12V rail is not on ?

**budm** · 09-11-2016, 08:20 PM

Re: 12V rail is not on ?

Originally posted by bianchi77

what Voltage will you see on the lamp that has open filament? = source voltage

source---probe--open filament--probe--lamp x 9------ground

voltage at open filament = source

am I right ?

Right, so what do think you should see when the diode does not conduct in reverse bias mode? If you do not see the same result then you know that DUT is letting the current flow when it should have block the current flow, and you can then check the leakage current of that DUT by measuring the Vdrops on the resistor that is connected in series with the DUT, and look up the spec of the diode.

**bianchi77** · 09-11-2016, 08:48 PM

Re: 12V rail is not on ?

ok, thanks for the information...keep learning....I love that

**bianchi77** · 10-10-2016, 06:50 AM

Re: 12V rail is not on ?

I've replaced SBL1040 with SBL2040 but I got no luck...
V Standby is on but no voltage on secondary...could be my primary transistor is faulty ?
Or my PWM chip is faulty ? chip = 2005 ....no response with PS_ON switch at all...

**bianchi77** · 10-10-2016, 07:06 AM

Re: 12V rail is not on ?

What happen if my PWM is not working ?

**budm** · 10-10-2016, 05:28 PM

Re: 12V rail is not on ?

Originally posted by bianchi77

I've replaced SBL1040 with SBL2040 but I got no luck...
V Standby is on but no voltage on secondary...could be my primary transistor is faulty ?
Or my PWM chip is faulty ? chip = 2005 ....no response with PS_ON switch at all...

So did you look up the spec sheet of the IC at least to get the pinout and to check the DCV of the IC PINS?

**budm** · 10-10-2016, 05:32 PM

Re: 12V rail is not on ?

Originally posted by bianchi77

What happen if my PWM is not working ?

PWM of what?Why don't you look up what the PWM is and what is it related to in the switching power supply?
What did you check the the primary side?
Did you recap the board?

**bianchi77** · 10-10-2016, 05:55 PM

Re: 12V rail is not on ?

Originally posted by budm

PWM of what?Why don't you look up what the PWM is and what is it related to in the switching power supply?
What did you check the the primary side?
Did you recap the board?

Primary side ? check all the transistor and FET ?
I got V SB....does it mean that my primary side is doing the job ? and there's no fuse blown...

PWM is a pulse width modulation and it's the way switching power supply generating a voltage...depends on the width of the pulse...
and that chip has two function over voltage / under voltage supervisor and PWM generator....will it break if there was short on the output ? because all / one of its input for protection sunk to the GND straight away , high current on it within few seconds...

I saw a smoke from 5V rail for few seconds but when I checked the diode for it...it's normal....I don't understand....

**budm** · 10-10-2016, 06:51 PM

Re: 12V rail is not on ?

Originally posted by bianchi77

Primary side ? check all the transistor and FET ?
I got V SB....does it mean that my primary side is doing the job ? and there's no fuse blown...

PWM is a pulse width modulation and it's the way switching power supply generating a voltage...depends on the width of the pulse...
and that chip has two function over voltage / under voltage supervisor and PWM generator....will it break if there was short on the output ? because all / one of its input for protection sunk to the GND straight away , high current on it within few seconds...

I saw a smoke from 5V rail for few seconds but when I checked the diode for it...it's normal....I don't understand....

Yeah, so the SB power supply is working BUT THE OTHER POWER SUPPLY IS NOT WORKING, you are not getting the 3.3V, -12V and +12V!

**budm** · 10-10-2016, 06:57 PM

Re: 12V rail is not on ?

If you are looking at the power supply board right now, you cannot tell that you have more than one power supply on that power supply board, if you cannot then you are trying to fixing something that you do not understand of what you have in your hands.

Over 100 posts and you still do not understand how many power supplies are in your board?
"I got V SB....does it mean that my primary side is doing the job ?"

Look at post 10 diagrams.
https://cdn.badcaps-static.com/pdfs/...83951b6882.pdf

I keep telling you do not understand the basic of what you are working on so you go all over the place trying to fix something you do not understand.
As yourself what are in the primary side to make this power supply to produce all those Voltages.

**bianchi77** · 10-10-2016, 08:39 PM

Re: 12V rail is not on ?

Originally posted by budm

If you are looking at the power supply board right now, you cannot tell that you have more than one power supply on that power supply board, if you cannot then you are trying to fixing something that you do not understand of what you have in your hands.

Over 100 posts and you still do not understand how many power supplies are in your board?
"I got V SB....does it mean that my primary side is doing the job ?"

Look at post 10 diagrams.
https://cdn.badcaps-static.com/pdfs/...83951b6882.pdf

I keep telling you do not understand the basic of what you are working on so you go all over the place trying to fix something you do not understand.
As yourself what are in the primary side to make this power supply to produce all those Voltages.

Ok, thanks for the diagram....doesn't matter for me if I need to learn over 100 posts....
I'll have a checked on 3 primary transistors and show you the photos later on....
Let's see what we get here...and go from there....
I have unsoldered the 3 primary secondary rectifyiers as well...so we can see the result as well...and tell me what you think ?

**stj** · 10-10-2016, 08:49 PM

Re: 12V rail is not on ?

you cant run it without the rectifiers, the controller monitors the output.

**budm** · 10-10-2016, 09:07 PM

Re: 12V rail is not on ?

"primary secondary rectifyiers" What the heck is that? you have rectifiers in the Primary (HOT) side and rectifiers in the secondary (COLD) side.
Beside, the rectifiers for the SB power supply or the Other power supply?

**bianchi77** · 10-10-2016, 09:19 PM

Re: 12V rail is not on ?

sorry...mistype...secondary rectifier...

**bianchi77** · 10-10-2016, 09:22 PM

Re: 12V rail is not on ?

here's the test from primary transistors...how do you reckon ?

Attached Files

**bianchi77** · 10-10-2016, 09:23 PM

Re: 12V rail is not on ?

I'm going to test the secondary rectifier and show you the result...give me a moment...
I still think that my 2003 chip had died already since it becomes the overvoltage or undervoltage protector...and it was short either 12V or 5V rail....

**budm** · 10-10-2016, 09:39 PM

Re: 12V rail is not on ?

BTW, that diagram in post 10 is not from me, I do not even know if it is matched your board or not.

**bianchi77** · 10-10-2016, 09:42 PM

Re: 12V rail is not on ?

Here's the secondary rectifier result.....3.3V rail is not good result it's showing resistor result 28 ohm and 205K result...it was brand new before I tested it in circuit...
Brand new from the tray 198 mV and 198 mV

Attached Files

**bianchi77** · 10-10-2016, 09:43 PM

Re: 12V rail is not on ?

How do you reckon from the test result ? talking about diagram, here's the pcb code :
Y-B200 ATX Ver:2.6

**bianchi77** · 10-10-2016, 09:45 PM

Re: 12V rail is not on ?

I don't have 2003 chip to test with....

**bianchi77** · 10-10-2016, 09:46 PM

Re: 12V rail is not on ?

Just now, I saw two burned resistors....near to 3.3V rectifier....I'll show the pictures...hold on...I'll take picture of them...that's why I saw a smoke yesterday, and it was resistor burn smell yesterday, but haven't seen it yet until now...R33 and R34

12V rail is not on ?

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