Seagate momentus overvoltage

[Steve]

I have a Seagate momentus 5400.2
St96812as sata laptop drive

When I run HDD Doctor for seagate it shows voltage high.
and immediately stops power to drive .
If I remove the PCB , it will power .. Output power is 12548 mV
Current is 0
With PCB connected , Power output jumps to 12830 mV


I checked the motor , the readings are approx 4 ohms


any ideas what the problem is ?



Thanks in Advance

Steve

[rchadwick]

Have you tried a different computer/power supply? Voltage shouldn't go up under load. Also, 12.8V is a bit high (Specs say it shouldn't be more than 12.6V). It could also be a software or hardware bug in HD Doctor for Seagate, which is why I'm waiting to upgrade my old Seagate product.

[Steve]

The voltage only goes up on this drive .. I can connect a different
drive and voltage is right at 12 volts

[rchadwick]

I wouldn't say it's impossible (A 5v to 12.8v DC-DC power supply, connected to the +5v and +12v lines on the drive would cause the symptom), but it's got to be pretty rare the voltage is actually higher. Have you checked voltages with a multimeter? Better yet, an oscilloscope? It's possible the drive is causing an unusual drain, creating a lot of ripple or spikes, and some voltage measuring devices may interpret this as a higher voltage, while the average voltage may be lower. If you have a multimeter, but no oscilloscope, a quick and dirty way to measure ripple is to turn the meter to the AC setting, at the lowest voltage setting. You shouldn't read more than about 15mv.

[Steve]

ok I checked 6 different drives , with Seagate doctor , and
Maxtor Doctor , on all drives except the one with the problem
when power is applied, the voltage drops .. but on this drive , as
soon as power is applied to pcb , the voltage spikes .
So there is definately something going on with this drive.

[rchadwick]

I should have been more clear. If the drive is bad, it can cause an unusual drain. My theory is that the voltage isn't actually higher, but HD Doctor thinks it's higher. The way to tell is to use something else to measure the voltage.

[Steve]

my bad, I should have stated, I did check voltages with multimeter
and 12 volt does in fact spike to 12.8
but voltages actually drop on the good drives

[rchadwick]

What about an oscilloscope? Or measuring on the AC scale?

[Steve]

no o-scope .. on ac scale 200 mv scale , spikes to 189 mv
then drops to .4 mv

[rchadwick]

I'm guessing you just want to test this drive with HDD Doctor for Seagate. If so, there are 2 easy possibilities..

1) Configure HDD Doctor not care about the voltage. Hopefully this can be done.

2) Put one or two electrolytic capacitors on the power input of the drive. They should be rated for more than the voltage (6.3 to 10 volts for the +5 line, and maybe around 20 volts for the 12v line), and be around 100uF to 500uF. Probably best to solder them right onto the drive, at the power connector. Just be sure to get the polarity and voltage right, or they will likely fill your room with some pretty smoke. This should smooth out the spikes, and HDD Doctor should show the voltage to be lower. You might also try lower value capacitors (.01uF) as well. These are usually rated for hundreds of volts, and non polarized.

A third possibility is to use a separate power supply. I've got a few cheapie IDE-USB adapters sitting around, and they all come with a power supply to run a HD without a PC's power supply. One of these might have a lower +12v, and work OK.

The fourth possibility is to troubleshoot the drive, and fix it. Of course, that would be easier if you can look at it in HDD Doctor.

[Steve]

UPDATE

This happens with HDD Doctor for maxtor and Seagate
It even does it with a healthy drive (laptop)

Further update .. and I don't know why I didn't think of it sooner
Laptop drives don't even use 12 volts ,
I removed the 12 volt lead from the sata power adapter ,
and it still spiked on the 12 volt output of the HDD doctor
even with the healthy drive .. only seems to happen with laptop drives

I guess it's time to contact David at SalvationData

[HardDiskBug]

Now, salvationdata once again proved, why after buying their products, one does nothing but cries and cries !

Big Hands for Salvationdata..........

[rchadwick]

Oops, I missed that it was a laptop drive. Things make sense now.
There REALLY should be a way to let things work anyway. I hate software that thinks it's smarter than us

[Steve]

Anyone else that has HDD doctor for Maxtor or for Seagate
Please check with a laptop drive ( sata OR Ide ) and see if you
also see this problem .


Thanks

Steve

[sceggy]

Potential problems, if no current drain on 12V:

(a) "Earth" leakage between ground wires in SD module
(b) Ground potential due to resistance between ground tracks in SD module

Have you tried putting a large wattage resistor between 12V and ground on the output of the SD module to mimicking a non inductive "motor"

Spiking could also be caused by back EMF from the motor caused by inductance, though unlikely.

Or the A/D converter is sampling incorrectly - are the ground circuits between the data, PSU and measurement properly connected?

scegs

[rchadwick]

I'm a little concerned by Salvation's decision to drill out certain screw heads, making it difficult to open these. I don't think Salvation is going to send out replacement units every time there's a new hardware revision. It looks like trying to update the hardware ourselves will be a difficult, warranty-voiding experience.

This time, I'm guessing the problem can be fixed good enough with a load resistor across the +12v, or a software fix.