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Spectravideo XPress 16 (SVI-838)

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Spectravideo XPress 16 (SVI-838)

by mrad01 » Mon Oct 20, 2014 9:25 am

Nice little rarity found on TradeMe last week. Thought I better "buy now". A Spectravideo XPress 16 - which was their last gasp before they stopped making machines. It *seems* like it is a 8088 IBM PC compatible with MSX2 hardware. I'll need to (somehow) find out more. I'll post up progress as I hopefully get it up and running. Included a monitor and keyboard.

There is this: http://samdal.com/svi838.htm

Here is a quick pic of mine:
Image
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Re: Spectravideo XPress 16 (SVI-838)

by tezza » Mon Oct 20, 2014 10:00 am

Very nice. I saw this pop up on Trade me and quickly disappear. If I was not so constrained for space I would have thought about it myself.

The first Xpress in on the cover here:
http://www.classic-computers.org.nz/bit ... sue4.3.htm.

I'll be interested to know how you get on with it.

Terry
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Re: Spectravideo XPress 16 (SVI-838)

by SpidersWeb » Mon Oct 20, 2014 12:40 pm

Ah it is real!

I had one when I was younger (not new, like something I got for $5 to play with). My only real memory was the PSU being on the weak side, and it wouldn't start up when I piggy backed a second generic 5.25" drive (memory a bit fuzzy). I went on the internet to find out what it was a year or so ago, but was never quite sure, but now I've seen your picture - it comes flooding back. Nice find.

And yeah, I used to boot MS DOS off 360KB floppies if I remember correctly. Never knew about or used it's advanced features (MSX graphics etc).
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Re: Spectravideo XPress 16 (SVI-838)

by mrad01 » Mon Oct 20, 2014 7:04 pm

Just about to take it apart for a quick cleanup and some photos. I guess I better track down some MSDOS 360k floppies - you don't remember which version of MSDOS?
I believe it will boot CP/M too - I would have no idea where/how that would happen. Love new stuff to learn.

SpidersWeb wrote:Ah it is real!

I had one when I was younger (not new, like something I got for $5 to play with). My only real memory was the PSU being on the weak side, and it wouldn't start up when I piggy backed a second generic 5.25" drive (memory a bit fuzzy). I went on the internet to find out what it was a year or so ago, but was never quite sure, but now I've seen your picture - it comes flooding back. Nice find.

And yeah, I used to boot MS DOS off 360KB floppies if I remember correctly. Never knew about or used it's advanced features (MSX graphics etc).
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Re: Spectravideo XPress 16 (SVI-838)

by SpidersWeb » Tue Oct 21, 2014 9:54 am

If it's PC compatible, it should be able to boot any version of MS DOS (even 6.22). CP/M-86 will run if MS DOS runs.

If I'm remembering accurately (it was a very long time ago), I probably would've booted off MS DOS 3.3 which became fairly standard on 8088's and I would've had lots of those boot disks lying about. I don't remember it coming with special disks so hopefully it doesn't need a special version.

If you get stuck for booters, send me a PM and I should be able to send one off.

Edit: seems it shipped with MS DOS 2.1 which isn't surprising (360KB support, but less overhead) http://www.samdal.com/images/svi/docs/sv838ad.jpg
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Re: Spectravideo XPress 16 (SVI-838)

by mrad01 » Sun Oct 26, 2014 5:12 pm

Being a long weekend there was (some) time to look into the XPress 16. I took it apart to give it an internal clean, then tried to power it on - dead. PSU it seems. (Apparently a weak point)
Here are a few photos of how it is constructed and a shot of the IBM PC 8088 compatible motherboard - with MSX2 chips onboard.

The PSU is two parts - the blackbox transformer (which the power cord goes to) then the power board itself. The board is labelled as the Spectravideo 838 Power Board - Version 2.0. From what I can see with the connectors, it seems like pretty standard IBM XT stuff.

Image

Image

Image

Image
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Re: Spectravideo XPress 16 (SVI-838)

by SpidersWeb » Fri Oct 31, 2014 11:52 am

If you know this stuff I apologise, but just in case any of this is helpful I'll type it anyway:

- test for 16V AC across input lines from the transformer
- check PCB board for output DC voltages (+12, -12, +5, and green might be -5? or maybe the return for the power switch? Not sure)
- if PCB outputs 0, retest with motherboard connected (some supplies need a load to turn on)
- if still outputting 0, disconnect PSU, and check the resistance between the coloured wires and ground (if any show near 0 ohms, that'd cause the PSU to shut down generally - assuming it has cut offs) **
- if power output is good, but machine does nothing, Supersoft ROM time

If the transformer is what's broken, I'd also check the power switch in it is actually still functional.


** unlikely as I don't see many tantalum caps which are the usual cause

External power brick inside the case cracks me up :) Motherboard somewhat remind me of the Commodore PC-10/20 series.
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Re: Spectravideo XPress 16 (SVI-838)

by mrad01 » Fri Oct 31, 2014 6:41 pm

Thanks for that - I had a couple of ideas - but this gives me a good set of test cases!

I see if I can cover them off this weekend and report back,

M

SpidersWeb wrote:If you know this stuff I apologise, but just in case any of this is helpful I'll type it anyway:

- test for 16V AC across input lines from the transformer
- check PCB board for output DC voltages (+12, -12, +5, and green might be -5? or maybe the return for the power switch? Not sure)
- if PCB outputs 0, retest with motherboard connected (some supplies need a load to turn on)
- if still outputting 0, disconnect PSU, and check the resistance between the coloured wires and ground (if any show near 0 ohms, that'd cause the PSU to shut down generally - assuming it has cut offs) **
- if power output is good, but machine does nothing, Supersoft ROM time

If the transformer is what's broken, I'd also check the power switch in it is actually still functional.


** unlikely as I don't see many tantalum caps which are the usual cause

External power brick inside the case cracks me up :) Motherboard somewhat remind me of the Commodore PC-10/20 series.
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Re: Spectravideo XPress 16 (SVI-838)

by tezza » Fri Oct 31, 2014 10:38 pm

SpidersWeb wrote:External power brick inside the case cracks me up :) Motherboard somewhat remind me of the Commodore PC-10/20 series.

You should see the inside of a TRS-80 Model 1 Expansion Interface. Not one, but TWO external power bricks nestled in the EI case...one for the expansion interface and one for the console/keyboard itself! :D
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Re: Spectravideo XPress 16 (SVI-838)

by LS120 » Sat Jul 30, 2016 10:04 am

how did you get on with the svi pc?? just i have some svi & msx stuff.. svi xpress 728 msx v1.5. also have the cpm & dos 5.25"..
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