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Well I found another Prototype....iisi

jajan547

Well-known member
Ok it arrived an hard drive is toast unfortunately but being that this says PVT NuBUS could this mean this is a typical iisi and this was a bit used to test the NubUs adapter that was paired with the PVT number on the bottom? What I mean is if you look at some iisi"s some have a black slot and some have white. Was there any difference or variation? If so being that this has a black slot could it mean it was used to test the newer Nubus slot and adapter compatability?
 

joshc

Well-known member
What I mean is if you look at some iisi"s some have a black slot and some have white. Was there any difference or variation?
Not that I know of. This was the case for a lot of Macs - Quadras and IIci as well, I've had both with either black or white NuBus slots. I guess it was just down to parts availability/supplier, perhaps factory location.
 

jajan547

Well-known member
Not that I know of. This was the case for a lot of Macs - Quadras and IIci as well, I've had both with either black or white NuBus slots. I guess it was just down to parts availability/supplier, perhaps factory location.
Well I'll investigate the chips and what not a bit further still find this an odd little find.
 

Johnnya101

Well-known member
Not that I know of. This was the case for a lot of Macs - Quadras and IIci as well, I've had both with either black or white NuBus slots. I guess it was just down to parts availability/supplier, perhaps factory location.
Noticed this on my IIs as well, my IIx had black slots, my current IIfx had white slots, and my IIfx from years ago had black slots.
 

3lectr1cPPC

Well-known member
Hard drive is probably fixable - try to see if there is any rubber bumpers on the head assembly that have gone sticky
 

jajan547

Well-known member
I recapped this machine because when you turn it on it wreaked of fish, so after recap it works but no sound and slow load up. I figured something was off so I tested with my TechStep and apparently the PSU was reading Hi at 5.83V and soft power on the keyboard won't work. I also still have no sound just a pop at boot followed by silence, also a chip had two pads eaten away one wasn't used but the other bridges to its neighbor pin as they share a trace so I bridged them. Here's where things get weird though after doing so I went to try the machine again and literally nothing it will not boot or start at all, I didn't recap the PSU so assuming it decided to die right then and there.
 

3lectr1cPPC

Well-known member
The IIsi’s PSU has awful caps. There’s 2 SMDs on the soft power board but the through-holes made by Elna I believe go bad as well and leak a LOT. A PSU recap will fix a lot of this machine’s issues for sure.
 

jajan547

Well-known member
The IIsi’s PSU is awful for caps. There’s 2 SMDs on the soft power board but the through-holes made by Elna I believe go bad as well and leak a LOT. A PSU recap will fix a lot of this machine’s issues for sure.
This is my 5th iisi and I swear they have the worst power supply ever made.
 

3lectr1cPPC

Well-known member
Yeah, knowing how bad to PSUs on these are was why I was so surprised that it turned on as is. Good luck getting it running again!
 

Byrd

Well-known member
This is my 5th iisi and I swear they have the worst power supply ever made.

Yeah they're not great to recap, especially that little vertical board that needs removal and is the site of most leakage. The power switch can also be problematic - I have to screw mine in at just the right spot for it to reliably power on. Soft power shutdown can also be problematic (or it just never turns off - you have to yank the power cable at shutdown).
 

MrFahrenheit

Well-known member
On the PVT IIsi that you have that had a 25mhz CPU, you said it came with a NUBUS adapter card. What is the FPU they installed on that card? Was it also 25mhz?
 

jajan547

Well-known member
On the PVT IIsi that you have that had a 25mhz CPU, you said it came with a NUBUS adapter card. What is the FPU they installed on that card? Was it also 25mhz?
The board on the PVT was 20MHz and the FPU is this.
 

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