Please help -- SCSI stupidity on my part (?)

[orb85750]

If the SCSI board is the problem at this point, then why are my Zorro slot voltages so far off from what they should be showing, given that nothing SCSI is attached (not even the 2091) when using my voltmeter?  

[darksun9210]

ok hang on, whats the current situation?

you take the A2091 out of the A2000 and it boots off of floppy just fine, even with the vlab motion installed?

it shouldn't matter what zorro slots either card is plugged into.

the Vlab motion iirc uses IDE drives for recording and playback, but may require a firmware upgrade to be able to support drives bigger than 8Gb.

forget about plugging scsi into the vlab card. for t'was never ment to be! :-D

my first step would be to strip the A2000 down to bear minimum and see if it powers on. then add parts back in to see what part stops the machine from working.

if your A2091 has gone pop, then i'd sit on amibay/ebay/whatever till you spot another one, or GVP, or supra or some such. maybe even an accelerator with onboard scsi  :-) i saw a fusion40 and blizzard2060 on ebay not so long ago, so they are out there...

[Zac67]

orb85750 wrote:

Hmm...
amiga.resource.cx lists these features for the VLab Motion:
* optional digital YUV or RGB component transcoders (50 pin feature connector)
* no [...] dedicated hard drives are required
* additional adapter for direct interfacing with the Video Toaster

So the 50pin seems to be the feature connector and NOT SCSI. I figured orb had consulted the manual. Obviously that complicates matters as just about anything might have been killed. :-(

@orb85750: Try to find out which pins carry power or GND and post those here, possibly we can get an estimate of what might be damaged.
These Zorro II slot pins are relevant:
+5V: pins 5 & 6
-5V: pin 8
+12V: pin 10
-12V: pin 20
ground: 1-4, 13, 25, 37, 49, 61, 73, 85, 87-91, 99-100
The GNDs are probably all connected together so any of them will be fine for measuring.

MY VOLTAGES checked on a couple of Zorro slots:
PIN 5: +5V
PIN 6: 0V to +0.3V
PIN 8: +2V
PIN 10: +5V
PIN 20: +2.5V (some charts leave this pin blank/unknown)

In any event, my situation does not look good, given that only pin #5 is giving the expected voltage.  ANY SUGGESTIONS at this point or should I simply look to buy another Amiga 2000 and hope that most of my expansion boards still work?  I thank you for your input.  (One less working Amiga in this world, thanks to me.)

Well, to make it clear: the pins are numbered like this
1-2
3-4
5-6
7-8
...
99-100

Pins 1-4 are GND, so on the end starting with #1 you'll have two pairs of opposing pins connected together, on the other end it's only two (99-100). Then count to the seventh pair (#13&14) and check which side is GND - that side is that of #1. Provided that service manual I consulted is correct. ;-)

[orb85750]

My Amiga is becoming crazier by the minute.   The good news is that I checked the *correct* pins now in a Zorro slot and they all checked out perfectly!  With no SCSI attached, the system  booted up fine with a floppy.  Then I inserted the Vlab motion board.  The computer powered up, but the floppy drive was never accessed and I had a black screen.  Tried again, but this time, the system turned on then off completely within 10 seconds.  Removed the Vlab motion.  System turned on and off again in 10 seconds.  So, now I cannot get the system to remain on or recognize the floppy drive even with no SCSI and no Vlab motion installed.  Whatever the problem is, it seems to be getting progressively worse.  Could it be some kind of grounding issue??  Is the power supply itself very suspect?

[Matt_H]

So now with nothing installed things are going up and down? That points to a PSU issue.

[orb85750]

Matt_H wrote:
So now with nothing installed things are going up and down? That points to a PSU issue.

That sounds reasonable.  But does it make sense that my tinkering over the past few days would make the issue worse?  Before the Vlab motion install attempt, the power supply worked 100% perfectly with not a single case of sketchiness.

[Matt_H]

The timing is strange, but things gotta fail sometime. The PSU to my 1200 was working beautifully one day and  then started doing things similar to yours the next.

I'm not going to say with absolute certainty that it's the PSU, but it's probably one of the easier things to find and replace. At least try to eliminate it as a variable. And if it's not the PSU, then you've got a spare. :-)

[orb85750]

Thanks again for the sensible advice.  I will be overjoyed if the power supply turns out to be the solution and nothing else is destroyed.  -Dave

[orb85750]

What is the metal bar that goes across the A2000 case from front to back, parallel to the boards?  Is it a grounding device or is it simply there to support the structure?  It is movable, so if it is a grounding device, what is the best place for it?  

[Zac67]

Just mechanical support...
The case bottom half is one piece running from the back to the front, so there's little point grounding both ends together yet again. ;-)