RE: WG6101 (Tempest) minor stuff

> And that R29 on the audio/reg board bothers me
> and would like
> to know what a burnt one will do. Should I refrain from
> turning it on until I
> fix that up? I assume so.
>
> Thanks for any help or suggestions anyone can make.

Hi Gregory,
Here's the text of Andy Welburn's ARII article. It should address the R29
question (and more!):

This article is semi-techie, don't worry if you don't understand it, you
don't have to be able to :) It gives you an idea as to what games companies
did when re-developing an old idea. Also, my interperetation of how these
things works may not be technically correct, but it fits the situation, i'm
not classicly trained, and therefore do not adhere to such sensible rules :)
I just want to get games going again like you do :)

Ok, so you've got yer new (old) atari video game, and it doesn't work..

Surprise, surprise.. You've done the neccesary steps to determine that
the fault lies in the Regulator/Audio board (AR2 or AR1). How do you
fix it? well.. first off, there is 2 main types of AR1/AR2 boards
that come in classic era atari videogames, called the AR1 and the AR2.
In the 70's in atari's infinite wisdowm, this job was actually done on the
game pcb itself. This meant the logic PCB could get very hot, taking actual
game logic out with it. The complaints were basically that if the regulator
section did go down, it meant the whole game pcb had to be removed and
replaced.. a costly excercise.. Atari split the section off, made the game
pcb logic do just the game logic and the sub-power assembly was located on
its own board, thus was born the Regulator/Audio board (AR1/AR2)... This was
cheaper and quicker to replace for the operator.

Anyhow, Atari started this trend from Lunar Lander onwards.. Lunar Lander,
Asteroids and Asteroids deluxe (atari's first three vector games) and
Football (4 player) all used the AR1. While audio amplification, and some
voltage regulation was done on this seperate AR1 board, there was still a
relatively large amount of power still regulated on the game pcb itself (36v
AC) which still caused some problems occasionally. After Asteroids Deluxe,
they re-designed this AR1 configuration, by simply extending the board,
regulating the 36v AC on there and piping 22v AC to the game pcb instead,
much better.. This configuration was to prove so versatile, atari stuck with
it from 1980 through to about 1984. From there it morphed into the AR3, and
from there came the 'new' switcher.. but that's a story for another day...
lets stick to AR1/AR2.

So anyway, as the time progressed, parts of the AR2 became redundant.
Instead of redesigning the boards, Atari simply omitted the redundant parts
leaving parts of the AR2 bare.

Now, for collectors today that can be a bit annoying. When someone says they
have an AR2 board spare, you often have to try and work out what revision it
is to see if it'll work in your machine :) below is a list of which games
used what revision boards, its not complete, but what i've been able to
ascertain :

A034485-01 - Asteroids, Asteroids Deluxe, Lunar Lander, Football (4 Player)

A035435-01 - Atari board versions of Xevious, Pole Position I + II, DigDug

A035435-02 - Battlezone, Centipede, Crystal Castles, Liberator, Quantum, Red
Baron, Star Wars, Tempest, Warlords, Return Of The Jedi, Arabian, Black
Widow, Major Havoc

A035435-03 - Missile Command, Monte Carlo

A035435-04 - Gravitar, Millipede, Space Duel

A035435-05 - Namco Board versions of Pole Position I + II, Xevious, DigDug

A035435-06 - Kangaroo

Now, you think, why is this important to me?? Well, you might not be able to
find the precise revision for your machine, this is a handy cross-reference.
In all honesty, if in doubt, use a revision -02, if you have one of these,
it will work on ALL of them, and they are the most common :) Golden rule?
The later the revision, the more parts they strip off.. with the exception
of the -01 which is the least populated version, no idea why it got the -01
revision.. When re-thinking the design, certain things were taken into
consideration, cost to produce, pros and cons.. so you find that the -03
board is actually loaded like an -02 baord but without the numerous test
points... pros.. cheaper/quicker to produce, cons... you can't hook
equipment onto the test points.. big deal :) well.. you say that, because
after the -03, they went back to using the -02 as operators didn't like the
idea they lost the test points.. the customer is always right eh?
The -05 and -01 revisions may seem a little odd, its the same game, why two
different board versions?? well, those games listed were actually licenses
that atari bought off of Namco (japan). Atari made up the cabinets and
filled them with either namco boards or their own boards, either to meet
demand quickly when it had a japanese release timed with a european release
or what i don't know :) Anyway, some cabinets had namco boards, and some had
atari boards, the namco boards always had the audio amplified on the game
PCB, like the rest of the industry by this point, but Atari insisted that
their version of the board would require external amplification, et voila,
one revision of the AR2 had the audio amp section on it, the other didn't..

Ok, history lesson over... HOW DO YOU FIX THEM?

Well, a lot of people go for shotgunning the entire board, you can buy
'kits', much like monitor cap kits, which contain all the critical
components on the board. Regardless of the problem on the AR2 you buy a kit
and replace everything accodring to the instructions. This is good in a way
if you don't want to hunt down the problem and fix it manually, besides the
AR2 has a number of large capacitors which like all electrolytic capacitors
can dry out, causing irregularities, or drifted values. The downside? well
its a good afternoons work to do it properly, and you might get away with
only spending £2 fixing it rather than £10. Or you might just like a
challenge :)

My way? ahh, it may be a bit of a bodge if you want to call it that, but it
works for me, and even if you do fit a 'kit' to your board i would
reccommend carrying out this further mod anyway....

First, a little bit of a theory lesson.. what does the AR2 do? well, it
supplies the game PCB with a nice clean set of voltages, +5v -5v +12v +/-22v
and 10.3v unreg. It also amplifies an audio signal from the pcb to drive the
main speakers in the cabinet. Now the +5v supply is the nifty bit, and
really, the most important bit. +5v drives the main game logic. Now, 20 year
old game PCB's don't like to have the +5v jumping about going from roughly
+3.5v to +6.5v, they want a nice steady +5v they can rely on. This is where
an OLD AR2 falls on its face.. Atari thought it'd be cool to make the AR2
intelligent. Bad move. We all know what happens to inteligence as we get
older ;)

Anyway, the best way to think of it is this.. the AR2 pumps out +5v to the
game board, but also has an extra feed coming from the game board to the
AR2. The AR2 then measures what voltage is coming back from the game PCB. If
there is a difference, it cranks up the output a little bit to compensate
for the loss. Loss of voltage is expected in a few metres of wiring running
round a cabinet, and plugs/edge connectors. But what happens 20 years down
the line when you have tired old wiring, and dirty oxidised connections that
you either dont think to clean, or can't clean efficiently? the AR2 isn't
doing anything wrong really, its doing its job, but it assumes that there
shouldn't be more than a 0.1v voltage drop in the wiring in a cabinet. If
the connections are so dirty, or have accidentally been broken or whatever,
the AR2 keeps cranking up the voltage to try and match its output. What can
happen is you can see the voltage going up and down as the AR2 tries to keep
up. if you measure the voltage on a game pcb and see the +5v going up and
down, be scared, this is when components fail.

Solution: fool the AR2 into thinking everything is hunkey dorey...

How? where the lines for the +5v leave the board and where the return
(sense) lines come back in, simply tie them together. By tying them together
at the output, the AR2 will be reading a return voltage of precisely what
voltage its just put out.. simple.. it isn't measuring a loss and therefore
wont try to compensate. The easiest way to do this is to locate J7, this is
the connector responsible for the +5v output and return. Turn the AR2 over
onto its back and solder onto the reverse where the pins for the connector
are in place. see diagram 1 for instructions on where to put in the links.
Use something like fuse wire or a component lead to solder over them,
something pretty thick, it can carry a bit of current, so make it thick on
the safe side.. The idea is to tie pin 1 to 2 and pin 3 to 6 remember to
translate the diagram in reverse when you flip the AR2 over :) the top side
of the AR2 board should be labelled which pin is which.

The only other thing i usually do is replace the 2N3055 power transistor
that sits right in the middle of the massive heatsink, they are the main
powerhouse for the +5v it appears, so you want that to be nice and reliable.
They are really easy to find, general purpose kinda component, they still
make them today so usually about £1.50 that will cost ya. Remember to make
sure when fitting a new one in that the case doesn't touch the metal
heatsink, there is a little rubber insulating mat inbetween the transistor
and the heatsink.. it is there for good reason, it is a heat conductive
layer that electrically insulates at the same time. Just make sure it goes
back on properly :)

Bingo.. that's all i usually do, and that has kept my 4 machines which use
an AR2 happy :)

common faults? well if burnout has occured in the past, its often apparent
that R29 and R30 go nuclear, often bursting into smoke and cratering the
board. if you can botch a repair in, replace them and carry out the steps
above and you shouldn't have any more problems.. some people say that R30
should be swapped with a higher wattage resistor, i've personally not done
that as its better for that resistor to smoke than the little regulator (Q1)
which is virtually unobtainable.

Once you've suitabley rectified the AR2, all that remains is to install it
in your game and power her up.. Of course, now is the time to go round and
clean/replace those edge connectors, and check for shorts or broken wires. I
know its tedious to clean/inspect everything, but hey, you want your game to
last yeah? do it then :) once installed in the machine and powered on, put
your voltmeter on the GND and +5v test points ON THE GAME PCB and read off
what the board is getting on the +5v line. Adjust R8 on the AR2 to get a
nice +5.00v - +5.10v reaching the game board and you're all set :)

If you neglected to clean the edge conectors and you close the back door
disturbing the wiring, you could now have knocked that nicely measured +5v
to something else... go clean them connectors :) If you hadn't carried out
the afformentioned mod, now is the time the AR2 would probably be squeeling
and spitting smoke. If you appear concerned by how hot the 2n3055 gets after
such a short time of being turned on, don't be, look at the size of the
heatsink its bolted to :)

ok, just briefly things to look at if you have certain symptoms :

*lack of -5v - check Q9 (7905) bolted to heatsink
*lack of +12v - check Q8 (7812) bolted to heatsink
*lack of audio, or distorted audio in speaker 1 - check Q5 (TDA2002)
*lack of audio, or distorted audio in speaker 2 - check Q7 (TDA2002)

enjoy
---------------------------------------------------------------------------
** To UNSUBSCRIBE from vectorlist, send a message with "UNSUBSCRIBE" in the
** message body to vectorlist-request@synthcom.com. Please direct other
** questions, comments, or problems to neil@synthcom.com.
Received on Mon Apr 22 07:34:55 2002