21 Sep
2010
21 Sep
'10
1:59 p.m.
The Alto monitor timing is pretty unique. The display
is portrait, 606
Is 'pretty unique' like 'slightly pregnant' ? :-)
x 808 with
the high frequency scan from top to bottom. Overheating and
horizontal deflection
failures are very common in Alto monitors. The most common cause of
failure is that>
the horizontal width coil overheats and unsolders itself from the PC
board. Because the
horizontal scan occurs across the narrower dimension of the tube, a
THis doesn't make sense to me. In the first part you're saying that th
high frequency scna in the vertical one -- that is that it's like a
normal monitor turned on its side. And they you talk about a width coil
which to me would always be associated with the fsster scan (horizontal
in anromal monitor), and yoy then say that it's the horizotnal scan on
the shorter tube axis (OK, I get that, it's a portait monitor) here too.
Can you tell me if the scan lines are horizontal or verticla here?
FWIW, the PEEQ portrait monbitors have horizontal scan lines alont the
shorter acixe of the screen.
lot of power is
dissipated in the width coil. It also burns up the paper tube it is
wound on, making
it impossible to adjust the width. I ended up rewinding a bunch of
them recently using
new coil forms and heavier wire.
Horizonal and vertical drive are hardwired in the display hardware.
You won't get a
raster until the display microcode is loaded and running, though, and
you have a long
way to go before you're that far.
Do you get syncpulses from the start? If so, at least things like the HV
should be coming up[ in the monitor (check this...)
If you are as insane as I am, you might make a little board with a clcok
oscillator and timing chain on it (TTL, FPGA, whatever you are
comfortable with) to genrate the sync pulses and some kind of fixed video
(corsshatch, checkerboard, etc)(. Then use that to test the monitor.
-tony