Delta PS Only 5vsb No Secondaries

[mmartell]

There is a V+ and V- as seen in one of the pics which I think is voltage across the main filter caps and that measures 330v when plugged in and doesn't change when I jump the pson pin to ground on main connector. When I DO jumper it there is a short "chirp".

I've changed out nine bulged caps. Where tollook/measure now ?

[Dgtech]

Re: Delta PS Only 5vsb No Secondaries

When you jumper the ps_on, do you momentarily jumper it or keep it jumpered solid?

[mmartell]

Re: Delta PS Only 5vsb No Secondaries

Uh oh. I keep it jumpered. Is it a momentary contact thing ?

[Dgtech]

Re: Delta PS Only 5vsb No Secondaries

No...you're good.

[mmartell]

Re: Delta PS Only 5vsb No Secondaries

I just read that some supplies are unhappy without a load so I will connect something to rule that out.

[mmartell]

Re: Delta PS Only 5vsb No Secondaries

Ok ruled it out, still no secondary voltages.

Looks like I need some old fashioned troubleshooting tips please.

[stj]

Re: Delta PS Only 5vsb No Secondaries

check the rectifiers on the output side for shorts.

[mmartell]

Re: Delta PS Only 5vsb No Secondaries

The ones on the heatsink ?

[stj]

Re: Delta PS Only 5vsb No Secondaries

yes

[RJARRRPCGP]

Re: Delta PS Only 5vsb No Secondaries

Looks like a fake Delta PSU.

[Agent24]

Re: Delta PS Only 5vsb No Secondaries

Looks like a fake Delta PSU.

I agree.

[lti]

Re: Delta PS Only 5vsb No Secondaries

I wouldn't call it a fake. They only used the name and didn't make any attempt to make it look like a real Delta PSU.

The output toroid looks burnt.

[mmartell]

Re: Delta PS Only 5vsb No Secondaries

The output toroid looks burnt.

What is that ? Transformer ?

There is a short. Thought it was the rectifier diode ? (heatsinked) but it was a smaller fast recovery diode in front of it that was shorted. Replaced it and stupidly put it all back together THEN tested again. There is still a short between each outer pin and the center pin on one of the rectifiers (my meter reads it as 50 ohms) where the other two don't do that. That part tested good out of circuit so I pulled a couple of parts up in the vicinity and can't find a shorted part.

Is that a normal reading for that rectifier or is there a spot I should be checking given the shorted diode I did find ?

[linuxguru]

Re: Delta PS Only 5vsb No Secondaries

Did you check the rectifier out-of-circuit or in-circuit? In circuit, the bleeder resistor for the +5v rail may be around 50 ohms, so you won't be able to measure the rectifier accurately.

On +5Vsb, replace the secondary electrolytics (1 or 2, typically 1000uF/10V) as well as a small primary-side electrolytic (typically 22 or 47uF/50V) near the auxiliary trafo.

If it still doesn't start up, unsolder and check all large secondary rectifiers and replace any that are shorted. Then check the primary switching transistors.

[mmartell]

Re: Delta PS Only 5vsb No Secondaries

Checked it out of circuit and it checked fine. Are you saying that I SHOULD be seeing that 50ohms because I don't see it on the other two rectifiers maybe they don't have bleeder resistors ?

Is it possible to point out the bleeder resistor on one of the photos above ? I'd like to unsolder one of the legs to see if the short goes away. Thanks

[stj]

Re: Delta PS Only 5vsb No Secondaries

the load resistors are big ones mounted vertical near where all the wires come out usually.

[mmartell]

Re: Delta PS Only 5vsb No Secondaries

Thanks stj, you nailed it. The resistor on the 5v rail traced directly back to the rectifier so I figured that would account for the measurements I was seeing. I put it back together and jumped pson and it came to life with all voltages. Only needed to replace one shorted FR153 diode.

Thanks again!

[Agent24]

Re: Delta PS Only 5vsb No Secondaries

I wouldn't call it a fake. They only used the name and didn't make any attempt to make it look like a real Delta PSU.

But why else would they call it "Delta" if not to try and fool people into thinking it was a real Delta? Probably hoping people who have never seen one close up would buy it thinking "I've heard Delta is good, so this must be a good PSU"

Still shady behavior, IMHO.

[mmartell]

Re: Delta PS Only 5vsb No Secondaries

I detected sarcasm in Iti's post meaning calling it a "fake" is an insult to counterfeits that try a little harder.

[momaka]

Re: Delta PS Only 5vsb No Secondaries

The "real" Delta is actually called Delta Electronics.

So technically, this PSU is not a fake, but they used a similar name on purpose, of course. Just like all of those other crafty brand names on knockingoff.com.

That aside, Delta PSUs are crappy. I wouldn't put one in any computer. I think newbie2 here on BCN upgraded one and still uses it. Thread should still be here. Just a bit old by now.