No power?

No power?

I have a P-133 that I tried to add a second (slave) HD to. I plugged in the power and ribbon cable and tried to start up. Heard a little noise. Very faint, can’t describe it. Turned the power of and on again, no faint noise.

Waited a minute, turned the power on, heard faint noise………same as above.

So I figured I fried the power supply, so I replaced the power supply and no power.

No I wonder if the original was ok but something else was happening.

I will get a multimeter and check both power supplies, but what else should I look for?

well if you unplug your new hard drive and then turn on your computer you will know if your power supply is broken or was just overloaded. Do you have a lot of things running?

I'll try that and I don't understand "a lot of things running".

Let me make sure...

Let me make sure I'm doing this right before I toss my power supply.

I plug the P8 & 9 connectors into the mobo, black wires on the inside together.

Plugged in the power cord to the computer and put the black lead to the black wire and the red lead to the yellow wire (down in the connector). No reading.

I don't have all the other connections that power the hard drive, etc. But I assume I don't need to do that to test voltage.


Still don't know why the other power supply didn't work although some of the connections were a little different.

Also I didn't test the second PS although it was working in the other machine a hundred years ago.

Also checked the fuse.

Anything I did wrong or should try?

You say some of the connections were a "little different" explain this. When you checked the fuse, was this a visual inspection, or did you check it with an Ohm-meter to be sure? Sometimes a fuse can blow and still appear to be fine.

What was the old PSU rated at and how many devices are in the machine?

Is the voltage selector on the PSU set on the right voltage?

The orig power supply has a female connector to the HD with a male at the end of that that connects to the power supply. Also on that connection is a wire that goes to a heat sink fan.

On the second power supply there is no wire to fan.

I only checked the fuse visually. How would I check it w/ my multimeter?

250w and only have CD ROM, floppy and HD.

I had voltage selecter set to DC w/ a "v" under it.

To check the fuse with a multimeter, just set the meter to test Ohms, then put one lead to one end and the other lead to the other end of the fuse, if it reads as a short, then it is good, if it gives no reading or reads open, then it is blown.

On the Voltage selector, I meant the one on the PSU not the meter. There is a switch on the back of most power supplies that has marked 115 and 220 or something similar, it may say 125 and 230. You have to set it to the correct line voltage for your outlets.

What were the voltages you read off of P8 & P9?

Sorry, 115v.

I get nothing.

Also, to check the fuse do I need the psu plugged in. Sorry, some of this is beyond my scope of experience.

When checking the fuse, the PSU should be off and best if unplugged. You'll either blow the fuse in your meter or cause damage by using the Ohms setting with power supplied. If possible, remove the fuse and check it out of the circuit.

Ten-four

OK. I checked my "bad" power supply in another machine and it boots up. Sorry bout that. Should have done that a long time ago, but live and learn.

Now what should I check.

Remember , the only thing I did orig was to try to add a "slave HD.

I will do that again.

Also, the other good PSU that I just tried makes a faint buzzing sound that sounds like it may be coming from the PSU but it's had to tell. It sounds like a fly flying around inside that you can barely hear.

It's definitely coming from the side of the computer with the HD and PSU.

When I re-installed the orig PSU back, the "buzz" is definitely coming from the orig PSU.

Maybe your new hard drive is having a short cirquit somewhere?
Try it in another computer, if you fry the PSU or the drive just doesn't work the it should be pretty clear.

I suppose you could try the ohmmeter on the drive inputs too.

Buzzing sound from PSU, sounds like an overloaded transformer. Though some older PSUs and even some newer cheap ones make a faint buzzing even when they are fine. Since you are having problems, I would suspect this may be the fault.

No Power P8 side?

Tried to install a "slave" drive on my P-133 with AT PSU.

Wouldn't boot. Disconnected "slave".

Discovered that the P8 connection on the mobo is the culprit, I think.

With no power to all drives and the CPU fan connected directly to the PSU nothing runs. If I disconnect P8 from the mobo the fan starts.

What now?

No Power P8 side?
No Power P8 side?

Tried to install a "slave" drive on my P-133 with AT PSU.

Wouldn't boot. Disconnected "slave".

Discovered that the P8 connection on the mobo is the culprit, I think.

With no power to all drives and the CPU fan connected directly to the PSU nothing runs. If I disconnect P8 from the mobo the fan starts.

What now?

what make of computer is this? some makers use proprietary motherboard hook ups. I had a dell that used a P7 connection to the motherboard and you couldnt use just any power supply because the connector was actually reversed from those on standard power supplies and motherboards. ( Dell's way of trying to make you buy from them)