Telcon Zorba screen issues

[AdamAnt316]

Hello everyone. I recently acquired a Telcon Zorba, one of the early models before the ModComp deal. Here are some photos:




Overall, it seems to be in pretty good shape, though it's missing the little cover which goes over the ports, and didn't come with any software. Unfortunately, when powered up, the monitor shows a vertical line in the middle of the screen, roughly in the expected shape of the logo 'splash':

Any idea what might be the cause? I'm hoping that it's something as simple as dirty controls in the monitor circuitry, but I don't know for sure. Further, are there any tricks involved with opening the case? I'm hoping it just involves undoing the various screws visible around the outside of the case, but again, I don't know for sure. Finally, is there a service manual available for these machines? Thanks in advance!
-Adam

(further question: is there a way to make the attached images appear larger than thumbnail size within the post?)

 

[ldkraemer]

http://www.zorba.z80.de/telcon.htm
http://oldcomputers.dyndns.org/public/pub/archiv/maslin/masl-dsk/images-97/zorba/index.html
http://www.classiccmp.org/dunfield/zorba/index.htm



Larry

 

[AdamAnt316]

Thanks for the reply. I found a service manual on the site which gives me a pretty good idea of what I need to know with regards to opening the case and whatnot. Will have to figure out what sort of BIOS software it has before I can make a set of disks; the archive in the first link gives disks for BIOS versions 1.6 and 1.7, and I'm guessing the former would be appropriate for this unit since it's a fairly early production model, but I don't know for sure. Said manual also gives a diagram of the layout for a "CRT alignment template" in the case, which I will provide a screenshot of below:

Any idea which adjustment might bring the screen more in-line with normal? It would appear that I have vertical, but no horizontal. Not sure if there are any other adjustments besides the ones on the "alignment template". Again, thanks in advance!
-Adam

 

[ldkraemer]

Adam,
I'd bet it's not any of the adjustments that would cause the fold over with no Horizontal sweep.
It's more likely the HOT (Horizontal Output Transistor), and a defective capacitor or two. I'd
delay tweeking any pots until the Horizontal circuit was verified.

The Floppy's are the easy part. You just need an Older DOS Computer and use 22DISK,
or use Dave Dunfield's IMAGEDISK to write the boot floppy's. You can use cpmtools, or cpmtools
built with libdsk to access the .RAW images. The .RAW images are created by Dunfield's utilities
TD02IMD, IMDA, IMDU, and BIN2IMD.

The definitions I have for the Zorba are:

BEGIN ZOR1  Zorba - DSDD 48 tpi 5.25" - 512 x 10
INSERT 22DISK DEFINITION
END

# ZOR1  Zorba - DSDD 48 tpi 5.25" - 512 x 10
diskdef zor1
  seclen 512
  tracks 40
  sectrk 20
  blocksize 2048
  maxdir 64
  skew 1
  offset 10240
  boottrk 0
  os 2.2
end

# libdsk data below
[zor1]
description = ZOR1  Zorba - DSDD 48 tpi 5.25" - 512 x 10
#sides = extsurface
cylinders = 80
heads = 2
secsize = 512
sectors = 10
secbase = 1
datarate = DD

#Flashfloppy
[zor1]
cyls = 80
heads = 2
secs = 10
interleave = 1
bps = 512
id = 1
#rpm = 360
rpm = 300
rate = 250
mode = mfm
iam = no

BEGIN ZOR2  Zorba - DSDD 96 tpi 5.25" - 512 x 10
INSERT 22DISK DEFINITION
END

# ZOR2  Zorba - DSDD 96 tpi 5.25" - 512 x 10
diskdef zor2
  seclen 512
  tracks 80
  sectrk 20
  blocksize 4096
  maxdir 128
  skew 1
  offset 10240
  boottrk 0
  os 2.2
end

# libdsk data below
[zor2]
description = ZOR2  Zorba - DSDD 96 tpi 5.25" - 512 x 10
#sides = extsurface
cylinders = 160
heads = 2
secsize = 512
sectors = 10
secbase = 1
datarate = DD

#Flashfloppy
[zor2]
cyls = 160
heads = 2
secs = 10
interleave = 1
bps = 512
id = 1
#rpm = 360
rpm = 300
rate = 250
mode = mfm
iam = no

So, the first thing you need to know is are the Floppy Drives 48 TPI or 96 TPI.
That will give you the proper Definition to use zor{1..2}.

Form there it will be easy to write the Floppy's with a DOS Computer, or early
Windows computer running in DOS Mode.

Waiting on a PM with your email address.


Larry