Ritmo ATX power supply schematic ?

[bianchi77]

Guys,

Does anyone know the schematic of this ATX PSU ?
abit odd, I can see FET on 3.3V output rail....

[momaka]

Re: Ritmo ATX power supply schematic ?

Does anyone know the schematic of this ATX PSU ?

This looks like run-of-the-mill generic low quality PSU, so I am 99.99999% certain you won't find an *exact* schematic for it.

That said, the three transformers in the middle and SG6105 PWM controller tell me this is just another typical half-bridge topology PSU. So you can grab the schematic off of any half-bridge ATX PSU available online and use it as a *guide*. Here is one I found that is based on a SG6105 PWM IC:
http://danyk.cz/s_atx02a.png

Again, use this only as a rough guide, and don't expect component values or positions to match. Your PSU should be similar to what is shown on that schematic, but very likely NOT the same.

abit odd, I can see FET on 3.3V output rail....

You should also notice that there is no second output toroid for the 3.3V rail and no small torroid(s) near the main transformer. This suggests the 3.3V rail is linearly regulated - a cheap method that is very inefficient.

In my opinion:
this PSU appears to be very low quality crap. I wouldn't attempt fixing it if I was in your position - not for computer use anyways (I've fixed some similarly crappy power supplies, but only as a learning experience or for fun).

[bianchi77]

Re: Ritmo ATX power supply schematic ?

It's for fun and learning experience.....usually I'll another rectifier SBL2040 and output toroid filter on 3.3V rail....

Do you reckon it has a secondary rectifier issue ? I measured SBL2040 on 5V rail with DMM diode test mode and got only 0.12V.....that's bad, isn't it ?

[bianchi77]

Re: Ritmo ATX power supply schematic ?

(I've fixed some similarly crappy power supplies, but only as a learning experience or for fun)

What was the issue with those you had fixed ? secondary rectifier issue ?
I got it because of shorted FET on motherboard I reckon...

[Dan81]

Re: Ritmo ATX power supply schematic ?

That said, the three transformers in the middle and SG6105 PWM controller tell me this is just another typical half-bridge topology PSU.

It's a Linkworld. The LPF2SS model number points to a 300W Linkworld,however I have doubts it can do a watt in spec. (it's beyond the definition of garbage,and not worth anything )

[bianchi77]

Re: Ritmo ATX power supply schematic ?

LPF2SS

schematic ?

[bianchi77]

Re: Ritmo ATX power supply schematic ?

This looks like run-of-the-mill generic low quality PSU, so I am 99.99999% certain you won't find an *exact* schematic for it.

That said, the three transformers in the middle and SG6105 PWM controller tell me this is just another typical half-bridge topology PSU. So you can grab the schematic off of any half-bridge ATX PSU available online and use it as a *guide*. Here is one I found that is based on a SG6105 PWM IC:
http://danyk.cz/s_atx02a.png

Again, use this only as a rough guide, and don't expect component values or positions to match. Your PSU should be similar to what is shown on that schematic, but very likely NOT the same.


You should also notice that there is no second output toroid for the 3.3V rail and no small torroid(s) near the main transformer. This suggests the 3.3V rail is linearly regulated - a cheap method that is very inefficient.

In my opinion:
this PSU appears to be very low quality crap. I wouldn't attempt fixing it if I was in your position - not for computer use anyways (I've fixed some similarly crappy power supplies, but only as a learning experience or for fun).

So what's the faulty of this Ritmo ?
Is it possible that SB1040 is faulty ?
I've tested on DMM = 0.17V but when I tried with LED, 1K and 9V battery it's doing normal way of diode...forward bias LED = on...reverse bias...LED is off...

If this SB1040 is not faulty ...what else can be faulty ?

it was shorted accidentally between 5 to ground or 12 to ground...and shut off......could be SG6105 ?

[budm]

Re: Ritmo ATX power supply schematic ?

Relation to this thread?
https://www.badcaps.net/forum/showth...340#post687340

[bianchi77]

Re: Ritmo ATX power supply schematic ?

nope it's different PSU but the same case I reckon...

[momaka]

Re: Ritmo ATX power supply schematic ?

So what's the faulty of this Ritmo ?
Is it possible that SB1040 is faulty ?
I've tested on DMM = 0.17V but when I tried with LED, 1K and 9V battery it's doing normal way of diode...forward bias LED = on...reverse bias...LED is off...

If the SBL1040 passes the diode test that you did with the LED, then it is NOT faulty. Do the same test with the other diode rectifier (the SBL2040)

could be SG6105 ?

No.
Those controllers (SG6105, TL494, KA7500) are very robust. Only a severe case of run-away 5VSB rail (over-voltage) can damage it, which is very rare. Also, if it was damaged, you'd have very burned spots on the board. I know because I've worked on such PSUs. Typically, the damage looks like this:
https://www.badcaps.net/forum/attach...3&d=1334112631

If this SB1040 is not faulty ...what else can be faulty ?

A lot of things could be wrong, so lets start with some order.

First, check mains fuse and NTC thermistor on input, as well as input bridge rectifier (typically 4 diodes on cheap PSUs).

If these are okay, next item is plug in the PSU and check the 5VSB rail (purple wire on ATX connector for your PSU) - you should get 5V +/- 0.25V.
...
So check these things and we will go from there. Also, we really DO need better pictures to help you troubleshoot this PSU.
This one is good (it's helpful):
https://www.badcaps.net/forum/attach...1&d=1472539862

But this one is useless:
https://www.badcaps.net/forum/attach...0&d=1472539862

Please make sure your pictures are clear and focused before posting them here. There's no point in posting pictures if we can't see anything on them.

[bianchi77]

Re: Ritmo ATX power supply schematic ?

I've fixed it already, broken oscillator transistors and FET...all DONE, thanks everyone..