Crush Buster Arcade No Sound No Control Repair
DataEast Crush Buster
The arcade board came in with symptoms: no sound, and doesn’t respond to controls
NF2 - NF5 missing as described on the notes. They are not resistors. They are “Noise Filter” ferrite beads. Probably rated 2200 Ohm at 100MHz but if measured with DC it’s almost like a copper wire.
Otherwise generally clean and tidy, maybe some factory/repairman rework around two crystal oscillators.
Diagnosis
NF2 -> +5V power, but NF1 which presents, also connects to 5V so essentially no change under normal load.
NF3 -> +12V power. It connects to a transistor very likely audio amplifier related
NF4 -> Speaker -, connects to amplifier output
NF5 -> Speaker +, connects to amplifier output
Unless the coin signal sent to an IC needs 12V, which is unlikely, the missing NFs will probably eliminate the sound, but not coin related.
NF12 -> Coin 1. Tested to have continuity.
NF13 -> Coin 2. Tested to have continuity.
So the coin issue might be elsewhere.
The repair
Upon power on, there is no sound as expected. No input can be received although I do see 1P coin signal get grounded upon pressing the key but no coin was registered. No sound but demo mode works fine.
First to do was make sure the 12V leads to nothing will explode. Tested amplifier and directed connected transistor without obvious problem. So I bridge NF3 + NF4 + NF5. Service button makes SFX now.Only hearing sound in actual demo fighting scene. Confirmed from YouTube video the intro has no SFX so this is fine. Audio amp runs warm as expected.
Upon further checking COIN1, COIN2, and SERVICE button input, it all goes to IC5, which epoxy has a crack already. Believed to be the same event caused the removal of NF2-NF5. The chip has a marking of “RCDM-I1 98”, and has 5V input on one side and GND on the other side. The pinout pattern seems to be “5V, IN1, OUT1, IN2, OUT2, IN3, OUT3, IN4, OUT5, GND”. It’s a pull-up resistor network IC, pretty simple but sealed in one package.
Lucky the client supplied two broken boards. Took IC2 from donor board and replaced IC5. Took 4 NF filters from the donor and replaced. Fully working with 1P + 2P coin and control, audio.
