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Luke
June 4th, 2006, 10:45 AM
Drive sometimes run propetly, and sometimes don't.
When it don't work propetly I can't boot from it and I can't run files from it
('General failure reading...' or 'Data error reading...' - depend on DOS version that I boot from diskette)
but I can dir directories and acces them.

I have done all tests by SpeedStor utility (including various media analise tests), and low level formated.
I made partition and formatted it. Still no bad sectors.

I'll try DOS 3.30, mayby it will help like in canuck's problem. Any other ideas?

atari2600a
June 4th, 2006, 10:53 AM
Well since the problem is analog, maybe it's a heating issue. It might also be a friction issue. Have you looked at the internals of the drive & checked if everything was moving properly?

bbcmicro
June 4th, 2006, 11:06 AM
Is that wise? If you are reffering to opening up the actual drive, dust and everything could cause havoc in there, plus drives are really, really hard to open unless you have the specific tool to do so.

If not I'll just go back to sleep.

zzz...

mbbrutman
June 4th, 2006, 11:07 AM
You really can't see inside of a hard disk without opening it, and opening it is a very very bad idea.

As Modem7 suggested these things change alignment on the heads when they warm up. You should let the drive spin for a while and the low-level format when it is at 'operating' temperature. That might help clear things up.

Also, early Seagate drives are well known for 'stiction' problems. Running the LL format a few times might help spread some of the lubricant on the platters more uniformly.

Remember, it's an old beast. They were designed to last for 5 years, not 25. A hard drive only has to last long enough for the next generation of hard drives to make it obsolete.

atari2600a
June 4th, 2006, 11:18 AM
Ah, HD! I'm so tired that I thought we where talking about High-Density floppy drives!

Terry Yager
June 4th, 2006, 11:22 AM
'Course, with a drive that's already MIA & PresumedDead, how much harm can you do by peeking inside?

--T

Luke
June 4th, 2006, 11:23 AM
Hehe, I'am not going to open it ;).
Before low level format computer was powered up for ~10 min and drive was tested for ~20 min i think, so it was warm.

Luke
June 4th, 2006, 09:23 PM
It looks like drive need to warm up for a while.

The drive was cold, I powered up XT and it siad: Disk boot failure.
So I booted from floppy and few times I was trying to run apps from HDD.
After that I've done soft reset and DOS 2.10 booted from hard disk.

modem7
June 5th, 2006, 12:27 AM
Do you have some other old computer in which to test the HDD?

Your HDD might actually be fine. Your related thread in the "PC and Clones" genre indicates that you are seeing intermittent keyboard, diskette drive and HDD errors, ie. you are seeing system-wide problems.

Therefore I would consider the PSU and motherboard as the most likely causes. On the motherboard, intermittent or (seemingly intermittent) problems can be caused by faulty RAM. Remember that the RAM test done by the POST (power on self test) is quite crude. And if the RAM is intermittent, the POST is less likely to detect it.

You could also have an intermittently faulty HDD or floppy which is occasionally shorting out the power supply for milliseconds at a time.
I consider that unlikely.

How about removing the HDD, then running an XT diagnostic tool for six hours, with the diagnostic just doing motherboard tests.

Luke
June 5th, 2006, 04:39 AM
It's 6 hours?! Lot of time...

FDD is good I think, something is only with connectors - now it works fine.
It's Tandon TM-100-2A commonly used in IBM XTs.

dongfeng
June 5th, 2006, 05:33 AM
Luke, your XT sounds identical to mine. 256k mainboard, ST-412 and Tanton floppy drive! I noticed on the Tandon that the power pins, one of them had broken free from the solder. I fixed that now :)

With the ST-412 disconnected completely, can you boot into Cassette BASIC without errors? And with a boot disk, to a DOS prompt?

Luke
June 5th, 2006, 09:27 AM
It was the most common configuration I think, you have 5153 or 5154 monitor?
I could have similar problem, I must check the drive!

I haven't tried to boot to C-BASIC but I can boot OS from diskette without any problems.
I've done Diag Disk tests - it said that something is wrong with CRC (something connected with FDD I think).
Diskette that I've used for test had many bad sectors...
Drive don't make any problems when I use it now.

Luke
June 6th, 2006, 10:49 AM
Propably I finally located where the issue is.
Drive don't recalibrate his heads at startup.

After booting up from diskette I tried to format drive - it said: 'Media type invalid or track 0 bad - disk unusable'.
But you know DOS sometimes says strange things,
I have started disk diag program and runned seek test, then started format and... it formatted disk good.

Jorg
June 6th, 2006, 01:17 PM
I have an identical machine and a similar hard drive issue. I can format it (low level). It just keeps telling me that track 0 is bad afterwards. Looks like the magnetic layer got to weak.

Luke
June 7th, 2006, 04:16 AM
I can format the drive, magnetic layer is fine I think (I made various media analyse tests).
The problem is that drive need to warm up it's heads
or maybe set to correct aligment before I can write something to it.

I'll low level format it again.
What interleave should I select?

Luke
June 7th, 2006, 10:13 AM
I'am slowly becoming mad with this drive :(.
Getting one to replace or even getting second flopy is nearly impossible here in Poland.

So. Really noone know where could be the issue? It's not recalibrating heads.

Btw. happy birthday bbcmirco ;).

DimensionDude
June 7th, 2006, 02:47 PM
Does the ST-412 use a stepper motor to position the heads? If so, perhaps the lubricant in the stepper motor has become dried and stiff, making it difficult to move the heads or position them correctly.

I'm not really sure how one would go about removing the old grease and putting in new...

Kent

Luke
June 8th, 2006, 03:58 AM
Yes, it use stepper motor.

Can I replace this ST-412 by other MFM drive? Would 40 Meg HDD work with 5160's controller (formatted to 10 Megs of course)?

Drive is dirty but I need canned air to clean it. I will get it, clean drive and change cables.

dongfeng
June 8th, 2006, 08:42 AM
It was the most common configuration I think, you have 5153 or 5154 monitor?

The previous owner of my XT had upgraded it to a VGA card, so it now uses a VGA display. If I can find an original IBM 5153 or 5154, I will change it back to that :)

modem7
June 8th, 2006, 08:07 PM
I'm guessing by your posts that your keyboard error has gone, and that the 601 error was a caused by a bad diskette ("Diskette that I've used for test had many bad sectors...").
That is, your only problem now is intermittent HDD operation ("Drive sometimes run properly, and sometimes don't. ")

I don't think another low-level format is going to do anything. But if you want to, note that changing the interleave is not going to affect the ABILITY of the drive to read/write data - it will just affect overall read/write speed. Just accept the default interleave at this time. You can worry about getting the optimum interleave later.

I think you are at the point of either a) testing the ST-412 in another computer, or b) as you've suggested, replacing the ST-412 with another MFM drive.

As for replacing the ST-412 with another MFM drive:

In an XT, the type of HDD controller you have determines what you can do. The early XT's (with an ST-412) were supplied with a HDD controller that could only support type 1 drives (drives that have 306 cylinders, 4 heads, 17 sectors per track, and a write pre-compensation cylinder of 128). You have probably got that controller.

Can you send a picture of the controller?

If you have that particular controller, then for diagnostic purposes, you can substitute the ST-412 with an MFM drive that has 306 or more cylinders, and has 4 or more heads. The controller will limit the use of the drive to 10MB. This is not a good long term solution because larger drives are sure to use a different write-precompensation cylinder.

If you have a different controller, it will probably support larger drives.

Luke
June 9th, 2006, 09:04 AM
It's Xebec controller, it only support 10 Megs drives.

I thought that is power issue. St-412 need at startup 3.5 amps.
In my XT there are 2 power cables P10 and P11.
I tried disconnecting FDD, but HDD still don't work at startup.

Hmm... very interesting...
POST don't see the drive if it have P10 cable attached, normally it have P11 and everything is okay.
Drive still work, because I connected it back to P11 and it was seen.

It could be power issue... I'am waiting for your ideas.

modem7
June 9th, 2006, 05:48 PM
In case you are not aware, later XT's (those with 20MB HDD) had a Xebec controller with a DIP switch block. That controller supported four different drive types.

In every IBM and clone PSU I've ever worked on, the wires from the power connectors are soldered to the same point in the PSU. For example, the +12V wire from each connector is solder to the same +12V point within the PSU.
Therefore if P11 fires up the HDD, then providing that P10 has the same four wires (+12V, GRND, GRND, +5V) then it should also power up the HDD.

If not, there may be a broken wire (rare) or one of the cylindrical metal contacts in the P10 connector has opened up too wide. First, check for a broken wire by measuring the voltages on the P10 connector. You should confirm the continuity of the GRND wires also, and so I suggest the following sequence:

1. Do not plug P10 into anything (IMPORTANT).
2. Connect NEG of multimeter to the PSU case.
3. Connect POS of multimeter to the +12V contact in P10. Multimeter should show +12V. This checks the +12V wire.
4. Connect POS of multimeter to the +5V contact in P10. Multimeter should show +5V. This checks the +5V wire.
5. Whilst leaving the POS of multimeter on the +5V contact in P10, move the NEG of multimeter to the first GRND contact in P10. Multimeter should show +5V. This checks out the first GRND wire.
6. Move the NEG of multimeter to the second GRND contact in P10. Multimeter should show +5V. This checks out the second GRND wire.


If that all measures okay, then I think one (or more) of the cylindrical metal contacts in the P10 plug has opened up too wide. This was a known problem in the days of the XT/AT. Some equipment (eg. FDD, HDD) had pins in their power supply sockets that were either smaller than normal, or larger than normal. If you moved a power plug from a device that used large pins to a device that had smaller pins, instant power related problems appeared.
Widened contacts in the plugs were also caused by repeated insertion/removal of the plugs (particulary if a wiggling motion was used).

Luke
June 10th, 2006, 01:51 AM
Stettings are correct? I think that this is something like DIPs:

http://img92.imageshack.us/img92/4386/dipnie8zj.jpg

dongfeng
June 10th, 2006, 02:05 AM
In case you are not aware, later XT's (those with 20MB HDD) had a Xebec controller with a DIP switch block. That controller supported four different drive types.

Oh, that's handy to know as I have the same Xebec controller! Do you have the details of the different drives this card supports? :)

Luke
June 10th, 2006, 02:41 AM
My cntroller don't have DIPs. It only support 10 Meg drives.

modem7
June 10th, 2006, 08:00 PM
Dongfeng,


│ 1 │ 2 │ 3 │ 4 │
─────────┼─────┼─────┼─────┼─────┤
type 1 │ ON │ ON │ ON │ ON │
type 16 │ ON │ OFF │ ON │ OFF │
type 2 │ OFF │ ON │ OFF │ ON │
type 13 │ OFF │ OFF │ OFF │ OFF │

where:

type 1 = 306 cyl, 4 heads, 128 WPC, 305 LZ, 17 S/T (10.2 Mb)
type 16 = 612 cyl, 4 heads, 0 WPC, 663 LZ, 17 S/T (20.3 Mb)
type 2 = 615 cyl, 4 heads, 300 WPC, 615 LZ, 17 S/T (20.4 Mb)
type 13 = 306 cyl, 8 heads, 128 WPC, 319 LZ, 17 S/T (20.3 Mb)


The type 1 catered primarily for the Seagate ST-412
The type 13 catered primarily for the IBM WD25 (a full height 20MB drive supplied with XT's)
The type 2 catered primarily for the Seagate ST-225 (a half height 20MB drive supplied with XT's)


If you had a HDD that that card didn't support, you would normally go and buy a third-party controller board that could.
In other cases, some IT support areas removed the boards PROM and replaced it with one that they had reprogrammed (altered the area that contained the drive information).

modem7
June 10th, 2006, 08:05 PM
Stettings are correct? I think that this is something like DIPs:


That 'thing' is what IBM called a shunt module. In a HDD (and diskette drive) it is used mostly to configure the 'drive select' logic. It is in the correct position/alignment.

More importantly, your picture shows me something I had forgotten about - something that can cause intermittent HDD errors. The chip labeled "T-RES" is in fact a terminating resistor pack. There must be one on the HDD that is attached to the final connector of the controller/HDD cable, and any other HDDs attached to the cable must have the resistor pack removed. If that rule is not obeyed, poor communications will result between the controller and HDD (due to signal reflections on the cable).
You have only have one HDD and so I expect to see a terminating resistor pack in place. Yours is there and is oriented correctly.

Note that diskette drives of the period use the same system - the diskette drive attached to the final connector must have a terminating resistor pack, and any others on the cable must have their terminating resistor pack removed.

Note that different drives mostly use different terminating resistor packs. That is, a Miniscribe 4567 might use a part number 1234 terminating resistor pack, and a Rodime 6543 might use a part number 5678 terminating resistor pack. They are not interchangeable. Therefore, if you need to remove a terminating resistor pack from a HDD (or diskette drive), tape it somewhere on the drive.

modem7
June 10th, 2006, 08:14 PM
Just like dirt/corrosion can build up on the pins of RAM chips over a long period, the resistor pack is similar.
It is worth removing/reinserting the pack a few times to remove any such build-up.

Luke
June 11th, 2006, 07:06 AM
Looks like it helped. I'am not sure,
I will power XT again after 2 hours and see if it really helped.

Luke
June 11th, 2006, 09:14 AM
Damn! I still can't boot from it... :(.
It's not this chip...

modem7
June 11th, 2006, 05:31 PM
Remember, your drive might be good. It could be the controller that's intermittent, or a bad cable, etc.
That's why you should find another MFM HDD soon (or move the ST-412 to another computer), so you can quickly prove/disprove your ST-412's serviceability.

Luke
June 23rd, 2006, 03:37 AM
Heh, it work normal now. I have just tried that method from Usenet that mmburtman found:
http://groups.google.com/group/comp.sys.ibm.pc.hardware/browse_thread/thread/fcb5ccec3562950f/0d8e7bd36e731b81?lnk=st&q=low+level+format+xt+int&rnum=1&hl=en#0d8e7bd36e731b81

Thanks!

modem7
June 24th, 2006, 01:42 AM
Cross your fingers. Remember, your problem was intermittent.

Luke
September 6th, 2006, 07:33 AM
That didn't helped for long.
But I might find out why it's not Okay.

Look:

http://img111.imageshack.us/img111/1281/screwfn6.jpg

Is screw here requied?
Maybe it's not screw, my English dictionary is missing somewhere, but you know what I mean?
I saw Jorg's pic of ST-412's motor:

http://members.home.nl/charon.styx/412.jpg

mikey99
September 6th, 2006, 08:42 AM
My ST-412 looks slightly different than both of those. It has a small
allen screw that extends slightly through where that white
part is on yours. I think this sets the Track 0 position. My idea
is to turn the screw in, which should push the arm down
and move the track 0 to another position on the disk.
Then run a low level format. The original post about this solution
specified 'primary formatting software', I think they mean low level
formatting.

My problem is the allen screw is SO small, I haven't found an
allen wrench to fit. But I will, eventually.

If your problem is intermittent, its probably not related to a bad track 0.

Luke
September 6th, 2006, 09:03 AM
But... maybe disk have problems with positioning?
When I do 'cold' power up maybe motor can't reach track 0 and so after warming up, motor is able to move to track 0 and propably set the head, so it can read whole disk...

mikey99
September 6th, 2006, 09:14 AM
But... maybe disk have problems with positioning?
When I do 'cold' power up maybe motor can't reach track 0 and so after warming up, motor is able to move to track 0 and propably set the head, so it can read whole disk...

Thats possible. I think the arm should rotate all the way clockwise, so that
it touches that white stop. That indicates the track 0. Try running the
computer and see if this is true when it warms up.

Unfortunately my problem was caused by the original owner not parking
the head before shipping to me. Its a lesson learned :-) Next time I will mail
a diagnostic diskette and have them park before shipping :-)

Luke
September 6th, 2006, 09:30 AM
Now computer is in parts, I'am planning to clean it...
I must do it tomorrow and check if it really reach that white screw.

mikey99
September 6th, 2006, 09:43 AM
Now computer is in parts, I'am planning to clean it...
I must do it tomorrow and check if it really reach that white screw.

If you have the XT Advanced diagnostics diskette, there are some tests
you can run, and watch the arm move from one end to the other.
I think its called "Measurement test"

mikey99
September 6th, 2006, 05:05 PM
If you have the XT Advanced diagnostics diskette, there are some tests
you can run, and watch the arm move from one end to the other.
I think its called "Measurement test"

Heres a closeup, you can see the screw that provides
a stop for the arm.

Elar
September 6th, 2006, 10:25 PM
Actually, Track 0 is set by optical sensor. The white part/screw acts as a mechanical emergency stop in case optical sensor fails for some reason. It prevents heads going "over the edge".

mikey99
September 7th, 2006, 06:13 AM
Actually, Track 0 is set by optical sensor. The white part/screw acts as a mechanical emergency stop in case optical sensor fails for some reason. It prevents heads going "over the edge".

Thanks for the info. If this is the case, then the only way to alter Track 0
position is to modify the part of the arm that is 'picked up' by the sensor,
or physically move the sensor (which would be a pain).
Maybe adding a small spring clip or something to the end of the arm. I'm willing to try anything to bring this drive back to life :-)

modem7
September 8th, 2006, 06:29 PM
Thanks for the info. If this is the case, then the only way to alter Track 0
position is to modify the part of the arm that is 'picked up' by the sensor,
or physically move the sensor (which would be a pain).
Note that because the stepper motor and head arm are untouched, the tracks will be written in exactly the same locations on the platter. The positioning of the track 0 sensor is a crude adjustment that affects which of those tracks is defined as track 0. And so your goal will be to adjust the sensor so that the track that's currently track 1 becomes the 'new' track 0.

Jorg
September 8th, 2006, 09:49 PM
So (just to get it right)- the 'arm' has to be made longer; not shorter?
(I'm thinking Ducktape ;) )

modem7
September 9th, 2006, 12:18 AM
Maybe it helps if I explain what a stepper motor is.
A stepper motor has a set number of angular positions. For example, stepper motor part number 1234 may have 1200 steps in a rotation (360 degrees).
Controlling electronic circuitry sends pulses to the motor to either rotate the motor by one step in a particular direction, or to rotate the motor by one step in the other direction.

When a drive such as the ST-412 powers up, the electronics doesn't know which track the heads are on, and so it does a 'recalibrate' action. The electronics simply sends pulses (in a particular way) to the stepper motor so that the motor rotates (in steps) in the direction that brings the heads closer to track 0, and continues to do that until the track 0 sensor is activated.

When the sensor is activated, the electronics then knows that the heads are on track 0. The electronics then keeps track (no pun intended) of which track the heads are on in a register.
So for example, after power-on, if the drive is instructed to go to track 5, the electronics will look in the track register, note that the heads are on track 0, then issue an appropriate pulse train to the stepper motor to advance the stepper motor by 5 steps. If the drive is instructed to go to track 2, the electronics will look in the track register, note that the heads are on track 5, then issue an appropriate pulse train to the stepper motor to retard the stepper motor by 3 steps.

(For the purists out there, yes, I should be using the word 'cylinder' in place of 'track', however, because the sensor is usually known as the 'track 0 sensor', it's better that I use 'track' in this case.)

Jorg
September 9th, 2006, 12:43 AM
Yes, I understand the calibration step (no pun intended either..;) ) of the stepper motor- I just wasn't sure in what direction the calibration point (== track 0) should be moved. I assume more inwards to avoid the edge of the platter, and that would be to make the drive think that it is at track 0, while it is at the (initial) track 1. That again would mean to make the arm longer, to trigger the sensor in the former track 1 position.

modem7
September 9th, 2006, 03:26 PM
Yes, you need the sensor to activate earlier. Thus looking at the earlier posted pictures, the sensor would need to be moved in a downwards direction, or that 'arm' extended.

I've opened up my XT to take a better look at a ST-412. The sensor can't be moved, but on the left of the sensor (as seen in the picutures) is what appears to be a block which can be raised/lowered by a silver screw. That block is there for a reason, and the only reason I can see is to adjust the sensor (I think it's a hall effect sensor rather than an optical sensor).

HALL EFFECT: See http://en.wikipedia.org/wiki/Hall_effect_sensor

Jorg
September 10th, 2006, 07:18 AM
That didn't helped for long.
But I might find out why it's not Okay.

I saw Jorg's pic of ST-412's motor:

http://members.home.nl/charon.styx/412.jpg

I took a better look at the above. As you can see, the 'arm' looks a bit irregular here. I took a better look and discovered there is already a piece of tape on it! I removed it, and then the arm looks the same as Luke's.
The tape extended the arm by appr. 4 mm.
It seems somebody already tried the 'move track 0 trick' here!

The copper nut is not original either. I removed it to find the same kind of notch Luke's picture is showing.

I can't test the HD, as I have no working floppy drive to boot from and try another low level format. So don't know if this changed anything.

Elar
September 10th, 2006, 11:02 AM
That block is there for a reason, and the only reason I can see is to adjust the sensor (I think it's a hall effect sensor rather than an optical sensor).

HALL EFFECT: See http://en.wikipedia.org/wiki/Hall_effect_sensor

Track 0 sensor is optical. Check the manual:
http://www.bitsavers.org/pdf/seagate/ST412_OEMmanual_Apr82.pdf

modem7
September 11th, 2006, 03:32 AM
The OEM manual. Well that's an authoritive source.
And so has anybody got a suggestion as to the purpose of that large metal block on the optical sensor?
If it was to counter the block on the other side (the block that has the stopper/limiter), surely the blocks would be the same size/weight.

mikey99
September 11th, 2006, 05:51 AM
Track 0 sensor is optical. Check the manual:
http://www.bitsavers.org/pdf/seagate/ST412_OEMmanual_Apr82.pdf

Wow, the original manual, now thats valuable info ! Thanks a lot for posting that link :-)

Terry Yager
September 11th, 2006, 07:50 AM
Wow, the original manual, now thats valuable info ! Thanks a lot for posting that link :-)

There's a whole lot of valuable info on bitsavers. You'd do well to bookmark the page for future reference. IIRC, the pageowner has recently made an appearance in these forums.

--T

mikey99
September 11th, 2006, 05:35 PM
SUCCESS!!! :-)

Well... I finally got around to testing this theory about moving the
Track 0 position on the disk by altering the length of the stepper
motor arm. And it actually worked !

To extend the length of the arm I used a small piece of one of
those foil write protect tabs. Cleaned the arm surface very well
and stuck the foil on there. Its very thin so as to not interfere
with the movement of the arm into the optical sensor. I think
that one day the adhesive may dry out and the foil may fall off
but its easy enough to cut another piece, llformat. I really just
wanted to prove that this old drive would still work. I doubt
I'll be storing any mission critical data on here :-)

I low level formatted using the XT diagnostics diskette.
Then Fdisk, and Format C: , Sys c:, reboot ! Thanks to everyone
for all the suggestions and info.

Heres a couple of pictures. One showing the stepper arm extension,
and a couple others. Thats a mono graphics card and a generic
640K memory card.

Luke
September 12th, 2006, 05:37 AM
That's good!

As I got XT in one piece now, I'll play with the ST412.

Luke
September 14th, 2006, 08:01 AM
It looks like my will work too.
I've done the same as Mikey and drive worked just fine after 'cold' power up.

I'll see how it will work next day.
If it will work, problem was in positioning.

mikey99
September 14th, 2006, 08:33 AM
It looks like my will work too.
I've done the same as Mikey and drive worked just fine after 'cold' power up.

I'll see how it will work next day.
If it will work, problem was in positioning.

Thats good news ! Maybe your drive has an intermittent
Track 0 problem. Could be caused by wear on the disk surface,
and moving Track 0 to a 'fresh' part of the drive solves the
problem.

The only problem I see with this solution is that the small
piece of tape may fall off one day. So now I'm trying to think
of something more permanent. Ideally should be made of metal
or hard plastic, and fastened more securely to the motor arm.
Maybe some type of metal clip made of spring steel. It needs
to be very thin to clear the optical sensor. Another possibility is to
move the optical sensor but I dont see an easy way to do that.

chuckcmagee
September 14th, 2006, 02:29 PM
Hmmm, for now, think I would just put a few very small dabs of superglue in a few spots around the edge of the write protector. Those things are pretty sturdy. Guess it could curl if you live in one of those super humid areas.

Luke
September 15th, 2006, 03:16 AM
Okay, I was happy too early.

Yesterday evening I've sticked piece of tape to motor's arm, before I've cleaned sensor with alcohol.
I've LF disk and formatted under DOS it gave me only few bad sectors.

Today it's the same thing as without tape... Disk boot error.
I'll propably leave that disk alone and look for other 10 mb one.

Or maybe someone have another idea?

Luke
September 16th, 2006, 02:31 AM
Mikey and others, there is wat to change pisition of sensor.
It's much more realible.

Just get that screw out and put something under sensor and you've got it higher.
I think that you understand this ;).

http://img243.imageshack.us/img243/9121/cuthereoh9.jpg

No, that's a bad idea...
It move track 0 back.

mikey99
September 16th, 2006, 06:12 AM
Mikey and others, there is wat to change pisition of sensor.
It's much more realible.

Just get that screw out and put something under sensor and you've got it higher.
I think that you understand this ;).

No, that's a bad idea...
It move track 0 back.

Luke, hi, actually I thought of doing that too. But the problem is that
it moves the sensor in the wrong direction :-(

By adding tape to the end of the arm, we are moving the position
of Track 0 'deeper' into the disk surface. In this case the sensor would
need to move down.

modem7
September 16th, 2006, 10:28 PM
Are you guys sure that that screw moves the sensor?
When I earlier had a look at my ST-412, all that screw appeared to do was lower/raise the metal block underneath the screw.

Luke
October 18th, 2006, 10:56 AM
Got it working!!

I used small piece cuted from metal jacket of 3.5" disk and then glued to the arm.
It works great now, formatted and running for few days without fault.
I just power it on and it's ready to boot, I don't need booting form diskette now and 'warming-up' the drive.

mikey99
October 18th, 2006, 03:33 PM
Got it working!!

I used small piece cuted from metal jacket of 3.5" disk and then glued to the arm.
It works great now, formatted and running for few days without fault.
I just power it on and it's ready to boot, I don't need booting form diskette now and 'warming-up' the drive.

Wow, thats great news ! Maybe the piece of metal you used this time
moved the Track 0 position a little further on the disk.

My ST-412 is also still working, although I haven't really used it for much lately. I power it on occasionally to play old DOS game's. I recently rescued a box of MFM drives and another box of 8-bit ISA cards from a guy who was sending them to the electronic recyclers :-) In the box of ISA cards I found an old WD-XT Gen2 MFM controller , which will work in my XT with several different drive types. Also in the box was an AST Sixpack Plus, which I installed in my XT. Just needed a new battery for the clock.

dongfeng
October 19th, 2006, 12:09 AM
Great news, Luke! Have fun with your ST-412 :)