Looking for a Bestec ATX-300-12E circuit Diagram

[Drexter]

Hi guys,

I have a burned Bestec power supply, the problem was at the IC 8, it shorted due to humidity and burned itself, I was able to see the inscription on top of it and it says, A 635 M, not very sure about the M, and looking at a past thread I saw that someone said that this power supplies had the A6351 pwr chip, so i figured it was the one it burned out on my power supply. But after I reviewed the datasheet I saw that pin 1 is Source, pin 2 is GND, and pin 3 is Vin. Knowing that, before i solder it i saw that on the track where they are supposed to be solder is a continuos one. what I mean is that if i solder them pin 1, 2 and 3 will be shorted, pin 4 is separetly. So this is where I ask you guys, would it be that the chip I bought is not the right one? not the A6351, or the track is bad due the burn out?. Cause it doesnt make sence to me that the pins 1,2, and 3 get welded tougether. Thats why I was looking for a Diagram for the power supply but I just dont find it anywhere. Any suggestions?

By the way, english is not my native tounge so please bare with me if I dont express myself correctly or with the proper terminology.

Thanks,

Paul

[everell]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

This schematic was drawn of the Bestec ATX-250 12Z, but is very much like your power supply. The 5vsb circuit is similiar for Bestec ATX-250 12Z, ATX-300 12E, and ATX-300 12Z. All use the A6351A pwm chip.

As for your question "pins 1, 2, and 3 welded together", you are probably looking at the pin numbering wrong on the bottom of the board. Pins 7 and 8 are tied together, and pin 6 is not connected to anything inside the chip. Therefore what you are probably seeing is pins 8, 7, and 6 tied together. Look at it again and let us know what you find.

[hkqq2010]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

This schematic was drawn of the Bestec ATX-250 12Z, but is very much like your power supply. The 5vsb circuit is similiar for Bestec ATX-250 12Z, ATX-300 12E, and ATX-300 12Z. All use the A6351A pwm chip..

I have a Bestec ATX300P5WB, it is always blown up the fuse. Too bad ah....
After I isolated the 5Vsb circuit, it now stop blown up the fuse ...
But unfornately, it is different from your provided circuit, it used TNY276PN power chip.
Anyway, I will continue to try fixing it up .... Thanks for your circuit.

[everell]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

Here is a schematic for a Bestec TFX0250D5W using the same TNY276 chip. Hope you are able to fix it.

[hkqq2010]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

Here is a schematic for a Bestec TFX0250D5W using the same TNY276 chip. Hope you are able to fix it.

Vow ... it is really good !!!
It seems very similiar to mine. I will try it tomorrow.

many ... many thanks.

[hkqq2010]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

Here is a schematic for a Bestec TFX0250D5W using the same TNY276 chip. Hope you are able to fix it.

I found that the resistance between EN/UV and S of TNY276 is only 320Ω. Therefore, no 5Vsb. I think it is burnt out.
I will buy one next time I visit the shop.

Besides, I found there are two Varistors, each across the big Cap, 680U 200V. One had burnt out. The other show that it is TVR10241. I am just wondering why it use a 240V varistor. Can I replace them with two 180~200V varistor?

Many thank in advance.

[everell]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

What brand is the 680 uF/200 volt capacitor? Show us some pictures of your power supply - I don't think I have seen that model Bestec.

[hkqq2010]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

What brand is the 680 uF/200 volt capacitor? Show us some pictures of your power supply - I don't think I have seen that model Bestec.

Thanks for your reply.
Capacitor is CapXon as attached. The varistor is VR44 & VR45

[hkqq2010]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

Thanks for your reply.
Capacitor is CapXon as attached. The varistor is VR44 & VR45

Two more photo.

[hkqq2010]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

Here is a schematic for a Bestec TFX0250D5W using the same TNY276 chip. Hope you are able to fix it.

Thanks for your help, after I replaced the TNY276 chip, it back to work now. I am using it to drive the PC which I type this reply.

Many thanks once again.

[JOYDIP]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

LOOKING FOR BESTEC ATX-300-12Z RevHR circuit Diagram

[JOYDIP]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

LOOKING FOR BESTEC ATX-300-12Z Rev: DHR circuit Diagram. ITS VERY URGENT. ANYBODY PL HELP.//

[everell]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

What part of your power supply is not working? Which circuit do you need a drawing for?

[JOYDIP]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

all voltage r ok but NO PG out from ic TPS3510

[JOYDIP]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

anybody have the circuit diagram of Bestec ATX 300-12Z smps using ic TPS 3510???

[everell]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

Your problem might be with the power good signal coming into the 3510 chip. Not much on the power good output from the chip. Here is a drawing of the power good input.

[JOYDIP]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

Hi dear everell, u r very correct, in the ic 3510 pin no 1 is PG input as showing in ur ckt. but my problem is no output from pin 8, which is PG out, whereas 12v, 5v, 3v3 present at pin no 7,6,5 resp. for which only CPU fan is on rest no action///

[JOYDIP]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

what should be voltage at pin no 1 of 3510???

[everell]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

what should be voltage at pin no 1 of 3510???

Looking at an actual oscilloscope measurement of a Bestec ATX-250 12Z which uses the same circuit, goes from zero to 2.2 volts. If it goes only part way, it can cause your problem. How you load the power supply can also cause this problem.

The power good output voltage should be about 2.7 volts. It is possible you have a bad 3510 chip.

[JOYDIP]

Re: Looking for a Bestec ATX-300-12E circuit Diagram

thanks everell, your information about the voltage of PIN 1 (2.2v) as well as the circuit. pin1 voltage was 0.5, replace R41 now it is working like new one/// thanks a lot again///