MacCon SE/30 component values

[beachycove]

I have a non-functional Asanté MacCon SE/30 network card, with an obviously botched repair (replaced components) at C17 and C20. Top left. It is a Revision 2 MacCon.

Can anyone tell me the original values? I would like to see if I can get it fixed, and starting with getting C17 and C20 replaced properly seems the obvious thing.

 

[joethezombie]

Are these the small ceramic capacitors up around the FPU socket?  If so, they are more than likely .1uF ceramic capacitors.  I've never had a problem with those, but I have repaired now 2 MacCons by replacing C7, the 22μ 16V tantalum pearl.  I think that guy blows out if someone connects a monitor to the AUI port.

 

[beachycove]

That's very useful, thanks -- there's more information in that answer than I have found in hours of searching elsewhere. Would it also blow if the cable were installed in reverse, by any chance? The thing isn't keyed, so it is easy to get wrong, but I don't know if that causes failure or not.

I still want to know what those C17 and C20 values are, though. 

 

[joethezombie]

I'm not sure if it would blow C7 if the cable were reversed.  Mine still have the white dot on the pin and cable to match up, so I've never gotten it wrong.  I'm only speculating that connecting a monitor blows it out.  Seems like the only wrong thing to do that would cause damage.  Both of the ones I repaired were installed.  One in a IIsi, and one in an SE/30.

What specifically is the problem with the adapter?  Is it seen at all by TattleTech?  

 

[beachycove]

I haven't tried Tattletech. The light is on on the daughtercard, with blinking as if sending/ receiving. Software is duly installed (on System 6.0.7, and System 7.1). Switching to Ethertalk in the networking control panels yields an error, with reversion to Localtalk. The supplied Asante Troubleshooting utility tells me that it can find no NIC installed in the machine (SE/30, running at last!). Same behaviour observed the day before in a IIsi. The SE/30 has been recapped, the IIsi has not but still boots fine.

Tattletech is the superior tool?

 

[joethezombie]

It allows us to see if the system is at least seeing the card properly identified on the bus.  If it is, perhaps the issue is with the driver or IP stack.  I don't know if you have second known working MacCon you can test in the existing environment.  Is the MacCon the only PDS card installed?

 

[beachycove]

Yes. I will get Tattletech installed in the next day or so and see how far I get.

 

[beachycove]

It is unseen by Tattletech. 

So I'd still like to know the values of those two components at C17 and C20 (all the stock ones have some tiny writing on them, so these should too -- if you have a MacCon card, can you take a look?). I think I'll see if I can replace them along with C7 and maybe all four tantalum pearls. The latter should be a doddle, so maybe I'll do them first and see how far that gets me; the former are likely to be difficult because of the tight clearances, but I am sure it can be done if the new cap/s don't make it work.

Mind you, there is nothing physically wrong with the caps that make it obvious that one has failed. Do tantalum pearls burn out/ explode on failure, or can they go bad more quietly?

 

[joethezombie]

Mine have no markings on those capacitors on any of my cards.  The tantalum pearls can fail with no external cues.  The ones I repaired looked perfect.  The first one I had completely shorted out, causing the machine in which it was installed to click repeatedly.  The 2nd one also looked pristine.  It would allow the computer to start, but the card was not found on the bus.  Both were fixed by replacing C7.

Just to be clear, when using TattleTech, you selected "Nubus/PDS Slots" from the drop-down, and then checked the "All slots" box at the bottom of the dialog?  It won't show it if you don't select the "All slots" box.

 

[joethezombie]

I was also going to mention to make sure the jumpers aren't set to $FE, which would interfere with the SE/30 internal video address.

 

[beachycove]

Your second card repair sounds like a reasonable precedent for mine. I've ordered four of the requisite tants from digikey, to have some to hand, but will try replacing C7 on its own in the first instance.

As for C17 and C20, well, I finally managed to find a high-ish resolution photo (from Trash, on here as it happens), and it appears that the original caps are the same as the many small dark ones on the card. I will leave what's there in place for the present, however, since for all i know presently, they might actually be the right components.

I very much appreciate your help. If C7 can be established as a common item needing repair, it would be a real help to people trying to revive these old and now rather valuable cards. Give me a week or so to get the parts and pop C7 in, and I will be back.