Mac SE/30 logic board problem

[360alaska]

Radial vs Axial,

Radial: Leads come out of the bottom

Axial: Leads come out the sides



Technically, what Uniserver did here is alright as long as it fits, It's OK to do this but it's ugly and it makes those caps look like they don't belong. The other thing to consider is that some expansion boards may not fit, but if your ok with it it's fine...

 

[just.in.time]

Thank you 360alaska for the clarification on the capacitor style naming convention.

P.S. the Portable battery I ordered from you months ago on eBay is alive and well, in a system that finally lives again

 

[360alaska]

I'm happy that your happy! As long as you don't let it drain down too much it will last a good long time!

 

[Unknown_K]

Unknown_K: you mention the audio circuits needing the proper type of capacitor. Are the particular capacitors used not the correct type? If they aren't, could they be causing the symptoms I'm seeing? I understand that issues with the Sony audio chip can sometimes cause system wide symptoms. I'm wondering if this is related?

I was referring to audible distortion.

http://www.reliablecapacitors.com/pickcap.htm

 

[techfury90]

Ceramic caps are not polarized (current only flows in one direction), whereas electrolytics are. Audio circuits depend on the behavior differences between the types to work properly. That's why you have distorted sounding audio.

Edit: besides, if you want to have electrolytics that don't leak, tantalum is an option. This was what Apple used on the 950, which is why they're relatively immune to cap issues. Ceramic is not an acceptable substitute for a polarized application, tantalum is.

 

[360alaska]

Basically,

Your problem is likely in this area:



UE8 issues are highly probable!

 

[just.in.time]

Okay, and with UE8, are the issues usually with the chip itself, or along the traces that lead to it?

 

[Unknown_K]

The Quadra 950 and 840av came out around the same time, there must be a reason they used tants on one and aluminum caps on the other.

 

[360alaska]

traces, but a bad chip is possible, sometimes the traces are rotted and the chip is rotted too! luckily that chip is still for sale

 

[Unknown_K]

I have seen plenty of green corroded chip legs on chip, it is not hard to imagine the corrosion went into the chip where the attachment wire are much thinner and one or more snapped.

 

[Juror22]

The negative leg on C2 looks like its not soldered quite right on the chip side of the board (from the photo). I would apply a touch of solder there to be sure.  The others look fine from what I can see in the pics. (I have this exact board, with the same funky fuses)

 

[techfury90]

It's ironic given that uniserver has an entire thread on UE8 issues on ThinkClassic.

 

[techfury90]

Actually, your incorrect, those fuses are original! Here's another pic of a similar board found from google:

This is an older revision SE/30 Board! I've seen a few like that...

From the picture I looks like some of the removable chips may have come loose, i'd suggest removing and reseating them.

Sure enough, you're right! I had never seen that before so I wrongly assumed that Apple only used those silvery SMD fuses.

 

[Unknown_K]

Maybe he wants more money to fix that chip.

Recapping a board is pretty simple, diagnosing circuit issues is another story. I can see somebody wanting more money to fix a problem not related to recapping but usually they would mention the issue before sending the board back (if they do fire it up after working on it to test) so it can be dealt with.

The last board I worked on was an SE/30. Since I have a few SE/30's it wasn't that big of a deal to pop the reworked board in, test the sound, floppy, ADB, and SCSI bus. If you don't have a system to use then you can't do that. And to be honest anytime you take the system apart to swap a board you have the small chance of breaking something.

I don't know the volume of repairs Uniserver does or what he charges for them, but I do suspect people could be wanting more for him then what he charges for. Do a recap yourself and screw it up, then send it out expecting somebody else to fix it cheap kind of thing, or just sending a board out that is too far gone junk and non economically fixable.

 

[techfury90]

Perhaps he does, I didn't see it mentioned though. More telling is that judging from what he himself has said about that chip, you'd think that if he powered the board up, he'd at least have been able to tell OP that there were further issues.

Which all comes back to square one: if OP had to tell uniserver what was wrong with it, then it must imply that either the board was damaged in transit (I find that unlikely, unless the solder job was of poor quality, but that's neither here nor there) or that it was never tested after repair. Considering that he probably has an SE/30 around to test it in, why wouldn't he have done that? Why would he let the opportunity to possibly make more money doing further diagnosis slide? It's not exactly something good to think about.

In short, I think uniserver's monopoly status remained for so long because for the most part, anyone who would have been capable of accurately criticizing his repair jobs wouldn't be doing business with him anyway, as they would have done a DIY recap job.

 

[Unknown_K]

In this hobby you need to be able to repair things yourself or spend some cash to have it done. I am cheap so I learned what I needed to learn and purchased the equipment to do it.

Having the internet and forums like this make the work SOOO much easier since you can talk about it with people that have a clue and see videos of the work being done. It also helps that the equipment you are working on isn't $1000+ so a mistake while learning isn't going to be a big financial hit.

 

[EvieSigma]

I can definitely speak to the quality of Unknown K's work.

 

[ScutBoy]

Hmm - I recapped my first SE/30 board yesterday. Got everything removed and cleaned over the weekend; I did pull up one pad, but found a connection point for a rework wire.

After the cap job, on power up I get a soft "pfft" from the speaker, no bong, no video. Guess it's time to pull it back apart and start checking my work.

I picked this board since it was mostly functional to begin with - starting to get fade/static in the sound. I didn't want one that may have had other problems... Oh well - I guess this is how we learn

 

[techknight]

Let me steer you in the correct direction here.

The simasimac followed by a distorted chime is caused by the address and possibly data bus control lines broken in between the ASC, SCC, SCSI, and SWIM. Sometimes there's an ASC line that breaks between the chip and the glu.

The most common breakpoint is between the SCSI and SCC. But you may find one or two that's broken back to the SWIM

 

[EvilCapitalist]

You've been Uniservered.

Your first problem was that you sent it to Charles.

But that's impossible! He tests everything before he sends it out! It must have been damaged in shipping. (/s)

I'll be the first to admit I would be a total kludge with a soldering iron but color me surprised with that board and fervent "uni-bashing" going on here.  I know why he was banned but I've never had any trouble with the quality of his work and I've sent loads of boards to him.  The closest I ever came to having an issue was when a board I sent him was too far gone to save but he set me up with another board he had already recapped.  I got a fully working board and he got a parts board and everyone was happy.