SE/30 simasimac - beyond recapping

[yoyomac]

Hi. I'd like to get some input from the experts out there. I got a SE/30 showing terminal simasimac symptoms (horizontal zebra stripes). Following the common advice I replaced *all* the caps C1,...,C13 on the motherboard and still get the simasimac. Pursuing further based on the recommendations at I "pulled up" the sound chip UB11, no success, still getting the simasimac. Last, I was going to replace the Bourn filter in RP2 but I'd like to get some feedback as to how likely it is to be the actual fix to the simasimac. The Mac did boot successfully a couple of times (erratically though) since the repair if I left it turned on with the simasimac for a couple of minutes, then turned it off, back on, etc.

Also I did try 2 different ROM SIMMs and cleaned up and reseated the RAM SIMMs, plus cleaned the board with compressed air between each soldering and the battery is only 2 years old, all to no avail.

Anybody experienced this situation or have a suggestion what to try next? Appreciate your help.

 

[Dennis Nedry]

Try wiggling each new capacitor. I find it quite common that one side or the other may appear soldered but in fact the solder did not "stick" to the pad on the logic board. A continuity tester could be helpful if you really want to be 100% sure.

Look for any deep scratches on the logic board too. I have a IIci with a deep scratch, and that required extensive repair.

 

[jsarchibald]

Dennis may well be right.

I came across a bunch of faulty eMac 1.25GHz computers, 7 have been successfully repaired by replacing the 8 dodgy capacitors (a well known and documented fact), and a further 4 still need repair. My guess is that the computers all still require further soldering, as Dennis alluded to. When I find the time, I'll take them apart again and touch up the soldering.

 

[yoyomac]

No luck. All the caps are solidly soldered and I checked there's good contact with a continuity tester between the cap and the back of the board. Has anybody experience replacing the Bourn network filter RP2 and successfully cure simasimac?

 

[Unknown_K]

Look for a broken trace, capacitor leakage could have taken out a copper trace.

 

[phreakout]

yoyomac,

Yes, I have had some marginal success in resurrecting a Simasimac-prone SE/30 logic board by replacing the Bourns filter. But the replacement doesn't work for every single board; only a select few that have been recapped by me needed their RP2 replaced. I ended up salvaging replacement filters from off of a dead Mac SE logic board I had laying around. They match the exact same part as the original SE/30 filters.

Good luck trying to get new replacements from a parts vendor like Mouser or Digi-Key. They sell 'em, but you end up having to buy more than 150 quantity at about $2 or $3 each. It will be cheaper to either pull 'em from a dead SE or SE/30 logic board or build one from scratch, like described in the Repair Mac article. Use a chip socket and wire up your own shouldn't be hard, either. Oh, and if you do replace part for exact part, make sure you install a chip socket anyway. It makes replacing that filter much easier than having to desolder it out of a board. I've had my share (too many) of legs broken off during the extraction process.

73s de Phreakout. :rambo:

 

[yoyomac]

Update. This is a good one. I ended up replacing the Bourn filter RP2 with a replacement I plucked from a dead SE/30 board (my first experiment with replacing the caps a couple years ago...) pretty much like Phreakout described. Excruciating process, took me a good hour just to extract it. It turned out not to help my simasimac problem unfortunately. At this point I was ready to give up and started browsing ebay for a replacement. Then I recalled a number of posts on the web about putting the motherboard in the dishwasher. I had nothing to lose but a couple of drops of dish soap, and it was a good way to pay my last respects to my SE/30... I washed the board carefully in soap water with a toothbrush and spend the next 12 hours hair drying it and blowing canned air at all angles every hour until dry. I mounted the board back in place, turned the power on and -- mirabile dictu -- the Mac showed me a nice uniform gray screen and started booting!! Unbelievable. There was no obvious trace of gunk on the board but a good clean up apparently took care of some bad contacts somewhere. I have been using the Mac for several hours since and it works fine. I did get an occasional 4-tone chime with the zebra stripes, but it might be because I didn't solder the RP2 (I just plugged it and bent the legs over the grommets for contact, traumatized by the idea of having to desolder it back). In any case that is great progress. Hope this story can be helpful to someone.

 

[yoyomac]

Btw, regarding supplies of the RP2 Bourn filter 4120R-601-250/201, I saw Quest Components appear to have them for $3/pce (2-8 units), minimum order $25. I didn't order since I could recycle one from my old board but probably worth it if you plan on servicing a couple of Macs.

 

[phreakout]

Can you describe in good detail what you did as far as washing the board in a dishwasher? I'm intrigued to maybe try it myself. Since I started this recapping business, I've been a bit fearful of damaging boards using this cleaning process, so I resorted to using a small wire brush and pick kit (you can get them at Radio Shack, btw; small yellow handle tools and a plastice bag) along with a bit of Isopropyl Rubbing Alcohol and lots of Q-Tips.

One interesting note, though. Apple, along with many other electronics manufacturers in the 1980s or 1990s, must have switched to a different type of solder. The mixture seems to need more heat in order to melt and is a bit cloudy, almost a light or darker gray cloudy color to it. This is part of the reason why it is so hard to remove lead-through-PCB components. That and the holes drilled into the PCB are smaller in diameter than what they ought to be.

yoyomac, this paragraph comment is in regard to the 3rd from the last sentence in the paragraph, about 2 posts ago. That is where I recommend using chip sockets for anything that is a genuine chip (IC) or looks like one (like RP2). I don't know where Apple went wrong by not putting sockets on their boards for every single IC, but that just makes my job more tedious to complete. With sockets, there's no need to desolder the old component out and resolder the new one in place; just pull out the old part and slip the new one in. Takes less than a minute to do.

Sorry, just one of my biggest gripes when it comes to electronics design. I guess they neglected this simple step after the Apple III debacle. Well, it wouldn't have happened if Jobs had allowed cooling fans be added to every single computer built. Woz was right all along. He thought these simple details out ahead of time, so he wouldn't have to deal with fixing it later. Why spend all your time fixing a hardware problem when you could be using the computer. A perfect example: The Apple II/II+/IIe.

That's my $.02. I'll get off my soap box for now.

73s de Phreakout. :rambo:

 

[Mac128]

Phreakout, you just stick the board in the dishwasher and thoroughly air dry it. Search these forums and google it. There are dozens of threads about it because people are always so shocked to find it almost always works.

Also, I've never seen a PC where every IC was socketed. Its just not cost effective. Apple had reasons for doing what it did, in any event, good or bad.

The Apple iii comment I don't get at all. It had lots of sockets, which partly contributed to the problem. But the main reason for the Apple iii debacle was poorly manufactured circuit boards where the traces did not have enough separation in some cases. Jerry Manock who designed the chassis conducted extensive tests confirming the fanless design was rock solid. He was later vindicated after the true problem was discovered. A fan was never added to the iii, yet inexplicably the problem went away a year later? No, the logicboards were corrected and the machine worked flawlessly, but it was too late, it's reputation was spoiled beyond repair, and the original myth is perpetuated. The main reason it failed had more to do with lack of software and failure to embrace the apple II as the later iigs did. As far as fans, many of our more knowledgable members will tell you with the correct components, Manock's fan less Macintosh works just fine.

 

[Concorde1993]

The Apple iii comment I don't get at all. It had lots of sockets, which partly contributed to the problem. But the main reason for the Apple iii debacle was poorly manufactured circuit boards where the traces did not have enough separation in some cases. Jerry Manock who designed the chassis conducted extensive tests confirming the fanless design was rock solid. He was later vindicated after the true problem was discovered. A fan was never added to the iii, yet inexplicably the problem went away a year later? No, the logicboards were corrected and the machine worked flawlessly, but it was too late, it's reputation was spoiled beyond repair, and the original myth is perpetuated. The main reason it failed had more to do with lack of software and failure to embrace the apple II as the later iigs did. As far as fans, many of our more knowledgable members will tell you with the correct components, Manock's fan less Macintosh works just fine.

He wasn't referring to the III at all, just the II, II+ & IIe. The III was a joke, btw. I am still in the process of getting one for $35 as they are quite rare.

Yoyomac- washing the motherboard sounds intriguing! I wonder if it would work on a Plus that has the wavy-line syndrome.

 

[phreakout]

Okay, my last 2 comments were basically a ranting over the fact that it is simple common sense when you design something. Steve Wozniak put chip sockets on the Apple II series because he didn't want to waste time desoldering faulty ICs from the PCB. Adding sockets would take him less than a minute to replace the part, compared to several minutes trying to desolder the ICs legs from each contact.

When Apple developed the Apple III, they did include chip sockets on the logic board. But Steve Jobs's decision to not put cooling fans in the Apple III caused one major problem; the heat generated while powered up and running caused the metal in the sockets to expand and eventually work the ICs out of their sockets. When this happened, the Apple III would appear DOA. Apple's solution to the matter was to literally lift the machine up off of the desk and drop it. This would cause the chips to reseat themselves. I don't believe that would even work all the time; you'd still have to get inside the case and reseat the chips by hand anyway.

The Apple III was not designed by engineers or technicians. It was designed by a committee or marketing department. If anyone has a copy of the book iWoz, look on page 226 through 230. I know that Woz doesn't explain about dropping the Apple III on a desk as a solution to its problem, but there are other sources that do mention about it. Yes, the problem was eventually fixed, but it tarnished the Apple III's reputation as being a serious business machine. And even Macs that are all-in-one models have similar heat problems, due to the case design and whether or not they have a fan.

Mac128, I do recall seeing DOS/Windows PCs with motherboards that have every chip socketed. Mostly they were clones of IBM XT and AT architectures from the 1980s, but in the 1990s it became a lesser known feature. Once boards started being made with only SMT components, then the need for sockets became less. Yes I did take a pot shot at the Apple III, but it was meant in good taste and to state the facts about good design practices, especially in electronics. I come from a background of being taught the old school way for modern design. It may cost just a bit more, but if it proves to make repair easier, then use it.

73s de Phreakout. :rambo:

 

[Mac128]

Phreakout, you are perpetuating an urban legend, most likely started by a disgruntled Andy hertzfeld or Daniel Kottke whom Jobs had denied stock options. There was no heat problem with the Apple III, Jerry Manock proved this with extensive tests and cleared his name at the time. The problem with the III was entirely related to the logic board. Again I ask, how did they produce a fully functional Iii a year later without fans and prevent the chips from continuing to pop out? The answer is, there was never a heat problem to begin with. Most of the chips came out of ill-fitting, loose sockets during shipping. Later IIIs used higher quality sockets and gold connections. It was this that caused the normal heating and cooling of any computer (even one with a fan) to contribute to chips working their way out of their sockets. As for a board full of sockets, there are definitely items that are better soldered to a board than socketed.

 

[H3NRY]

The original /// had a problem with the RAM module which plugged into the motherboard with the cheap tin-plated pins and sockets common at the time oxidizing, as well as chips walking up out of sockets. It did get pretty hot inside the case, since there was no airflow, and that aggravated the problems. Switching to higher quality sockets and connectors which could take a bit of heat solved the reliability problems, and Apple replaced the early boards for free.

The main reason the /// failed is Apple deliberately made it incompatible with software for the Apple II except for the most basic, low-end stuff. They didn't want customers running the Apple II Visicalc and accounting packages on the new machine. They believed people would replace their software just as Apple I owners had when the II came out. The difference is Apple I owners' libraries consisted of a half-dozen cassettes of utilities and a game of "Hunt the Wumpus". Apple II owners had large libraries which they were reluctant to discard, and there was very little software for the ///. The /// was also quite expensive compared to a II with an 80-column card and an accelerator which was functionally equivalent and in fact about twice as fast.

When the /// came out, I was very disappointed at its limits. Same for the IBM PC. It took the Mac and a year of software development and hardware hacking before my main computer shifted away from the Apple II. In fact, my early Mac programs were written and debugged on the Apple II with the S-C 68K cross assembler.

 

[jsarchibald]

phreakout, I made your signature! I am very chuffed, what an honor!

 

[phreakout]

Off Topic: (jsarchibald) - Yeah, I happen to see you post that in another thread and thought it was rofl. Is it okay that I use it in my signature area? If not, I'll remove it. Your welcome, btw.

On topic, somewhat: (Everyone else) - I'm willing to accept all possible answers. Some of what I've heard might be folklore and some may in fact be the truth. It's really hard to say who is right without admitting that you were there and witnessed all these events. By that, I mean that you were an engineer or some higher up position at Apple and were privy to all the facts. Since we all know that Apple keeps to themselves and never divulges the truth, we have to come to our own conclusions as to what might have happened. My sources were taken from Apple Confidential 1.0, 2.0 and iWoz. Wozniak is worthy enough and has recorded his memories for us to enjoy. I can imagine he would only be dishonest if he were joking and all in good spirits.

73s de Phreakout. :rambo:

 

[Mac128]

Phreakout, Apple confidential is wildly speculative and contains some biased inaccuracies based on who they were able to get statements from at the time. Granted we all go on available sources, but Woz didn't actually say that by your own admission. Plus there is a bit of revisionist history with all of these characters. However, the thermal issues were debunked by Manock himself in a lecture, where he discussed the sophisticated tests used to prove the problems lay elsewhere, since everyone pointed the finger at him immediately. In fact it was Manock's tests which led them to scrutinize the logic board more closely and discover its microscopic flaws. The myths persist, because nobody really cares about how something is resolved, they tend to run with the first thing they heard. The real failure of the Apple III was that after the initial launch the sales and marketing people wanted nothing to do with it, so there was never any effort put into clarifying what the real problem was, and thus it died, with most everyone remembering it was because of a poorly designed case.

 

[yoyomac]

Back to the original topic. So after the wash the Mac worked fine for 2 days then started giving the simasimac increasingly frequently and now it's back to not booting any longer, sitting at the zebra screen. I went around my new caps and resoldered a few, also I did solder the replacement RP2 for good but it didn't help.

One question I have to ask though. The specs for cap C6 are 1 uF 50V, the closest I could find at the local electronic store (RadioShack) is 1 uF 35V, I was wondering if there could be a problem of premature failure under stress. I had a C6 at 1 uF 35V on a different board run fine for several years but I wanted to ask.

 

[Concorde1993]

One question I have to ask though. The specs for cap C6 are 1 uF 50V, the closest I could find at the local electronic store (RadioShack) is 1 uF 35V, I was wondering if there could be a problem of premature failure under stress. I had a C6 at 1 uF 35V on a different board run fine for several years but I wanted to ask.

You always want to find a capacitor with a higher voltage rating than the original cap in order to compensate for fluctuations in the power supply (i.e., surges, etc.). I learned this when the capacitors were being replaced on my Plus. A capacitor with a lower voltage rating will not be able to tolerate the stress of the power supply, so try to find one with a higher voltage rating. Furthermore, I would recommend finding a capacitor made by General Electric (or any well-known brand; avoid anything made exclusively by RadioShack). They are very reliable, and will save you from having to repair the Mac again.