Zenith Z-90 startup

Mister PDP vintagecomputersmn at gmail.com
Sat May 12 14:29:36 CDT 2018


I have had this issue with a number of H/Z89s I have. The terminal board
and the logic board are two separate systems, so it seems to be common for
the logic board to go down while the terminal board keeps working. I would
check voltages on the logic board, then take it out of look for blown
tantalum caps and burnt traces. The tantalum caps used in these systems
seems to like to cause issues, with 5\8 of my systems experiencing issues
with them. If that doesn't do the trick then check the power regulators on
the logic board, as those can cause issues too.

I'm not too familiar with the terminal setting on these systems, but I
would check the DIP switch settings with the manual and see if there are
any settings changed. There are many good sources for the manuals online
last time I checked

On Sat, May 12, 2018 at 1:23 PM, Jules Richardson via cctalk <
cctalk at classiccmp.org> wrote:

> Any Zenith Z-90 owners out there (which appears to be the same thing as a
> Z-89 / Heath H89, but with a DD soft-sectored disk controller)?
> I was given one up a couple of days ago which isn't giving the expected
> "H:" prompt at power-on - but it *does* give a blinking cursor, and hitting
> off-line lets me type, and characters get echoed to the screen.
> Right-shift-reset clears the screen and gets me back to the cursor.
> Before I dig deeper, I'd like to verify that this isn't a feature, i.e.
> that it's not auto-magically dropping into "terminal mode" at startup :-)
> Unfortunately while I have masses of documentation for the machine, I'm
> lacking a basic user guide which might shed light on any such mode; some of
> the more detailed documentation that I have talks about rerouting the port
> cabling to use the system purely as a terminal, but doesn't mention doing
> any other configuration.
> cheers
> Jules

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