Mac SE/30: no video, no chimes - Dead even after recap

[nvdeynde]

I've got an SE/30 logic board from a fellow collector for repair, actually recap only but they apparently send me the hopeless cases.

It was dead, no video and no sound/chimes at power on, no simasimac too.

I recapped the board and checked all the traces to the capacitor. No result: it does not chime and screen remains blank.

It does not try to boot from FDD or HDD either.

Am I looking for a video issue or a power one ? The Analog board is good, 100% sure of that.

I measure +12v and +5v on the external FDD connector and speaker makes a small pop when powering on or pressing reset so it must get some juice I suppose.

I have swapped the Video Rom, UE6, UE7, UG6, UG7, UI6 ( they were socketed ) from a good SE/30 board but no dice.

I don't have a scope so I'm not really looking forward to checking all traces and VIA's in the power or video circuit so if someone could point me into the right direction that would be very helpfull.

 

[trag]

You might start by identifying the +5V pins on the common chips (85C30, 53C80, 68030, VIA, various PLDs) and check to see that there's good 5V at each of those pins.

After that I'd check continuity between CE on the ROMs and where ever that's meant to go. If you're getting nothing, then the CPU is failing to do anything pretty early in the boot process. So, either a critical component lacks power, or a very important connection.

Next, I'd check address and data line connections between the CPU and the ROM.

Is the ROM known to be good?

 

[nvdeynde]

Even without the Video Rom and Rom Simm, an SE/30 typically shows horizontal lines ( so fake Simasimac ).

It's probably a broken trace somewhere or a dead CPU as the board really doing nothing.

However there are so many traces to check if one wants to test the complete video and power circuit that I probably not going to begin with it.

I don't have a scope, I would buy one if I had the money...

Would one with the help of a scope find the cause faster ?

 

[uniserver]

dumb question, have you tried the soaking it over night in a bath of baking soda/water? then blasting it off with the air compressor in the morning?

 

[JDW]

You don't need an oscilloscope. But what you do need is a good set of schematics, a DMM with Continuity Check mode, and lots of hours of your time. Even then, you may not find the problem. I myself did just that and eventually gave up and shipped my board to our own TechKnight a year ago:

viewtopic.php?p=195477#p195477

viewtopic.php?f=7&t=18026

It still hasn't been repaired because he hasn't come across the necessary parts.

You may be better off with a totally new board. My case is a bit different though because my board has a socketed CPU, which are more rare than the soldered ones.

 

[nvdeynde]

You may be better off with a totally new board

I agree 100% that chances are thin to find the cause and it will take hours of testing traces, then again it's not even sure there's a problem with the traces.

The only problem is: who is going to sell me a working/repairable SE/30 board ?

A while I go I asked one in the Trading section and got zero replies xx(

 

[JDW]

I found SE/30 boards in EBAY in the past, although it took a few months if patient waiting. Because I live in Japan, I needed to wait for a logic board only auction, seeing the Air shipping for the entire Mac is cost prohibitive.

 

[uniserver]

I believe there is stuff that really does get damaged by ESD. You have no idea what the genius did with it before you got it.

 

[nvdeynde]

I found SE/30 boards in EBAY in the past, although it took a few months if patient waiting. Because I live in Japan, I needed to wait for a logic board only auction, seeing the Air shipping for the entire Mac is cost prohibitive.

Here on Ebay Belgium, UK and Germany, there's very little vintage Apple hardware to find. Like you say, if a Compact Mac comes for sale, it's a complete one. Parts are almost impossible to get here in Europe, Ebay USA is better but things like an SE/30 logic board is very rare.

We could use a fellow collector in the USA that buys the complete Mac and sells us the parts we need. Wouldn't that be a great project ?

I believe there is stuff that really gets damaged by ESD

I do agee that ESD can damage boards, however I still have to see my first case. Maybe the dead SE/30 board is my 1st case as visually, under a huge magnifying glass of 20x, I see nothing wrong with it.

I do pack all my parts very well myself in anti-static bags, not something I can say from the boards that were send me to me.

It's something I definately recommand to everybody.

 

[uniserver]

under a huge magnifying glass of 20x, I see nothing wrong with it.

oh really. What were you looking at? Did you have your x-ray googles on with that?

ESD damage is going to be inside the IC.

The only other way to tell is to fire it up, then probe some lines with scope or dmm.

However , w/o a custom extension cable, I have no idea how one would do that with the se/30.

 

[nvdeynde]

oh really. What were you looking at? Did you have your x-ray googles on with that?

I'm well aware that ESD damage isn't visible from the outside !

What I wrote is that the board is dead and has no visible "Outside damage" while examining is thoroughly so probably one or more IC's are dead, which can be caused by ESD.

It's one of the cleanest SE/30 boards I have had in my hands, nevertheless it's dead.

I've been going through the power schematics today and everything that should have power actually gets power so that isn't the cause, so it can be the video circuit, broken CPU or fried IC's caused by whatever...

 

[uniserver]

at work our furnace died, in the manual it listed a "start up" procedure, witch was quite useful, because of that i was able to figure out what was wrong.

SE/30 Start up-

So as soon as you hit the power switch,

? The CPU says anyone out there, Give me input

? Then rom says ok here you go.

? Then POST? Ram Check?

? Video?

? Then mouse Cursor?

? OS Strapping / Boot Procedure

 

[JDW]

nvdeynde, it cannot be said that ESD damage "to any chip" will cause Simasimac lines at startup. Some damage will cause merely a blank screen with no lines at all. And although I do not know every chip that does cause Simasimac stripes, some among us, like TechKnight, have learned from practical experience (repair of many SE/30 boards) which chip typically die and which exhibit Simasimac stripes at startup. Have a look at TechKnight's comments on that here:

viewtopic.php?p=173470#p173470

Since the BOURNS filters are a very common cause, I bought several and had them shipped to Techknight last year. But as he writes in that post, he suspects one or more other chips are bad too, so he was wanting to lay his hands on a junk (nearly impossible to repair) SE/30 board so he could extract those chips and put them on my board to see if that would resolve the Simasimac.

But the fact remains that if a trace is broken, then changing out any number of chips won't fix your board. So examining traces with both high magnification AND a DMM with Continuity Check (while using schematics to guide you) is time consuming but not in vain. It's just that after confirming all the traces are good (as I myself did with two SE/30 boards I shipped to Techknight), and after pulling all the socketed chips and replacing them with known-good chips from a known-good SE/30 board, there still could be one or more chips (possibly including the BOURNS) that would need to be replaced to finally fix the board.