MacCon SE/30 ethernet SMD components

[beachycove]

I just went out and bought a multimeter to try to diagnose the problem with a failed SE/30 MacCon ethernet card. The multimeter tells me that two of the SMD components on the card are bad. Everything else on the card seems good.

The components in question are at the top left, where the ribbon connects, at C17 and C20, and are both marked/ labelled A5.

Naturally, I now want to source the components and replace them, but having been trained in the Humanities and being new to this kind of thing, have a dumb question about the meaning of that label: Am I looking for a couple of 5A SMD fuses, A5 diodes, transistors or something else?

 

[phreakout]

Pics please. :b&w:

73s de Phreakout. :rambo:

 

[beachycove]

As you insist, this is the actual item. The failed SMD components are not actualy visible in the photo, as they are between the 68882 socket and the ribbon connector, but they are identical to the two tiny brown/ silver components visible in the photo, immediately to the left of the 68882 socket. They both read A5.

I do not have the tripod etc. necessary to get a proper close-up; being bifocally challenged, I could only see the minute lettering with a magnifying glass.

My working hypothesis, based purely on a Google search for "SMD A5," is that they are diodes. There are maybe 12-15 of them scattered over the surface of the card, so they could hardly all be fuses.

 

[wally]

SMD multilayer ceramic capacitors are sometimes marked with two digit EIA code for capacitance value. A5=.1 microfarad.

See http://my.execpc.com/~endlr/markings.html for SMD ceramic cap markings.

Probably these are capacitors, especially if their positions are marked on the PC board with C prefixes followed by unique numbers.

 

[phreakout]

Okay, the "A" either stands for Attenuator or Assembly, more preferably "sub-assembly". I'm leaning more towards attenuator. I doubt it could be anything other than that.

Update: wally has beat me to it. He may be 100% right. It's hard to tell from the angle the pic is made at.

73s de Phreakout. :rambo:

 

[beachycove]

I will go with Wally's suggestion, given the provenance. The board is old enough to use such markings and the locations of most (not all) of the A5-marked SMD components have C plus a number written, thus C17, C20 in the case of my two.

Thanks.

 

[dougg3]

I'm late to the party, but I just wanted to third the suggestion that they are capacitors. I have an Apple ROM SIMM from 1990 that has several SMD capacitors that also say A5 on them (standing for, like wally said, 0.1 uF).