Macintosh SE SuperDrive Floppy and SCSI Issues

[Unknown_K]

nevermind file is too big

 

[DJComputerGuy]

........ok then?

 

[Unknown_K]

It was just the SCSI diagram for the SE out of the guide to macintosh family hardware version 2.

Pin 25 on the external plug goes to Term Power that ends on 1N4001 diode to 5V (that's the one that burned?).

Pin 4 /RTS has a 10Kohm resistor going to 5V.

Then you have the NCR5380 SCSI chip which you replaced.

There is an /EOP line on the SCSI chip that goes to 5V with a 1Kohm resistor.

Not much else between the external SCSI plug to blow up (outside of a burnt track).

 

[DJComputerGuy]

Hmm, interesting, should i test those resistors? Also, yes, the 1N4001 did pop on my unit and was replaced.

So, if i were to purchase another SE board, how much am i looking to pay for one these days roughly?

 

[Unknown_K]

Are those 10Kohm resisters the terminating resisters? Yes, check them to see if they are blow and look for any burnt tracks. Would be better to save the board you have.

 

[DJComputerGuy]

Where would those resistors be exactly? i want to make sure i am looking at the right area of the board. 

 

[Unknown_K]

Not sure if it is a single 10K resistor or terminator pack.

 

[DJComputerGuy]

Anyone else have any ideas of things that could go wrong with the SCSI bus?

 

[DJComputerGuy]

It has been a few months since i have last posted here. Pulled my SE out from it's storage place, i want to see if there is anything more i could possibly do to get that SCSI Bus working again. So far i have replaced the CR1 Diode and the AM5380 SCSI Chip, but still no cigar. I was debating on buying another board, but i need something to do, so i want to try to fix my current one. If anyone has any suggestions o what i should look out for or things i should check, please let me know. 1.4 MB floppies are not very spacious.