On Mon, 14 Jun 1999 00:38:25 -0500, Rodger Boots <rlboots@cedar-rapids.net>
wrote:
>Well, getting ready to go to a trade show, so won't be back here until Friday.
>
>When I get back there's some projects to do:
> Keltron/Atari high voltage power supply.
> Interesting thing here is that, although both
> Cinematronics and Electrohome uses the
> same 19VARP4 picture tube the specs are
> different! (anode voltages are at NO load,
> even though current specs are given):
> Cinematronics specs are:
> 16,000 volts @ 250 uAmp
> 400 volts @ 1 mAmp
> 90 volts @ 8 mAmp
> (focus grid of tube is grounded)
> input voltage is 25 volts
> Electrohome specs are:
> 12,000 volts @ 200 uAmp
> 400 volts
> 90 volts
> (focus is adjustable 0 to 400 volts)
> input voltage is 40 volts
This difference has always bothered me. You can easily adjust an Electrohome
monitor through a full range of focus. The Cinematronics focus adjustment was
so worthless they got rid of it in later models. I've always wanted to rewire a
Cinematronics monitor the same way they wired the Electrohome and see if a nice
'sharp' image could be had. I have a feeling Cinematronics blew it, when
wiring up the CRT.
I was told by a Cinematronics tech that the reason for the higher voltage is
that's what the Keltron put out, and it seemed to work ok. The Keltron was
originally designed as a HV unit for some medical product, when someone at
Cinematronics happen to notice it would work well for them. The price of the
voltage tripler alone (that big grey block on the old Vectorbeam monitors) was
more than the full Keltron unit.
> Vector yoke project. Object is to take an
> inexpensive TV yoke and see how hard it would
> be to rewind it for vector. Horizontal windings
> would be OK as-is, vertical would need rewound
> to match horizontal.
>
> Color vector high-voltage supply project. Need to
> find data on the care and feeding of a 19VLUP22.
> Anyone know if the Ampliflame tube uses the same
> voltages?
>
> G08 "bullet-proof" deflection board project. I have
> come up with a bipolar/FET cascoded output circuit
> with possibilities. It has current limiting built in and,
> in theory, is more than a match for anything a Sega
> vector could do to a monitor. But theory doesn't always
> get you there, so there will have to be cruel and inhumane
> tortures tried on the circuit first before releasing it on an
> unsuspecting world. It is an odd circuit, to say the
> least. I have a friend that is into custom modification of
> high power audio amps that I'll chat with first. His
> modified amps have a habit of NOT dying, so his input
> will be valued. But the circuit DOES look like it could
> handle full deflection into a shorted yoke without damage,
> time will tell.
>
>If any of this flies I'll probably have someone else build them,
>just don't have that kind of time.
Nice projects dude!
-Zonn
Received on Mon Jun 14 23:02:30 1999
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