no monitor output with power hungry mobo?

[montanglo]

but when you test the power supply though with an ancient motherboard it powers up pc ok and outputs picture to monitor screen
The more power hungry mobo(that though used to work with the mentioned ps)now works ok only with another power supply
Replaced otput filtering capacitors inside the power supply (although visually they looked ok) with Jamicons but still the same problem, what to check next please-perhaps big primary side el.caps give such symptom?

[370forlife]

Re: no monitor output with power hungry mobo?

What make/model/wattage is the power supply?

If it is a nicer brand power supply and lower wattage it may have OCP (over-current protection) that is kicking in. Jamicon's are not recommended caps, also. Or you may have a very heavy 12v load with a light 5v load with a group regulated power supply and are crossloading it, causing the 5v to go up and the 12v to drop to a unsafe level.

[montanglo]

Re: no monitor output with power hungry mobo?

ps is Orion 250w and it worked ok before with now problematic mobo
but not any more although I guess new Jamicons have lower esr and higher capacitance than the old ones I replaced
What is exactly crossloading(I did not screw up anything on PCB and as I wrote PS works fine with older mobo)
Also should I suspect big 220micro 200v caps or some power switching element

[370forlife]

Re: no monitor output with power hungry mobo?

Crossloading is when you have a larger load on the 5/3.3v rails and a low load on the 12v which causes the 12v to raise in voltage, and the other 2 rails to decrease in voltage. It can also work the other way, where the 12v has a large load which causes the 12v to drop, and the 5/3.3 rails to increase. This is a cause of group regulation, where the psu has large filtering coils on the output side of the unit, and usually two rails will share one coil, while one gets it's own. Usually the 12/5v will share the largest one, while the 3.3v gets it's own smaller one. In some low end units, all three rails share the same coil.

Usually harder for the main caps to die, but if they are really off brand caps than they might have very little capacitance left in them.

Now is this orion a HEC orion? In that case, it may have OCP as HEC's lower end units may not be real good, but they do have some basic protections.

[montanglo]

Re: no monitor output with power hungry mobo?

could be crossloading because there are only 3 coils but adding/removing devices does not make a difference and as mentioned, before everything worked fine.Main caps being electrolitic in case they are half dead should stop not start making problems once they get warm which leaves perhaps half dead one of secondary elements byq28e or lt807s whichever is on a 12v rail because it goes to agp graphics?

Crossloading is when you have a larger load on the 5/3.3v rails and a low load on the 12v which causes the 12v to raise in voltage, and the other 2 rails to decrease in voltage. It can also work the other way, where the 12v has a large load which causes the 12v to drop, and the 5/3.3 rails to increase. This is a cause of group regulation, where the psu has large filtering coils on the output side of the unit, and usually two rails will share one coil, while one gets it's own. Usually the 12/5v will share the largest one, while the 3.3v gets it's own smaller one. In some low end units, all three rails share the same coil.

Usually harder for the main caps to die, but if they are really off brand caps than they might have very little capacitance left in them.

Now is this orion a HEC orion? In that case, it may have OCP as HEC's lower end units may not be real good, but they do have some basic protections.

[370forlife]

Re: no monitor output with power hungry mobo?



That is group regulation, 2 coils for 3 rails.



Independent regulation, 3 coils for 3 rails.

Whichever one it is, it dosen't really matter as you said it still does not work with different loads.