA1795, and 2SB1203
Jestine
==========================
Dear Jestin,
I have a 15'' LCD Monitor HCM510 LSA, HCL make monitor
which is having display goes after some time, I have corfirmed the LCD panel ok, problem in the conversion
board, pls. gide me to repaire this board. I have cheked both mosfets in output section found
ok.
Thanks & Regards
Michael
HI Michael,
You may need to check the backlight because a bad backlight could cause such problem.
Jestine
After few days-Michael sent me this
email:
Replaced other working backlight tube, now the monitor is
working fine, thanks for your valuable suggestion.
Michael
=============================
Hi Ganesh,
Just one to ask you one question.
Lets says,we want to remove the bad SMD ic in any of the
main circuit board.so we will use blower, right.so was is the best temperature to set at blower,when we solder
back the good SMD ic at board?
The temperature i usually set to 400 to 450 degree
celcius. When we solder it back i just use my normal solder gun 25 to 30 watt will do.
Jestine
============================
Jestine could you recommend the right multimeter to
purchase.Thank you.
Sent from my iPhone
HI Charles,
For analog meter get a Sunwa Meter (must have x10k ohm range). For digital meter get any good brand like Fluke,
Sanwa, and etc.
Jestine
===========================
Hi,how are you?Hope you always fine indeed.Thanks for the
info about transistor c5707 in your blog.It's a good post.Few shool in my area use lot of dell lcd monitor and
they send to me about 30 unit lcd monitor symptom like this.But the problem is the spare part.So last school
holiday i travel to few places for vacation and drop by at the electronic store and found out this transistor in
kuantan for rm 7.00 ea,in Muar for rm 5.00ea but in Seremban it just rm 3.00 ea.At least the problem is
solved.I'm gonna open my own electronic and computer shop in the end of this year.Hope everything going well as
planned.Lastly can you tell me your experienced and advise about how you charge your customer base on job that
you already done.Thanks for all the support.
HI Farizal,
Nice to hear from you and the Seremban electronic shop sell that part very cheap! I'm charging a customer on a flat
rate basis. I'm charging RM100.00 for a 15 and 17" LCD Monitor and this charge will inclusive of labour and spare
parts. If i can't find any parts and can't repair the monitor, i will return the monitor back to customer free of
charge. It is more like a give and take situation. Congratulation on setting up your repair business!
Jestine
===========================
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