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Attempting to restore a Maxell-bombed SE


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Hi, I'm SirAzazel and i'm new to the 68kmla community. I've always had interest in retro computing and consoles, but in the last year I've grown interest in vintage Apple technology, and bought for very cheap and fully recapped the logic board of an eMac to fix constant freezes of the machine, got for free a Quicksilver, G5 2Ghz DP and a Cinema Display, cleaned them, and repaired the Quicksilver video card.

 

When I was younger I was given this fully functional SE FDHD, and somewhere between 2016-2017 the Maxell battery exploded. I cleaned as best as I could the motherboard, but i didn't know what else to do so I left it at that.

 

Now I'm more experienced and I'm trying to make the SE live again. Yesterday I removed the bad U2B and U4B filter, checked continuity at the traces that looked bad (all the traces I checked were fine). I'm wondering if I'll have to remove the 26LS32 and the 8530,SCC chips.

bad_chips.png.07a3a4d37c0edd1fc3e979a01b7918ad.png

 

They look awful in my opinion, but the 26LS32 i believe are part of the sound circuit, and  thus not necessary for booting and testing the machine?

Do you happen to know what does the 8530 do? Would you remove it? I don't know where to get one, that might be a problem. Cleaning the chip's legs, board and putting it back on doesn't sound like a good idea to me.

The SCSI controller on the left of the battery looks fine, all rom chips are fine, the 68k looks fine too... The machine has 2Mb of ram and a 40Mb quantum drive that spins up and sounds great, floppy disk drive don't know if it works but I haven't got a way to test it

 

I don't know if this board will be salvageable or not, but it doesn't look as bad as I thought in the first place. If it does not work, I'll have some chips to take out and maybe use in future restorations, at least. I hope the inner layers aren't corroded and all traces work. I'm grateful I tried to clean up the mess back in the day, I don't think it had any possibility of survival if I hadn't.

 

I can post more photos if you want to see more about the board. Thank you for trying to help!

 

 

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20 hours ago, sirazazel said:

Hi, I'm SirAzazel and i'm new to the 68kmla community

 

Welcome to the forums!  Nice to have you aboard.

 

20 hours ago, sirazazel said:

Now I'm more experienced and I'm trying to make the SE live again.

 

Have you tried to power it on?  What actually happens?

 

20 hours ago, sirazazel said:

They look awful in my opinion, but the 26LS32 i believe are part of the sound circuit, and  thus not necessary for booting and testing the machine?

Do you happen to know what does the 8530 do? Would you remove it? I don't know where to get one, that might be a problem. Cleaning the chip's legs, board and putting it back on doesn't sound like a good idea to me.

 

Both the 26LS32 and the SCC are involved with the serial circuitry.  The 26LS32 is a line driver chip, they generate the actual voltages that go out of the serial port.  The SCC makes the serial ports work on a logical level, if that distinction makes sense.  26LS32s are still available new.  I think SCCs in that package aren't made any more, but they're not particularly rare, if you need a replacement.

 

20 hours ago, sirazazel said:

part of the sound circuit

 

The sound circuit is actually weirdly important in these Macs, because it monitors the voltages from the power supply to make sure they're stable.  So the computer won't actually boot if the sound chip isn't working :-).

 

20 hours ago, sirazazel said:

I don't know if this board will be salvageable or not, but it doesn't look as bad as I thought in the first place. If it does not work, I'll have some chips to take out and maybe use in future restorations, at least. I hope the inner layers aren't corroded and all traces work. I'm grateful I tried to clean up the mess back in the day, I don't think it had any possibility of survival if I hadn't.

 

Don't despair :-).  Even if you have to replace the whole LB, they're not really very rare at this stage of the game.  You might like to have a look at the SE Reproduction thread in "Hacks and Development" here, too:@Kai Robinson has a project on the go to recreate new SE logic boards, and even if that's less useful, there's lots of schematics and stuff linked in that thread that could be of use in working out whether this is salvageable or not.

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On 3/19/2021 at 1:01 AM, cheesestraws said:

Have you tried to power it on?  What actually happens?

Yes! Back in the day, the screen showed a checkerboard pattern.

Now, it shows a black screen. I hear floppy and hard drive activity, the fan spins up, but there's no video. I guess something is now dead on the LB since these machines I believe need some form of logic board input to power on the CRT.

 

I believe the CRT works though, because when I power off the machine, a vertical white line briefly flashes in the center of the screen, so the CRT works but does not display an image.

Tried manipulating the potentiometers on the analog board, same behavior the only difference was the position and brightness of the white line, so I discarded for now an analog board problem.

 

On 3/19/2021 at 1:01 AM, cheesestraws said:

Both the 26LS32 and the SCC are involved with the serial circuitry.  The 26LS32 is a line driver chip, they generate the actual voltages that go out of the serial port.  The SCC makes the serial ports work on a logical level, if that distinction makes sense.  26LS32s are still available new.  I think SCCs in that package aren't made any more, but they're not particularly rare, if you need a replacement.

 

I have just looked up on eBay for prices, and i think i'll change the 26LS30, the two 26LS32 and the 8530, they aren't particularly expensive. Do you happen to know a better place than eBay for buying replacement chips?

On 3/19/2021 at 1:01 AM, cheesestraws said:

The sound circuit is actually weirdly important in these Macs, because it monitors the voltages from the power supply to make sure they're stable. 

That's weird but kinda makes sense 8-o

 

On 3/19/2021 at 1:01 AM, cheesestraws said:

Even if you have to replace the whole LB, they're not really very rare at this stage of the game

They are in Spain, shipping costs are prohibitive here and in local listings they ask absurd prices for non-working machines...:'(

And on eBay I auctioned on some SE FDHD boards, but lost all of them.

Potentially, being my machine an SE FDHD I could put a SE/30 board on it, am I right?

 

On 3/19/2021 at 1:01 AM, cheesestraws said:

You might like to have a look at the SE Reproduction thread in "Hacks and Development" here, too:@Kai Robinson has a project on the go to recreate new SE logic boards, and even if that's less useful, there's lots of schematics and stuff linked in that thread that could be of use in working out whether this is salvageable or not.

And yes, that project is awesome! In fact, that was the first post I saw on this forum, and the reason I made an account! I'm following it, @Kai Robinson's work is amazing.

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19 hours ago, sirazazel said:

Tried manipulating the potentiometers on the analog board, same behavior the only difference was the position and brightness of the white line, so I discarded for now an analog board problem.

 

I agree that this is an LB problem, especially since it's maxell bombed, but before you do anything else, it's still worth checking the voltages that the PSU is giving out and that the logic board is receiving, because if they're not right, nothing will work, regardless of how much you fix on the LB :-).  This is especially worth doing if you've been fiddling with the pots on the AB, because some of them affect the output voltage.  You can do this externally to the machine, so you don't need to probe inside while it's powered on (an exciting proposition given how much mains power there is sloshing about).

 

Do you have a multimeter/voltmeter?  If not, a cheap one will be extremely useful.  If so, look at this pinout of the floppy connector:

 

https://old.pinouts.ru/HD/MacExtDrive_pinout.shtml

 

You can look between pins 5, 6, and 7 and ground to check that the LB is seeing the right voltages (helpfully labelled on the pinout).

 

20 hours ago, sirazazel said:

I have just looked up on eBay for prices, and i think i'll change the 26LS30, the two 26LS32 and the 8530, they aren't particularly expensive. Do you happen to know a better place than eBay for buying replacement chips?

 

For the 26LS32s, I just got them from a normal electronic parts provider when I was putting in an order anyway.  I haven't had to order 26LS30s or a replacement SCC; eBay is probably fine, if you do the normal due diligence on the supplier :-).

 

20 hours ago, sirazazel said:

That's weird but kinda makes sense 8-o

 

It's a triumph of pragmatic engineering over theoretical neatness, isn't it.  The sound chip already needs to know whether its voltages are stable or not so it can make sound, so why not make it also monitor them for the rest of the board? :-)

 

20 hours ago, sirazazel said:

They are in Spain, shipping costs are prohibitive here and in local listings they ask absurd prices for non-working machines...:'(

 

Oh, yes, I see your location now.  If all else fails, you could try posting in the trading post here; people are sometimes more inclined to part with boards and stuff if they know it's actually going to restore a machine.  And shipping often seems to be cheaper off eBay too...  Unfortunately I donated my last surplus one to the reproduction cause, or I'd offer one myself.

 

20 hours ago, sirazazel said:

Potentially, being my machine an SE FDHD I could put a SE/30 board on it, am I right?

 

You can put an SE/30 board in any SE case; the only thing to note is that older SEs don't have the cutout for a PDS card to go through.  I think SE FDHDs all have the newer chassis, but I'm not sure.  Probably someone better informed will come along and correct me.  Either way, it doesn't matter unless you're going on a card hunt...  SE/30 LBs are noticeably more expensive than SE ones, unsurprisingly, but it is a major performance boost.

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Replace the 26LS32's with: https://www.mouser.co.uk/ProductDetail/Texas-Instruments/AM26LS32AIN?qs=IF4wzcbwb3pexB1pCN0RUQ%3D%3D

 

The 26LS30's aren't available anymore - not for about 10 years, but UTSource still have billions of them available, new-old-stock. I bought about 100 of them in both DIP and PLCC format. 

 

For the 85C30 - they're also still available new: https://www.mouser.co.uk/ProductDetail/ZiLOG/Z85C3008PSG?qs=qbjGrYYs%2FskQJuc71lxRTQ%3D%3D

 

For the MC3488, if that needs to be swapped out - use the SN75150: https://www.mouser.co.uk/ProductDetail/Texas-Instruments/SN75150P?qs=%2Fha2pyFadugGewJon5jG6tUyjrmoRQINuPJj7tuCz4I%3D - they're direct pin compatible replacements (the SE/30 uses the 75175's, as do most other macs, so no issues with the 75150). 

 

Socket the PCB for new chips, too, rather than soldering in the chips. 

 

Overall the board doesn't look too bad at all - you'd really benefit from an ultrasonic clean and scrubbing the affected area's with lime juice, then tone out the pins with the multimeter to make sure no traces are dead.

 

However, i've seen MLCC capacitors that look fine, until you give them a nudge, and they turn to dust. Or the leads of resistors that look fine but again, poke them and they disintegrate - replacing all the passives in the area is certainly an idea - and yes, that includes all the axial electrolytics. Just be methodical and gentle in your approach, take your time and use plenty of DECENT flux (AMTech 559 or 223 would be fine). If you're using a desoldering gun, don't apply too much pressure to a pad, they're easy to wreck. And don't heat for too long in one spot, if using hot air, or an iron - you don't want to cause internal delamination of the PCB. 

If it all fails to work, well...keep the board to one side for the custom parts (the ADB, GLU & BBU chips) and keep your fingers crossed for the v1.5 board :D

 

 

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On 3/19/2021 at 5:12 PM, cheesestraws said:

Do you have a multimeter/voltmeter?  If not, a cheap one will be extremely useful.  If so, look at this pinout of the floppy connector:

 

https://old.pinouts.ru/HD/MacExtDrive_pinout.shtml

 

You can look between pins 5, 6, and 7 and ground to check that the LB is seeing the right voltages (helpfully labelled on the pinout).

That's a great idea! Yes, i do have a multimeter. I'll check if current voltages look right. Thanks!

 

On 3/19/2021 at 5:12 PM, cheesestraws said:

Oh, yes, I see your location now.  If all else fails, you could try posting in the trading post here; people are sometimes more inclined to part with boards and stuff if they know it's actually going to restore a machine.  And shipping often seems to be cheaper off eBay too...  Unfortunately I donated my last surplus one to the reproduction cause, or I'd offer one myself.

If it's broken, I may put a WTB post here, asking for a SE or SE/30 logic board. I'd prefer mantaining the machine in it's original state, but the speed and upgradeability of an SE/30 board are also a thing to consider.

 

And if it was broken I'd buy the SE reproduction to try to put a working SE by myself, that'll be fun!

 

On 3/19/2021 at 5:12 PM, cheesestraws said:

I think SE FDHDs all have the newer chassis, but I'm not sure

I'm 99% sure my case has the PDS slot, so it is possible.

On 3/20/2021 at 12:27 AM, Kai Robinson said:

Replace the 26LS32's with: https://www.mouser.co.uk/ProductDetail/Texas-Instruments/AM26LS32AIN?qs=IF4wzcbwb3pexB1pCN0RUQ%3D%3D

 

The 26LS30's aren't available anymore - not for about 10 years, but UTSource still have billions of them available, new-old-stock. I bought about 100 of them in both DIP and PLCC format. 

 

For the 85C30 - they're also still available new: https://www.mouser.co.uk/ProductDetail/ZiLOG/Z85C3008PSG?qs=qbjGrYYs%2FskQJuc71lxRTQ%3D%3D

 

For the MC3488, if that needs to be swapped out - use the SN75150: https://www.mouser.co.uk/ProductDetail/Texas-Instruments/SN75150P?qs=%2Fha2pyFadugGewJon5jG6tUyjrmoRQINuPJj7tuCz4I%3D - they're direct pin compatible replacements (the SE/30 uses the 75175's, as do most other macs, so no issues with the 75150). 

 

Did not know Mouser had a warehouse in Barcelona! I'll buy all the replacements I can there, they aren't expensive at all. I prefer to have all the affected chips swapped for new chips, really. Better safe than sorry.

On 3/20/2021 at 12:27 AM, Kai Robinson said:

Socket the PCB for new chips, too, rather than soldering in the chips. 

Yes, that is the plan

 

On 3/20/2021 at 12:27 AM, Kai Robinson said:

Overall the board doesn't look too bad at all - you'd really benefit from an ultrasonic clean and scrubbing the affected area's with lime juice, then tone out the pins with the multimeter to make sure no traces are dead.

It ain't perfect but I think it's salvageable. I washed it recently with soapy water and let it dry at the sun for 2-3 days but it's still not perfect. I don't have an ultrasonic cleaner, but I'll try the lime juice method. I checked continuity on the worst looking traces and they all were fine.

 

On 3/20/2021 at 12:27 AM, Kai Robinson said:

However, i've seen MLCC capacitors that look fine, until you give them a nudge, and they turn to dust. Or the leads of resistors that look fine but again, poke them and they disintegrate - replacing all the passives in the area is certainly an idea - and yes, that includes all the axial electrolytics. Just be methodical and gentle in your approach, take your time and use plenty of DECENT flux (AMTech 559 or 223 would be fine). If you're using a desoldering gun, don't apply too much pressure to a pad, they're easy to wreck. And don't heat for too long in one spot, if using hot air, or an iron - you don't want to cause internal delamination of the PCB. 

Yeah, some of the passives in the area were just disintegrating. I replaced some of the worst looking ones before removing u2b and u4b, to see if that would fix something, but made no difference. I've checked the rest of the passives nearby with my multimeter and they seem to be in spec.

 

I used an iron and a wick to desolder the chips, and now i'm concerned about the internal delamination:eek: I hope I was careful enough

On 3/20/2021 at 12:27 AM, Kai Robinson said:

If it all fails to work, well...keep the board to one side for the custom parts (the ADB, GLU & BBU chips) and keep your fingers crossed for the v1.5 board :D

That might be a very fun project to try out, and it'll sure be very rewarding to make an entire SE board by myself hahaha. If nothing works, I'm certain I'll buy one. Congratulations on your SE reproduction, it's awesome work!

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One thing to bear in mind - get axial 104 MLCC caps - all the MLCC's on the board - barring three of them, are 100nf/0.1uF decoupling capacitors. Stock up on 3.3k and 47 Ohm resistors, while you're there!

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Another thing to be aware of: crud can easily hide under the SCC. On my Maxell bombed one, there was a through-hole via that was corroded and electrically non-conductive that was hidden under the SCC. A lot of crud was there. I ordered replacements on eBay, hacked out the old one, and installed the new one after fixing the via.

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On 3/21/2021 at 5:25 PM, Kai Robinson said:

One thing to bear in mind - get axial 104 MLCC caps - all the MLCC's on the board - barring three of them, are 100nf/0.1uF decoupling capacitors. Stock up on 3.3k and 47 Ohm resistors, while you're there!

Will do when I place my order on Mouser - last time I bought passives on my local electronics store they were ridicously expensive. I'll stock on everything I may need online.

On 3/21/2021 at 7:50 PM, LaPorta said:

Another thing to be aware of: crud can easily hide under the SCC. On my Maxell bombed one, there was a through-hole via that was corroded and electrically non-conductive that was hidden under the SCC. A lot of crud was there. I ordered replacements on eBay, hacked out the old one, and installed the new one after fixing the via.

Yeah, i'll desolder the SCC too and swap it out if necessary. It looks like it has some crud under the 3 first pins, so at least I'm going to remove it, clean it, install a socket and test it.

 

 

I'll keep you all posted when I can continue with the restoration, hope i can bring back another SE to life!

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Just for reference, here is the thread of my bombed out restoration:

 

 

I believe it is the third page that shows where I took the SCC out and found the crud waiting on the board.

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On 3/23/2021 at 12:42 AM, LaPorta said:

Just for reference, here is the thread of my bombed out restoration:

This'll be useful. One question, how did you clean up the solder on all the through-holes that were cut?

I have some through-holes I can't remove the solder and part of the leg that's inside.

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I'm working on bombed-out SE at the moment, as well. For through-hole components whose legs were left stuck, I found that a repeated sequence of flux, solder, flux, solder, etc. would loosen them up enough in most cases. It really depends on the amount of corrosion. Also, taking a very fine point and scratching away the top layer of corrosion on a via or component hole to reveal healthier solder underneath helped where there was just too much crap for the flux to deal with. It was tedious, careful work, but it got the job done.

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Just as the others said, it’s just a time-consuming process. Usually, one side has better heat transfer than the others. Also, cutting it out first helped because then the chip wasn’t acting as a huge heat sink.

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On 3/23/2021 at 3:40 PM, sirazazel said:

This'll be useful. One question, how did you clean up the solder on all the through-holes that were cut?

I have some through-holes I can't remove the solder and part of the leg that's inside.

Some through-holes might be connected to the ground plane, which will soak up the heat of your soldering iron. I have a hot air gun that I use in conjunction with the iron in these cases.

 

As noted earlier, new solder (and flux) helps.

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I'd like to re-emphasize testing the power supply voltages before you go replacing everything in sight on the logic board. An out of spec power supply will mean you'll never get troubleshooting feedback and you'll spend endless days tweaking the logic board to no effect.

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Hi, yesterday I had a little bit of time and started to remove chips and clean the bombed area of the logic board. I was able to remove nearly all of the stuck legs of the through-holes, there's only the left leg of C5 remaining.

This is how it looks now.

imagen.thumb.png.1823bb8bc5789b31d73a5bcc4fd9c3f6.png

I'll remove the broken I/O shield ASAP, it looks awful.

 

Later today I'll check PSU voltages and keep you updated. I'm now waiting for U2B and U4B to arrive and continue trying to get it to show something on the screen.

 

 

 

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