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[SOLVED] ATX 300W power supply in problem

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O no I didnt mean on Q3, I mean on T3, that is trafo on circuit, its marked as T3, transistors have Q prefix.

---------- Post added at 00:49 ---------- Previous post was at 00:47 ----------

Yes I will use the same values, but with resistors you can use stronger metal oxide about 1W, few wats, they are small, but take the same value.
 

Ok fine, sorry i got it T3 is a transformer... It will take a little time to check this all... i will be here soon after checking and replacing the components...

I have one last question... Why are the Capacitors like this glued using hot glue... Is it for any technical reasons...? I have found it in the same circuit that C25 and C29 are glued together...
 

Why are the Capacitors like this glued using hot glue... Is it for any technical reasons...? I have found it in the same circuit that C25 and C29 are glued together...
Click to expand...

Electrolytic capacitors can vibrate at low frequency and make cause of mechanical damage. They are often mechanically fixed to the PCB with adhesive to prevent that.

---------- Post added at 01:29 ---------- Previous post was at 01:03 ----------

Also check R27 near shunt regulator U2.
 

All this talk get no ware first rplace the capasitors they must be in place or u will have high ripple on violet +5 and this volt is used for the 3.3 v out module
 

I have replaced those capacitors and the burned resisters namely R34 , R33 and R36 , and the diodes D7 (Schottky) and the D9 with an new one and here is the results...

1. Fan--OFF
2.R36--- Fuming + Fired....
3.R33 and R34 starts Fuming following R36
4.Capacitors start Heating...
5. So i switched off the supply...
6. Total time of the process --- 30 sec.

Can anyone please help.....
 

When the output is not stable or low there is a fed back telling the input to work harder and so heat up.
 

dselec said:
When the output is not stable or low there is a fed back telling the input to work harder and so heat up.
Click to expand...

so is there any solution for this problem.... i dont need that 3.3v connection any more just need the 12 V supply... so is there any method by which we can extract these 12 v from this circuit by deactivating any particular block like these capacitor and resister arrangement...
 
Last edited:

There is probably a short circuit on your board ..
this can be the most common reason i can think of .. to cause sudden problems as in your case
is your circuit usually open ? .. any chances of water drops falling onto it .. or maybe sweat (this is what could have happened to the resistors) - this happened to me before
another reasons of shorting could be pieces of component cut out pieces .. resistor leads etc ... or solder fallen onto the supply

do not turn on your supply until the problem is found and corrected ...
to make the supply partially functional (12v only) i shall try to sort out some steps ..
shall need to study your circuit first // will get back to you when i have something worthwhile
 

amu_cpln said:
There is probably a short circuit on your board ..
this can be the most common reason i can think of .. to cause sudden problems as in your case
is your circuit usually open ? .. any chances of water drops falling onto it .. or maybe sweat (this is what could have happened to the resistors) - this happened to me before
another reasons of shorting could be pieces of component cut out pieces .. resistor leads etc ... or solder fallen onto the supply

do not turn on your supply until the problem is found and corrected ...
to make the supply partially functional (12v only) i shall try to sort out some steps ..
shall need to study your circuit first // will get back to you when i have something worthwhile
Click to expand...

I dont think its a problem caused by the short circuit by solder waste and so.... I have crosschecked circuit PCB for any external short circuit....and found nothing like that..
obviously i am not using it anymore for my PC... instead i was trying to recycle that old electronic junk to atleast a 12 V power supply for my HHo cell....
If you have any solutions please let me know...

Thank You.
 

Can anyone get me the best link for studying SMPS design from ground zero level....
 

Some fine additional material :
 

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