Atari Vector Monitor Repair/Upgrade

Contents:


Chapter 7) Atari Star Wars High-Voltage Board (transistor!)

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:

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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.

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Chapter 8) Major Havoc Installation Instructions TM-268

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.

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[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).

  1. Set the Deflection PCB on a clean work surface.
  2. 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.
  3. Connect two type-1N756A Zener diodes together and solder as described in step 2.
  4. On the component side of the Deflection PCB, locate the yellow wire connected to resistor R1 (left center of the PCB).
  5. 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.
  6. Solder the other cathode lead of the two type-1N754A Zener diodes to the nearest ground on the PCB as shown in Figure 8.
  7. 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".]
  8. 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.
  9. Solder the other cathode lead of the two type-1N756A Zener diodes to the nearest ground on the PCB as shown in Figure 8.
  10. 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.
  11. 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.
  12. 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.]
  13. 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.
  14. 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.]
  15. 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.
  16. 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.]
  17. 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.

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Chapter 9) Atari Field Service bulletin

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.

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[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

  1. 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.
  2. Connect the two 1N756A Zener diodes together as shown in Figure 1. Use the same technique as described in Step 1 above.
  3. Remove diode CR2 and solder in a type-1N4002 diode in its place. [NOTE: On older monitors, CR2 is labeled D602.]
  4. Remove diode CR11 and solder in a type-1N4002 diode in its place. [NOTE: On older monitors, CR11 is labeled D702.]
  5. Remove resistor R12 and solder in a 12 Ohm, 1/4W resistor in its place. [NOTE: On older monitors, R12 is labeled R609.]
  6. Remove resistor R35 and solder in a 12 Ohm, 1/4W resistor in its place. [NOTE: On older monitors, R35 is labeled R709.]
  7. 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.
  8. 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.
  9. 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.
  10. 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.]
  11. 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.
  12. 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.)]

...


9.1) STAR WARS Vector-Generator PCB


9.1.1) Shaky Video

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.


9.1.2) Zero-Ohm Resistor Jumpers

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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