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Rotten SE motherboard traces


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Hi everyone,

I finally acquired an SE from eBay hoping that it doesn't have any big issues. The seller claimed that it powers on boots into the disk question mark logo. It did. I asked to see a pic of the motherboard but the seller unfortunately didn't have tools to open it.

Upon receiving the SE, I opened it and took out the motherboard to clean with 99%IPA, but I found that there were some traces which are badly rotten/scratched off (see pic) They seems to lie on the left edge above the ram area. (see pics).

Before cleaning it with IPA, I didn't observe any oily/grasy area near the thru-hole capacitors, just dry dusts. I don't think they leaked (or. maybe leaked yrs ago and dried?), but I did find a dead fly on the board, maybe it ate them? Lol. The battery didn't have any leakage, I just clipped it.

 

After cleaning it with IPA Qtips, i powered it on and played with it for several days (intermittantly ~2h per day). It still works. I'd like to ask what those traces are for? They seem to connect the ram area to the "yellow single-in-line resistor" ? (sorry I dunno what the yellow thin components are).

Are those traces important? How can I fix them? For the moment, this machine has 1M ram (4*256K), 2*800k floppies hooked up to the onboard floppy sockets, no HDD, no external SCSI, no external Floppy, ADB port works.

 

I could not return this item since the seller didn't accept return, and it is "item as described" since it boots up fine, I don't want to blame the seller either since he/she tested as much as he/she could, but just to say it's risky to buy things on ebay if not thoroughly examined/tested, (since it was on ebay) I paid no cheap money for it, and it was dying, I'm feeling sad...

I hoped that I lived in an area where there're lots of yard sales of those cute things at reasonable prices.....sigh... Now if i buy another old SE board it will cost another 100 bucks.... So I'd like to seek some cheap repairing or preservation solutions.

 

I have very very limited soldering skills, will that be repairable by myself? i live in a small city in Canada, very hard to find a vintage electronic repair shop or those who have knowledge/skills to repair them. If I cannot repair them, how can I protect them from futher degradation/dammage?

Any advice is appreciated. Thanks!

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Edited by ivannudem
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Everything works?  I think it's a fair call to not give the seller a hard time - it works, and I wouldn't expect a detailed breakdown of components from any old Mac bought unless it was given a deep overhaul and indicated as such.  

 

The traces appear to be largely intact - you could test for continuity yourself.  Rubbing old traces firmly with a cotton bud can damage them, a very gentle wipe down or dusting is usually enough and you can use clear nail varnish to protect the fragile traces if particularly concerned.  SEs are one of the more rugged early Apple machines, what you have discovered is purely from age not misuse or corrosive agents.

Edited by Byrd
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Posted (edited)


Hi, Thanks everyone for the reply, maybe my pic was too small,

I zoomed them in, the major concern is to the left of the yellow RP1 and RP2,. there seems to be some traces already broken, I could not see any bronze copper at all.

I'd like to know do I need to repair them, I don't know what are the functionality/roles of those traces. What tested and confirmed working are internal Floppies, external ADB port, nothing else is tested, esp. scsi, since I don't have spare scsi drives nor external 19pin floppy drive.

 

Even if i leave them as-is, I'd like to preserve them from further degrading since this is a really old 1986 version mobo (with the "cuttable" resistor to select ram size, not dip ones), it seems to have trace copper peeling off/scratched off everywhere (elsewhere is not this bad), the photoed area are the worst places.

Does anyone know what those traces are responsible for? They seem to be connected to the ram sockets, now 1MB ram works fine, but I don't have larger ram sticks to test whehter there would be problems if I upgraded to 4MB ram in the future.

 

lastly, I'm not a grumpy retaliatory buyer, since the seller did his/her best to test/describe, It's not his/her fault. I just have bad luck....

 

Thanks.

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Edited by ivannudem
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They look intact, a hard break of a millimetre of two would be grounds for suspecting something is up, but everything works by all appearances so you're good.

 

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Hi Byrd, thanks. But I'm really concerned about this area (in pics) there seems to be only 0.1mm copper still connected, I really fears that they would chip off/oxidate overtime and just breaks...  is there a way to strengthen/repair them to make them thicker? Or I was thinking about bodge wires to connect the RP1 and the ram slots, but too complicated, I need to desolder the sockets and the RPs, since the contact points were underneath, also if I use bodge wire to reconnect, the ram slots won't sit flat on the board again (since there'd be bodge wires going thru underneath)

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These traces routing between RP1 and RP2 and the RAM SIMMs are the RAM address lines.  The filters themselves are inserted to properly condition signal reflections on these high-frequency lines.  The current-rating of the full-width traces as printed is actually quite high, around 2 amperes... far more current than is actually used.  Although 39 ohms is a relatively low resistance, still you'd have to have quite a bit more trace degradation before this is an issue.  0.1mm width should be fine.

 

Another note, looks to me like there is soldermask on the surface of the trace impurities in question, is there?  My guess is that weird inconsistencies in the soldermask thickness could make it look a bigger problem than it really is.  If the soldermask is intact, it could have been an original manufacturing defect, but the traces are protected from oxidation as long as the soldermask is intact.

 

If you are concerned about the integrity of the soldermask in the area, you can apply additional soldermask coating, or apply conformal coating.

 

rp1_rp2_detail.png.96803fb069464b1bba11018327d50a64.png

Edited by quorten
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Also it's worthy of note.  The two traces you've pointed out specifically are RA5F and RA6F.  These are easily exercised regularly by 8KB memory block accesses, so testing with 1MB of RAM is plenty.  If you're not worried about the RP1 traces on the rear side of the board, more RAM should work just fine.

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Hi 6502, Thanks a lot for your explanation. The previous owner seemed to store it in a basement for a longtime, since there are some rusts on the mounting rack (i dunno how it is called, the metal thing where there are screw wholes to mount this mobo on the mainbody).

I don't know if those were just solder masks peeling off or the actual traces has also got rotten. Its strange since nowadays most solder mask above traces are light green, but I dunno why the traces look yellow/bronze, so I suspect that to some depth the traces have also got damaged....

 

It seems to me the surface of the traces have been chipped off, but I'm not sure whether just the on-top solder mask was chipped off or it has damaged the copper below, nor did I know how thick those traces are... for the moment, everthing runs fine, the Finder will occupy 100+KB ram so it definately passed 8KB, and I've played simcity 1.1 on it which used around 500-800K more.

 

But this is really something of concern since they are ADRESS LINES! (thanks for your diagram) I really need to do something to preserve/protect/defend those address lines from being corroded/oxidated further...

Unfortunately i didn't took even higher res photos (I'll need to open the case again and discharge lol) But there some minor "chipped off" solder mask or traces (not sure how deep they are) elsewhere on the board, but not that bad.... 

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Posted (edited)

In terms of the colour of the traces, its more likely thats just the colour they used back then.

 

In terms of the corrosion on the traces, this is not uncommon for a machine of this age - it depends on how it's been stored. The solder on your board looks faded/slightly corroded too, so that would also indicate its been stored in a possibly damp/humid environment for some time.

 

But the fact is, SEs are old - so issues like this are to be expected, as with any vintage machine.

 

Check for continuity, if the traces are OK, you may want to recoat them, with new UV solder mask or nail varnish (scrape back the old mask first).

 

If you are really really concerned, luckily you can buy brand new SE boards courtesy of @Kai Robinson who reverse engineered the SE logic board, so you can now buy a brand new blank PCB to move your components onto. That obviously requires some time/effort, but it would give you the peace of mind that all the traces are brand new ! See more about it here:

 

Personally, the above is what I would do if I were you, time for a new board to start fresh, but I suppose it also depends on how much you desire to retain the original parts as well.

Edited by joshc
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Agreeing with the above; if they are working, I would be inclined give it a good clean and to coat the dodgy-looking bits with a bit of new solder mask or similar, if the copper is actually visible, and then leave well enough alone.  You can always add patch wires later, if need be, but for the moment, if there's continuity you're probably fine.  Protect it from the air and it should be good for a while, at least.

 

I wouldn't personally go down the 'new board' yet, as that one looks basically fine, just a bit used.  If traces start actually failing, it's an option to consider.  But for now, I think a light touch is probably a better option.

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Leave the board alone until it stops working (of that will ever happen, looking at the board I’d say it will just keep working forever if nothing else fails)

Adding patchwires where they’re not needed is just going to make things worse.

Those old boards have traces that are good for a lot of current by todays standards. You‘ve got a ton of room for play there even if they are corroded - which I actually doubt they are. It’s just the way the soldermask looks on those boards. All of my first rev SE boards look like that.

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On 4/22/2021 at 5:41 PM, Bolle said:

All of my first rev SE boards look like that.

 

Well good to hear that!  I was about to go down the rabbit hole of pondering how soldermask can degrade over time and allow humidity to breach the surface.

 

Also on another note, I'd add that there have been SE boards that were exposed to much more humidity than this one and have a correspondingly more corroded mounting bracket.  But apparently many of those still work fine.

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Hi, thanks everyone for the explanations. I'll leave it as-is. Hopefully this was only the non-uniform solder mask issue on top of the traces and the traces were intact.

 

I have noticed another two small problem, i'm not sure what are the causes (propably analog board need recapping? This thing was never recapped, but the caps on the Analog board didn't budge)

1. The right-hand side of the edges of windows have some artifects, seem to be extending bright-dark lines/straight ripples towards outside (right side), just 0.5-1 cm and they ended. (as shown in pics)

they're not very obvious, but I saw active listing on ebay now shows the same problem but much worse. Is this a Analogue board issue or an logic board issue? Is this capacitor related issue or chip-related, I heard that some chips on logic board such as UEx could also fail and result in bad display?

 

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2. The screen is not very very bright when the brightness knob is turned to the max (I don't know what should be the maximum brighness look like), I know at this age, all caps, even the flyback transformer are old and aging towards "death" (sad). I could live with it. I could live with it, 

but an worrying thing is that when turning the brightness knob, only the last 1/2 range seems to change the brightness, from nearly black (very very dim pics) to full brightness, and the first 1/2 range seems to do nothing, from absolutely black to the very very dim stage. Is this non linear behavior of the brightnes knob normal? Or there's something wrong with the AB or even Logic board?

Thanks.

 

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Ghosting and drifting of the CRT image is to be expected in a 34 year old computer.  Recapping of the analog board, power supply may result in a slightly improved and more stable image (in my case it made it brighter, however there remains some very mild "noise" at times).  The CRT brightness knob is quite broad in its range, what you have described when adjusting brightness is normal.  The brightness pot could be cleaned with electronic solvent cleaner spray if keen.  There are also programs to calibrate and measure the display, adjust focus with the back of the SE off, but I wouldn't consider unless particularly bad.

 

In the nicest way, you seem to be worrying about lots of things.  It's old; yes it will require maintenance, but please just enjoy it and the hobby! :)  

Edited by Byrd
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On 4/23/2021 at 6:29 AM, ivannudem said:

but the caps on the Analog board didn't budge

 

They don't always bulge, they often just leak slowly from the bottom of the capacitor. As this point, any SE that hasn't got a recapped analog board is way past due having this done.

 

On 4/23/2021 at 6:29 AM, ivannudem said:

The screen is not very very bright when the brightness knob is turned to the max


I usually advise against running old CRTs very bright anyway, it will only wear it out quicker (depending on how much you plan on using your SE).

 

On 4/23/2021 at 6:29 AM, ivannudem said:

but an worrying thing is that when turning the brightness knob, only the last 1/2 range seems to change the brightness,

 

That's normal but something that can be adjusted if it bothers you that much, it doesn't mean anything is broken or about to die though, so I would probably leave it as it is.

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On 4/23/2021 at 6:23 AM, quorten said:

Also on another note, I'd add that there have been SE boards that were exposed to much more humidity than this one and have a correspondingly more corroded mounting bracket.  But apparently many of those still work fine.

 

Yeah, one of my first revision SE boards looks like the mounting bracket has been used as an anchor for a very small boat.  Rest of the board still works fine and no particular sign of corrosion anywhere else.

 

On 4/23/2021 at 6:29 AM, ivannudem said:

I'll leave it as-is. Hopefully this was only the non-uniform solder mask issue on top of the traces and the traces were intact.

 

The SE is a robust machine, in general, and if you do need to come back and do more intrusive maintenance later, it's not particularly hard.  Relax for the now. :-)

 

On 4/23/2021 at 6:29 AM, ivannudem said:

Is this a Analogue board issue or an logic board issue? Is this capacitor related issue or chip-related

 

Almost certainly AB, but also about as expected for a computer this old.  Recapping the AB is probably a good idea, but there's no need to do anything more dramatic than that.

 

On 4/23/2021 at 6:29 AM, ivannudem said:

I heard that some chips on logic board such as UEx could also fail and result in bad display?

 

You'd know about it if they did.  One of the nice things about the SE is that because it's robust and fairly simple, when it breaks you know about it.  It's not a machine you need to look at and go 'is this sliding downwards into brokenness'?  If you have an LB video issue, generally, you will get large, unmissable artefacts.  Don't worry about it.

 

On 4/23/2021 at 6:29 AM, ivannudem said:

only the last 1/2 range seems to change the brightness

 

Has someone replaced the potentiometer on the AB at some stage with one with the wrong taper?  It's quite possible to break the legs of the potentiometer, and if someone did that then replaced it without paying attention, some of the available replacements would do that.  Either way, not worth worrying about if it does let you adjust the brightness more or less :-).

 

21 hours ago, Byrd said:

In the nicest way, you seem to be worrying about lots of things.  It's old; yes it will require maintenance, but please just enjoy it and the hobby! :)  

 

Seconding this hard.  What you have there is an SE that looks in perfectly normal condition for an SE of that age.  Do basic maintenance and it'll keep going for quite a long time.  No need to worry about it too much.

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Thanks everyone for your replies. Regarding the “CRT ghosting/drifting to the right” problem I searched carefully in the whole forum and find Someone with exactly the same problem (tho much worse than mine):

https://68kmla.org/forums/topic/60642-se30-crt-ghosting-bleeding-to-the-right/
after recapping, swapping, and ruling out several components, he finally concluded the problem comes from the CRT Itself. Recapping the analog board won’t resolve it, only way was to swap for another CRT tube...

 

So if someone encounters the same “bleeding to the right” problem, they’d know what to swap and avoid wasting time... but for the moment, i don’t have extra money for it and CRT is hard to find by now... I’d rather sell this unlucky guy and try to buy another from eBay... but once again, on eBay if it doesn’t boot to desktop with opened windows, it’s hard to judge if it has “drifting/bleeding” to the right problem only on the gray boot up/floppy icon screen (where lots of machines listed on eBay has no OS)...

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Hi,

 

your ghosting is minor and not unexpected for a CRT that's probably had thousands of hours of use.  Focusing on the CRT itself (recapping of other components aside), the slight imperfection may be due to something like movement of the magnets, yoke coil - again something you don't want to tamper with noting how good the display already presents. 

 

CRT image display is never perfect and most Apple 9" displays have deep burn in or other issues, so you're ahead.  You're not nearly close to the issue in the other thread you found. You've picked up a good unit :)

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Posted (edited)

Hi, Byrd, Thanks for your reply. I will live with it. When I opened the case, I noticed the CRT was manufacured in 1987 so more than 30 yrs.... I almost lost love for it and wanted to abandon this "child" and sell it (since i'm a bit perfectionist), but after listening to so much advice/ so many comments, I elected to keep it as raising a handicapped boy....lol. (Maybe not an approprieate metaphor, since at this age for a computer it should be a centenarian...)

 

Just curious, I'm dumb in electronics, and I don't know the details of how CRT works, I just know there is an eletron emitter/filament which emits electrons and the high voltage from the flyback transformer will accelerate/attract it towards the front screen, meanwhile the coils on the yoke will apply a magnetic field to bend the eletron beam to sweep across the screen to fully render a frame. (Not sure if i'm right?) But what part will casue this kind of ghosting? The yoke coils?

 

Thanks.

Edited by ivannudem
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