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Robotrontechnik-Forum » Technische Diskussionen » EC-1834 hard drive not working » Themenansicht

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000
23.06.2022, 00:08 Uhr
Escaper



Hello dear forum dwellers! I hope it's okay if I write in English. I did study German in school, but it was many, many years ago and I don't remember much, unfortunately.

Recently I've become a happy owner of Robotron EC-1834 machine. It was in pretty good condition when I bought it but it did have a few issues (keyboard didn't work, floppy drives worked one time out of ten, etc.). I fixed most of those issues, but now I am facing an issue which doesn't seem to be easily solvable. The operating system does not see the hard drive (Robotron K5504.20).

Here's how the problem manifests itself. I power on the computer. There is a system diskette (DCP DOS 3.30) in floppy drive A:. System starts to boot. At some point during boot-up, the LED on the HDD lights up for a couple of seconds, then it goes out and booting continues. After booting finishes, the operating system does not see the HDD. If I type "c:<Enter>", I get message to the effect "Invalid drive specification" ("Ungültige Laufwerksangabe").

I read somewhere (probably on this same forum) that Robotron hard drives of the era had this issue with oil inside HDD becoming alike rubber with time and preventing the heads and disks from moving. This seems not to be the issue in my case though, as I clearly hear the disks starting to rotate when I power on the machine and the motor moving the heads as well. So, mechanical part seems to be in order. It doesn't seem necessary to me to take the hard drive apart to clean inside.

So, it looks to me like the problem is with the electronical part. Either in the hard drive controller card, or in the hard drive itself, or both. Here's the simple things I tried to exclude them as cause of the problem:

- Checked connectivity in both interface cables between the HDD controller card and the hard drive. They both are okay.
- Read the image of the EPROM chip on the controller card. Its content is totally ok, it matches one of the EC-1834 HDD controller ROM images I found on the web.
- Tried switching jumper connectors on the controller (they define the type and model of the drive). No effect.
- Cleaned the controller card, took out the controller chip out of its socket and put it back in. No effect.
- Removed all extension cards except bare minimum (video, FDD and HDD controllers) to exclude their influence. Still the same.
- Ran HDINIT utility found on the system diskette several times. Mostly, it just errors out saying that the drive OR controller is defective. But one time it did start formatting the drive! It took it around 15 minutes to finish and during that process the motor was clearly moving the heads. However, when the process finished, the program reported that all 615 x 4 = 2460 sectors were bad. So disappointing. And then back to square one -- I cannot switch to drive C: because "Invalid drive specification".

Does any of this ring a bell? At least it would be very helpful to understand where the problem lies--is the hard drive dead, or controller is glitchy, or...

Any help is appreciated!

Dieser Beitrag wurde am 23.06.2022 um 00:43 Uhr von Escaper editiert.
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001
23.06.2022, 08:21 Uhr
Rüdiger
Administrator



Zitat:
Escaper schrieb
Hello dear forum dwellers! I hope it's okay if I write in English. I did study German in school, but it was many, many years ago and I don't remember much, unfortunately.



Welcome!


Zitat:
This seems not to be the issue in my case though, as I clearly hear the disks starting to rotate when I power on the machine and the motor moving the heads as well.



The sticky oil problem affects parking mechanism of the head, not the spindle motor.
What type of hard disk is in your EC?
--
Kernel panic: Out of swap space.
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002
23.06.2022, 08:34 Uhr
Escaper




Zitat:
Rüdiger schriebThe sticky oil problem affects parking mechanism of the head, not the spindle motor.
What type of hard disk is in your EC?



It's Robotron K5504.20. It has capacity 20 MB, as far as I understand.
Motor that moves the heads seems to work fine as well. When the power is off, I can rotate the motor all the way, and then, when I turn the EC on, the motor moves the heads back to the normal position. Also the heads were moving when the EC was formatting (or trying to format, rather) the disk. Does this sound like the heads motor is in order? Or can it still be faulty?

Dieser Beitrag wurde am 23.06.2022 um 08:36 Uhr von Escaper editiert.
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003
23.06.2022, 08:49 Uhr
Rüdiger
Administrator



Zitat:
Escaper schrieb
It's Robotron K5504.20.



This disk does not have the sticky oil problem.
Do you expect there is software at the disk which should be rescued?
--
Kernel panic: Out of swap space.

Dieser Beitrag wurde am 23.06.2022 um 08:50 Uhr von Rüdiger editiert.
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004
23.06.2022, 08:51 Uhr
Escaper




Zitat:
Rüdiger schrieb
This disk does not have the sticky oil problem.
Do you expect there is software at the disk which should be rescued?


Nope. It's totally fine to lose whatever is on the disk.
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005
23.06.2022, 11:52 Uhr
MarioG77

Avatar von MarioG77

Hello,

in the worst case, it could be replaced by an XT-IDE board.
For the (almost any of the different variants) standard XT-IDE you would need a straight DIN41612 64(a+c) connector and an ISA card edge slot.

I had completed a native XT-IDE board this month. I just need to mount it together, to confirm it's working as expected...

With that you could use any IDE drive (or flash card with adapter) on the computer.

About the controller - sorry, I don't have any idea at the moment. Luckily my disk is working, except for some failing sectors...

Regards Mario
--
Gruss Mario

Betriebsbereit: KC85/3, KC85/4, PPC512, PC1512, EC1834, Soemtron 286
Zu restaurieren: 2x PC1715, EC1834, D004 Basis+Floppy
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006
23.06.2022, 16:04 Uhr
RP



Ist der 20 PIN Anschluss an der MFM Platte am richtigen Controller Anschluss gesteckt? eine Unterbrechung des 20 PIN Anschlusses zum Controller verursacht genau das beschriebene Fehlerbild.

Die MFM Platte an einem anderen MFM Controller mit Hilfe von DISK MANAGER testen.

https://www.youtube.com/watch?v=PCSNsjocbts

Rolf
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007
24.06.2022, 10:49 Uhr
Escaper




Zitat:
in the worst case, it could be replaced by an XT-IDE board.


Thanks for the idea about XT-IDE! That sounds interesting. I'll look into it.
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008
24.06.2022, 10:52 Uhr
Rüdiger
Administrator


You could send/bring your disk and HDC to somebody owing a functional EC1834 to determine the problem reason.

Where do you live?
--
Kernel panic: Out of swap space.
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009
24.06.2022, 10:55 Uhr
Escaper




Zitat:
RP schrieb
Ist der 20 PIN Anschluss an der MFM Platte am richtigen Controller Anschluss gesteckt? eine Unterbrechung des 20 PIN Anschlusses zum Controller verursacht genau das beschriebene Fehlerbild.


Yeah, both interface cables seem to be okay. I used my multimeter to check every wire. I'll doublecheck though. As for whether the cables are connected to the right connectors on the controller side... Not sure. I didn't swap them. Unless the previous owner did that, they should be in the right places. Maybe some of you guys can make a photo and post it here? I'll post mine.


Zitat:
RP schrieb
Die MFM Platte an einem anderen MFM Controller mit Hilfe von DISK MANAGER testen.

https://www.youtube.com/watch?v=PCSNsjocbts
Rolf


Thanks! Gotta find another MFM Controller or an MFM hard-drive though to check that.

Dieser Beitrag wurde am 24.06.2022 um 11:02 Uhr von Escaper editiert.
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010
24.06.2022, 11:00 Uhr
Escaper




Zitat:
Rüdiger schrieb
You could send/bring your disk and HDC to somebody owing a functional EC1834 to determine the problem reason.

Where do you live?


I live in St.Petersburg, Russia... People interested in retro computers here mostly collect Soviet computers. Robotron is a rarity. But I'll try to find someone with a working machine. Thanks!
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011
24.06.2022, 11:09 Uhr
Rüdiger
Administrator



Zitat:
Escaper schrieb
I live in St.Petersburg, Russia... People interested in retro computers here mostly collect Soviet computers. Robotron is a rarity. But I'll try to find someone with a working machine. Thanks!



You could visit Sergej Frolov in your town: he has such a computer, as far I know in functional condition.
http://www.leningrad.su/museum/show_calc.php?n=78
--
Kernel panic: Out of swap space.
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012
24.06.2022, 11:11 Uhr
Escaper




Zitat:
Rüdiger schriebYou could visit Sergej Frolov in your town: he has such a computer, as far I know in functional condition.
http://www.leningrad.su/museum/show_calc.php?n=78


Oh, I heard of him! He's a known retro collector. I'll contact him. Thanks!
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013
24.06.2022, 11:17 Uhr
Rüdiger
Administrator


If you exchange disks of different types, remember to set the switches at the HDC correctly.
--
Kernel panic: Out of swap space.
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014
24.06.2022, 11:19 Uhr
Escaper



Here are my connections on the hard-drive controller (not sure if I can embed the images directly in the post):

http://retrobytes.ru/storage/20220624/IMG_2029.JPG
http://retrobytes.ru/storage/20220624/IMG_2030.JPG
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015
24.06.2022, 11:19 Uhr
Escaper




Zitat:
Rüdiger schrieb
If you exchange disks of different types, remember to set the switches at the HDC correctly.


Will do.
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016
24.06.2022, 11:31 Uhr
Rüdiger
Administrator



Zitat:
Escaper schrieb
Here are my connections on the hard-drive controller (not sure if I can embed the images directly in the post):

http://retrobytes.ru/storage/20220624/IMG_2029.JPG
http://retrobytes.ru/storage/20220624/IMG_2030.JPG



Seems they are plugged correct.

The marked sides of the plugs at the other ends are really pointing to Pin1 at the HDD?
Measure if +5V, +12V and ground arrives the board the the HDD!

Possibly it makes sense to check the contacts of the DIP switches at the HDC via ohmmeter.
--
Kernel panic: Out of swap space.

Dieser Beitrag wurde am 24.06.2022 um 11:33 Uhr von Rüdiger editiert.
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017
26.06.2022, 00:52 Uhr
Escaper




Zitat:
Rüdiger schriebThe marked sides of the plugs at the other ends are really pointing to Pin1 at the HDD?


They do.


Zitat:
Rüdiger schriebMeasure if +5V, +12V and ground arrives the board the the HDD!


The voltage measured is: 12.4V and 5.4V. Seem quite alright to me.

In fact, I am now inclined to think that the HDD just has too many bad sectors in crucial areas. Particularly, a couple of diagnostics utils I ran reported about 25 bad sectors in the very beginning of the disk (cylinders 0 through 9, or something like that). Even though I can do a low-level format of the disk (it stopped reporting all sectors as bad, now it's somehow down to just 25), my understanding is that after formatting I have to run FDISK utility to create partitions. Well, that program just wouldn't start saying "Read error on hard-disk". Looks to me like I have an irreparable hard-drive with bad sectors in areas that are crucial to the operating system.

So, my options seem to be:

a) Get another MFM hard drive and hope it works, OR
b) Get (or make) an IDE-XT card and use it with an IDE hard drive, OR
c) Just load things from floppy diskettes. This works quite well, by the way. Yesterday I ran a few games, e.g. the original Tetris. Looks very authentic with the green glow of the monitor.
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018
26.06.2022, 09:38 Uhr
RP



im Bereich der fehlerhaften Sektoren am Anfang der Platte eine nicht DOS ( DCP) Partition mit hdinit erstellen, danach die aktive primäre DOS Partition erstellen, sie beginnt dann nach dem fehlerhaften Bereich. Änderungen auf Platte schreiben.
Rechner EC1834 mit System Diskette neu starten; mit format c:/s Festlatte formatieren und System übertragen.

Rolf

Dieser Beitrag wurde am 26.06.2022 um 09:39 Uhr von RP editiert.
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019
26.06.2022, 09:53 Uhr
Escaper



Hm, this is an interesting idea. I didn't know I could do that with hdinit. Thanks, RP, I will try that and report back!
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020
02.07.2022, 14:55 Uhr
Escaper



So, I finally got to trying that idea. I didn't find where I can create a "non-DCP" partition in hdinit (or any kind of partition for that matter). The only thing I seemingly can do before starting the low-level format is creating the "BAD-TRACK-LISTE". I am asked to enter cylinder number and head number for each of the defective part of the disk. So I entered the complete first 12 cylinders, i.e.:

Cylinder - Head
0 - 0
0 - 1
0 - 2
0 - 3
1 - 0
1 - 1
...
11 - 0
11 - 1
11 - 2
11 - 3

After low-level formatting I am presented with the map of bad tracks:

http://retrobytes.ru/storage/20220702/bad-sectors.jpg

I exit the hdinit utility. However, from there on I am back to square one.

A: \> fdisk
Leserfehler auf der Festplatte ("Disk reader error")

A: \> format c:
Ungültige Laufwerksangabe ("Invalid drive specification")

Is the drive completely dead? Or there is hope?

Dieser Beitrag wurde am 02.07.2022 um 15:10 Uhr von Escaper editiert.
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021
02.07.2022, 16:15 Uhr
RP



https://winworldpc.com/product/ontrack-disk-manager/3x

versuche an Stelle von hdinit, mit Disk Manager Seagate 1988

Der gesamte "MBR" der Patte Fehlerhaft hatte ich noch nicht, kann ein Virus sein.
Der kann sich auch auf deiner Installation Diskette befinden! und den MBR der Platte verschreiben.

https://de.wikipedia.org/wiki/Parity_Boot.

Mit schreibgeschützter Diskette, (Viren frei)! starten. Eingabe fdisk/MBR
Rechner ausschalten, kein warm Start! (Virus bleibt im RAM) neu starten.

Diskette (mit Schreibschutz) mit "Disk Manager Seagate" einlegen, mit Eingabe dm/m Disk Manager starten und Festplatte initialisieren.

Rolf
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022
02.07.2022, 16:58 Uhr
Escaper



I took DCP boot diskette from here:

https://vetusware.com/manufacturer/Robotron/?author=1058

Could it contain a virus? Is there a more reliable place to get the DCP boot diskette image?

I will try the Seagate Disk Manager now and will report back.
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