SCSI Trouble -- unpowered EIII lights up when connected to a Macintosh?!?!

[viszla-ator]

ON EDIT --  May 20, 2009

I'm revising my original title and post to relflect where this issue is today:

If I connect my EIII keyboard to an old Mac, several of the LEDs on the front light up, even though there is no power provided to the EIII.  Additionally there appears to be a little bit of power being applied to the LCD.

The macs I have tested are

-- SE
-- SE/30
-- Color Classic
-- PowerMac 7100

They all cause the EIII to "light up"

If it matters, it is one of the early 4MB EIII's

I did recently change the internal hard drive, I cannot remember if it did this before I did that, as it was in storage for a couple years (I KNOW -- why in the world did I cut myself off from it that way).

Any idea what is going on and how I can fix it?

-------------------------------------------------

OLD POST

If I connect my EIII keyboard to an external scsi disk (all old ones from the classic Mac days) or to an old Mac, several of the LEDs on the front light up, even though there is no power provided to the EIII.

If it matters, it is one of the early 4MB ones. 

I did recently change the internal hard drive, I cannot remember if it did this before I did that, as it was in storage for a couple years (I KNOW -- why in the world did I cut myself off from it that way).

Any idea what is going on and how I can fix it?

[dr.c]

Your external hard disk is providing +5V by the pin 26 of the SCSI plug, wich is TREMPWR (Treminator power)

DISCONNECT IMMEDIATELY, URGENT   URGENT   URGENT   URGENT   URGENT   URGENT   URGENT   URGENT   URGENT   URGENT   URGENT   URGENT   URGENT   URGENT   URGENT 

OPEN THE CASE OF YOUR EXTERNAL HARD DISK AND PUT THE JUMPERS AS TRMPWR OFF

If you don't know how, tell wich king of disk (brand, model) or better, put here the link to load the configuration manual and I will tell you how to do this.

[viszla-ator]

dr.c:

Thanks for the reply -- I should be able to figure that out for the external drives.

However - what about the Mac?  Do you think that is the drive or is it something on the motherboard I have to tackle.

(I did not power up the EIII when this happened so I think everything is OK>

[viszla-ator]

I am beginning to wonder if it is something inside the EIII.

I have tried:

-- Mac 7100
-- Mac 8100
-- Mac Color Classic
-- Mac SE/30

and they all cause the unpowered EIII to "light up."

I am only connecting momentarily.

What do you think?

[dr.c]

Did you try to power the EIII ?

I don't like this...

If you are familiar with opening machines, check if the LARGE flat cable ON TOP of the machine, coming from the left side and going to the second board of the card cage (processor) has no trace of heat.

Let me think a bit... I don't know... it "rings a bell", these diodes... I would have to ma a course here about SCSI ans termination, but it would take me hours.

[viszla-ator]

Yes I have opened this EIII a couple times, and the one I had before too.  I may not be able to do it for a couple of days because I like to have a block of time which I will not be interrupted.

I understand the basics of SCSI termination as I worked with Mac and SCSI drives since about '87.

I will dig into the EIII manual section on SCSI as it may have some info I have overlooked.

====

As to the "new" drive I put in a little while ago, I terminated it.

If it was unterminated, the EIII won't start up (at least mine won't).

I put in a Quantum 700MB Trailblazer - Apple branded, model TR70S026 Rev 01 - A S043C.  I set it to ID2, which was how the original 40mb internal was set up.

THANKS for your help -- if anything occurs to you, let me know.

[dr.c]

I called a friend (this came back to me, I remember I fixed his machine about 15 years ago) and he said to me that his machine was doing this and he never had problems !

You wrote :

"I put in a Quantum 700MB Trailblazer - Apple branded, model TR70S026 Rev 01 - A S043C.  I set it to ID2, which was how the original 40mb internal was set up."

This is the internal disk ? Because just before, you wrote :

"As to the "new" drive I put in a little while ago, I terminated it.
If it was unterminated, the EIII won't start up (at least mine won't)."


I don't care about your internal disk ! 

WICH disk is doing problems with diodes ?

[viszla-ator]

Troubleshooting Summary:

-- Disk issue appears to be resolved.
-- Mac issue is not resolved

--

It appears that I can trace the diodes lighting up when disk attached to a particular style/brand of external drive case.

Drives that are in other cases do not cause the diodes to light.  Drives in those cases do.

Furthermore, an empty case causes the diodes to light.

These are APS brand external cases, a US company that went out of business around the time Apple dropped SCSI.

They appear to work fine with my EIIIx as well as my Roland sampler from the same era. 

Here is my guess -- the cases feature a switchable active termination.  Even though I have the switch off, it must be supplying some low level power. 

----
   BUT IT IS STILL HAPPENING with the Macs!?

Tonight I tested with a Mac SE.  Same thing. 

I would really like to work this out as I was looking forward to some retro sample editing!  You know I cannot find any mention of tech support on the emu site anymore.

====

Turns out I only have one of the EIII manuals, not the hardware one.  I am going to see if maybe emulatorarchive has it.

Thanks for thinking about this. Let me know if something comes to mind.

[dr.c]

Here is my guess -- the cases feature a switchable active termination.  Even though I have the switch off, it must be supplying some low level power.

Maybe also a bad ground, floating potential. Be carefull !
====


But, finaly, is it working, with lighten diodes or not ?

[viszla-ator]

It works with external hard drives if I use the right external case. 

It does not work with Macs. 

This is a shame because I would like to edit samples on the Mac.

I am going to change the title:

SCSI Trouble -- unpowered EIII lights up when connected to a Macintosh

Surely there are people here who have successfully connected EIII's to macs?

I did write e-mu tech support but I doubt I will ever hear from them on this.

[dr.c]

What you can try :

The SCSI should normaly be a 50 wire one, with centronics connector.

The Power termination is wire 26. Try to make a cable extension with a male and female connector, and cut the wire 26, this will cut off the PWRTRM.

If you are going from the mac to a hard disk, it should be from a 35 pin connector to a 50 pin. After then, going from the disk to the EMU. This cable can be made with two CENTRONICS connectors and flat cable. I will make a picture tomorrow, its late here now (22:00). Cheers

[viszla-ator]

dr.C - thanks I look forward to the pictures.

[viszla-ator]

Digging around in my box of treasures, I do have several flat SCSI cables.

I will need to find some Centronics connectors for this adaptor as I don't have those.

I wonder also -- with a standard 25 to 50 pin scsi cable, maybe it is possible to remove one of the male pins on the 25 pin side?  Does that make any sense?

[dr.c]

Yes, but if it dooesn't work, you won't be able to step back !!!

Prudence, first !!

[viszla-ator]

That might not be the end of the world as I have several of those cables.

However I realize that I have a couple of external cases with dead power supplies.  Those contain

50 pin female centronics ----> flat ribbon cable -----> 50 pin female centronics.  

Perfect for this extention cable.  Now if I can figure out which is wire 26.  I will pull one of this tomorrow, take a picture and post it up.

ON EDIT - ok I see that one edge of the ribbon cable is marked in RED.  Is this wire 1 or wire 50?