Multicade Boards - 48 in 1, 60 in 1, Etc.

[channelmaniac]

Model: 48-in-1
Symptom: Dead. LEDs on the board flash in sequence.

Took the plastic top off the board to troubleshoot the CPU section. If the 74LV273 ICs and the audio DAC were tapped, the screen would go from blank to garbled and the audio would pop. Reflowed the solder on those SMT chips. Board would boot but had a "data error" on Arkanoid and would reboot if the board was tapped firmly.

Reflowed the solder on the SDRAM IC to fix the reboot. Entered the game's setup menu and turned off Arkanoid. This effectively turned the game into a 47-in-1.

The code for the games is kept in a surface mount flash ROM and is not easily fixed outside the factory. Turning off Arkanoid allowed the board to boot and the other 47 games to play.

[channelmaniac]

Layout and Troubleshooting notes for 48-in-1 and 60-in-1 boards

These boards are almost identical under the plastic cover. They use different FPGA chips since the 60-in-1 also has connections (on later boards) for trackball controllers.

U31: CPU - Intel XScale LUPXA255A0C200
U49: SDRAM - 64 Megabit (8 Megabyte) - mfg varies
U19: Flash ROM - 32 Megabit (4 Megabyte) - mfg varies (Contains boot code? and game code?)
U8: EPROM - 256k x 16 bit - mfg varies - (Contains FPGA code?)

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Audio:

U39: CT6630CR (48 in 1) - 16 bit audio DAC
U39: M6335G (60 in 1) - 16 bit audio DAC

These DAC chips feed a volume control and a TDA2003 audio output IC.

U39 is under the plastic cover.

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Video:

U37 and U38 are 74LV273 chips. These and the surrounding resistors form the RGB video output section of the board. The resistors form an inexpensive "DAC" function on the outputs of the 273 chips.

U26 is a 74LV245 chip. This chip drives the video sync output.

Check these chips and the resistors if the video output is incorrect. They are located under the plastic cover.

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If there is a corrupt game on the board it will stop booting and give an error screen. The fix is to turn off that game. Flip DIP switch 4 to get into the Setup Menu. Once there, on the first screen is the overall setup for the game. Keep moving down on the player 1 joystick to step through the games. Turn off the problematic game to skip it and its error.

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These games ARE repairable as long as the CPU is OK.  The CPU is BGA mount and difficult to replace without specialized tools/training.

Spare SDRAM ICs can be found on cheap 64Mb PC-133 SDRAM DIMMs. The 74LV family of chips are 3.3v chips. Be sure to replace them with the same family of chips for proper operation.

The biggest problem I've seen on these boards is poor soldering. Reflowing the SDRAM, Flash ROM, and the video/audio SMT chips will fix a lot of intermittent problems.

[channelmaniac]

Tip: Replacing that pesky cover...

When repairing the multicade boards that have the plastic cover over the CPU section of the board do NOT use RTV silicone. When RTV cures it leaches acetic acid which is a mild corrosive. Normally this wouldn't be a big deal except that there is no ventilation under the plastic cover so any fumes leached under it have no place to escape.

Use Rubber Cement or some other type of glue to hold it in place. Try not to use something that hardens as it will be difficult to clean up if you have to repair the board again in the future.

[Ken Layton]

Several people have reported video sync problems on these boards. Most of the time I think they have the wiring in the cabinet wrong.

[channelmaniac]

These boards are pretty fragile. The outputs for sync are a simple 74LV245 in a VERY small SMT package. It doesn't have a huge amount of heat dissipation and isn't very hard to damage.

What makes it harder to repair is that these boards have a silly little plastic cover over that section of the board. You have to cut the melted pegs and remove the cover to work on it.

RJ

[channelmaniac]

Model 48-in-1
Symptom: Runaway controls

The board would act like all the buttons for player 1 were randomly pressed. U29, a 74LS245, handles player 1 inputs and was shorted to ground on several inputs. RP26 tied 4 inputs high and the resistor on the Player 1 Start button was open. C64 was shorted. Replaced U29, RP26, and C64. Tested game.

[channelmaniac]

Model: 60-in-1
Symptom: No sync

Replaced bad IC at U26 and tested.

This IC is a 3.3v 74LV245A and is under the plastic cover in the very center of the board.

NOTE: A 74LVT245A will work as a replacement IC.

[channelmaniac]

Model: 60-in-1
Symptom: No blue on video

Replaced 6 blown resistors in the resistor ladder on the blue output. The 8.2k ohm resistor was still good. These are all VERY tiny surface mount resistors and are in this order for each of the color outputs:

102 (1k ohm)
241 (240 ohm)
471 (470 ohm)
102 (1k ohm)
202 (2k ohm)
392 (3.9k ohm)
822 (8.2k ohm)

Use a small chisel tip iron and liquid rosin flux when placing these resistors. It takes plenty of patience and a magnifying glass of some type.

[channelmaniac]

Model: 48-in-1
Symptom: No sync

Replaced blown LV245 IC at U26. Tested.

*NOTE*: If the board is hooked up without the video ground connection then the risk of blowing this chip is much higher.

[channelmaniac]

Model: 60-in-1
Symptom: No audio

Replaced a bad TDA2003 audio amp chip and a blown 240 ohm surface mount resistor. Tested board.

[channelmaniac]

Model: 36-in-1
Symptom: Will not move down

Board had a defective, missing solder joint on pin 3 of surface mount resistor pack RP26 from the factory. Resoldered connection and tested.