1990 Apple Macintosh SE/30 Repair & Restoration

Way back in 2023, I bought my first Apple Macintosh SE/30, to go alongside my 1986 Mac Plus, 1991 Mac Classic I, and 1993 Mac Classic II. This was in unknown condition and bought sold-as-seen on eBay, requiring at least service and probably repair – it came with its matching MO116 ADB keyboard and G5431 ADB mouse.

The Macintosh SE/30 is a personal computer designed, manufactured and sold by Apple Computer. It is the fastest of the original black-and-white compact Macintosh series with a 16MHz 68030 CPU with 68882 FPU and up to 128MB RAM, included either a 40MB or 80MB HDD, and had a 1.44MB 3.5″ FDD as standard. The SE/30 wasn’t discontinued until 1991 when it was succeeded by the Macintosh Classic II, which – despite featuring the same CPU and clock speed – was not as fast as the SE/30 due to its 16-bit data bus; it also only supported up to 10 MB RAM, lacked an internal expansion slot, and made the FPU an optional upgrade. Its relative rarity and its status as the fastest and most expandable compact Mac make these quite collectible, and even non-working examples typically sell for quite a lot of money.

The Macintosh SE/30 suffers from three major problems:

• They have a 3.6V lithium battery in a holder on the mainboard to power the battery-backed PRAM and RTC, and these have a habit of physically leaking corrosive battery alkali (see “battery bomb“) and causing damage to the mainboard and chassis.
• The SMD electrolytic capacitors on the mainboard have a habit of failing and physically leaking corrosive electrolyte, which can not only prevent the system from working, but can also cause damage to the PCB and its components – see my general advice for electrolytic capacitor replacement for more detailed information on the process of replacing them.
• The connectors between the analogue board and CRT display often get cracked solder joints due to mechanical stress which can cause intermittent connections and loss of video – sometimes hitting the side of the machine can bring it back temporarily, but the solder joints need to be reflowed.

I must therefore emphasise: if you have an Apple Macintosh SE/30 in original condition, it needs to be serviced! The original battery needs to be removed, and the original electrolytic capacitors need to be replaced. These systems are dying, day by day.

Testing the computer

On its arrival, it seemed to be in good physical condition, however it had a disk stuck in the drive and when I tried powering it on it didn’t chime and it only displayed horizontal stripes, commonly known as a “simasimac” pattern indicating hardware failure.

The next step was to open the computer up and check inside.

Disassembling the computer

If you work on a CRT or any other mains-powered equipment, you do so at your own risk – please refer to my general guidance for working on CRT displays.

The Mac SE/30 is easy to dismantle with basic tools: there are four torx T15 screws holding the rear case in place, two near the mainboard ports at the bottom rear, and two inside the carry handle recess at the top rear (which will need a long screwdriver bit or “Mac Cracker” to access).

With the case opened, it was immediate disappointment. There was a lot of corrosion on the mainboard shielding and case inner paintwork, which could only mean one thing: a leaky PRAM battery. The interior was also incredibly dusty and dirty, everything was covered with a thick, sticky, and metallic dust.

The digital board is removed by sliding it out along its two holding rails and disconnecting it from the analogue board, floppy drive, and hard drive. This unit also had a PDS network adapter fitted, which needed to be unscrewed from the chassis so the board could pull out, then it unplugged from the PDS slot.

As soon as it was out, it was clear that it was a complete mess – battery leakage covered the entire bottom corner of the board, up to the ROM SIMM, FPU, and video ROM. There was even leakage on the underside of the board. It was immediately apparent that saving this machine would require a lot of work.

Digital board assessment

The digital board was a complete mess, and the thick layer of dirt made it difficult to properly assess the damage from the battery leakage – I removed RAM SIMMs, ROM SIMM, and the remains of the battery and holder, then cleaned the board off with deionised water and blew it dry with an air blower.

There was still some more persistent corrosion underneath the old battery holder which I had to scrub off before I could properly see all the trace and via damage; I also removed some of the surrounding components including the RTC IC which was destroyed, and I also removed all of the SMD electrolytic capacitors from the entire board – these had started to leak and caused nasty corrosion to their pads.

The battery corrosion had also spread to underneath all of the SMD ICs in the area, as well as under and into the PDS slot and ROM socket, corroding the contacts. I removed the RAM multiplexers and some of the resistor packs, and the damage was significant – there was a lot of trace damage and some component pads were non-existent.

Even the ROM SIMM was badly corroded, though I managed to clean it up to some extent using a fibreglass pen. I had no way of testing whether it actually worked.

I attempted to fit a new set of eight RAM multiplexers and fix their traces and pads, and whilst this was somewhat successful, it took a long time and was very difficult due to the traces being so thin and so badly damaged. I looked at the extent of the damage to the rest of the area – the wrecked pads, traces, and vias – and decided that this board was realistically beyond saving, so made an alternate plan.

Digital board rebuild

Battery leakage is such a common problem that there is actually a community-made reverse-engineered replica design for the SE/30 PCB, which really is an incredible piece of work – you can actually go to a PCB manufacturer such as JLCPCB or PCBWay and buy these boards with whatever finish you’d like.

This is quite expensive unless you’re buying them in bulk, though. Will at CayMac, a vintage Apple enthusiast and repair specialist, very kindly sold me a spare purple PCB which already had most of the small parts (“birdseed”) – capacitors, resistors, diodes, and transistors – populated, though is missing thirteen ferrite beads on the underside and Q1, Q2, and D3 on the topside that need to be transferred across.

Most other parts are available to buy off-the-shelf with the exception of a handful of custom Apple ICs, which can only be bought as new-old-stock or taken from a donor SE/30 mainboard. A full bill-of-materials is available here.

I started the rebuild by salvaging all of the through-hole components from the original board, though not all of these would be re-used.

The mainboard support bracket was difficult to properly desolder as it has a large thermal mass. It was also quite rusty, so I cleaned it up with a wire brush.

I then removed each SMD IC with hot air and fitted them to the new board one by one, taking care to ensure that they were cleaned off underneath and soldered correctly – excluding the RAM multiplexers which I bought new.

Soldering the SMD ICs first like this gives you enough clearance to be able to properly solder them into place and inspect that they are correctly seated and fitted.

I then installed new electrolytic capacitors – the original SMD parts were aluminium electrolytic capacitors with a liquid electrolyte, however its very common for those recapping compact Macs to use tantalum electrolytic capacitors – these use a solid electrolyte, meaning that they will not physically leak. See my general advice for electrolytic capacitor replacement for more detailed information on the process. A capacitor list for the SE/30 digital board is available here.

I also fitted three replacement fuses at F1, F2, and F3 using 1.1A 8V 1812-sized self-resetting polyfuses, as the originals fell apart when I tried to remove them.

I then started installing all of the through-hole components, including sockets for any standard ICs as well as a CPU socket, replacement RAM SIMM and ROM SIMM sockets, and a new PDS slot that I got along with the board from CayMac – the CPU was not socketed from the factory on this board, the original RAM SIMM sockets were of poor quality, the original ROM socket was damaged by battery leakage, and I didn’t trust the old PDS slot either. The new board uses a CR2032 coin cell for its PRAM battery which is unlikely to leak, so I bought a new holder. I also built and fitted a replacement RTC based on the ATTiny85, as the original RTC was destroyed.

Analogue board rebuild

Before testing the new digital board, I wanted to clean and service the CRT neckboard and analogue board, which generates the main power supplies for the digital board as well as the high-voltage and vertical/horizontal deflection for the CRT display.

This primarily involved reflowing any bad or suspect solder joints, replacing all of the aluminium electrolytic capacitors on the board, and fitting a new cooling fan and connector. Unlike earlier compact Macs, the SE/30 does not have RIFA mains filter capacitors which need to be replaced. The PSU is also serviced later.

The analogue board is held in place to the chassis with four cross-head screws and an earthing wire – two of these screws have a metal contact sheet around them. The CRT anode cap can be disconnected and the neckboard removed, the CRT yoke connector removed, and the analogue board carefully pulled out – all of this taking care not to damage the delicate neck of the CRT.

The SE/30 analogue board has a standalone PSU which supplies the main voltage rails for the system – this simply unscrews from the analogue board and unplugs from P3.

The insulation on the back of the analogue board is held in place with four plastic clips.

Cracked and cold solder joints are common in equipment of this era, especially on joints which are under physical stress, such as on connectors and under heavy components like the flyback transformer – it’s a good idea to check over the boards looking for bad joints, as these can cause all kinds of weird and intermittent issues. Ideally the original solder should be removed, and replaced with new solder. In this case, there were bad solder joints on the CRT yoke connector and brightness control potentiometer, so I reflowed these joints as well as those on the flyback and all other connectors.

The SE and SE/30 analogue board using through-hole aluminium electrolytic capacitors which are typically fairly reliable, however I still decided to replace them as a matter of course – see my general advice for electrolytic capacitor replacement for more detailed information on the process.

I couldn’t find any commercially available capacitor packs for the international version of the Mac SE analogue board, so I just made up my own by noting the specifications of all of the electrolytic capacitors on the board, and ordering a set of high-quality known-brand (i.e. Panasonic, Nichicon, etc) 105C-rated parts – a capacitor list is available here.

The original 3.9uF 35V bipolar capacitor at C15 is no longer available, so I replaced this with a 3.9uF 250V film capacitor – this does not fit the exact same 8mm footprint but can be made to fit by bending the leads. Some SE analogue boards already have a film capacitor fitted to C15 from the factory, which likely does not need to be replaced.

The original cooling fan was quite loud due to its bearings wearing out, so I decided to replace it with a modern 60mm x 15mm 12Vdc fan. This came with a JST-XH connector pre-fitted, so I also installed a 2-pin JST-XH header on the analogue board – this required modifying the PCB slightly by drilling a hole for the ground connection, but makes the wiring far neater and allows for the fan to be more easily changed.

I also decided to replace the flyback transformer with one from an analogue board with fewer hours on it – it seemed to be working OK but the glue around the core had went very dark from absorbing moisture and the core band had started to corrode, which indicated a hard life and likely a shorter usable lifetime. I salvaged the other part from a second battery-bombed SE/30 that I bought to try and get a working system.

The analogue board was then reassembled and tested.

If you lose any of the plastic pop-rivets for the rear cover, you can still buy R3055 parts.

Power supply rebuild

The SE and SE/30 had a couple of different types of PSUs – this machine has a Sony CR-44 PSU for which a capacitor list is available here and a capacitor kit is available here.

I also replaced the two mains filter capacitors with suitable 220nF safety capacitors.

Digital board testing and diagnostics

With the rest of the system serviced, I could now test the rebuilt mainboard, and unfortunately I still had exactly the same symptoms as when I’d started: no startup “bong” and horizontal stripes on the display. This heavily implied that at least part of the original issue had been transferred to the new mainboard.

I tested the system using a known-good set of RAM and ROM SIMMs and a video ROM, and there was no change in symptoms – the symptoms were the same even without any RAM, ROM, or video ROM installed, implying that the system was failing to boot quite early in the intialisation process.

It is difficult to get access to the SE/30 mainboard in-situ for testing, however it is possible to test the mainboard outside the case using a speaker on flying leads and a 20-pin ATX extension lead, which handily fits the digital-to-analogue interconnect.

I ended up getting so desperate that I even bought a second sold-as-seen SE/30 on eBay in case it had a working mainboard to take parts from, however unfortunately this was also battery-bombed and in similar condition to the first one. It ended up being quite useful for salvaging parts from including the CRT, flyback transformer, and ICs.

I replaced UI12 (AM53C80 SCSI controller) and UG12 (Z0853006 serial controller) as these were running quite hot and had been hit by leaked electrolyte from the old capacitors, however there was no change in symptoms.

All original PAL ICs (UI6, UG6, UG7, UE6, UE7, UH7) were running quite hot, especially UH7, so I programmed and fitted all replacement parts, however there was no change in symptoms. UH7 is a PLCC package and is quite tricky to solder properly, so I fitted a socket onto it to ensure proper contact, but again there was no change in symptoms.

I triple-checked my soldering and work at this point – there are a total of thirteen ferrite beads on the underside of the board that need to be swapped and it turns out that I had only swapped twelve of them, I had missed L15. This meant that power was not being provided to part of the mainboard.

After swapping L15, the system still only displayed horizontal stripes but it now made a long “chime of death” startup sound which didn’t stop. The SE/30 has a long and short “chime of death” which indicate hardware failure – typically a long chime like this indicates RAM/ROM access issues, and the fact that it occurs immediately at boot indicates that the RAM/ROM test is failing very early on. The chime should stop after its last note, so it seems like the system is crashing after this test.

I decided to try replacing some of the smaller logic ICs which had been transferred from the old board and these are fairly cheap and were likely exposed to electrolyte due to being close to several capacitors, specifically UD8/UC8/UB8/UA8 (74F253s), UE8 (74LS166), UG8/UF8 (74LS393s), and UJ6 (74LS30).

Now the system still only displayed horizontal stripes and gave a long “chime of death”, however now the chime stopped so the system didn’t seem to be crashing any more.

I managed to borrow a working SE/30 mainboard for testing so I could check some of the SE/30-specific parts in a working system – I did this for the ROM SIMM, RAM SIMMs, video ROM, and DIP PALs, which all tested OK. I also tested the non-working mainboard with the video ROM and DIP PALs from the working one, with no change in symptoms.

I tried removing both video RAM ICs and the system still gave a death chime but nothing on the display – with only one VRAM IC fitted it gave a checkerboard pattern, so I assumed this meant that the VRAM was probably OK.

I did some other basic checks: Y2 was outputting a 32MHz clock as expected; I checked continuity along the address/data line path which includes the video multiplexers, RAM multiplexers, RAM, ROM, VROM, CPU, VIAs, etc, which seemed OK; I checked soldering on the UH7 socket, checked the signals on UH7, and tried with another original part installed, but everything seemed OK. I resoldered UE10, UH7, both VIAs, the ROM SIMM socket, CPU socket, resistor packs, and RAM multiplexers, but no change in symptoms.

At this point, I was really pulling my hair out and getting frustrated – I had been working on this machine for about two years on-and-off when I had the time and energy, and I felt like I just kept going around in circles – I just wanted it to work. I went quite mad and started replacing all kinds of parts, trying to find a problem.

I replaced UD1 (74F240), RP1/RP4/RP5/RP6 (22R), RP9 (200R), and RP7/RP8 (1kR) with new parts, however there was no change in symptoms.

I bought a new-old-stock Apple 3440042B RTC IC (UK4) to fit in case the replacement that I built was causing problems, but there was no change in symptoms. I even replaced the CPU (UK8), glue chip (UI8), and ASC (UE10) using parts from the other damaged board in case one of these was bad, but again no change in symptoms.

I removed the FPU (UI5) in case it was causing problems, but there was no change in symptoms, so I reinstalled it; I socketed UD12 and UF12 (AM26LS30JC) and removed these for testing as they were running warm, but no change in symptoms; I removed UJ11 (SWIM), UL11 (ADB), UK11 (6522), UK12 (6522), UG12 (8530), and UI12 (SCSI) for testing and to check for any shorts or damage underneath, then the system did not boot at all, so I refitted them.

I even removed the CPU socket, battery holder, and all of the RAM SIMM sockets to check underneath in case there were any kind of shorts, but it all looked OK.

At this point, even with a lot of extremely useful advice and guidance from the wonderful people on the VCF forums, I knew I needed more help. Will from CayMac very kindly offered to take a look at my board for a very reasonable price, and shipping to and from the Cayman Islands for a small flat parcel was also not too expensive.

Will has a lot more repair experience with compact Macs and in particular the SE/30 than I do, as well as platform-specific test equipment and known-good parts, so this was a very sensible move. He offers repairs and also entire board swaps, and I would absolutely recommend him to anyone who may be interested.

Sure enough, he managed to get the mainboard fully working quite quickly and tested it thoroughly using diagnostic software and loopback dongles. He diagnosed a handful of bad solder joints including on the serial IC sockets which prevented the serial port from working, and also three ICs, for which he kindly provided replacement parts: the video ROM and two GALs (341-0754-A and 341-0755-A).

I had tested parts these earlier, so it’s likely they either died or were killed at some point during my rework and troubleshooting of the board – no wonder I’d kept going around in circles, I hadn’t re-considered these parts.

When the board arrived back to me, I tested it out and it with a working Apple ROM SIMM fitted it would start up to a flashing disk icon but wouldn’t boot onto a working BlueSCSI drive; with an SE/30 MACSIMM fitted it would either behave the same or would give an intermittent “sad Mac” error code – 0000000F 00000001, which corresponds to a generic bus error. Sometimes when the computer was warm or after handling the board, the MACSIMM could boot to the disk icon.

I removed the SCSI IC (8530) in case it was causing problems, but there was no change in symptoms; I reinstalled a different part to no effect either. I also de-socketed the DIP resistor packs on the top edge of the board in case these were making intermittent contact, but there was no change in symptoms.

I reflowed a few solder joints on the FPU and noticed a bad trace that I had probably causd which was shorting the /RMC line to the ground of RP7 – I repaired this with a jumper wire but there was no change in symptoms. I think removing and reinstalling the FPU several times caused this trace to lift.

I used a “Disk Tools” floppy disk to try and help diagnose the SCSI bus – sure enough, SCSI devices could be seen, so it seemed SCSI itself was working OK.

Lack of SCSI auto-boot can apparently be due to issues with the RTC/PRAM. I noticed that the RTC socket was quite loose – this wasn’t a problem for the replacement I’d built as this had very thick pins which had stretched the socket out, but could be causing contact issues for the original DIP-8 IC. I replaced the RTC socket and sure enough, the system booted correctly into System 7.0.1 installed onto the BlueSCSI.

It’s likely that the board worked fine for Will with the RTC seated properly, then it’s been shook around during transit and caused the intermittent fault.

The moral of the story is, don’t be afraid to ask for help! The retro computing community is full of many fantastic, knowledgeable, and very helpful people.

Digital board upgrades

Now that the board was working properly, I wanted to finish it off with some nice upgrades, specifically 128MB (2 x 16MB x 4 kits) PurpleRAM and a 2MB PurpleROM from Jurassic Computing.

Floppy disk drive servicing

The 3.5″ 1.4MB floppy disk drive in later compact Macs usually requires a service due to its old age – the eject mechanism gets gummed up and doesn’t work properly any more, the eject motor gear has a habit of cracking and failing, the drive internals get dusty, and the read/write heads will probably need a good clean.

The FDD needs to be removed for servicing – the drive caddy is held into place on the chassis with four cross-head screws, and the drive itself is held into the caddy with another four cross-head screws.

The FDD had an aftermarket plastic sleeve fitted which was supposed to help protect against dust, but it seems to have done the exact opposite, so I threw it away. The drive also had a disk jammed stuck into it, which I had to cut out.

I won’t go into detail about the drive service procedure, as Adrian Black has an excellent video on the subject – it basically involves dismantling the drive, cleaning the old grease and any grime, adding new lubricant to the stepper rails and screw, cleaning the read/write heads with IPA, and cleaning the microswitches with contact cleaner.

The eject motor was actually completely burnt out and didn’t work at all, probably because of the jammed disk, so I had to swap it with a working spare. I decided to replace the original brittle eject gear inside the new eject mechanism using a 3D-printed replacement, which should last much longer.

HDD upgrade

The computer still had what appeared to be the factory HDD fitted, a full-height 3.5″ 40MB Quantum SCSI HDD – this spun up but made an awful screeching noise and wasn’t bootable, so needed to be replaced.

Even if the old drive worked, these old mechanical drives are starting to die out – they’re unreliable, noisy, slow, and difficult to interface with, and as such I prefer to swap them for a solid-state alternative (i.e. an SD card) where possible.

For the SD card adapter, I decided to go with a BlueSCSI, for various reasons: they’re easy to find, cheap to build/buy, are easy to set up and use, and because I’d already made some for my Mac Plus, and had spare parts in stock.

The BlueSCSI fits into a 3D-printed 3.5″ drive adapter using a pair of M2.5 x 5mm screws. This can be installed into the drive caddy using the original HDD screws.

Usually I would take a backup of the original HDD onto the SD card, but with the HDD not working, I just flashed it with a blank System 7.0.1 image.

The drive caddy can then be fitted back into the computer case, and connected to the SCSI cable – a power adapter cable is not required as power is provided over the SCSI bus in the SE/30, and I typically remove the original HDD power cable too as it is no longer necessary. The BlueSCSI has pin headers for both power and drive activity LEDs, so I connected the SE/30 front LED to the drive activity header.

Chassis cleaning and painting

The metal chassis was in poor condition due to the battery leakage; I even had to use WD-40 to get some of the screws for the FDD/HDD caddy out.

This wasn’t a functional problem, but it did look nasty and spoiled the neatness of the rest of the computer interior for me, so I wanted to clean it up.

I cleaned off the worst of the corrosion with a wire brush followed by coarse then finer grades of sandpaper, then treated the corrosion using a rust treatment gel.

I then primed and painted the chassis using metal primer and metallic grey paint.

While the chassis was apart, it was a good opportunity to remove and clean the CRT.

Keyboard cleaning

The keyboard and mouse that came with the system were pretty filthy, so I disassembled and thoroughly cleaned both of these.

Reassembly and testing

The reassembly of the computer is the opposite procedure to its disassembly.

The original CRT was quite dim and had a bit of burn-in, so I swapped it out with the one from the other SE/30 which was in better condition – I needed to adjust the CRT centering rings to bring the image in properly afterwards.

After all of this work, I tested the Mac SE/30 with the SD card adapter installed, and it now booted correctly into the operating system loaded onto the SD card.

With the computer reassembled, it is all working perfectly!

• All keys register correctly.
• All mouse inputs work OK.
• Internal HDD works OK.
• Internal FDD works OK.
• External SCSI interface works OK.
• Monochrome video on internal CRT works OK.
• Internal speaker works OK.
• Audio output works OK.
• 128MB RAM registers OK.
• NMI and reset buttons work OK.

I made the following frame out of the original mainboard, and hung it up on the wall in my office as a reminder never to buy compact Macs sold-as-seen on eBay again.

I can make the joke now that this SE/30 had me pulling my hair out…