Prototype MPC 3000 - SCSI PCB

Hey,

I finally got all parts to build an internal card reader for my beloved MPC 3000.
However, after I boot the MPC and try to make the reader active, boom: Error FF48... Ok, I thought, it's probably the SCSI fuse which has blown.
So I bought a resettable fuse. I just opened my MPC to change the fuse and saw some weird (as if the other parts of my MPC aren't werid enough...) things on my SCSI board.
I compared the board with images from the internet and there are some significant differences...

Here is mine:


if you do a search on google (MPC 3000 SCSI), there are some images of the "normal" board. The main difference is, that my fuse is behind the 26-pin SCSI port.
So I wanted to ask if someone else could take a look at their board and tell me, if I'm really the only one with this PCB.

But I got another problem/question...
On the backside of the PCB


Beside those wires, there is this tape/band under the fuse (not this black 4 pin thing):



Does anybody know what this is and why it is there?? I could imagine that this is some type of electric tape or something. But I don't know. I have to remove it, to replace the fuse, but I'm a bit worried

Would be glad if someone could take a look and enlighten me...


Greetings

Elias,

Regarding the wires, you have broken traces on the board and the wires are used to jump across break. It does look as if those breaks in the trace are intentional .

IC 902 is a voltage regulator. I cant understand why that is soldered on the bottom of the board. My scsi board has IC 902 and its on the top side, but in a different location.

This tape is most likely there to prevent the voltage regulator from arcing on the legs of the D901 diode. I wouldnt suggest permanently removing it unless you desolder and resolder the regulator back on the top side of the board. im sure you will be fine removing it temporarily to replace the fuse.

Simon may be able to provide a little more insight to why this was done. Im guessing there are some issues with the ic's. Whoever did this may be the only person to know why it was done like so.

Hey C-Quence, thanks for your answer! Much appreciated.
I brought the SCSI PCB to a local technician and asked him if he could place the voltage regulator on top. He did it and also replaced the blown fuse with a resettable one.
Now all seems to work fine!

Still a bit confused about the different PCB layout...
And I found another thing. On the AD/DA PCB, there are a few "blank spots".
IC119
C210
C208

I searched the service manual but found nothing about these...

Strange that it has the same part numbers, but different layout.

My guess would be that it is a production prototype.

Jumper wires and cut traces would be factory.