Cave Games

[channelmaniac]

Model: Dangun Feveron / Fever S.O.S.
Symptom: Static in sound, bars and garbage in graphics

Resoldered cracked solder joints on U4 and UA2 to fix the graphics corruption. The board can now be jostled and the graphics remain as they should.

Resoldered the Yamaha sound chip and the matching surface mounted sound DAC. Ths sound DAC had 2 pins not soldered down. Now the game has reliable sound but still crackly.

Replaced every electrolytic cap on the game as they were in VERY bad shape physically. The 1000uf caps were smashed and deformed and the other caps looked as if they were lifted and soldered back down from only the top of the board.

The static problem on the sound was caused by a missing capacitor at C35. I couldn’t find a schematic or a value for that missing cap. First replaced the missing cap with a .1uf monolithic cap but it sounded muffled. With a .001uf monolithic cap it’s sounding nice and crisp on the highs.
 

[channelmaniac]

Model: Dangun Feveron
Symptom: Corrupt background graphics

Background graphics were a speckled pattern with a black bar running through them. They were the still speckled when the background should've been clear.

Replaced bad SRAM IC at U45. All of it's data lines were chattering with garbage signals.

[channelmaniac]

Model: Dangun Feveron / Fever S.O.S.
Symptom: No sounds. Crackling noises only.

Someone had attempted a repair on this board and had poorly resoldered the Yamaha sound IC and DAC.

Replaced a bad 32Mb EPROM at U19. Board played sound but it was distorted. Recapped the audio section then replaced a bad UPC452. It crossed to an LM324 in the datasheets but that sounded full of static. Replaced it with a TL084 and the sound was nice and crisp.