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@JagLally:
The A500 GVP controllers are usually not terminated internally, just relying on the termination to be present on the harddrive in combination with the short cable ~10cm cable. Stubs of ~10cm are allowed on a scsi chain according to spec and this creates a scsi chain of 0cm at the harddrive where the termination is and the controller will be on the stub.
If you have an external device with some sort of cable length, you will need internal termination as the total scsi chain length becomes long enough to create reflections, which is the reason you have termination.
This raises another issue with the GVP cards which are that they do not provide termination power to the bus (you should measure just below 5V at pin 26 on the internal connector and pin 25 on the external connector). With harddrives, you can usually bodge-fix this by setting the drive to either power its own termination or supply termination power to the bus, but say if you have a separate terminator internally, it will need termination power supplied from the bus, disregarding if it is an passive or active terminator.
Measure to verify termination power and check if the SCSI2SD can be configured to supply termination power to the bus, then measure again - without termination power separate terminators cannot work.
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