Thank You takimoto and Elfen for supporting help

Takimoto: I tested the voltage on the external floppy connector and its 12.4 V and 4.9 V. Same result at beginning when the HD is working and later when only the internal floppy is working. Is that OK?

Elfen: I tested the Bourns filter and I think RP10 is defect. There is no capacitance between pin 19 and 20. Between pins 12-18 and Earth (pin20) its 220-300pF when measured on the board. Pin 19 and 2 is named RDDATA in the schematics and is connected to RDDATA and SENSE on the SWIM chip and connected to the external floppy connector. No change during Cold and hot. The resistors are OK  The other two Bournes filter are OK.

I connected a working external floppy drive and the floppy disk is spinning but the disk is ejected. Strange that the internal floppy connector is working.



I will replace the Bourns filter RP10 from another SE/30 bord . That board is destroyed by a Maxell battery but the

Bourns filter measured OK.

A new error message today when HD stops working: "System error  "Finder" bad F-line instruction.

I will report later.