My old Mac LC has a lot of sentimental value. My first Mac. The result of a major saving up exercise. Bought primarily for the final year of my Computer Science degree. I squeezed quite a long life out of it, with a DayStar accelerator card that I bought out in the States while attending the MacWorld Expo 1993 (and there is a story to that) but it has been in its original box for over 24 years.
I fully intend getting this machine going again, probably using a BlueSCSI or similar. But I had seen from the many retro-computing YouTubers varying levels of capacitor and battery leakage. So today was a quick inspection to see if it is similarly affected.
On first inspection, the battery looks ok. No sign of leakage, but quite flat, only able to deliver 41 mV as opposed to the 3.6V. If that’s a date code on the battery 11/89, I guess expecting any change remaining after 35 years was optimistic.
At a glance, there didn’t seem to be much problem near the caps. Although on closer inspection, it is clear that some of the component solder joints are matt with a green tinge – so, not so good. For now, I cleaned as best I can with isopropyl alcohol. The cotton swabs turning a horrible greenish colour kind of confirms the leakage. The board however does look in decent condition with the traces looking good.
Recapping is going to be vital I think before applying power back to the machine.
Additionally, it was also pretty sad to see how brown the casing had turned. It has spent a few years in a brightly sun-lit room before being boxed up, and is no-longer the nice light grey I remember. I’ll have to consider retro-brighting – but for me, this particular unit is a one-off. I don’t want to mess it up and I live in a flat – with no outdoor area for the sun part of the process, it is going to be a challenge.
My first Mac… The LC, case suffering the ABS plastic browning PRAM battery – thankfully without leakagePRAM battery – manufacture year 1989 ?Isopropyl alcohol swabbing around the leaked capsDayStar accelerator card – cost me a fortune, but brought 68030 and a math co-processor to the LC
TLDR: I need to make the following repairs to my Roland Alpha Juno 2
Fix the touch sensitivity of one of the keys
Fix the non-sounding keys
Replace the back light
Replace the battery
Give it a good clean, inside and out
Using online articles and YouTube videos, I get into the repairs after sharing my history with this synth.
I saved up and bought it new in around 1986. I originally had a couple of small Casio keyboards PT-50 and MT-400V, and got my hands on a Roland SH-101 but wanted to step up to a polyphonic synth.
I was on a year out after my A-Levels, and earning, so a bus ride to into Manchester to hand over some cash (around £700 if i recall) and pick up my new Roland Alpha Juno 2. I’d never call myself a musician – I just enjoyed playing with the synthesis and trying to emulate the sounds of my favourite artists and bands of that time: Jean Michelle Jarre, Gary Numan, Ultravox, Human League, OMD and Pink Floyd.
I have always liked this synth and the feel of its semi-weighted keyboard and it seems to have lately found some popularity as a retro synth used by artists such as Kebu.
The synth (and home made amp) came with, as I left home in 1988 to study for my Computer Science degree. It survived the halls of residence and two student houses despite a near constant fear of being burgled.
In my first year however, it started behaving erratically and needed a repair. Rock city in Middlesborough did the repair job, which included replacement of the memory backup battery and some fuses. It hadn’t been again since. I’m amazed that the patches programmed over 30 years ago remain intact. Having owned it from new, I attach a lot of sentimental value to this synth and I don’t want to ruin it while I attempt to repair it.
I was able to find the reference materials on manualslib. Additionally I searched and found a number of repair videos on YouTube:
Since I am going to change the battery, I need to dave the patch memory. To do that I used SysEx library on my Mac, and on the Juno, pressed simultaneously:
Data transfer
WRITE
Bulk
This sent 16 messages (4.2 Kb) to SysEx Library, which seems tiny by todays standards, but represents the 64 user defined patches.
Bad keys
First I marked the affected keys with tape:
The bottom C key, always plays 20% louder than other keys
The top D key, always plays 100% velocity, no matter how softly played
The middle G key does not sound
Once inside, removing the keybed is a delicate and fiddly process – since the main board is slotted into the keybed. A rough hand could easily cause damage to that board. Ever careful to take photos of all the connectors in place, to provide reference for reassembly.
The main board sitting under, and slotted into the keybed.
The approach I took unscrew the board from the frame and slide it out, disconnecting the many connectors. Once the main board was free, I unscrewed the keybed from outside of the case and worked on it separately, away from the delicate electronics.
To get to the contacts we need to first remove the keys to which there are 3 stages:
Remove the springs, keeping the shorter springs of the black keys separate from the larger springs for the white keys
Underneath the keys, unstick and put aside the ‘Key Stoppers’ (clear plastic strips) that prevent the keys from slipping forwards.
The keys will now pull forward and can be removed
Despite a good portion of its time boxed, thirty-odd years of dirt had certainly built up. With all the keys removed, all the dirt was brushed and vacuumed away, then the graphite pads of the affected keys cleaned. Removing the glue used to stick the key stoppers was the most time consuming effort.
Key StopperDirt accumulated under the keysThirty or so years of dirt between the keysDirt on the graphite pads of affected keys
All the keys went into a bucket of mildly soapy (washing up liquid) water for gentle but thorough cleaning before reassembly.
Backlight
In many of the restoration videos the LCD display is replaced with an LED display. I opted for replacing the electroluminescent strip with a new one. I managed to do this simply by desoldering the two connectors and slipping the strip out – without detaching the display from the frame.
Alpha Juno 2 display, faded backlightAlpha Juno 2 – Display moduleAlpha Juno 2 – Old electroluminescent strip desoldered and removalAlpha Juno 2 – Replacement electroluminescent stripAlpha Juno 2 – Replaced electroluminescent strip – without detaching the moduleAlpha Juno 2 – Replaced electroluminescent strip – nice and bright
Battery replacement
I opted to replace the soldered battery with a battery holder and standard CR3032. It was impressive that after over thirty years powering the memory for the user patches, the battery still held a good charge. Despite no liquid leakage, there was a white powdery coating building up on the battery.
Backup batteryBackup battery still with good voltage after more than 30 years. 2.8V would when problems occurred.replacement battery, in a holder rather than directly soldered
Aftertouch
The remaining issue is that I have lost aftertouch. On testing the resistance of the aftertouch strip, I can see it changing with pressure. I hadn’t tested it before the disassembly, so this might have been an issue already rather than something I introduced. I may need to change the resistance range, but I haven’t yet worked out what that should be. One for the next project.
Conclusion
Aftertouch aside, I now have a clean, working Roland Alpha Juno 2. It makes a great MIDI controller for working with any DAW. But in some ways that is a waste for what is actually a decent synth from the late 80’s
My iPhone 6s is starting to show its age, with the battery barely lasting a day, and much less if actually used, it is time for a new phone or battery. The original plan being to do this ahead of my Christmas travels. A positive Covid test put paid to the Christmas travels, the kit was already on its way.
Possibly the most important instruction, and one that I think saved me from some trouble, is to discharge the existing battery before commencing the work. I then spent considerably longer than the suggested 45 minutes making this change. Reasons for spending so long:
I only have this kit and no spare parts. Unlike a repair shop, if I break something I’d then have to order replacement parts and be without a phone over that period. I was particularly fearful of breaking the screen and spent an age gently warming with a hair dryer before gently releasing it from the frame.
A surprising amount of dirt had found its way into the phone and needed a good clean up, along with the old glue strips from the screen on which I used a good amount of isopropyl alcohol to clear them up.
The old battery peel-back strips both immediately tore, leaving the battery firmly fixed in place
iFixit iPhone6s Battery replacement kitiFixit iPhone6s Battery replacement kit – openiPhone 6s, screen openingiPhone 6s, screen opening, and muck insideTrying to prise up the battery after the release strips have snappedOh no, battery pierced and still firmly stuckThe sticky culpritsAll clean and new battery installed
I realised I had pierced the battery when it emitted a sweet pear-drop kind of smell. Fortunately it had little or no charge, and I think only the outer skin was pierced. Moving more quickly I finally pulled it out, sealed the tear in the battery skin with electrical tape, and placed it in an unsealed tin box for a number of days. Later taking it to a recycling facility and advising that the skin had been pierced as it was handed over.
The new battery lasts well and gives the phone a new lease of life.
In preparation for the repair work expected on the SH-101 in particular, I anticipate needing to see the output waveform. Only considering audio signals, so there is no need to sample high frequencies.
The JYETech DSO Shell kit with sample rates up to 200KHz should do the job, and was a decent inexpensive project to get back into the swing of my soldering skills. I did find my old 15 watt soldering iron inadequate for soldering the large BNC connector, and so got hold of a 25 watt Antex (good to see the same brand going strong) which did the job.
Organising at least a basic workbench for the electronics work will make things easier, allowing kit to be set up over a number of days without competing with other desk space. In my case, it was time to pull out of storage my old MFI computer desk (from around 1989) which originally housed my Atari 520 STFM, its SM124 monitor and Epson LX80 (extremely loud) dot matrix printer. With those boxed up it is time to pull together some basic tools for my upcoming electronics work. That will include:
Restore Roland SH-101 – Boxed for 30 years, has a severe fault possibly with the oscillator IC
Restore Roland Alpha Juno 2 – Some keys not working, and faded back-light
Restore my old amplifiers, speakers and bring back into operation – possibly re-housed
So the key tools are a mix of old and new:
Soldering Iron 15W – though subsequently replaced with a 25W
De-solder suction tool
Soldering repair mat
Helping hands
Long nose pliers
Snips
A digital multimeter
One tool missing that I feel I need for the SH-101 repair is some kind of oscilloscope. To get us up and running, I have opted to build a kit – The JYTech DSO Shell.
My professional focus is now firmly in a world of Product Ownership having joined a company building a RegTech platform. Outside of career interests, it it time to return to some older hobbies.
I have a growing interest in retro-computing, having grown up with most of the machines common in the retro-computing space. Indeed I still own my old ZX Spectrum, Atari 512 STFM and Mac LC. I definitely want to give the Mac LC some care and attention. I find inspiration for this from YouTube channels:
I dabbled in electronics through my youth… typically projects alongside my computing and musical interests. My main effort was in building amplifier kits and speakers. Having been in storage for a couple of decades, they’ll need a good servicing if they are ever to be used again.
Where I can make simple repairs, I can and will. I have a couple of old synthesisers which need work. Again, I find great inspiration via a number of YouTube channels:
I have an old NAD-320 amp and pair of JBL Control 1G speakers attached to the TV, but hadn’t used them in a while. Trying out Netflix and finding Hans Zimmer Live in Prague, the TV speakers were certainly inadequate. But what an awful crackling sound from the JBLs. They were about 20 years old, but hadn’t had too much use. Taking off the grill, and the reason was clear…
The foam, around the main cone had gone crispy, cracked and started falling apart. Even 20 years on it is still possible to buy JBL Control 1 speakers new, but I didn’t want to dump these if they could be repaired.
There are a number of repair videos on youtube (search for “jbl control 1 foam repair kit”) and I found a kit on eBay (though the seller doesn’t appear to be there at the time of writing) consisting of replacement foam baffles and glue.
(edit 9/9/2020: A decent repair video published this year)
Armed with these and a screwdriver, I set about it. Taking photos before disconnecting anything to make sure I could reconnect properly…
Then it is time to get rid of the old foam, held in place by glue in addition to being clamped to the speaker case. Firm but delicate screwdriver action required, especially where the foam is glued to the cone…
Since the foam had denatured it was quite difficult to clean away from the metal frame.
Kicking myself when a slip of my scraper slightly damaged the left part of the cone – though not enough to go through, and not damaging performance in any detectable way.
That done, glue applied around the metal frame and to the back of the cone, and the new flexible foam pressed into place and reassemble…
End result – looking like speakers again, and more importantly sounding crisp and clear.
