Atari Vector Monitor Repair/Upgrade
Contents:
One word of caution about replacing the HV transistor (note that I said
"transistor", NOT "transformer"; we are shifting gears); double check
the part that you receive BEFORE you install it. Why? Here is a
transcription of a note I found tucked in a Star Wars manual which also
mentions how to tell if your HV transformer is (probably) bad, where to
mount a fan to lengthen its life, and a possible way to tell if your
tube is bad. I have no idea where it came from:
====================START====================
Atari STAR WARS HIGH-VOLTAGE BOARD
by Avery Petty
A.P. Engineering
Huntington Beach, CA
Recently, I repaired a whole fleet of Atari STAR WARS. I sent someone
to the distributor to get the 'hard-to-find' high voltage transistor
BU406D [NOTE: The transistor he is talking about Q3 labeled as "NPN
7-Amp. 400V Power Transistor" in the manual's parts list.]. He came
back with a BU406, no "D". The "D" must appear on the transistor. It
means there is a high voltage diode in the package. So beware, even the
distributor can goof!
What will it cost you? Your game maybe. Without the diode, using the
BU406, the high voltage will work for awhile [sic], but will burn up the
flyback transformer which cost [sic] $90.00 [NOTE: It's much
more than that now]!
If you are repairing a High Voltage board, and after replacing all the
capacitors, the two 24 volt regulators, and related parts and the high
voltage transistor with a BU406D, and you still don't have high voltage,
and don't know why, you can be sure it's your flyback transformer. If
in doubt, pull it out and put it in a working STAR WARS and see, it will
only take 5 minutes [NOTE: this is a severe under-estimate; I'd say it
is at least a 15 minute job not including swapping them back if that
needs to be done, but then again he is a professional and I am just a
hack :>].
When you finally fix it, put a fan under the board -mounted [sic] on the
wood rail the board is mounted on, blowing on the High Voltage board.
This is something that should be done to all STAR WARS, because the
flyback is the most expensive part there [NOTE: advice to be heeded for
all Atari color vector games].
If your high voltage won't get up to at least 19,000 volts, you may have
a bad tube. Look for real [sic] bad phosphor burn or a color missing.
====================STOP=====================
Here is some text from the Major Havoc conversion kit installation
instructions (TM-268). It describes the Atari sanctioned upgrade and
includes instructions for converting the Amplifone Deflection Board PCB
to the "official" upgrade. Thanks to Tony Jones (ant@palm.cray.com) for sending this to me.
====================START====================
[NOTE: Atari did copyright these
documents and they are clearly marked with a copyright symbol.]
Major Havoc Installation Instructions TM-268
I. MODIFY THE AMPLIFONE DEFLECTION PCB
NOTE: The following procedure applies to those Space Duel,
Gravitar, and Black Widow games that used an Amplifone display. If your
game has a Wells-Gardner display, perform "H. Modify the Wells-Gardner
Deflection PCB" [found later in this document].
Perform the following procedure to modify the Amplifone Deflection PCB
(see Figure 8).
- Set the Deflection PCB on a clean work surface.
- Connect two type-1N754A Zener diodes together, anode to anode,
as shown in Figure 6 [found later in this document]. Use a
soldering iron to solder the two anode leads together.
- Connect two type-1N756A Zener diodes together and solder as
described in step 2.
- On the component side of the Deflection PCB, locate the yellow
wire connected to resistor R1 (left center of the PCB).
- Solder one cathode lead of the two type-1N754A Zener diodes
(soldered together in step 2) to the yellow wire on the soldered
side of the Deflection PCB as shown in Figure 8.
- Solder the other cathode lead of the two type-1N754A Zener diodes
to the nearest ground on the PCB as shown in Figure 8.
- On the component side of the Deflection PCB, locate the orange
wire connected to Resistor R24 (right center of the PCB).
[Figure 8, entitled "Modifying the Amplifone Deflection PCB", showing a
full scale picture of the solder side of the Deflection PCB, has been
omitted for obvious reasons. It does not show anything that cannot be
derived from the included text; it was merely a "visual aid".]
- Solder one cathode lead of the two type-1N756A Zener diodes
(soldered together in step 3) to the orange wire on the soldered
side of the PCB as shown in Figure 8.
- Solder the other cathode lead of the two type-1N756A Zener
diodes to the nearest ground on the PCB as shown in Figure 8.
- On the soldered side of the Deflection PCB, solder the cathode
lead of a type-1N4002 diode to the emitter of transistor Q17 as
shown in Figure 8.
- Scrape away the green protective coating at a convenient point on
the PCB, and solder the anode lead of the type-1N4002 diode to
the collector of transistor Q17 as shown in Figure 8.
- On the soldered side of the Deflection PCB, solder the anode lead
of a type-1N4002 diode to the emitter of transistor Q16 as shown
in Figure 8. [NOTE: This is the opposite of what you did in
step 10.]
- Scrape away the green protective coating at a convenient point on
the PCB, and solder the cathode lead of the type-1N4002 diode to
the collector of transistor Q16 as shown in Figure 8.
- On the soldered side of the Deflection PCB, solder the cathode
lead of a type-1N4002 diode to the emitter of transistor Q7 as
shown in Figure 8. [NOTE: This is the opposite of what you did
in step 12.]
- Scrape away the green protective coating at a convenient point on
the PCB, and solder the anode lead of the type-1N4002 diode to
the collector of transistor Q7 as shown in Figure 8.
- On the soldered side of the Deflection PCB, solder the anode lead
of a type-1N4002 diode to the emitter of transistor Q6 as shown
in Figure 8. [NOTE: This is the opposite of what you did in
step 14.]
- Scrape away the green protective coating at a convenient point on
the PCB, and solder the cathode lead of the type-1N4002 diode to
the collector of transistor Q6 as shown in Figure 8.
====================STOP=====================
Here is an Atari Field Service bulletin courtesy of Al Kossow
(aek@haxrus.apple.com)
which describes modifications to the Amplifone
monitor to make it more robust. All the diagnostic/repair stuff is new
and compatible but the rest seems to be similar to part of the previous
Major Havoc documentation upgrade but they do differ in some respects.
I would advise that you only implement 1 of them unless you are sure
they are compatible (I am not). If anybody knows if any are compatible
(or not), let me know. For now, I am listing them as
mutually-exclusive; mix at your own risk. I'd take the time and hassle
to do the first one even though it is a lot more work.
====================START====================
[NOTE: To my knowledge, Atari never
bothered to copyright these field service bulletins and they are not
marked with a copyright symbol.]
TECH TIP from the Atari FIELD SERVICE DEPARTMENT
Atari Color X-Y Display Deflection PCB
You should do the following modifications to help prevent the Deflection
PCB from failing. THIS MODIFICATION SHOULD ONLY BE PERFORMED BY A
QUALIFIED TECHNICIAN.
Parts List
Quantity Description Part No.
----------------------------------------------------
6 Type-1N4002 Diode 31-1N4002
2 Type-1N754A 6.8V Zener Diode 131002-001
2 Type-1N756A 8.2V Zener Diode 32-1N756A
2 12 Ohm 5% 1/4 W resistor 110000-120
- Connect the two 1N754A Zener diodes together as shown in Figure 1.
The connection is made as follows: bend the anode ends of
both diodes into a "fish-hook" pattern. Hook the two fish-hooked
leads together, and solder them. Remember that too much heat
will destroy the semiconductor material.
- Connect the two 1N756A Zener diodes together as shown in Figure 1.
Use the same technique as described in Step 1 above.
- Remove diode CR2 and solder in a type-1N4002 diode in its place.
[NOTE: On older monitors, CR2 is labeled D602.]
- Remove diode CR11 and solder in a type-1N4002 diode in its place.
[NOTE: On older monitors, CR11 is labeled D702.]
- Remove resistor R12 and solder in a 12 Ohm, 1/4W resistor in its
place. [NOTE: On older monitors, R12 is labeled R609.]
- Remove resistor R35 and solder in a 12 Ohm, 1/4W resistor in its
place. [NOTE: On older monitors, R35 is labeled R709.]
- Find the Y-Deflection Circuit (upper left area of the schematic).
Resistor R1 has two leads to it. Find the lead that goes to the
yellow wire. Connect this lead to the cathode of one of the
type-1N754A diodes. Connect the cathode of the other type-1N754A diode to ground.
- Find resistor R24. It has two leads: one runs to an orange
wire. Connect this lead to the cathode of one of the type-1N756A
diodes. Connect the cathode of the other type-1N756A diode to ground.
- Find the type-2N3792 transistor Q17. You will be installing a
type-1N4002 diode across the transistor's emitter and collector.
Solder the cathode lead of the type-1N4002 diode to the emitter,
and solder the anode to the collector of this transistor.
- Find the type-2N3617 transistor designated Q16. You will be
installing a type-1N4002 diode across the transistor's emitter
and collector. Solder the cathode lead of the type-1N4002 diode
to the collector, and solder the anode to the emitter of this
transistor. [NOTE: this is the opposite of what you did in Step 9.]
- Find the type-2N3792 transistor Q7. You will be installing a
type-1N4002 diode across the transistor's emitter and collector.
Solder the cathode lead of the type-1N4002 diode to the emitter,
and solder the anode to the collector of this transistor.
- Find the type-2N3716 transistor Q6. You will be installing a
type-1N4002 diode across this transistor's emitter and collector.
Solder the cathode lead of the type-1N4002 diode to the collector
and solder the anode to the emitter of this transistor. [NOTE:
this is the opposite of what you did in Step 11.]
FIGURE 1 Making Fish-Hook Connections
CATHODE +-+------+ +------+-+ CATHODE
--------+ |1N75#A+--------+1N75#A| +-------- Diode Connection
+-+------+ ANODES +------+-+
[NOTE: You get the idea; snub diodes across the deflection amps, back to back
Zeners on the input to ground. Since I made these modifications, I
haven't had a deflection amp go out (but I'm running the game with the
back off now, too.)]
...
PROBLEM: Some games may have shaky video after a 15-minute warm-up.
The video will start to shake in the high-score screen. The words
PRINCESS LEIA'S REBEL FORCE will start to flutter and then worsen to an
up-and-down movement of about 1/8 inch. In its worst state, the scores
will also move back and forth.
SOLUTION: Change the 10K Ohm resistor R83 on the Vector-Generator
PCB to a 20K Ohm resistor.
STAR WARS Color X-Y Display [Amplifone ONLY; not Wells-Gardner models!]
PROBLEM: The BROWN zero-ohm jumpers (W1 or W2) on the Deflection
PCB open up on the High-Voltage PCB. Zero-ohm resistors look like
regular resistors, but are marked on the PCB assembly and the schematic
with a W followed by a number.
SOLUTION: Replace the jumpers with pieces of wire. NOTE that the
/white/ and /tan/ jumpers are good and don't have to be replaced.
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