Electronics > Repair
W&G sna-20/23 spectrum analyzer repair
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Gerhard_dk4xp:
Sorry, I've been away for a week.  The DOS files for the SNA are under:

<        http://www.hoffmann-hochfrequenz.de/downloads/sna_arch.zip               >

Seems like it is classified as a security risc also here  but can be overridden.

It won't stay there for long.
Looks like I have work to do on my web site.
Gerhard
alexturner:
Thanks Gerhard,

I've downloaded it and am compiling a bunch of disks I'm slowly getting access to. I'll create a repo somewhere to share when I get it working.

On booting your disk I noticed the the same banding issue as the OP. I saw this was also the case when I started the SNA software from the C: drive from a DOS 6.22 disk. In breaking into a DOS shell with ALT+F10, I saw the debug errors which all cite the missing contents of the B: drive, I suspect these will go away when I get the image. By some stroke of luck I'm in contact with the person who has my calibration disk and hopefully I'll see it this week, we'll see.

I'll report back with status none the less.

Alex
alexturner:
Does anyone have more of an idea about the zebra banding that occurs after the main-sw loads? Looking into the fairly scarce service manual it appears as if the AT board boots using VGA BIOS, however when the application loads there is a faster, application specific TI graphic chip that takes control and it's at this point the banding appears; so I suspect an issue here. The graphics board (BSK-3) is quite sophisticated and includes a switch to direct video to the EL display or the RGB TTL port on the rear of the unit. I suspect my best course of action is to purchase a TTL to VGA adaptor and see if I can get an image out the rear port (the diagnose switching, etc).

If not it appears the unit might be dead on a count of there being a couple of critical FPGA's which drive the EL display that firmware will be long lost to.

Have any of the original posters on this thread who have had banding issues on boot resolved this?

Alex
alexturner:
Does anyone have the install disks??
Gerhard_dk4xp:
On microcontroller.net there appeared someone asking a question and in the context
it was clear that he has a working SNA23/33. I asked him for the floppy images but he
never resurfaced.

Tonight I took a floppy whose bit image is in the sna_arch.zip file that you should
have got. It tries booting into DOS but cannot find
\DOS\himem.sys
\DOS\country.sys
\DOS\ANSI.sys  and at least 2 other files.

The files are on the disk but there is no \DOS directory.
So I made one and COPIED them to that directory. The 1.44MB floppy is only abt.
half-full, and I copied also some more that are mentioned in config.sys and autoexec.bat.
I also commented out the first or second line in autoexec.bat that hides the commands
that are executed. I want to see them.

The floppy then booted into dos but I got the Zebra screen again.
I then rebooted and aborted it just before the W&G-specific things are started.
(many CTL-Cs).  That left me with a working DOS command line.
I can make DIR C:  or DIR B: and get the contents listed. That means that the flash disk c:
and the ram disk B: are OK.  I also did chkdsk c: and that worked ok.

Nevertheless, when I try to boot without floppy it says the hard drive is broken.

The bottom 2 or 3 lines of the built-in screen are missing, that's a royal pain. Use some
CR to see all the answers. Maybe a ANSI.sys param is wrong.
And I have a German keyboard while the system expects US.
That can probably be healed with the right parameters to country.sys. I wished I still had
my dos handbook.

I used a HAMA USB floppy drive to mount the floppy under Linux. The port must be
USB3 because that delivers more current to the floppy drive; else seek errors abound.
I'll make some screen shots tomorrow, too tired for now.

Cheers, Gerhard

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