Williams System 3 - 7 - Revision history

Chibler: /* Driver Board */ Added drawing error in all WMS S3-7 driver board drawings.

2026-09-23T21:01:16Z

Driver Board: Added drawing error in all WMS S3-7 driver board drawings.

← Older revision		Revision as of 16:01, 23 September 2026
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	===Driver Board===		===Driver Board===
	[[File:System3-7DriverBoardLayout.jpg\|300px\|thumb\|left\|Williams System 3-7 driver board layout]]~~<br>~~		[[File:System3-7DriverBoardLayout.jpg\|300px\|thumb\|left\|Williams System 3-7 driver board layout]]
	* [[media:05-driverlogic-sys3-6.pdf\|System 3-7 Driver Board Logic Diagram]]		[[File:System3-7DriverBoardDrawingError.jpg\|300px\|thumb\|right\|Williams System 3-7 driver board layout error]]
	* [[media:04-driverboard-sys3-6.pdf\|System 3-6 Driver Board Assembly Drawing]] (Note: The Tables for Solenoids, Switch Matrix and Lamp Matrix are examples for Firepower. However the wiring colors and locations do not change from game to game. System 7 does not use Driver Solenoids to trigger sounds, and that is covered in the Sound Board section.)		* [[media:05-driverlogic-sys3-6.pdf\|Improved System 3-7 Driver Board Logic Diagram]]
	* [[Media:wms-sys3-6_driver-board_layout.pdf\|System 3-6 Driver Board Layout]]		* [[media:04-driverboard-sys3-6.pdf\|Improved System 3-6 Driver Board Assembly Drawing]] (<b>Note:</b> The Tables for Solenoids, Switch Matrix and Lamp Matrix are examples for Firepower. However the wiring colors and locations do not change from game to game. System 7 does not use Driver Solenoids to trigger sounds, and that is covered in the Sound Board section.)
	* [[Media:wms-sys3-6_driver-board_schematics_1of2.pdf\|System 3-6 Driver Board Schematics (1 of 2)]]		* [[Media:wms-sys3-6_driver-board_layout.pdf\|OEM System 3-6 Driver Board Layout]] (<b>Note:</b> all OEM drawings contain the error detailed at right.)
	* [[Media:wms-sys3-6_driver-board_schematics_2of2.pdf\|System 3-6 Driver Board Schematics (2 of 2)]]		* [[Media:wms-sys3-6_driver-board_schematics_1of2.pdf\|OEM System 3-6 Driver Board Schematics (1 of 2)]]
			* [[Media:wms-sys3-6_driver-board_schematics_2of2.pdf\|OEM System 3-6 Driver Board Schematics (2 of 2)]]
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Chibler: /* Reset Circuit Summary */

2026-09-10T20:03:48Z

Reset Circuit Summary

← Older revision		Revision as of 15:03, 10 September 2026
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	===Reset Circuit Summary===		===Reset Circuit Summary===
	Connectors were mentioned above for completeness. While ~~I agree~~ a ~~good~~ 40-~~way connector~~ is essential for correct operation of ~~this era of~~ games, changing the Bridge Rectifiers in the backbox or rebuilding connectors probably won't help fix the reset circuit .		Connectors were mentioned above for completeness. While a perfectly connected 40-pin board interconnect is essential for correct operation of System 3 - 7 games, changing the Bridge Rectifiers in the backbox or rebuilding connectors probably won't help fix the reset circuit.

	That because the '''BR's are only for the Lamps and Solenoids''' and won't fix a problem with the MPU power (or reset) as that is sourced directly from the PSU. The ~~+5v~~ logic power comes from a regulator on the ~~PSU~~ board, and the ~~+5v~~ for the reset pins of ~~the~~ MPU ICs is created on the MPU from the +12v unregulated supply.		That because the '''BR's are only for the Lamps and Solenoids''' and won't fix a problem with the MPU power (or reset) as that is sourced directly from the PSU. The 5VDC logic power comes from the LM323K regulator on the power supply board, and the 5VDC (logic 1) for the reset pins of MPU ICs is created onboard the MPU from the +12v unregulated supply.

	If you are looking here because game resets (reboots to attract mode or locks up) when flipping the flippers, it makes sense to check and rebuild the solenoid power circuit as well. That is the flipper power on games prior to System 7 when 50v flippers and a Flipper Power Board was introduced. You should also read the [http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#WPC_5VDC_Power_Derivation_Path WPC section], ~~while the games only similar-~~ the approach ~~for~~ resets caused by power fluctuations is sound. It takes you from the 'AC mains' wall plug right through to the power needed on the boards.		If you are looking here because game resets (reboots to attract mode or locks up) when flipping the flippers, it makes sense to check and rebuild the solenoid power circuit as well. That is the flipper power on games prior to System 7 when 50v flippers and a Flipper Power Board was introduced. You should also read the [http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#WPC_5VDC_Power_Derivation_Path WPC section]. While the game systems are not identical, the approach to address game resets caused by power fluctuations is sound. It takes you from the 'AC mains' wall plug right through to the power needed on the boards.

	Topics such as electrolytic capacitors aging and drying out, testing the Bridge Rectifiers and checking and tweaking the LM323K 5V regulator on the Power ~~Baord will~~ all ~~be the same or very similar~~.		Topics such as electrolytic capacitors aging and drying out, testing the Bridge Rectifiers and checking and tweaking the LM323K 5V regulator on the Power Board are all applicable.

	==The Blanking Circuit==		==The Blanking Circuit==

Chibler: /* Connectors, connectors, connectors */

2026-09-10T19:57:50Z

Connectors, connectors, connectors

← Older revision		Revision as of 14:57, 10 September 2026
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	If the game starts to reset for no reason during play, or when both flippers are engaged, it may be worth first re-pinning the connectors at 1J2 on the MPU Board and at the outputs from the PSU. This is always a good step even if it does not fix the immediate issue, as it avoids power problems later on.<br>		If the game starts to reset for no reason during play, or when both flippers are engaged, it may be worth first re-pinning the connectors at 1J2 on the MPU Board and at the outputs from the PSU. This is always a good step even if it does not fix the immediate issue, as it avoids power problems later on.<br>

	This will involves replacing the header pins on the PSU board and the female connectors on the cables. The pins are .156" and square pins are preferred, although round are still available. Use phosphor bronze. On the female side, crimp pins ~~of the trifuricon type~~ are ~~best~~.		This will involves replacing the header pins on the PSU board and the female connectors on the cables. The pins are .156" and square pins are preferred, although round are still available. Use phosphor bronze. On the female side, [https://www.pinballlife.com/156-trifurcon-crimp-terminals.html Trifurcon] crimp pins are highly recommended to improve male pin to female pin physical connection, ahem.

	Second prize goes to reflowing solder to the back of the header pins, and just replacing the female IDC connectors with new ones. In that case rather than a crimper, the .156" 'punch-down' tool '''''must''''' be used for this replacement to work correctly. If the correct tool is not used, the IDC housing and pins will be damaged, especially if a screwdriver or some other makeshift tool is used. After that, the wires just don't seat correctly and will not maintain proper contact. Always cut back to clean wire and punch down correctly to a new IDC connector, reusing an old one rarely works.		Second prize goes to reflowing solder to the back of the header pins, and just replacing the female IDC connectors with new ones. In that case rather than a crimper, the .156" 'punch-down' tool '''''must''''' be used for this replacement to work correctly. If the correct tool is not used, the IDC housing and pins will be damaged, especially if a screwdriver or some other makeshift tool is used. After that, the wires just don't seat correctly and will not maintain proper contact. Always cut back to clean wire and punch down correctly to a new IDC connector, reusing an old one rarely works.

Chibler: /* Add Fuses Between the Transformer Secondary and Backbox Bridge Rectifiers */

2026-09-10T19:50:41Z

Add Fuses Between the Transformer Secondary and Backbox Bridge Rectifiers

← Older revision		Revision as of 14:50, 10 September 2026
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	Williams failed to include fuses in the AC connection between the transformer secondary and the solenoid and controlled lamp bridge rectifiers. In theory, the primary power fuse should blow if one of these bridges short. However, this is not always the case. Sometimes, the bridges short in such a manner that the wiring from the transformer secondary to the bridge becomes the fuse, and the wiring insulation melts until something gives.		Williams failed to include fuses in the AC connection between the transformer secondary and the solenoid and controlled lamp bridge rectifiers. In theory, the primary power fuse should blow if one of these bridges short. However, this is not always the case. Sometimes, the bridges short in such a manner that the wiring from the transformer secondary to the bridge becomes the fuse, and the wiring insulation melts until something gives.

	This problem can be addressed by adding 2 fuse blocks and two 8 amp slo-blo fuses. For each bridge, ~~afuse~~ is added between either transformer secondary wire and the bridge. The AC inputs to the bridge are both marked with a 'tilde' on the BR which looks like an 'S' on it's side: '''~'''. The wire colors are typically red for solenoids, and blue for the controlled lamps. However, it is best to consult the game schematics to confirm.		This problem can be addressed by adding 2 fuse blocks and two 8 amp slo-blo fuses. For each bridge, a fuse is added between either transformer secondary wire and the bridge. The AC inputs to the bridge are both marked with a 'tilde' on the BR which looks like an 'S' on it's side: '''~'''. The wire colors are typically red for solenoids, and blue for the controlled lamps. However, it is best to consult the game schematics to confirm.

	Although the preferred method is to put fuse holders on the backbox wall, installing fuses in any configuration is paramount. One way is to use inline fuse holders, and solderless crimp butt connectors. This is a quick and easy alternative, even though it may not be the prettiest solution.		Although the preferred method is to put fuse holders on the backbox wall, installing fuses in any configuration is paramount. One way is to use inline fuse holders, and solderless crimp butt connectors. This is a quick and easy alternative, even though it may not be the prettiest solution.

Chibler: /* Quick Start: Repairing a Williams System 3-7 MPU */

2026-07-25T21:32:11Z

Quick Start: Repairing a Williams System 3-7 MPU

← Older revision		Revision as of 16:32, 25 July 2026
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	</li>		</li>

	<li>Verify the ROM contents. The OEM ROMs at least 30 years old, and have been subjected to thousands of hours of heat~~, consequently~~ reducing their reliability. Replacing them with known good ROMs is a better option if possible.</li>		<li>Verify the ROM contents. The OEM ROMs are at least 30 years old and have been subjected to thousands of hours of heat reducing their reliability. Replacing them with known good ROMs is a better option if possible.</li>
	<li>Measure power coming onto the board at the filter capacitor. About 5VDC should be present, with very little AC component (measure AC too).</li>		<li>Measure power coming onto the board at the filter capacitor. About 5VDC should be present, with very little AC component (measure AC too).</li>
	<li>Test socketed processors and PIAs in a known working board. AMI branded chips seem to experience a much higher failure rate than any other brand and are always suspect (this is also especially true for an AMI 5101 RAM chips).</li>		<li>Test socketed processors and PIAs in a known working board. AMI branded chips seem to experience a much higher failure rate than any other brand and are always suspect (this is also especially true for an AMI 5101 RAM chips).</li>

ForceFlow: /* How the Switch Matrix Works */

2026-07-21T03:53:59Z

How the Switch Matrix Works

← Older revision		Revision as of 22:53, 20 July 2026
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	:A 7406 or 74LS06 will work and are common parts.		:A 7406 or 74LS06 will work and are common parts.
	;Two 4049 (or 14049 "CMOS Hex Inverter / Buffer) is used to 'read' the Rows.		;Two 4049 (or 14049 "CMOS Hex Inverter / Buffer) is used to 'read' the Rows.
	:The MC14049 or CD4049UBCN are common examples, although any 14049 or 4049 16-leg DIP will work. ~~Unlike~~ the 7406 ~~they rarely fail and cause problems~~.		:The MC14049 or CD4049UBCN are common examples, although any 14049 or 4049 16-leg DIP will work. However, these chips are significantly less likely to fail than the 7406 chips.
	:''(Hex in this context refers to six inverters contained in the one IC package. It's nothing to do with the computer (or math) Hex meaning of 'base 16'.''		:''(Hex in this context refers to six inverters contained in the one IC package. It's nothing to do with the computer (or math) Hex meaning of 'base 16'.''

ForceFlow: /* How the Switch Matrix Works */ Subjective statement removed

2026-07-21T03:48:11Z

How the Switch Matrix Works: Subjective statement removed

← Older revision		Revision as of 22:48, 20 July 2026
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	;Two 7406 (Hex Inverter / Buffer with open collector HV outputs) is used to 'drive' the Columns.		;Two 7406 (Hex Inverter / Buffer with open collector HV outputs) is used to 'drive' the Columns.
	:A 7406 or 74LS06 will work and are common parts~~. If you rebuild or repair a board replace them because they tend to fail of old age now more frequently~~.		:A 7406 or 74LS06 will work and are common parts.
	;Two 4049 (or 14049 "CMOS Hex Inverter / Buffer) is used to 'read' the Rows.		;Two 4049 (or 14049 "CMOS Hex Inverter / Buffer) is used to 'read' the Rows.
	:The MC14049 or CD4049UBCN are common examples, although any 14049 or 4049 16-leg DIP will work. Unlike the 7406 they rarely fail and cause problems.		:The MC14049 or CD4049UBCN are common examples, although any 14049 or 4049 16-leg DIP will work. Unlike the 7406 they rarely fail and cause problems.

ForceFlow: /* Quick Start: Repairing a Williams System 3-7 MPU */

2026-07-21T03:47:10Z

Quick Start: Repairing a Williams System 3-7 MPU

← Older revision		Revision as of 22:47, 20 July 2026
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	<li>Verify the ROM contents. The OEM ROMs at least 30 years old, and have been subjected to thousands of hours of heat, consequently reducing their reliability. Replacing them with known good ROMs is a better option if possible.</li>		<li>Verify the ROM contents. The OEM ROMs at least 30 years old, and have been subjected to thousands of hours of heat, consequently reducing their reliability. Replacing them with known good ROMs is a better option if possible.</li>
	<li>Measure power coming onto the board at the filter capacitor. About 5VDC should be present, with very little AC component (measure AC too).</li>		<li>Measure power coming onto the board at the filter capacitor. About 5VDC should be present, with very little AC component (measure AC too).</li>
	<li>Test socketed processors and PIAs in a known working board. AMI branded chips seem to experience a much higher failure rate than any other brand and are always suspect~~. This~~ is especially true for an AMI 5101 ~~ram~~.</li>		<li>Test socketed processors and PIAs in a known working board. AMI branded chips seem to experience a much higher failure rate than any other brand and are always suspect (this is also especially true for an AMI 5101 RAM chips).</li>
	<li>Use a logic probe to test the processor reset signal at pin 40. The signal should start low at power on, then go high a split second later.</li>		<li>Use a logic probe to test the processor reset signal at pin 40. The signal should start low at power on, then go high a split second later.</li>
	<li>With a schematic of the board handy, “sanity check” each pin on the processor to ensure each leg is doing something that makes sense. i.e. data lines D0-D7 should be pulsing.</li>		<li>With a schematic of the board handy, “sanity check” each pin on the processor to ensure each leg is doing something that makes sense. i.e. data lines D0-D7 should be pulsing.</li>

Frg: /* Quick Start: Repairing a Williams System 3-7 MPU */ AMI 5101

2026-07-20T22:38:51Z

Quick Start: Repairing a Williams System 3-7 MPU: AMI 5101

← Older revision		Revision as of 17:38, 20 July 2026
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	<li>Verify the ROM contents. The OEM ROMs at least 30 years old, and have been subjected to thousands of hours of heat, consequently reducing their reliability. Replacing them with known good ROMs is a better option if possible.</li>		<li>Verify the ROM contents. The OEM ROMs at least 30 years old, and have been subjected to thousands of hours of heat, consequently reducing their reliability. Replacing them with known good ROMs is a better option if possible.</li>
	<li>Measure power coming onto the board at the filter capacitor. About 5VDC should be present, with very little AC component (measure AC too).</li>		<li>Measure power coming onto the board at the filter capacitor. About 5VDC should be present, with very little AC component (measure AC too).</li>
	<li>Test socketed processors and PIAs in a known working board. AMI branded chips seem to experience a much higher failure rate than any other brand and are always suspect.</li>		<li>Test socketed processors and PIAs in a known working board. AMI branded chips seem to experience a much higher failure rate than any other brand and are always suspect. This is especially true for an AMI 5101 ram.</li>
	<li>Use a logic probe to test the processor reset signal at pin 40. The signal should start low at power on, then go high a split second later.</li>		<li>Use a logic probe to test the processor reset signal at pin 40. The signal should start low at power on, then go high a split second later.</li>
	<li>With a schematic of the board handy, “sanity check” each pin on the processor to ensure each leg is doing something that makes sense. i.e. data lines D0-D7 should be pulsing.</li>		<li>With a schematic of the board handy, “sanity check” each pin on the processor to ensure each leg is doing something that makes sense. i.e. data lines D0-D7 should be pulsing.</li>

Frg: /* How the Switch Matrix Works */ 7406 replacement in switch matrix

2026-07-20T22:35:44Z

How the Switch Matrix Works: 7406 replacement in switch matrix

← Older revision		Revision as of 17:35, 20 July 2026
Line 2,778:		Line 2,778:

	;Two 7406 (Hex Inverter / Buffer with open collector HV outputs) is used to 'drive' the Columns.		;Two 7406 (Hex Inverter / Buffer with open collector HV outputs) is used to 'drive' the Columns.
	:A 7406 or 74LS06 will work and are common parts.		:A 7406 or 74LS06 will work and are common parts. If you rebuild or repair a board replace them because they tend to fail of old age now more frequently.
	;Two 4049 (or 14049 "CMOS Hex Inverter / Buffer) is used to 'read' the Rows.		;Two 4049 (or 14049 "CMOS Hex Inverter / Buffer) is used to 'read' the Rows.
	:The MC14049 or CD4049UBCN are common examples, although any 14049 or 4049 14-leg DIP will work.		:The MC14049 or CD4049UBCN are common examples, although any 14049 or 4049 16-leg DIP will work. Unlike the 7406 they rarely fail and cause problems.
	:''(Hex in this context refers to six inverters contained in the one IC package. It's nothing to do with the computer (or math) Hex meaning of 'base 16'.''		:''(Hex in this context refers to six inverters contained in the one IC package. It's nothing to do with the computer (or math) Hex meaning of 'base 16'.''

← Older revision		Revision as of 16:01, 23 September 2026
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	===Driver Board===		===Driver Board===
	[[File:System3-7DriverBoardLayout.jpg\|300px\|thumb\|left\|Williams System 3-7 driver board layout]]~~<br>~~		[[File:System3-7DriverBoardLayout.jpg\|300px\|thumb\|left\|Williams System 3-7 driver board layout]]
	* [[media:05-driverlogic-sys3-6.pdf\|System 3-7 Driver Board Logic Diagram]]		[[File:System3-7DriverBoardDrawingError.jpg\|300px\|thumb\|right\|Williams System 3-7 driver board layout error]]
	* [[media:04-driverboard-sys3-6.pdf\|System 3-6 Driver Board Assembly Drawing]] (Note: The Tables for Solenoids, Switch Matrix and Lamp Matrix are examples for Firepower. However the wiring colors and locations do not change from game to game. System 7 does not use Driver Solenoids to trigger sounds, and that is covered in the Sound Board section.)		* [[media:05-driverlogic-sys3-6.pdf\|Improved System 3-7 Driver Board Logic Diagram]]
	* [[Media:wms-sys3-6_driver-board_layout.pdf\|System 3-6 Driver Board Layout]]		* [[media:04-driverboard-sys3-6.pdf\|Improved System 3-6 Driver Board Assembly Drawing]] (<b>Note:</b> The Tables for Solenoids, Switch Matrix and Lamp Matrix are examples for Firepower. However the wiring colors and locations do not change from game to game. System 7 does not use Driver Solenoids to trigger sounds, and that is covered in the Sound Board section.)
	* [[Media:wms-sys3-6_driver-board_schematics_1of2.pdf\|System 3-6 Driver Board Schematics (1 of 2)]]		* [[Media:wms-sys3-6_driver-board_layout.pdf\|OEM System 3-6 Driver Board Layout]] (<b>Note:</b> all OEM drawings contain the error detailed at right.)
	* [[Media:wms-sys3-6_driver-board_schematics_2of2.pdf\|System 3-6 Driver Board Schematics (2 of 2)]]		* [[Media:wms-sys3-6_driver-board_schematics_1of2.pdf\|OEM System 3-6 Driver Board Schematics (1 of 2)]]
			* [[Media:wms-sys3-6_driver-board_schematics_2of2.pdf\|OEM System 3-6 Driver Board Schematics (2 of 2)]]
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