SUMMARY: IPC with weak (?) AUI port

From: Ted Rodriguez-Bell (ted@ssl.Berkeley.EDU)
Date: Tue Jun 04 1996 - 19:23:06 CDT

I asked why an IPC might be able to talk to the network only when it's
plugged into a Delni box. All the answers were variations on:

  Open your IPC. Near the SCSI port you will find 2 fuses (look for
  cylindrical objects about 1/4" dia x 1/4" long). The one closest to
  the side of the IPC is the ethernet fuse. The neighbour is the SCSI
  fuse. There is also a keyboard fuse near serial port B.

...And the ethernet fuse had indeed blown. For the benefit of other
people who may have this problem, the fuses are labelled 125V/2A/LF;
they're made by Littelfuse the side of the box says they're 125 volts
and "Micro 2A 273". You can't buy them directly from the manufacturer
in quantities less than 1000, but the first electronics house we
called had them in stock for $4 for one or $13.75 for five.

I took the answer from the concise words of:
        Bob Hoffman
        Birger Wathne
and other correct answers were provided by:
        Glenn Satchell
        chuck smoko
        Brian L Plante
        David Moline
        Nicholas R LeRoy
        Mike Fischbein

My thanks to them all.

In case anyone wants to know the symptoms, the original request was:

> Gentle managers:
> We're in the process of changing our whole building network from taps
> off an Ethernet backbone to 10baseT lines coming off a central hub. I
> tried to switch one of our old IPCs from the old AUI line to a 10baseT
> line via an Asante transceiver. It didn't work. The problem is that
> apparently the transceiver gets the power it needs from the network
> port on the Sun, and this machine wasn't giving it any. This isn't
> endemic to IPCs, as we have several others that are happily running
> with similar transceivers; we also tried several transceivers and none
> of them lit up.
> Making the story even stranger, the networking people tried to tidy
> things up, and changed the AUI line to this machine. It used to come
> from a Delni box (which is an AUI hub); when they changed it so it
> came directly from the ethernet tap the machine again couldn't see the
> network. After connecting the Delni box to that line and the machine
> to the Delni, the Sun is again seeing the network.
> Do you have any suggestions or even an idea of what's happening? I'd
> hate to have to get a new motherboard for this machine; it hardly
> seems worth it. Does anyone know of a source of AUI/10baseT
> transceivers that use an external power source instead of pulling
> power off the motherboard?

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