Sega Naomi by channelmaniac
Symptom: Fails self test
Self test showed IC29 as bad. Replaced IC29 and re-ran the test.
IC29 was a standard 62256 surface mount type SRAM IC.
Symptom: Dead
System gave raster but no picture. Inspection of the board turned up a leaking .1f 5.5v memory capacitor. The electrolyte spread on the board and started corroding things.
Desoldered the BIOS ROM and the serial EEPROM holding the code for the Altera FPGA chip. Cleaned the electrolyte from the board and inspected the board for damage. The corrosion damaged a plate thru under the serial EEPROM socket, causing the FPGA chip to not load its code from the EEPROM upon boot. Repaired the trace, replaced the bad memory cap, and tested the board.
The EEPROM chip connects to the Altera chip as follows:
Pin 1 - Pin 12
Pin 2 - Pin 1
Pin 3 - Pin 37
Pin 4 - Pin 4
Pin 5 - Ground
Pin 6 - No Connection
Pin 7 - +5v
Pin 8 - +5v
Symptom: Broken USB jack and noisy fan
Replaced the noisy fan and USB jack.
USB jack was tough to find. Desoldered the jack and took it to an area "computer junk store." Found a Pentium II board in their scrap bin that had the same jack. Desoldered and installed it on the NAOMI system. Played a game of Marvel vs. Capcom 2 to test the system.
Symptom: Has audio but no video.
Traced the video output back to the RAMDAC chip. The RAMDAC was finger blistering hot. Replaced the RAMDAC (Sega # 315-6145) with one pulled from a parts NAOMI board.
Symptom: Intermittent controls
Replaced a broken USB jack on the I/O board. Checked and replaced a leaking memory backup capacitor.
Symptom: Error 01: This game is not acceptable by main board.
Connector CN1 had 4 bent pins. Replaced bad connector with one from a parts board and tested.
