Re: Amplifone Design... Wonders me

Hello Zonn,

Nice to read your extensive reply about amplifone regulation.

> No low voltage regulation.
>
> I noticed this a long time ago. Every properly working Amplifone I've
owned has
> had a less stable picture than every properly working WG6100.

So it is normal to have the image wobble at the outlines over maybe as much
of 1/4-1/8 of an inch... ???
It is SO annoying... the wobble is made up of the difference in X and/or Y
input frame frequency and the 50Hz (60Hz in US). The amplification factor
(gain) of the amplifiers is modulated by this frequency. A 53 Hz frame
screen looks ugly (3 Hz wobble), 50 or 70 and greater frame frequencies look
better.

> The Amplifone's whole reason for existence was price reduction (and maybe
supply
> problems with the WG6100 as well). The first thing they got rid of was
the low
> voltage power regulator -- they replaced it with a wire. The second thing
they
> got rid of was the high voltage regulator, it was replaced by a
> feroresonance(sp?) design that does not regulate as well as an active
regulator.

I'm not so sure this was done to make things cheaper.
Star Wars wants to be able to defocus the beam to create some special
effects. Notice how the enemies laser shots are defocused and therefore look
really cool and cloudy (in stead of a bunch of lines) such as i.e. Tempest.

A little history I once heard telling:
First Atari deviced a HV supply in which a vacuum tube could change the
focus, but ofcourse this was not feasible for mass production.
Then they decided they could also overdrive the RGB inputs, causing the beam
current to go up in such way the HV supply voltages drop and the beam is
defocused.

A very well regulated HV supply doesn't work well (or too well) in this
case. Maybe this is why the amplifone has it's kind of regulation... to
enable 'blurry' vectors.

> From a manufactures point of view, this made the Amplifone a much nicer
design.
> Wires are much more reliable (and cheaper!) than the highly unreliable low
> voltage regulator design in the WG6100. In the HV section the poor design
of
> the WG6100's HV section was also replaced by a wire (ok a coil, but it's
just a
> long wire wrap around something).
>
> If it wasn't for a manufacturing defect in the Red HV transformer, these
> monitors would most likely have been very reliable.

While the deflection board is essentially the same as that of the WG61xx
range... Maybe the TO3 mounting made all the difference...

> From a collector's point of view the removal of active regulation in the
two
> critical parts of the monitor's design leads to shaky vectors and a screen
that
> blooms when more vectors are drawn (leading to even more shaky vectors).
>
> In an arcade most of the players aren't going to pay much attention to a
little
> shakiness on the display, as long as the game is working, they'll play it.
>
> But when it's in your collection it can bug the hell out of you!
>
> The solutions are to regulate the LV and HV sections yourself. By using a
lab
> supply like you did, you restored regulation in the LV section. Another
> possible solution is to back fit a LV2000 (you'll need to mount a couple
of
> heatsinked power transistors somewhere.)

Well, if it is really normal for the Amplifone to have some shakyness, I'll
just HAVE to do just that...
It looks SOO much better connected to the lab power supply... really
rock-solid!

> For the HV section your most likely best bet now is to use one of the
newly
> designed HV replacements Fred's come up with. Before that it would mean
> retrofitting a WG6100 HV section into a Amplifone, but the WG6100 HV
section
> itself, was not a great design from both an engineering and reliability
> viewpoint. It'd be better to just get the Wintron HV xmfr.

I definitely would..

Does anyone have the WG61xx replacement HV module installed?
It would be interesting to know wether you really loose the defocused enemy
shots and explosions in Star Wars due to the better regulation!

> The Wintron HV will restore the reliability of the Amplifone, but it still
lacks
> decent HV regulation.

... If that ia actually what we want... :)

Mendel

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Received on Tue Mar 9 14:41:07 2004