help, PSU without PG SIGNAL

[venksp]

Re: help, PSU without PG SIGNAL

Nothing I can read from it. Looks brown/orange color with a Black stripe at the end.

[budm]

Re: help, PSU without PG SIGNAL

So you remove the resistor and it shows 87K off the board? Pictures of the resistor so we can see the color code?
To me 87K is high value for that circuit.

[venksp]

Re: help, PSU without PG SIGNAL

Sorry - I am unable to get a clear Color picture. But I can see it with magnifying glass. There are brown lines at the either ends of the resistor and inner rings are Red, Orange ,Yellow . Using the digikey 5 band calculator it shows as 1.2Meg.

[venksp]

Re: help, PSU without PG SIGNAL

Here i tried to get a picture of the resistor.

[budm]

Re: help, PSU without PG SIGNAL

It looks like Brown, Yellow, Red, Red, Brown = 14.2K 1 % to me. Or 14.3K if one of the third bad is Orange.
1.2M is not going to give enough PGI sensing Voltage if the feeding Voltage is only 15V, 1.2V (1.2V or above but <7V) is the typ Threshold Voltage, so if it is 14K / 2K Voltage divider resistor, then with 15V feeding Voltage then you will have about 1.8V at PGI pin. OR unless the feeding Voltage is NOT supposed to be 15V? You need to find out where that 15V is coming from.
And it is measured out to be 87K?

[venksp]

Re: help, PSU without PG SIGNAL

Is is possible for the resistor to change value intead of complete open. In that case if the Original value was a 4.2K then the PGI voltage might work.

[venksp]

Re: help, PSU without PG SIGNAL

I changed a 4.2K and momentarily got 2.8 Volts at the PGI . THe fan spins and stops and all voltages show and go to 0. Before this resistor no PGI but all voltages were OK.

[budm]

Re: help, PSU without PG SIGNAL

Did you try using 12K or 15K resistor?
They use 1% resistor for a reason so see how much tolerance the circuit can tolerate.

[venksp]

Re: help, PSU without PG SIGNAL

I have not tried 12 K yet. But as i mentioned the 4.2K gives a voltage ~2.8 and the Fan starts and stops also the Voltage slowly decreases in other pins (eg from 12 to 0)

[JoeBug]

Re: help, PSU without PG SIGNAL

Here are two drawings of my psu that might help you.

This helped me a lot
the PSU was FSP ATX-4035-HEN. 0 ovlts on the PG pin, good voltage on the others (+12 +5 and so on)
the PG IC seems to be another one, but markings and ratings (R92, R93) was the same. In my case R92 was black .. it wasnt shorted but it was reading some resistance.. when i clean it, it becomes open. replace it with a 51 ohms +-10% (it was reading 55 ohms with the DMM). now PG pin reads 5.03-05 volts. Now i am testing it on a PC, works fine for the moment.
sorry for my bad english, 10x again for the tips..