"Invalid Address Mark Detected" on a Zenith ZF-158, most likely WD1002-ZEN ISA card issue!

[SirShanova]

Good evening! Any suggestions to fix an "Invalid Address Mark Detected" error, most likely stemming from the ISA card?

I bought an IBM PC XT clone today, a Zenith ZF-158-42, with the disclosure that there were hard disk issues. Upon taking it home and examining the minuscule information that I can find on this machine and it's very similar counterparts, I have discovered that it has had one of it's two factory 5.25 inch floppy disk drives (the bottom) replaced with a hard disk drive. The previous owner kept the hard drive's ST-506 ISA controller card unplugged and in an antistatic bag in the chassis, as this was a known issue. With it uninstalled, it boots into the MS-DOS 3.30 boot disk perfectly and flawlessly. Of course, after plugging it in, it did not perform so flawlessly.

The Miniscribe Corporation 8425 21 megabyte hard drive with a 5.25 inch adapter, despite what the owner said, is not what I believe to be the issue. With the card and drive both plugged in, I get the "Invalid Address Mark Detected" error. Trying different combinations of different ST-506 cable orientations, still got an "Invalid Address Mark Detected" error. With the hard drive unplugged and the card still plugged in, got an "Invalid Address Mark Detected" error. With the card unplugged and the drive...well, unplugged, no more error because obviously the drive isn't interfacing with anything. Is this a card issue? Is this a BIOS issue?

Other relevant specs are that the system still has it's original 512kb of RAM, it's original Intel 8088 processor, and the ISA card used by the hard drive is an WD1002-ZEN.
Any help is appreciated! I've attached some photos of the machine and it's ISA card. I'm also including all the documentation on this machine I have found. Please let me know what I can do to remedy this, I adore this machine!

P.S. These documents are too big to be attachments, here are their archive.org links:

Wayback Machine

Wayback Machine

 

[SirShanova]

Additonally, the hard drive light flashes "SOLID, BLINKING, BLINKING, BLINKING" on repeat, so long as the drive receives power.

 

[jafir]

An intitial warning, I know nothing about this computer, but it seems like there are manuals online here: https://ia801008.us.archive.org/29/...-150_PC_Users_and_Operations_Manual_Guide.pdf
(And it looks like there are some at minuszerodegrees, but I had trouble connecting just now).

Anyway, it suggests there is a builtin monitor. Can you try pressing ESC while powering it on and seeing it will drop into the monitor? If so then you might be able to boot from the floppy (instead of the hdd, Winchester the manual calls it) by typing bf. Then you might be able to prepare the hdd. The manual suggests the error you’re getting it from there being no OS on the drive, but I’d imagine a hardware problem keeping it from reading might do the same.

Also you might need zenith z-100 pc ms-dos disks, as it looks like there are specific utilities to partition the hdd.

 

[modem7]

The Miniscribe Corporation 8425 21 megabyte hard drive with a 5.25 inch adapter, despite what the owner said, is not what I believe to be the issue.

Additonally, the hard drive light flashes "SOLID, BLINKING, BLINKING, BLINKING" on repeat, so long as the drive receives power.

That sounds like it might be one of the error codes that the 8425 drive is known to flash on its LED at power on (even if disconnected from controller)
See the ''Message Readout' section of the 8425 document at [here].
Do you see a match with what the drive is flashing?
If not, provide us with a video, because we might see a match.

 

[SirShanova]

An intitial warning, I know nothing about this computer, but it seems like there are manuals online here: https://ia801008.us.archive.org/29/...-150_PC_Users_and_Operations_Manual_Guide.pdf
(And it looks like there are some at minuszerodegrees, but I had trouble connecting just now).

Anyway, it suggests there is a builtin monitor. Can you try pressing ESC while powering it on and seeing it will drop into the monitor? If so then you might be able to boot from the floppy (instead of the hdd, Winchester the manual calls it) by typing bf. Then you might be able to prepare the hdd. The manual suggests the error you’re getting it from there being no OS on the drive, but I’d imagine a hardware problem keeping it from reading might do the same.

Also you might need zenith z-100 pc ms-dos disks, as it looks like there are specific utilities to partition the hdd.

After spamming the ESC key with both the drive and the ISA card plugged it, it announced my memory size and brought me to the screen below. Time to enter the bf command!

 

[SirShanova]

That sounds like it might be one of the error codes that the 8425 drive is known to flash on its LED at power on (even if disconnected from controller)
See the ''Message Readout' section of the 8425 document at [here].
Do you see a match with what the drive is flashing?
If not, provide us with a video, because we might see a match.

The video is below, will search for a match:

https://imgur.com/5FX2wCq

 

[SirShanova]

An intitial warning, I know nothing about this computer, but it seems like there are manuals online here: https://ia801008.us.archive.org/29/...-150_PC_Users_and_Operations_Manual_Guide.pdf
(And it looks like there are some at minuszerodegrees, but I had trouble connecting just now).

Anyway, it suggests there is a builtin monitor. Can you try pressing ESC while powering it on and seeing it will drop into the monitor? If so then you might be able to boot from the floppy (instead of the hdd, Winchester the manual calls it) by typing bf. Then you might be able to prepare the hdd. The manual suggests the error you’re getting it from there being no OS on the drive, but I’d imagine a hardware problem keeping it from reading might do the same.

Also you might need zenith z-100 pc ms-dos disks, as it looks like there are specific utilities to partition the hdd.

Typimg bf into the monitor terminal created a large amount of audible hard drive activity (does not sound to be dying, which is good) and then dropped me into the same screen I see when I boot from the floppy. Attempting to open fdisk, however, leads to the reconfirmation that there are no fixed disks present. I have the two install disks for commercial (I believe) MS-DOS 3.3. As I have no method to acquire, let alone copy a Zenith Z-100 DOS floppy, we will have to see if this will do for now.

Attached are a few images of the monitor:

 

[SirShanova]

That sounds like it might be one of the error codes that the 8425 drive is known to flash on its LED at power on (even if disconnected from controller)
See the ''Message Readout' section of the 8425 document at [here].
Do you see a match with what the drive is flashing?
If not, provide us with a video, because we might see a match.

Under this document’s Features entry, under the Message Readout section, what I seem to be experiencing is a “Code 8 - Unable to uncover Track Zero sensor.”

In a previous discussion you contributed to, you assisted in fixing this issue for another system. I will see what I can do here. Will give an update when I can judge the scope of the fix!

 

[SirShanova]

Under this document’s Features entry, under the Message Readout section, what I seem to be experiencing is a “Code 8 - Unable to uncover Track Zero sensor.”

In a previous discussion you contributed to, you assisted in fixing this issue for another system. I will see what I can do here. Will give an update when I can judge the scope of the fix!

So, examining my drive, I am searching for any jumper that could be the one described in that discussion. I found two possible options. One, highlighted (in red on image,) is a bank of four in a straight line. Curiously, two of this “J12” batch were shorted together (in light blue in image.) I have separated them, but will wait for someone here to deliver a verdict before I power on the drive with them disconnected. I’ve searched high and low for any images of another 8425F, and the only example I’ve been able to find does not have the two contacts touching. Then again, that model is advertised as not working .

Additionally, J13, highlighted (in yellow on image,) bears a resemblance to the similarly named JP13 routine outlined in the discussion. Does this mean anything? Possibly not, possibly so, I can not be certain (I’m pretty certain it isn’t, but it’s worth a mention.

How do I proceed?

Color coded:
Un-shorted J12 pin example:
eBay listing image:
eBay listing:
Archived in the Wayback Machine at:
http://web.archive.org/web/20221009050343/https://www.ebay.com/itm/313999301599

 

[modem7]

Under this document’s Features entry, under the Message Readout section, what I seem to be experiencing is a “Code 8 - Unable to uncover Track Zero sensor.”

Having looked at the video you provided, I agree.
So, what does "Unable to uncover Track Zero sensor" mean?

The photo below shows one side of a similar stepper motor, not the one in an 8425, but close enough.

The drive moves the heads in and out by activating the stepper motor in the applicable direction. As that happens, the shaft rotates. Because the stepper arm (a.k.a. interrupter) is attached to the shaft, it rotates as well. When the arm is in the 'track 0 sensor', the drive knows that the heads are on track (cylinder) 0.
When the drive is powered on, one or more of the drive's self-tests involve seeing if the signal from the track 0 sensor changes as expected. "Unable to uncover Track Zero sensor" means to me that a test could see that the track 0 sensor was activated (i.e. indicating that heads on track/cylinder 0), then the test had the stepper motor move the heads way from track/cylinder 0, but discovered that the track 0 sensor was unexpectedly still activated.

Some possible causes:
- Faulty stepper motor (i.e. stepper fails to rotate, or improper rotation)
- Faulty stepper motor drive electronics (i.e. stepper fails to rotate, or improper rotation)
- Faulty 'track 0 sensor'
- Faulty 'track 0 sensor' processing circuitry
- Other

In the thread that you pointed to in post #8, gslick suggested a problem where perhaps the screw securing the arm to the shaft had become loose, resulting in either:
- the shaft moving, but not the arm; or
- the arm is somehow now at the wrong angular position on the shaft (a position that does not correlate to the heads being at track/cylinder 0).

The eBay listing included, "the head and interrupter move as they should." Are you still seeing that at power on of the drive? Is the arm well secured on the shaft?

 

[modem7]

(And it looks like there are some at minuszerodegrees, but I had trouble connecting just now).

A problem at my website hosting provider. No estimated resolution time.

 

[hornbetw]

SirShanova, the problem is obviously the Magic Smoke coming out of those 2 RIFA ICs! That's a scary sight seeing ICs with the name RIFA on them. Their caps are prone to smoking enough! I never knew RIFA made ICs.

 

[SirShanova]

SirShanova, the problem is obviously the Magic Smoke coming out of those 2 RIFA ICs! That's a scary sight seeing ICs with the name RIFA on them. Their caps are prone to smoking enough! I never knew RIFA made ICs.

If you want a closer look, I’ll attach them below. Now, what can be surmised looking at an IC, I don’t know, but still:

 

[SirShanova]

Having looked at the video you provided, I agree.
So, what does "Unable to uncover Track Zero sensor" mean?

The photo below shows one side of a similar stepper motor, not the one in an 8425, but close enough.

The drive moves the heads in and out by activating the stepper motor in the applicable direction. As that happens, the shaft rotates. Because the stepper arm (a.k.a. interrupter) is attached to the shaft, it rotates as well. When the arm is in the 'track 0 sensor', the drive knows that the heads are on track (cylinder) 0.
When the drive is powered on, one or more of the drive's self-tests involve seeing if the signal from the track 0 sensor changes as expected. "Unable to uncover Track Zero sensor" means to me that a test could see that the track 0 sensor was activated (i.e. indicating that heads on track/cylinder 0), then the test had the stepper motor move the heads way from track/cylinder 0, but discovered that the track 0 sensor was unexpectedly still activated.

Some possible causes:
- Faulty stepper motor (i.e. stepper fails to rotate, or improper rotation)
- Faulty stepper motor drive electronics (i.e. stepper fails to rotate, or improper rotation)
- Faulty 'track 0 sensor'
- Faulty 'track 0 sensor' processing circuitry
- Other

In the thread that you pointed to in post #8, gslick suggested a problem where perhaps the screw securing the arm to the shaft had become loose, resulting in either:
- the shaft moving, but not the arm; or
- the arm is somehow now at the wrong angular position on the shaft (a position that does not correlate to the heads being at track/cylinder 0).

The eBay listing included, "the head and interrupter move as they should." Are you still seeing that at power on of the drive? Is the arm well secured on the shaft?

View attachment 1247174

There appears to be no movement of the stepper shaft at all:

https://imgur.com/a/uy3WgHd

Edit: From that 8425 manual, It appears as if the J8 jumper is the stepper motor. Will report back with my findings.

 

[SirShanova]

There appears to be no movement of the stepper shaft at all:

https://imgur.com/a/uy3WgHd

Edit: From that 8425 manual, It appears as if the J8 jumper is the stepper motor. Will report back with my findings.

It appears as if my drive does not have any J8 jumper. However, the diagram also doesn’t have a J12 jumper. Is there a possibility these two things could be related?

 

[modem7]

There appears to be no movement of the stepper shaft at all:

So that explains the Code 8. Obviously the hunt is now on for why?

Try not to focus on missing jumpers. Sometimes those jumpers are missing because they were only used during manufacture. But of course, it is something that would be good to eliminate. I took a look at what Miniscribe drives I have, but they are model 3650's, somewhat different.

With power off, are you able to manually rotate the shaft? Strictly speaking, one shouldn't do that - why the 'Do not rotate interrupter' sticker is there, but hey, you presently have an unusable drive.

If not, a seized stepper motor is a possibility. Rubber stop within the drive all gummed up, holding heads in track/cylinder 0 position?

If yes, then position arm at about half way point, then apply power, just to see if stepping works in at least one direction.

 

[modem7]

... out of those 2 RIFA ICs!

The PBL3717's are the driver chips for the stepper motor. My Miniscribe 3650's use them as well. The internet shows that they were made by a few companies.

Below, you can see by the discolouration of the PCB, that the PBL3717's can get quite hot.

 

[SirShanova]

I will be return with more findings in a few weeks. Just had to catch a plane. I’m going to put this on hold until around thanksgiving. See you all then!