Obsession console or processor shuts down intermittently or will not power up. Upon checking diagnostics screen, "Retries to get slave data" is displayed over and over.
The message indicates that the 486 CPU and the Serf PCB are not communicating. The 486 CPU sends out a signal to the Serf and expects a response. If no response, then this message is generated in the diagnostic screen.
Work around / Fix
Typically this problem is indicative of one of two things:
- The majority of voltage drops in Obsession 1's is due to corrosion on the power connector, so first all power connections (particularly the long white one directly on the power supply) should be undone cleaned with a non conductive contact cleaner and reseated . This will correct many low voltage issues and will prevent premature connector toastiosity.
- Sometimes a drop in the 5vdc rail on the Power supply or a DC wiring connection has gone bad. The power supply and wiring checkout, then the other possible cause is a hardware failure on the Serf PCB. At this point, the Serf will need repair.
How to Check the Power supply on the Obsn Console:
Verify that the Serf Card is getting proper DC voltage by metering between TP1 and G2. The Serf Card is located in the center of the bottom tray. Locate the I960 heatsink, TP1 is approx at 1 o'clock. G2 is approx at 6 o'clock. You should get 5.05vdc between these two points.
If not, adjust voltage at the power supply so that you get 5.05vdc between TP1 and G2.
The power supply is to the left of the Serf card. Locate the metal "U" on the power supply. A small black or blue trim pot, with a yellow or white "phillips" insert is in the upper right corner of the "U". Turn the trim pot counter-clockwise to increase voltage.
While trimming power supply always jiggle or move the wire harness directly from the power supply. Pay close attention to the terminal strip or any browning of the white molex connector.
How to trim the power supply on the Processor unit:
Use all above, except Serf is located on the top. Power supply is located on bottom.