Valley Spectra IV - Revision history

Jimpal: /* MPU board */

2022-02-15T10:23:07Z

MPU board

← Older revision		Revision as of 05:23, 15 February 2022
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	== MPU board ==		== MPU board ==

	The MPU is based on the 6503 processor which is a 28-pin version of the 6502. This is not a common processor and seems that one of the few other places it shows up is on ~~an early~~ Gottlieb System 1 ~~sound card as used in~~ Buck Rogers. Having access to another board using a 6503 is a good method of validating at least the CPU chip is ok.		The MPU is based on the 6503 processor which is a 28-pin version of the 6502. This is not a common processor and seems that one of the few other places it shows up is on a Gottlieb System 1 (Buck Rogers, Genie, Totem, etc.) and System 80 (Spiderman, Panthera, Counterforce, etc.) sound boards. Having access to another board using a 6503 is a good method of validating at least the CPU chip is ok.

	Many of the IC's may be soldered to the board. In order to test out of circuit it will need to be carefully unsoldered to remove. If it tests ok it is recommended to carefully clean the leads and install a socket for easy service in the future.		Many of the IC's may be soldered to the board. In order to test out of circuit it will need to be carefully unsoldered to remove. If it tests ok it is recommended to carefully clean the leads and install a socket for easy service in the future.
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	It appears that at some point there was an undocumented small daughterboard installed on the MPU board. It seems that the function may be to keep the MPU in RESET if the zero crossing isn't seen. There needs to be more research on that. However that board can be removed and a 4093 chip installed in it's place. If that happens a jumper has to be removed and a diode installed otherwise that new 4093 chip will be blown. The original schematic shows the 1n4148 diode but when the change was made to install the daughterboard was done it was changed to a jumper.		It appears that at some point there was an undocumented small daughterboard installed on the MPU board. It seems that the function may be to keep the MPU in RESET if the zero crossing isn't seen. There needs to be more research on that. However that board can be removed and a 4093 chip installed in it's place. If that happens a jumper has to be removed and a diode installed otherwise that new 4093 chip will be blown. The original schematic shows the 1n4148 diode but when the change was made to install the daughterboard was done it was changed to a jumper.


	== Solenoid/Sound Driver board ==		== Solenoid/Sound Driver board ==

Rdoerr: /* Main Board */

2022-02-12T22:24:08Z

Main Board

← Older revision		Revision as of 17:24, 12 February 2022
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	=== Main Board ===		=== Main Board ===
			Corrosion! This is the number one issue to deal with and resolve. If there is corrosion is MUST be dealt with. There are no reproduction or replacement MPU boards. The only option is to repair. To do it properly all the components in the corrosion area must be removed. Then the corrosion cleaned off. Usually requires multiple steps of scraping, treating with white vinegar, sanding, and/or scotchbright pads. Once the corrosion is abated as best as possible it is very common that many traces will become open. Each one will have to be noted and then either trace repaired if minor or a jumper wire soldered to bypass if significant. Also when components are soldered back in place on the board soldering may be difficult due to any traces of corrosion. Often requires scraping with an exacto blade or similar.

			For the IC's new quality dual leaf DIP sockets should be installed. Some people prefer machine pin sockets which are fine too. Just don't resolder the IC's directly back into the board. It will just make future work easier if the chips are in sockets.

			If the legs on the ROM chips are corroded or broken then a new EPROM will need to be installed. Even if the board had three separate ROM chips the easiest replacement is just to burn a combination ROM and rejumper the board for that single ROM. The MPU will support it.

	=== Solenoid/Sound Driver Board ===		=== Solenoid/Sound Driver Board ===

Rdoerr: /* Power Supply */

2022-02-12T22:14:26Z

Power Supply

← Older revision		Revision as of 17:14, 12 February 2022
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	== Power Supply ==		== Power Supply ==
			The power supply on these is pretty straightforward. For servicing the most likely repair would be to replace the aging electrolytic caps. These are located on the power board attached to the side of the card cage under the playfield.

	== Re-Pinning ==		== Re-Pinning ==

Rdoerr: /* Display board */

2022-02-12T22:12:18Z

Display board

← Older revision		Revision as of 17:12, 12 February 2022
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	== Display board ==		== Display board ==
			The display board uses all LED displays so it should be relatively trouble free. As issues are reported and resolved this section will be expanded.

	== Power board ==		== Power board ==

Rdoerr: /* General Information */

2022-02-12T22:10:56Z

General Information

← Older revision		Revision as of 17:10, 12 February 2022
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	Before working on the machine you need to know how to get into it! The top sets on the machine and can be locked into place. The locks are somewhat unique in that the whole cylinder moves in and out. They push in place to lock the top. To remove all four have to be unlocked and pop out to release the top. The key should be the same for all four of those locks. Once the top is unlocked it just lifts straight off. When reinstalling it fits in any position. If you look carefully at the corners one will mention about inserting coins so you can tell how it should set on the machine.		Before working on the machine you need to know how to get into it! The top sets on the machine and can be locked into place. The locks are somewhat unique in that the whole cylinder moves in and out. They push in place to lock the top. To remove all four have to be unlocked and pop out to release the top. The key should be the same for all four of those locks. Once the top is unlocked it just lifts straight off. When reinstalling it fits in any position. If you look carefully at the corners one will mention about inserting coins so you can tell how it should set on the machine.

	Once the top is off you can raise the playfield. This is done by grabbing onto the thick metal guide rail at the top of the playfield and lifting up. It helps to pull out the shooter rod for clearance. Just be careful NOT to grab the playfield by any of the plastics to avoid breaking any of those.		Once the top is off you can raise the playfield. This is done by grabbing onto the thick metal guide rail at the top of the playfield and lifting up. It helps to pull out the shooter rod for clearance. Just be careful NOT to grab the playfield by any of the plastics to avoid breaking any of those. There should be a wooden prop rod stored in one of the legs. It has a V notch on one end that goes under the card cage support and the other just sits in the tub. If the rod is missing get a friend to help hold the playfield as you work on it.

	== Unique features ==		== Unique features ==

Rdoerr: /* Summary of Issues */

2022-02-12T22:08:50Z

Summary of Issues

← Older revision		Revision as of 17:08, 12 February 2022
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	As is the case with 40+ year old technology, many of the active components on these boards are obsolete and may at times be difficult to find exact replacements. They do share many of the common electronic components but there are a few unique parts that are not so common. To date, some "drop in" substitutions have been found for several difficult to find components. This information is contained in the Technical page.		As is the case with 40+ year old technology, many of the active components on these boards are obsolete and may at times be difficult to find exact replacements. They do share many of the common electronic components but there are a few unique parts that are not so common. To date, some "drop in" substitutions have been found for several difficult to find components. This information is contained in the Technical page.

			The game code only would expect certain switches be closed (like the outhole) and can do some really odd issues if any other switches are closed when starting a game. For example if one of the standup targets (switch 16) is stuck closed on the playfield the game will still start but it may start on ball 2! Once fixed it plays as it should and balls start on ball 1. Just a really odd issue if you aren't aware that can happen.

	== Troubleshooting (Electronic) ==		== Troubleshooting (Electronic) ==

Rdoerr: /* Rotation board */

2022-02-12T22:05:01Z

Rotation board

← Older revision		Revision as of 17:05, 12 February 2022
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	== Rotation board ==		== Rotation board ==
			The rotation board sits inside the rotating drum. It has an IR sensor that shines down and will change state when it is sitting on one of the off white pads on each leg. If it isn't detecting that pad and the pads are clean then it can be adjusted with a potentiometer on the board.

	== Display board ==		== Display board ==

Rdoerr: /* Lamp Driver board */

2022-02-12T22:03:06Z

Lamp Driver board

← Older revision		Revision as of 17:03, 12 February 2022
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	== Lamp Driver board ==		== Lamp Driver board ==
			The lamp board uses a dedicated transistor for each lamp on the playfield.

	== Rotation board ==		== Rotation board ==

Rdoerr: /* First Time Power-Up */

2022-02-12T22:01:02Z

First Time Power-Up

← Older revision		Revision as of 17:01, 12 February 2022
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	=== First Time Power-Up ===		=== First Time Power-Up ===
			Before attempting to power on one of these machines the MPU and boards in the card cage have to be inspected for battery damage. If there is that will need to be addressed and resolved first.

			For a first power up or after the RAM or battery backup power source has changed the memory contained in the 5101 chips has to be reset. Otherwise you will see abnormal behavior even if the boards themselves are ok. In order to reset the memory the machine has to be powered off, playfield lifted up, and the connector to the sound section of the Solenoid/Sound driver temporarily disconnected and a special RESET card be plugged in. Then power on the machine and you should see all 0's on all displays indicating that the RAM was reset. Power down the machine, remove the card, then plug the connector back in and lower the playfield.

			Once the RAM is reset the game should boot normally. However it may not play normally until you use the coin door interface to adjust and set the remaining settings. From that point on it will be fine unless the battery backup to keep the memory fails resulting in garbage data. When that happens you need to go back and use the RESET card again after addressing the memory power issue. This will mess up a lot of people if the reset process isn't followed.

	=== Main Board ===		=== Main Board ===

Rdoerr: /* Re-Pinning */

2022-02-12T21:53:13Z

Re-Pinning

← Older revision		Revision as of 16:53, 12 February 2022
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	== Re-Pinning ==		== Re-Pinning ==
			The most likely area to require repinning would be the connectors right near the MPU batteries. Any that show signs of corrosion should be replaced. They use the same pins as many of the Gottlieb System 1 or System 80 so they are still available. Along with replacing any bad pins the edge connector on the PCB should be reconditioned so that there will be a solid connection again.

	== Errata ==		== Errata ==