Test old MFM hard drive

[roadrash]

I have a ancient hard drive out of a just as ancient portable computer that I need to test on the bench because its stopped spinning up in the computer.
I managed to find a pinout for the 26 pin ribbon connection but I am unsure which connections to make from my bench psu to test if it spins up.
The power and motor connections on the drive that I can see should allow me to test it are: GND, +12v, +5v, Motor on and drive ready. I am just unsure which to connect to make the motor spin.
As well as the GND and +12v connections, which on there own do nothing, do I need to also take +5v or +12v to the motor on or drive ready at the same time to make the motor start spinning?

[goontron]

Re: Test old MFM hard drive

Well, measure the voltage of the motor on and drive ready pins. If they have 3.3/5v on them then ground them through a 100ohm resistor and see if it works. If they don't have voltage, connect them through a 100 ohm resistor to 3.3v. If no response, 5v.

[stj]

Re: Test old MFM hard drive

nooooo.
hardrives use multipole motors driven by sequenced pulses!
that's how the speed is regulated.

[goontron]

Re: Test old MFM hard drive

^ Not all of them. What drive do you have OP?

[eccerr0r]

Re: Test old MFM hard drive

If I remember correctly and I had many MFM and RLL HDDs in the dark ages of computing, these disks should start spinning up immediately when power is applied. It would be exceedingly rare to find a MFM (ST506-interface) HDD that does not spin up right away when power is applied.

Also note that both +5 and +12 need to be applied. If you apply one but not the other, it may not spin.

[eccerr0r]

Re: Test old MFM hard drive

26 pin? wait a minute...
I thought there were two cables (three including power) for ST506 interfaces.
The 34-pin very-much-like-but-not-same-as floppy disk cable ("Control") and the 20-pin well shielded data cable ("data") which is serial from the head. MFM disks also predate 3.3V signaling though I don't recall what level the data comes out from the disk...

And I believe all HDD spindle motors are indeed multi pole motors that require multiphase signals to drive -- all except those really old ones that use AC power to synchronously rotate the platter. The head actuators, those have changed over the years. The oldest ones (and probably most of them in general) use stepper motors for the head.

It would be curious as to the model of the disk indeed.

[stj]

Re: Test old MFM hard drive

yea, there should be 2 ribbon cables and a standard 4pin power plug.

[roadrash]

Re: Test old MFM hard drive

My mistake its a Old conner 3.5" and its not MFM but IDE.
You are right eccerr0r it should spin as soon as its connected especially these old ones as it takes a while for them to spin up to speed.
I have a goos idea whats happened no though and I dont think ts worth trying to sort out now. The first time I had this drive spinning I had to help it by moving the spindle with long nose pliers because it was stuck. I had to do this a few times whenever I tried to use the computer. Ive just read that some of these old drives do get stuck when the heads get stuck to the magnetic covering on the disk platters and this is not something t;hat can be rectified so the drive is no use now. I am going to use a Ide CFcard adaptor to emulate a 40mb hard drive instead. Thanks for your help.

[stj]

Re: Test old MFM hard drive

before you do, remove the drive pcb and look at the pads that connect to the motor & heads.
some are silver plated and get tarnished.
if it's not shiny, clean the pads.

[stj]

Re: Test old MFM hard drive

btw, cf adapters arent worth the cost now - or the cards arent i should say.

look at these instead.
http://www.ebay.co.uk/itm/332247062499
and
http://www.ebay.co.uk/itm/351131265761

[goontron]

Re: Test old MFM hard drive

^ Not to mention if you get the right SD card you can blow those slow CF cards out the water!

[eccerr0r]

Re: Test old MFM hard drive

Yeah "sticktion" is a problem in older drives, though I don't recall Conner being one of them (Quantum was notorious). I suppose both of these companies have been absorbed and gone now...

Conner CP3000 was a very popular drive IIRC.

And I still am very gunshy with SD cards. I have yet to see an SD card that gets my stamp of approval for use as a general purpose OS disk drive replacement (whereas CF and even one Flash USB have). Perhaps with just running MSDOS it might not be such a problem however, but not for Windows, not for Linux, not for any modern multitasking OS.

[MeepsterNotchy]

Re: Test old MFM hard drive

All the old Connor's I have spin up and seek test fine, but nothing more after that, not sure what causes it as it's quite annoying because I feel like it's something so simplistic! They sort of die a silent death, you could put it.

[goontron]

Re: Test old MFM hard drive

^ Jumpers?

[roadrash]

Re: Test old MFM hard drive

Further research revealed the model of Zenith portable computer I have has a unique JVC designed 26 pin MFM/Rll type interface that is made especially for this type of computer and is incompatible with any thing else. Turns out the hard drive is not a conner, as I though it was was its a JVC JD3824R00-1. I replaced all the caps on the computers motherboard but still the drive is dead. Apparently the drive only spins up after the interface has initialised so it wouldn't spin up anyway just putting 12v to it on the bench. I can turn the drive spindle so its not stuck anymore. Here are pictures of the controller and the hard drive pcb side.

[stj]

Re: Test old MFM hard drive

does the computer have isa slots?

[roadrash]

Re: Test old MFM hard drive

No nothing like that. or i could have use another controller and drive. They have been trying to work this interface out with the intention of making a cf/sd card emulator but nothing yet finished so its get this drive working or its a floppy only computer now

[stj]

Re: Test old MFM hard drive

so about the connector, is the pinout known?
maybe its a subset of isa on a smaller connector.

[eccerr0r]

Re: Test old MFM hard drive

dark ages of computing where custom hardware is customer lock-in

Curiosity, what model computer is this?

[roadrash]

Re: Test old MFM hard drive

here are some info on this drive. The computer it comes off is a Zenith Supersport I repaired & re-capped