Troubleshooting your Tempest Machine, by Gregg Woodcock This article is Copyright worldwide 1991, 1995; all rights reserved. This is a file I have put together which should get you started on repairing your non-working Atari Tempest game. It lists all the problems I have seen and lots of information from the various manuals. Monitor failures are much more common than game board failures (in fact, I find the game boards to be fairly robust) and that topic is so lengthy that it is covered in another file. The last portion of this document includes the self-test instructions and DIP switch settings from the manuals so you might want to start there. Let me start out by stating that arcade games in general tend to have a lot of problems with safety interlock switches which shift position or deteriorate so that they no longer close all the way (to be fair to the interlocks, sometimes it is the cabinet that warps pulling the engaging panels away from the interlocks). If you get no power at all and have checked the fuses, make sure you check the safety interlocks to make sure they are all engaged and conducting. Also check for breaks in the wall cord as these get a lot of yanking and abuse. Replace the plug if the earth ground pin is broken off. Another good idea when you are making repairs is to install high-quality sockets when you replace any IC. If it went bad once, it is likely to go bad again and you can save time, effort and heat stress to the PCB by performing a solderless replacement the next time it goes bad. If you have a Tempest game board that doesn't seem to be working, check to make sure the game isn't paused! I have seen several boards come my way that were "broken" but merely had the pause switches set. The game instantly "locks up" and you never get a picture or any response to inputs and the spot killer lights; all symptoms of game board failure which fools many people. Before you assume you have a game board failure, be sure that switches 1, 2, 7 and 8 on the 8-toggle DIP swtich bank at location N13 are NOT set to Off, Off, Off and On, respectively; this combination is marked "Demonstration Freeze Mode" in the documentation and pauses the game. As far as I know, no other Atari game of any era has a pause switch in it but I wish they all did; it is very handy for those marathon sessions when nature calls! The first thing to check when you have a known good monitor and a game PCB that does not produce video is the adjustment potentiometers. I recently spent a whole weekend verifying the vector generator circuitry on a Tempest PCB only to find a hairline separation of the leftmost pin (when looking at the side of the pot with the dial) of R168 (Y SIZ). When this pin is floating, the spot killer kicks in and there is no video at all! When being improperly stored or transported, these components take a lot of abuse and are bent back and forth. Too much of this and the legs simply break (usually only 1 at a time so it isn't all that obvious). Occasionally these cheap pots will simply go bad and fail to work (yielding a permanent 0 or infinite resistance) so you might check their resistance range with a multi-meter even if all the pins are OK. Simply replacing that 1 pot fixed my board. When replacing these pots, I lay them flat against (parallel with) the PCB to lower their profiles so that they stick out less. This problem can happen on any Atari vector game; black-and-white or color. The other common cause for a board with no video is a failure of the AM6012 digital-to-analog converters that feed the X and Y sections of the vector generator circuitry (1 chip for each signal). If your game has scraggly vectors that start out OK but get messed up as the game warms up or if your vectors are totally trashed (particularly if it is only in 1 dimension), you are probably observing the effects of a bad DAC. Of course if you let the symptoms continue, the DACs will fail altogether and you will have no video at all (since the spot killer will kick in). The best way to check these is by using cold spray to stabilize the DAC. If you spray the chip and the game clears up then you know that chip is failing (this works for any IC). Otherwise you could remove the old DAC and replace them with a known good DAC from another board (installing sockets in the process). Similar video symptoms can occur as a result of less frequently failing parts such as the LF13201 analog switches and the TLO84 op amps. All Atari games of the early era were subject to bad solder joints and this should always be the first place you start checking when you have problems. I know for a fact that most of the monitor failures in the field are not due to overheating (at least not directly) but due to lockups in the game board which cause the monitor to saturate and overheat its semiconductors. There are 2 boards that comprise the Tempest board set. The larger of them is about 2 feet long by 1 foot wide and is known as the "vector generator PCB". It contains all the game ROMs, among other things. The other smaller board is about 1 foot square and is known as the "math box". The most common cause of lockups and resets is bad solder joints on the interbaord connector that lets these boards communicate with each other. Whenever I get a new board set, I resolder these whether they look like they need it or not. The next most common cause is bad circuit board edge connectors on the wiring harness. If they are marginal at all, do yourself a favor and replace them! They can be cleaned fairly well by spraying them with "tuner cleaner" (available at Radio Shack) and then reseating the connector a few dozen times but this is only a temporary solution because the real problem isn't so much dirt as poor tension due to age and heat stress (and poor initial quality). Similar problems are common with the fuse holders in the power supply, particularly F2. F2 is rated at 20 amps and ultimately feeds the +5 supply. It can get overheated and loose spring tension and this will cause resets. This can usually be fixed by cleaning and bending the clips tighter which avoids having to replace the holders. Two of the socketed 40-pin chips on the math box (locations B/C2 and C/D2) are called "Audio I/O N-Channel MOS/LSI Custom Chips" by the manual but at least the schematics refer to them by their "real" name which is "POKEY". The most frequent thing to go bad on the Atari math boxes besides the ROMs are these POKEY chips. The POKEY was designed by the Atari home computer division for the Atari 400 computer. It stands for POt KEYboard controller and it has a sound generator, random number generator, input buffering, and much more all on one chip. The symptoms of a bad POKEY are that control input or sound output is not normal or missing altogether. The POKEY in Tempest at B/C2 controls the spinner inputs so if your spinner is flakey and the opto-electronics check out (they frequently fail), this is probably your culprit. The self test should be able to confirm the diagnoses. If you see a "P" or "Q" in the middle of the screen then one of the POKEYs is bad (see chart below). I like to order POKEYs from American Techna-Vision since you get an entire 40 PIN chipset intended for machines in the Atari 8-bit computer line. Besides the POKEY, you get a GTIA, ANTIC, and PIA. Order catalog number AK675, "40 Pin Large Scale Integrated Circuit Chip Set". On top of that they have the cheapest shipping, no minimum order (that I am aware of) and accept credit cards. You can also scavenge POKEYs from inside of many Atari 7800 cartridges, most notably Ball Blazer although they are also used in Commando and Summer Games and I suspect that Dig Dug, Dark Chambers and Jinks also have one. The POKEYs are the chips that have the Atari part number "C012294B-01" on them. B & C ComputerVisions 5917 Stope Wway El Dorado, Ca. 95623 (530) 295-9270 FAX 9271 E-mail myatari2@myatari.com Web site: www.myatari.com atari pokey our part# ICA294 $5.each shipping 1 to 100 $8.00 Best Electronics 408.243.6950 (Atari POKEYs $5+$? S/H+$4.75 COD; $12 min) American Techna-Vision 510.352.3787 (Atari POKEYs $5; #AK675) The other 4 socketed 40-pin chips on the math box (at locations E2, F/H2, J2 and K/L2 on Tempest) are called "transistor array"s by the manual and the chips themselves carry only the Atari part number 137004-001 on them in an attempt to hide their true identity (to keep people from making illegal copies of the game?) They are really 2901 bit-slice ALUs, which were very popular and are fairly commonly available. They were made by AMD and a number of other vendors. In a technical sense the part really is a transistor array, but calling it that serves no purpose other than obfuscation. These go bad every now and then and will generate an "M" on the self-test screen. NOTE: the "M" is a generic "M"ath box failure indicator and does not necessarily indicate that an ALU is bad; lots of failures cause the "M" indicator to appear but one of the most frequent causes is bad ALUs. The cheapest place I have found for these is: B.G. Micro, Inc 800.276.2206 (2901 AMD brand ALUs $0.55 each) From page 6 of TM-190, 2nd printing, "Tempest Operation, Maintenance and Service Manual" D. SELF-TEST PROCEDURE This game will test itself and provide data to demonstrate that the game's circuitry and controls are operating properly. The data is provided on the monitor and the game speaker; no additional equipment is necessary. Part 1 of the self-test procedure includes a display of the operator-selectable game options, and game time and high score table information. Part 2 includes ROM and RAM, control panel and monitor information. We suggest you run the self-test procedure any time you collect money from the game or any time you change the game's options. Refer to Figure 5 for location of the self-test switch and option switches. To run the self-test, follow the instructions outlined in Figure 6. Figure 5: Location of Self Test Switch, Volume Control and Option Switches. [NOTE: I will not attempt to draw the pictures but will describe in detail what they show. One shows the bottom of the front of the machine with the coin door wide open. An arrow points to a rectangular assembly which juts out into the from the *inside* of the cabinet located about 1/3 the way down the left side of the opening. There is a blow-up of this area which shows that this rectangle consists of a volume control potentiometer which increases as you rotate clockwise and also shows a slide toggle self-test switch for European games. US games have the self-test switch in the standard location for most of Atari's early games. Look in the very upper-right corner (towards the hinge) of the interior of the coin door and you will find a switch with a long stem. The last picture shows the location of the game PCBs which are in the middle of the back of the machine mounted on the right (looking from the back) side panel. There are 3 DIP switch packs on the big game board ("vector generator PCB") and 1 on the small one ("math box"). DIP switch packs are located at K10/11 (4 switches), L12 (8 switches), and N13 (8 switches). Together these 3 packs are labeled "Options Switches".] SELF-TEST PROCEDURE PART 1 The information below is displayed on the screen if you set the self-test switch to on during the attract mode [i.e. after the game has been turned on]. Look at the displayed numbers for SECONDS ON and SECONDS PLAYED. If these numbers run together vertically, make adjustments to the X and Y outputs of the game PCB [particularly the BIP controls]. To go to the Self-test Part 2, rotate the control knob until the message PRESS FIRE AND SUPERZAPPER FOR SELF-TEST appears on the monitor. Then press both FIRE and SUPERZAPPER. To end the operator information display, set self-test switch to off. +------------------------------------------+ TIME GAME | /--- PLAYED (Seconds) TIME GAME ON | PRESS FIRE AND ZAP FOR SELF TEST / | (Seconds) ----------\ / | NO. OF 1- | \----> 1158 SECONDS ON / /--- PLAYER GAMES SWITCH | 0 SECONDS PLAYED <---/ / | TOGGLE 1 ------------\ 0 1 PLAYER GAMES <-----/ | NO. OF 2- | \ 0 2 PLAYER GAMES <----------- PLAYER GAMES COIN MECH | \ 0 SECONDS AVERAGE <---\ | MULTIPLIER ----------\ \----+ +-----\ \----- AVERAGE | \----->|X11 | \ | GAME TIME ALL 8: | |BONUS ADDER 0|<---\ \ | SWITCH AT N13 | v v \ \ | SWITCH (Coin Modes) --------------> 0 0 0 0 0 0 0 0 \ \------ TOGGLE 8 | \ | SWITCH AT L12 -------------> 0 0 0 0 0 0 0 0 \------- BONUS ADDER (Game Play) | | | 0 0 0 0 0 0 0 0 <-------------- LAST 4: | | SWITCH AT D/E2 LIVES | _ _ _ | (Game Difficulty) PER GAME -----------------> < > < > < > MEDIUM <--------- GAME DIFFICULTY | | | | | | | | | (c) MCMLXXX ATARI | NO. OF | BONUS EVERY 20000 | CREDITS ------------> CREDITS 1 1 COIN 1 PLAY <-------- COIN MODE | | +------------------------------------------+ OPERATOR INFORMATION DISPLAY To erase High Score Table: 1. Turn control knob until top line reads PRESS FIRE AND START 2 TO ZERO HIGH SCORES. 2. Press both FIRE and START 2. 3. The word ERASING appears and blinks on the screen until the entire table is erased. WAIT UNTIL THE WORD ERASING DISAPPEARS before continuing with other tests. To erase Game Times: 1. Turn control knob until top line reads PRESS FIRE AND START 1 TO ZERO TIMES. 2. Press both FIRE and START 1. 3. The word ERASING appears and blinks on the screen until the entire table is erased. WAIT UNTIL THE WORD ERASING DISAPPEARS before continuing with other tests. SELF-TEST PROCEDURE PART 2 Instruction 1: Set self-test switch to ON (see figure 5). Press RESET on the PCB, or turn power off and on again. Test 1 Passes: After about 5 seconds, the monitor displays the picture below. No sounds are produced +------------------------------------------+ | +--- | ENTIRE WHITE ROM AT R1 | | | | FRAME VISIBLE IS BAD ----------> +--- |<- AND WITHIN 1/2 | | | | INCH OF | +--- | MONITOR EDGE. | \ / | | \ / | | X | | / \ | AUDIO 1 IS BAD | / \ +--- | (Pokey at B/C2 | | | | on Math Box) ----------------> |--- | | | | TOGGLE TOGGLE ----------------------+ | +---------------- SWITCH 8 SWITCH 1 |_____________|_____________|______________| | v v | SWITCH AT L12 SWITCH AT N13 -------------> 0 0 0 0 0 0 0 0 /------- (Game Play) (Coin Modes) | / | | 0 0 0 0 0 0 0 0 <----/ /------ SWITCH AT D/E2 START 1 ---------------\ / | (Game Difficulty) | \ 0 0 0 0 0 0 0 0 <-----/ | START 2 --------------\ \-----\ /-------------------- SUPER ZAP | \------\ \ / _ | FIRE ----------------\ 0 0 0 0 0 0 0 0 /_\ <---- CONTROL KNOB | \-----------/ | | | SLAM SWITCH --------\ 0 0 0 0 0 0 0 0 <-------------- RIGHT COIN | \--------------/ / \ | LEFT COIN ---------------------------/ \---------------- CENTER COIN +------------------------------------------+ TEST 1 FAILS: RAM FAILURE is indicated by a sequence of 1 to 12 tones and an R displayed in top half of screen. You will hear a short low tone and see a short flash on the LED start pushbutton for each good RAM chip, and a long high tone accompanied by a long pulse on the start pushbutton for a failing RAM chip. The test stops with the first failing RAM. To restart the sequence, press RESET on the PCB, or power game to OFF then to ON again. Identify the bad RAM chip with the table below. Example: four short low tones followed by a long high tone indicates failure of RAM at location M3. LONG HIGH TONE BAD RAM CHIP LOCATION ON ANALOG VECTOR-GENERATOR PCB ================ ====================================================== 1st R2 2nd P2 3rd R4 4th P4 5th M3 6th M4 7th L3 8th L4 9th K3 10th K4 11th J3 12th J4 ROM FAILURE is indicated by a vertical pair of hexadecimal numbers on the top of the screen. The top number indicates the location of the failing ROM(s). Ignore the bottom hexadecimal number in the pair. Identify the bad ROM with the table immediately below. DISPLAYED NO. BAD ROM CHIP LOCATION ON ANALOG VECTOR-GENERATOR PCB =============== ====================================================== B R1 A P1 9 N/M1 8 L/M1 7 K1 6 J1 5 H1 4 F1 3 E1 2 D1 1 R3 0 N/P3 * EAROM, AUDIO AND MATH BOX FAILURE are indicated by a single letter in the center of the display. Identify the failure with the table below. DISPLAYED LETTER FAILURE PCB LOCATION ================== ============ ================== E EAROM C3 (Aux. PCB) P AUDIO 1 B/C2 (Aux. PCB) Q AUDIO 2 C/D2 (Aux. PCB) R RAM See RAM test above M MATH BOX ** * If this ROM is bad, you will hear a continuous low tone, and the program may be unable to display a screen. ** Math-box failure is explained in TM-195, Tempest Troubleshooting Guide. Instruction 2: Activate start, fire, Superzap, SLAM, and coin switches (activate coin switches by inserting at least one coin in each coin slot. You will not trip the coin counters as long as you are in self-test). Test 2 passes: As switch activates, you'll hear a beep and 0 changes to 1 on the screen. TEST 2 FAILS: You will not hear a beep and 0 will remain on the screen for the defective switch. Instruction 3: Rotate encoder wheel clockwise and counterclockwise. Test 3 passes: The right hexadecimal number on the screen will increase with counter clockwise motion, and decrease with clockwise motion. [NOTE: If your board has EPROM 136002-117 at location J1 instead of 136002-217, you will see a straight line that behaves like the second-hand of a watch rotating around one end in the same direction that you spin the control knob instead of seeing the hexadecimal numbers 0-F.] The -217 EPROM removes the high score backdoors.] TEST 3 FAILS: Incorrect [opposite] progression of numbers indicates encoder wheel harness wires were connected incorrectly. No number change indicates encoder wheel [optos] is bad or harness wires are loose [or POKEY is bad]. Instruction 4: Observe the white frame around the outside of the screen. Test 4 passes: Each frame corner should be within 1/2-inch of each monitor bezel corner. TEST 4 FAILS: See Tempest Drawing Package [or my other file on how to repair the monitor] to adjust video pots. Instruction 5: Activate SLAM [tilt] switch. Test 5 passes: A white cross hatch pattern appears. A character set appears at the bottom of the screen. TEST 5 FAILS: If display is not centered and symmetrical on the monitor, adjust video pots (see Tempest Drawing Package [or my other file on how to repair the monitor]) on the main PCB. If character set is incorrect, check Vector ROMs (see Troubleshooting Guide). Instruction 6: Activate SLAM [tilt] switch. Test 6 passes: Horizontal and Vertical lines cross in the center of the screen displaying a large "plus" sign. Audio I/O 1 and 2 alternate to produce 4 tones. TEST 6 FAILS: Lines not crossing indicates [BIP] video pot[s] on main PCB needs adjusting (see Drawing Package [or my other file on how to repair the monitor]). No sound indicates failure of an audio amplifier and/or the custom audio chip(s). Instruction 7: Activate SLAM [tilt] switch. Test 7 passes: Tests purple, cyan, yellow, white, green, blue, and red for color and intensity. Displays seven groups of vertical lines, each with right line the brightest and left line the dimmest. TEST 7 FAILS: Use this pattern for tracking adjustments (see the Color X-Y Monitor Manual [or my other file on how to repair the monitor]). Instruction 8: Activate SLAM [tilt] switch. Test 8 passes: A checkerboard pattern touches the sides and corners of the monitor. Rotate the control knob to change color. TEST 8 FAILS: Use this pattern for purity and convergence adjustments (see Color X-Y Monitor Manual [or my other file on how to repair the monitor]). Instruction 9: Activate SLAM [tilt] switch. Test 9 passes: A white frame is displayed on the screen. TEST 9 FAILS: Perform math-box signature analysis (see Troubleshooting Guide). Instruction 10: When satisfied with test, set self-test switch to OFF position. E. OPTION SWITCH SETTINGS 1. Bonus Play Feature Tempest (TM) offers a bonus play for certain combinations of coins inserted. This bonus feature is operator-selectable, meaning you may choose to offer it or not. With your game set at 25 cents per play, players who deposit four successive quarters or a $1.00 coin, then press the start button, can receive a bonus play. Therefore, players can receive 5 plays for $1.00. This bonus feature encourages players to insert more money than just the minimum 25 cents required for one game. Various other bonuses are also available (see Figure 8). From TM-190; 2nd printing: FIGURE 7 GAME OPTION SETTINGS To change toggle positions on the switch assemblies, you need not remove the game PCB. The switches are accessible when the Tempest (TM) Analog Vector-Generator PCB is mounted in place. To change positions on the Auxiliary PCB slide the board out as far as possible. When changing the options, verify proper results on the monitor display by *performing the self-test*. Note that changing an option on any of the following eight toggles will *not* cause an immediate change on the monitor screen during the attract mode. --------------------------------------------------------------------------- Settings of 8-Toggle Switch on Tempest Analog Vector-Generator PCB (at L12) 1 2 3 4 5 6 7 8 Option --------------------------------------------------------------------------- On 1-credit minimum $ Off 2-credit minimum On On English $ On Off French Off On German Off Off Spanish Bonus life granted at every: On On Off 10,000 points On On On 20,000 points $ On Off On 30,000 points On Off Off 40,000 points Off On On 50,000 points Off On Off 60,000 points Off Off On 70,000 points Off Off Off No bonus life Off Off 2 lives per game On Off 3 lives per game $ On On 4 lives per game Off On 5 lives per game Settings of 4-Toggle Switch on Tempest Auxiliary PCB (at D/E2) N Game difficulty* O On On Medium $ T On Off Easy Off On Hard U Off Off Medium S E On Minimum rating range: 1,3,5,7,9 $ D Off Minimum rating range tied to high score --------------------------------------------------------------------------- $ Manufacturer's suggested settings * Easy - Enemies move slower and one less enemy shot on the screen at one time. Hard - One more enemy, enemies move faster and 1-4 more enemy shots on the screen at one time. For pricing for "credits," see Figure 8. Changing toggles 1-5 erases the high score table. FIGURE 8 GAME PRICE SETTINGS The table below contains the switch settings for those options relating to game price, coin mechanism multipliers, bonus play, demonstration and freeze mode. This information is useful if you want to view all 99 levels of play or freeze the action, if you need to temporarily set the Tempest (TM) game on free play, or if you have German coin mechanisms in your door. To achieve bonus plays, all coins must be inserted before pressing the start button. If you choose the two play minimum, set toggle 8 at PCB switch assembly L12 to *off*. The Demonstration Mode** allows you to choose any level (1-81) in the ready-to-play mode and accelerate through the tubes without having to kill the enemies. Freeze allows you to stop the action. The score is zeroed at the end of the game in this mode. Set the toggles per the table below for the Demonstration Mode. Next rotate the control knob. You may choose level 1 through 81 during the ready-to-play mode. Press either START button to accelerate through the tubes. Press the FIRE button to clear the spikes at the bottom of the tube. To freeze play, set switch 1 to off. --------------------------------------------------------------------------- Toggle Settings of 8-Toggle Switch on Tempest Analog Vector-Generator PCB (at N13) 1 2 3 4 5 6 7 8 Option --------------------------------------------------------------------------- Off On Free play Off Off 1 coin* for 2 credits On On 1 coin* for 1 credit $ On Off 2 coins* for 1 credit On On Right coin mech x 1 $ On Off Right coin mech x 4 Off On Right coin mech x 5 Off Off Right coin mech x 6 On Left coin mech x 1 $ Off Left coin mech x 2 On On On No bonus coins $ On On Off For every 2 coins*, game adds 1 more coin* On Off On For every 4 coins*, game adds 1 more coin* On Off Off For every 4 coins*, game adds 2 more coins* On On On For every 5 coins*, game adds 1 more coin* On On Off For every 3 coins*, game adds 1 more coin* Demonstration and Freeze Mode** On Off Off On Demonstration Mode Off Off Off On Demonstration-Freeze Mode --------------------------------------------------------------------------- * In the U.S>, a "coin" is defined as 25 cents. In Germany, a "coin" is 1 DM. $ Manufacturer's suggested settings ** If you press RESET during this mode, game will lock up. To recover, set switch 1 to on. FIGURE 9 COIN COUNTER OPTION SETTINGS [These toggles determine which coin mechanisms activate which counters] --------------------------------------------------------------------------- Toggle settings of 4-Toggle Switch on Analog Vector- Generator PCB (K10/11) Two coin acceptors Three coin acceptors 4 3 2 1 in the coin door: in the coin door:* --------------------------------------------------------------------------- On Off Both acceptors activate all Left acceptor activates one N N coin counters simultaneously. coin counter; center and O O right acceptor activates T T another coin counter. /Not for any currently designed U U 3-mech coin door/. S S E E Off On Both acceptors activate 2 Left and center acceptor D D counters separately. $$ activate one coin counter; right acceptor activates N N another coin counter. O O T T Off Off Both acceptors activate 2 Left, center and right counters separately. $$ acceptors activate 3 coin U U counters separately. $$$ S S E E On On Both acceptors activate all All 3 are same denomination D D coin counters simultaneously. $ and they activate all coin counters simultaneously. --------------------------------------------------------------------------- $ Manufacturer's suggested settings for games with 1 coin counter. $$ Manufacturer's suggested settings for games with two coin counters. $$$ Manufacturer's suggested settings for games with optional second and third coin counters. * See Drawing Package DP-190 for additional components required for operating the third coin counter.