atx YLP-013 Repair help please

[humblesmith1]

Re: atx YLP-013 Repair help please

Started it up and the 5Vvsb output is 5.89 volts.

No smoke

No other outputs

Will have to check the WT7520 when I get more time.

What regulates the 5vsb? seems a little high.

[370forlife]

Re: atx YLP-013 Repair help please

There is a 50v, 47uf cap near the 5vsb transformer that might need to be replaced.

[humblesmith1]

Re: atx YLP-013 Repair help please

Thanks I'll pull it and check it out. I think that I have one here and will just replace it.

Any ideas about the main supplies?

[humblesmith1]

Re: atx YLP-013 Repair help please

The cap reads 47 uF.

Any other ideas?

If I check ripple with scope on the bench , what should I expect?

[humblesmith1]

Re: atx YLP-013 Repair help please

The 431 reference has 2.525 volts on one side and about 1.94 on the other.

The 5vsb output is now 5.6 vdc with 140mv ripple (still a little high)

No other outputs up yet.

[Th3_uN1Qu3]

Re: atx YLP-013 Repair help please

TL431 looks ok. Try replacing the optocoupler in the 5vsb circuit. These circuits are built ass-backwards - as the opto goes weak or if the resistors setting the divider go open, voltage goes up. WT7520 has a maximum voltage of 5.5v - if it ever went much past 6v the WT7520 could have died.

[humblesmith1]

Re: atx YLP-013 Repair help please

Thanks a lot!

I'll try to find an optocoupler.
Is the fairchild H11AA817C the right part?

And I'll check the divider resistors.

Do you know what values they should be?

Don't know where to buy a WT7520, do you know of a supplier?

[Th3_uN1Qu3]

Re: atx YLP-013 Repair help please

Anything with 817 in the part number will do for the opto, they're all compatible. Most of the time i see Everlight EL817 or Cosmo ones. As for the WT7520, unfortunately i have no clue where to get one, short of another similar PSU.

[humblesmith1]

Re: atx YLP-013 Repair help please

Thanks Again.

I'll try to get the parts and the see......

[humblesmith1]

Re: atx YLP-013 Repair help please

installed the opto
output = 3.6 v
found low esr 470uF 10 v needs replacing

[humblesmith1]

Re: atx YLP-013 Repair help please

can't find the main chip

now it is garbage

I learned a lot though

[rattman]

Re: atx YLP-013 Repair help please

I know this is an old post. I have the same power supply
450 Watt and was wondering if you know the value of C28?
Hope I'm in the right place. Thank you in advance.

[Bill Sullivan]

Re: atx YLP-013 Repair help please

211 pico 1KV