SATA /PATA external supply ?

[Marianelforum]

Re: SATA /PATA external supply ?

...if I ask someone else doing it, I will not learn....there's no point on that...

I understand and maybe even patially agree, but learning cannot come only from experiments, there has to be a good theoretical base, it allows you to look at things from another perspective, and also it prevents you from making basic ( and often costly ) mistakes.

The converter only seams simple from the component count point of view, but that's just an illusion, as a matter of fact this converter involves complex math and calculations in the design part, it is a fragile balance between component vallues and working parameters.

...If there's no voltage at all, is it possible that my coupler is gone ? or the triode TL431 ?

I can't remember the last time i found a deffective opto on a PC supply unit, but you can easily check it removed from the board, use a DMM set on the diode function, check the led side of it, it shoud read about 1V drop in one way, and open circuit in the other, the transistor part should read open circuit because it is like measuring a npn bjt on CE. If you need to be sure than get a 1,5V battery, a limmiting resistor ( let say 100 Ohms ) , and power the led side of the opto with it, than conect the digital multimeter ( still set at the diode function ) at the transistor side, what you are doing is powering the led, so the phototransistor inside will activate, the dmm should read some tens or hundreds of milivolts.

TL431 is not a triode, it is a thermal compensated voltage regulator, it has a 2,5V refference, and an error amplifier, all in one TO92 case. I guess you could call it an adjustable zener.

...and I reckon 1N4007 will not be able to do the job...

It most definitely cannot! In fact it could blow up!

probably the short on bulb if I put 0.22 ohm, because of slow 1N4007 ?

Of what bulb are you talking about?
Anyway, you must have that 0,22 ohm resistor for the converter to work propperly.

[bianchi77]

Re: SATA /PATA external supply ?

I got 300 ohm on optocoupler when testing it with battery an DMM

[bianchi77]

Re: SATA /PATA external supply ?

probably the short on bulb if I put 0.22 ohm, because of slow 1N4007 ?

[bianchi77]

Re: SATA /PATA external supply ?

It's a small circuit to learn...

[bianchi77]

Re: SATA /PATA external supply ?

Thanks for the suggestion, I carefully handle the circuit, I know, there's a high voltage area, and I clear the capacitor always before handle it...
if I ask someone else doing it, I will not learn....there's no point on that...
Why don't I buy a new one then ??
I want to learn that's why I'm doing it...
Experiment is part of learning from me...of course with caution...
I wear a glove and measure the voltage first before play with the PCB...

If there's no voltage at all, is it possible that my coupler is gone ? or the triode TL431 ?
and I reckon 1N4007 will not be able to do the job...

[Marianelforum]

Re: SATA /PATA external supply ?

if I use a different coupler, does it matter ?
I don't have the exact replacement for it...

Most of the cheap ATX power supplies have that optocoupler, what you want to see is that "817" code, and there are loads of psu's with it.

if I put a lower resistance the bulb will on....short circuit...

R1 establishes a current loop for the self oscilating flyback converter, it needs to be the exact vallue in ohms, so .22 of an ohm ( 0,22 Ohm ), the power rating could be other vallue as long as it is not a lower one.

is it because D5 = FR107 and I replace it with 1N4007 ...
looks like it must be fast recovery one ?

You cannot use a nomal diode for RCD snubber on a high frequency switch mode power supply, 1N4007 is way too slow to do the job, you can use UF4007 in stead or any other ultrafast diode with a voltage rating of at least 600.

You really should stop experimenting with stuff wich you do not understand, you could cause a great deal of damage of even worst you could receive an electric shock ( wich could kill you!!!!! )! Ask before trying something, and in situations like this when it is clear you do not understand the converter and the risks involved with playing with it, i would recommend you go to someone that knows what he's doing.

[bianchi77]

Re: SATA /PATA external supply ?

ok, thanks for the advice, I'll wait for FR107 then....

[Khron]

Re: SATA /PATA external supply ?

No - the 100v rating of the FR302 is way too low. I wouldn't use anything under a 400-600v rated ultrafast diode there.

[bianchi77]

Re: SATA /PATA external supply ?

is it possible I temporarily use FR302 replacing FR107 ?

[bianchi77]

Re: SATA /PATA external supply ?

ok...anything else faulty do you reckon ? output = 1.3V and 0.3V....abit weird...
no short on high voltage side....bulb completely off..

[vinceroger69]

Re: SATA /PATA external supply ?

if the old diode is a ultra fast type yes the replacement may cause issues you really need to replace like for like with the parts even more so if your learning untill you gain more experience in finding suitable replacements.

[bianchi77]

Re: SATA /PATA external supply ?

1N4007, trr = 30uS, FR107 = 500nS.....could it be a problem...?
my 1N4007 can not take the speed ?

[bianchi77]

Re: SATA /PATA external supply ?

is it because D5 = FR107 and I replace it with 1N4007 ...
looks like it must be fast recovery one ?

[bianchi77]

Re: SATA /PATA external supply ?

the original resistor was 0.22 ohm and you have replaced with a 22 ohm? i would get the correct 0.22 ohm and put that one in.

if I put a lower resistance the bulb will on....short circuit...

[bianchi77]

Re: SATA /PATA external supply ?

if I use a different coupler, does it matter ?
I don't have the exact replacement for it...

[vinceroger69]

Re: SATA /PATA external supply ?

if I use a different coupler, does it matter ?
I don't have the exact replacement for it...

the original resistor was 0.22 ohm and you have replaced with a 22 ohm? i would get the correct 0.22 ohm and put that one in.

[bianchi77]

Re: SATA /PATA external supply ?

if I use a different coupler, does it matter ?
I don't have the exact replacement for it...

[bianchi77]

Re: SATA /PATA external supply ?

I'm fiddling the schematic at post 18, I put R1 22 ohm/ 2W, since I don't have the exact replacement, does it matter with the voltage output ?
or?

[bianchi77]

Re: SATA /PATA external supply ?

I got the output 0.3V and 1.3V, suppose to be 12V and 5V, could it be opto coupler ?

[zx8401]

Re: SATA /PATA external supply ?

A Basic test to see if the opto coupler is working is to connect 1.5v to the led side and see if the transistor side goes low resistance in value.
The meter should show open circuit with no voltage applied.
Here is a piccy to show the connection.