Author Topic: Midway Games (Read 103458 times)

channelmaniac · « **Reply #420 on:** August 08, 2023, 09:56:57 PM »

Model: Galaga
Symptom: Dead

Replaced all 24/28/40/42 pin sockets and unencapsulated resistor packs. Replaced radial audio and reset caps with proper axial caps. Tested. White screen. Replaced bad ROM 4 and retested.

channelmaniac · « **Reply #421 on:** August 10, 2023, 07:25:56 PM »

Model: Galaga
Symptom: Dead

Replaced all 24/28/40/42 pin single wipe sockets and unencapsulated resistor packs. Soldered one 08xx with multiple broken pins into a machine pin socket to salvage it. Tested.

channelmaniac · « **Reply #422 on:** August 10, 2023, 07:27:23 PM »

Model: Galaga
Symptom: Dead

Replaced all 24/28/40/42 pin single wipe sockets and unencapsulated resistor packs. Soldered the 05xx starfield generator chip with multiple broken pins into a machine pin socket to salvage it. Tested. RAM error. Replaced bad 08xx on CPU 3 and tested. Graphics glitch with repeating character slices, but with OK text. Replaced bad 74LS86 at 4C with a racing output on pin 8 and tested.

channelmaniac · « **Reply #423 on:** August 11, 2023, 11:29:28 PM »

Model: Galaga
Symptom: Random crashes and reboots

Board would show doubled up text on the screen, both horizontally and vertically.

Found address bus AB5 signal on the far side of the 74LS367 chips shorted to ground by 113 ohms. Replaced bad 74LS138 at 1P and tested.

channelmaniac · « **Reply #424 on:** August 30, 2023, 03:26:51 AM »

Model: Galaga
Symptom: Dead. Garbage on screen

Board was missing resistor pack in the sound section and the Program ROMs were all mixed up in their sockets.

Replaced all 24/28/40/42 pin single wipe sockets and unencapsulated resistor packs. Replaced incorrect radial caps with axial caps. Replaced 50-pin CPU board interconnect socket. Put the program ROMs back into their proper sockets. Board booted to the explosion sound and RAM OK. Checked the ROMs for CPU 2 and CPU 3. Replaced bad ROM at location 3E for CPU 3. Tested. Missing motion sprites. Reseated PROM at 1C and retested.

channelmaniac · « **Reply #425 on:** September 18, 2023, 01:03:30 AM »

Model: Mortal Kombat II
Symptom: Error in UE13

Reflowed IC at UE13 and tested.

channelmaniac · « **Reply #426 on:** September 18, 2023, 01:04:50 AM »

Model: Mortal Kombat II
Symptom: Loud piercing audio output

Removed J6 to isolate the digital side and DAC. Sound persisted. Removed C106 and sound disappeared. Replaced bad TL074 OpAmp and replaced 5 radial capacitors. Tested.

channelmaniac · « **Reply #427 on:** September 20, 2023, 11:38:40 PM »

Model: Mortal Kombat II
Symptom: Dead. Missing RAM chip.

Replaced missing 44256 DRAM chip and patched a damaged trace. Tested. Board was dead. Replaced damaged DSP CPU socket and tested. Repaired bent pins on sound connector and tested with sound board.

channelmaniac · « **Reply #428 on:** September 20, 2023, 11:39:10 PM »

Model: Mortal Kombat II
Symptom: Sputtering sound

Recapped sound PCB and tested.

channelmaniac · « **Reply #429 on:** September 20, 2023, 11:39:48 PM »

Model: Mortal Kombat II
Symptom: Sputtering sound

Recapped sound PCB, resoldered audio amp chip, straightened bent pins on the ribbon cable connector, and tested.

channelmaniac · « **Reply #430 on:** September 21, 2023, 11:47:52 PM »

Model: Mortal Kombat II
Symptom: Dead. Missing RAM chip

Replaced missing 44256 RAM chip and patched a damaged trace. Straightened bent pins on multiple connectors. Tested. Game started and immediately went to Game Over. Reflowed UE13 (Custom DMA Controller IC) and retested.

channelmaniac · « **Reply #431 on:** September 21, 2023, 11:49:44 PM »

Model: Mortal Kombat II
Symptom: Dead: Missing ROMs. Labeled "Bad UE13"

Replaced 2 missing ROMs with programmed EPROMs. Would not boot. Replaced damaged DSP CPU Socket and tested. UE13 failure. Reflowed UE13 (Custom DMA Controller) chip as it had visibly broken solder joints on multiple pins. Retested. Straightened multiple bent pins on connectors and replaced a broken pin for Coin 3. Tested.

channelmaniac · « **Reply #432 on:** September 21, 2023, 11:50:34 PM »

Model: Mortal Kombat "T-Unit"
Symptom: UG22 error

Replaced missing UG22 ROM chip. Straightened multiple bent connector pins. Tested.

channelmaniac · « **Reply #433 on:** November 04, 2023, 03:44:09 PM »

Model: Mortal Kombat II sound board
Symptom: Missing parts

Replaced 3 missing ROMs and reprogrammed the 3 existing ROMs as they suffered bit rot. Recapped the PCB. Installed a missing audio amplifier chip and heatsink. Tested.

channelmaniac · « **Reply #434 on:** November 27, 2023, 08:29:49 PM »

Model: NBA Jam Sound PCB
Symptom: Dead

Replaced 32 pin socket on U3 and replaced bad U3 that failed checksum tests on the programmer. Replaced broken sockets on the YM2151 and the YM3012 DAC. Repaired a dead trace on the 74LS138 decoder and one between the CPU and the ROM at U3. Now the board would give 3 beeps during diagnostics indicating a bad U3. Patched a dead trace on the 74LS138 to the data latch handling the upper memory paging of the ROM at U3. Board now passes all tests and plays properly.

channelmaniac · « **Reply #435 on:** November 27, 2023, 11:38:47 PM »

Model: NBA Jam Sound PCB
Symptom: Dead

Replaced bad 24 pin socket on the YM2151 chip. Replaced bad 6264 SRAM chip and tested.

channelmaniac · « **Reply #436 on:** December 05, 2023, 03:18:19 AM »

Model: NBA Jam Sound PCB
Symptom: Dead. Convert to Mortal Kombat

Replaced broken 3.579MHz crystal and missing main filter cap. Replaced U3, U12, and U13 EPROMs with ones programmed for Mortal Kombat. Board played, but sounded fuzzy and distorted. Recapped PCB and retested successfully.

channelmaniac · « **Reply #437 on:** December 11, 2023, 07:01:46 PM »

Model: Mortal Kombat II sound PCB
Symptom: Please rebuild

Recapped the PCB and cleaned under the 2200uf cap as it was leaking. Tested.

channelmaniac · « **Reply #438 on:** December 12, 2023, 07:58:09 PM »

Model: Galaga
Symptom: Stuck on white screen

Board had a rebuild kit installed by owner.

Replaced bad 2k x 8 SRAM on the video PCB. Removed multiple shorted pad to trace solder blobs on the CPU board. Patched a dead trace between the 08xx chips for CPU 1 and CPU 2 (pin 26 to pin 15) and tested.

channelmaniac · « **Reply #439 on:** December 15, 2023, 10:01:01 PM »

Model: Space Invaders
Symptom: Dead, lines on screen

Replaced program ROMs with freshly programmed EPROMs and tested.

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Author Topic: Midway Games (Read 103458 times)