Re: Asteroids display problem

At 22:57 15/06/2002 -0500, you wrote:
>I guess it's time to start rooting out an inexpensive replacement. Wish
>me luck.

No-one has yet mentioned the alternative to the AD561J - the AM3012 (or
modern day equivalent, the DAC312HP). Much cheaper than the AD561J and
readily available.

However, it's not exactly a drop in replacement - there is provision for it
on the board (look at the the existing AD561J DACs and you'll see two
unoccupied pads). You'll need to therefore add a suitable socket (or solder
the DAC directly to the board if you wish) BUT you'll also need to add the
support components, ie caps and resistors. It WON'T work unless these are
added. I know, I've tried.

This is a lot easier on rev 5 boards and later (as mentioned, I've done it
and it works just fine) but on earlier boards (such as rev 2) the locations
of the AM3012 support components aren't marked on the board, plus there is
one resistor pad missing (easy enough to attach the resistor though).

The Asteroids Deluxe schematics will provide you with the relevant cap and
resistor values, but as I've done the mod myself I decided to note them
down, as follows:

Asteroids Rev 05 board:

AM3012/DAC312 at D12:

R148 = 10K +/- 5% 1/4W Resistor
R149 = 10K +/- 5% 1/4W Resistor
R150 = 4.7K +/- 5% 1/4W Resistor
R151 = 10K +/- 5% 1/4W Resistor
R152 = 8.2K +/- 5% 1/4W Resistor
C124 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C125 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C126 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C127 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C128 = .1uf Ceramic Disc 25v Radial Lead Capacitor

AM3012/DAC312 at B12:

R153 = 10K +/- 5% 1/4W Resistor
R154 = 10K +/- 5% 1/4W Resistor
R155 = 4.7K +/- 5% 1/4W Resistor
R156 = 10K +/- 5% 1/4W Resistor
R157 = 8.2K +/- 5% 1/4W Resistor
R158 = 2.2K +/- 5% 1/4W Resistor
C129 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C130 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C131 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C132 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C133 = .1uf Ceramic Disc 25v Radial Lead Capacitor

Early revisions of Asteroids boards (for example, Rev 2) that have no
location markings for these extra components yet that do have the
ready-made yet
solder filled holes:

Same as for Rev 05, BUT the location R158 is missing from the board - to
fit R158,
attach one lead to the left hole of R157 and the other lead to the metal
ground that
is so prevalent in this area

Asteroids Deluxe Rev 01 board:

AM3012/DAC312 at C/D11:

R81 = 10K +/- 5% 1/4W Resistor
R82 = 10K +/- 5% 1/4W Resistor
R89 = 4.7K +/- 5% 1/4W Resistor
R90 = 10K +/- 5% 1/4W Resistor
R119 = 8.2K +/- 5% 1/4W Resistor
C52 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C53 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C80 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C90 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C91 = .1uf Ceramic Disc 25v Radial Lead Capacitor

AM3012/DAC312 at A/B11:

R83 = 10K +/- 5% 1/4W Resistor
R84 = 10K +/- 5% 1/4W Resistor
R91 = 4.7K +/- 5% 1/4W Resistor
R92 = 10K +/- 5% 1/4W Resistor
R124 = 8.2K +/- 5% 1/4W Resistor
R125 = 2.2K +/- 5% 1/4W Resistor
C54 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C56 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C82 = .1uf Ceramic Disc 25V Radial Lead Capacitor
C90 = .1uf Ceramic Disc 25v Radial Lead Capacitor
C97 = .1uf Ceramic Disc 25v Radial Lead Capacitor

Hope that helps someone,
Phil

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Received on Sun Jun 16 02:40:16 2002