Phase5 Blizzard 2060 SCSI issues

[Zac67]

Since you've ruled out a bad cable, I'd very seriously look into the possibility of a bad contact on the board. Double check the SCSI connector (have you tried the external one?), the Glogic chip and the small buffer chips.

It makes a big difference whether every single byte gets garbled up or just every 2nd, 4th or so. If the latter is the case I'd bet on one of the buffers or a contact around there.

[Zac67]

I'm not sure how to verify the SMD mounted chips by just looking at them. The connectors pins seems to be OK though.

You'd need at least a logic tester for that... As rkauer has pointed out, the terminator is worth checking as well: switch it off and replace with an external one - but then again, it'd garble all data transmitted.
Back to the buffers: they're probably 74hct244 or 245. If your soldering skills are adequate, I'd swap them out all the same, can't cost too much.

Found a decent photo - they're 74fct2245
pinout:

Code: [Select]

742245
8-bit 3-state noninverting bus transceiver with integrated 25O series
output resistors.
Enable and direction pins control output enables.

    +----------+             +---------------+
DIR |1  +--+ 20| VCC         |/EN|DIR| A | B |
 A0 |2       19| /EN         |---+---+---+---|
 A1 |3       18| B0          | 1 | X | Z | Z |
 A2 |4       17| B1          | 0 | 0 | B | Z |
 A3 |5  742  16| B2          | 0 | 1 | Z | A |
 A4 |6  245  15| B3          +---------------+
 A5 |7       14| B4
 A6 |8       13| B5
 A7 |9       12| B6
GND |10      11| B7
    +----------+