1) What if the Blue ESR meter shows ‘00′ when we check capacitors, does it mean short or very good capacitor.
2) I’ve proven to myself that the meter isn’t effective caps in circuit. Better check it out of circuit.

If your meter cable is too long then it will give you the “00″ result. Make sure the each cable is 30cm long and i found that the esr meter is very good in testing e-cap on board.
3) What is the function of ‘memory’ capacitor and how does it work. I don’t remember if you had mentioned about it in your ‘Testinf E components’ book.

Could you explain this because i have not come across a cap meter that have memory?
4) HP1925 LCD monitor power LED is there but no display. I found few caps popped up in the P supply area and replaced them but no change. 17 volts and less that 5 volts available at the connector to the main board. One polyester film cap found to have high ESR. Replacing that too didn’t solve the problem. Back light lamps seem good. From the beginning I notice very low light appears on for less than a second and the monitor goes to stand by mode. It’s puzzling to me. Please give a clue.

When it already shutdown does the supply voltage to the inverter IC still present? If not suspect a bad mainboard (assuming the mainboard is getting all the correct voltages).

I have a question regarding blue ring tester. When testing a good flyback all lights will light contineous or will flash all the ligth only?

It depends on the flyback belong to how many inches of the Monitor. Generally the 14 to 17″ will show from 7 to 8 LEDs. 19″ and above will have about 4 to 5 LEDs

I used the test coil that is included in the set. and my finding only lit all the lights for a seconds and gone out. i mean the light is not continually on while still connected to the coil, is it normal or not?

Try scratch off the coil wire tip as it was laminated and do not have a good contact. If after removed the lamination and the LEDs still go off then the meter may be not fully assembled and need to recheck again. A good meter should show steady 8 LEDs

i’m facing one problem in my smps that is unstablize or variation in 35 V DC and little sound tik tik sound in power supply but 24V DC is stablize no variation in voltage i thought the sound is coming from smps transformer.Please give me solution for fix it.i’m waiting for your helpfull reply.

You mean you have two output lines 24v and 35 V and only the 35 v not stable? If yes then check along the 35 v line and look for bad filter cap and also the load that is connected to the 35 volt line.

Can I turn on the PSU and measure the voltage at the secondary side of the transformer,

with the secondary side removed? I mean, I desolder all of the pin of the transformer at the secondary side,

and remove the optoisolator and then turn the PSU on and measure the voltage on the secondary side of the transformer.

If the secondary side doesn’t have any output voltage,could it be caused by fault at primary side?

because the primary side on the tranformer pin have voltage.

No you can’t because it may blow the primary side due to no load condition.

QUESTION

Thank you so much. I have question, What is the function of an IC
SE130 (3 pins) Can you give me its pinouts. Thank you so much
again.

Here is the link:

http://pdf1.alldatasheet.com/datasheet-pdf/view/38243/SANKEN/SE130N.html

Second problem , what causes when a relay in a power supply wont
work or power pilot light wont light, Your help would be a great help
and much appreciated. Happy Valentine’s Day in advance and more
power…

Power side problem and you need to test out all the components in it. It can be a shorted diode, transistor, open resistor, bad cap and etc
--------------------------

muliple regulated power supply

in a muliple regulated power supply if i increase the value of the capacitor from 100uf to 150uf what will happen to the out put voltages is there any dammage to the components in the circuit?


Hi Sahraoui,

There will be no problem to the power supply

-------------------------

TEA1504

Please provide me Pin and Voltage details of IC TEA1504 Supply regulater. Please sir.


Thanks and Regards
Daniel

HI Daniel,

Try check this link:

http://pdf1.alldatasheet.com/datasheet-pdf/view/19711/PHILIPS/TEA1504.html

--------------------------------

QUESTION

If the MCU doesn’t send any power on signal to power supply or inverters what do you normally do? (sometimes there’s not even remote diode lit on the front TV panel

ANSWER

First, the MCU is programmed to run if it received supply voltage and some important signals like the H/v signals. If the MCU program or the MCU itself have problem, it will not output the on signal. You can either reprogram the MCU (if you have the programmer) or replace with a MCU that already have program in it

Do you suspect MCU to be bad or EEPROM or FLASH memory to be faulty

ANSWER

From experience, it is usually the MCU

Is it best in this case to replace whole main board or something else

ANSWER

If you could get the MCU with the program and is cheaper than the mainboard then replace only the MCU
---------------------------------------

QUESTION

When you replace a capacitor in a power supply, is there a maximum voltage above the original capacitor’s voltage. For example, if the original capacitor is 1000uF 10V and I replace by a 1000uF 35V … is 35V too much

ANSWER

The best is to use a voltage that is slightly higher like 16 volt. A higher volt would cause more and have less space for installation

When you replace a MOSFET in a SMPS or the inverter circuit by another MOSFET but different part number…what are the most important things you need to check on the datasheet to make sure the replacement part is ok? By the way, I already know that I have to check for NPN or PNP type…

ANSWER

For mosfet, you need to check the voltage, amp and watt and make sure the ohm value is not too high or too low

------------------------------

QUESTION FROM SUDAN

What kind of meter do you recommend to buy
for testing MOSfet(what is the meter that you use
for testing in 10Kohm range

ANSWER

any branded meter that have the x10 k ohm range

Only 10Kohm range is needed,
if meter goes beyond 10Kohm range,
then that meter in not suitable for testing
MOSfet

ANSWER

Don’t get the 100K ohm range because the voltage in the meter is not high enough to accurately test the Mosfet

-----------------------------------------------------------

QUESTION

how to test this STR6656 five pins if good or bad

ANSWER

Power On the set and test the supply input voltage and output waveform. The best is to direct replace the power IC and retest. Before that make sure all the components are tested good first

-------------------------------------

Ayaa Ahmed
from Egypt
Ask
How does a solid state relay work


Answer

A solid state relay (SSR) is an electronic device to switch the electrical current, rather than an electromechanical device.
An electromechanical relay uses a magnetic coil and mechanical contacts. When current flows through the coil, it pulls down a piece of iron called an armature, causing the mechanical contacts to touch and thus close an electrical circuit.

A solid state relay has no mechanical moving parts, but instead uses a three terminal device such as a triac (triode AC), back-to-back tyristors, or FET (field effect transistor) to conduct the electrical current. When the third terminal (gate) is energized by the control input, the device conducts.

Essentially the solid state relay controls a larger electrical current by accepting a small control signal. There are no moving parts.

Advantages of solid state relays are: they have no internal arcing or contacts to wear out, can last virtually forever, can have extremely low control input requirements, and are immune to vibration or G-force chatter
-------------------------------------

Iphone digitizer problem

Hello.

I bought a used iphone 3g a week ago and it worked completely fine until yesterday when i went to type in my passcode the screen would not respond to my touch at all. I restarted it 4 times and still nothing. Since its not under warranty the only problem I can see is that the dogitizer is broken or stopped working.

I bought a brand new digitizer and front glass and everything to replace it. But i want to MAKE SURE.....there are NO other parts that can be affecting the touchscreen from not working right? when someone calls my iphone....it rings and everything works on the lcd.....i just cant answer it because it wont sense me touching it.

Thanks for your input

Answer

If everything else works fine, replacing the screen/digitizer will take care of your problem. Just be VERY careful when you remove the LCD from the old assmebly as it is very fragile and can easily be broken even with the slightest or tap

ABOUT LOGIC PROBE

i want to ask you question about logic probe
you said that the truth table is important to use logic probe
i cannot find the relation both of them i read in many forums that when green led light up that mean low voltage
red led means hi voltage and i didnot use logic probe ……………………..and i donnot know how the truth table is important to do this job

ANSWER

You need to get a logic probe to test on board that have the TTL ICs.Find the IC part number and then to see which type the IC belong to whether is OR GATE, NAND GATE and etc. From there, refer to the OR GATE, NAND GATE truth table and test it with your probe with power On to the board you are testing