Macintosh Classic – Recap

If you have older computers at some point they will start to fail. Could be you lose sound on the system. Video may show up kind of wonky. Smoke, sparks and fishy smells coming from the computer. While these machines will last a long time, they will eventually succumb to issues.

If the hard drive or the floppy drive fails then it’s relatively easy to replace those mechanical parts. Same thing goes for a video card or memory. But then there is an issue on one of the boards it gets a bit more harry and potentially costly.

I have a Macintosh Classic (all in one, little black and white screen Macs) here. I plugged it in the week and it didn’t start up. I saw a little whisp of smoke and then turned it off. I open the case and looked at the boards. I tried to turn it on again and I saw some sparks on one part of the board. All of these older boards have Capacitors that will fail over time. When they do, they can leak their fluid and end up bridging connections and causing all kinds of trouble.

I pulled the Analog Board, its the main power board on this Mac, and saw a few capacitors that have failed (leaked stuff). On this particular unit there are 25 capacitors on the board. “Recapping” is just coined name of replacing the capacitors on the board. The whole process goes like this:

  1. Identify all the capacitors. Capacity, Type, Size, Voltage.
  2. Order a new set. I used Mouser.com.
  3. Desolder the old capacitor. Remove it from the board.
  4. Clean up the area for that old cap.
  5. Solder in the new capacitor. They have polarity, so make sure you put it back in the proper orientation.
  6. Repeat for every capacitor.
  7. While in there, clean up any other areas, make sure the goop is removed and no other parts are affected.

While working on something like an Analog Board, be very careful. This has some high voltage connections and you need to handle things properly. On these little units you have to discharge the CRT properly. If you don’t, you can electrocute yourself, even after the unit has been unplugged. The CRTs hold a charge!

While everyone has their own setup for their work area, here is what I have and used during this project:

  • Anti-static mat that I work on.
  • Desoldering Iron (suction bulb type) to remove old parts.
  • Solder Iron, I have a Hakko setup with temperature controls.
  • Thin and Thick solder, I mainly use the thinner strand but have the thicker stuff for the larger components.
  • Flux, this is the goop that helps the solder to spread properly. I have a syringe of it to apply small amounts exactly where I’m going to solder.
  • Solder wick, the copper braid to suck up solder. I use it after using the Desoldering Iron to clean up the contact pads.
  • Magnifying Lamp so I can see up close the exact area I’m working on.
  • Isopropyl Alcohol (99%) to clean the pads and goop.
  • Torx tools (the long ones) to get into these little Macs
  • Discharge tool to drain the CRT. There are official type tools but there are many homegrown tools.

Once the recap is done you place it all back together and test how you did. Does it work? Mine did. But while I’m inside the guts of this machine I also did the following:

  • Recapped the Logic Board. The capacitors on the logic board are surface mount so it’s different than above.
  • Replaced the PRAM battery

Now purchasing the new capacitors is confusing. There are a lot of parts out there and you have to know what you are buying. I looked at each capacitor, wrote down the values, measured the width and so on. While on the Mouser website I basically abused their filter system to get the right parts. There are lots of brands as well but I saw that most of the caps on the board was by Nichicon so I stuck with that brand.

To help out with anyone having to recap this particular Analog Board, I’ve providing the exact parts list I generated at Mouser.

Mouser #Mfr. #DescriptionOrder Qty.Price (USD)Ext.: (USD)
647-UPW2E4R7MPDUPW2E4R7MPDAluminum Electrolytic Capacitors – Radial Leaded 250volts 4.7uF 10×12.5 ‘20% 5LS1$0.46$0.46
647-UVR2E221MRD6UVR2E221MRD6Aluminum Electrolytic Capacitors – Radial Leaded 250volts 220uF 22×30 20% 10LS2$3.39$6.78
647-UVK1H010MDDUVK1H010MDDAluminum Electrolytic Capacitors – Radial Leaded 50volts 1uF 5×11 20% 2LS5$0.22$1.10
647-UFW1H100MDDUFW1H100MDDAluminum Electrolytic Capacitors – Radial Leaded 50volts 10uF 20%1$0.17$0.17
647-UKW1E221MPDUKW1E221MPDAluminum Electrolytic Capacitors – Radial Leaded 25volts 220uF 20%1$0.54$0.54
647-UVR1E100MDDUVR1E100MDDAluminum Electrolytic Capacitors – Radial Leaded 25volts 10uF 5×11 20% 2LS1$0.17$0.17
647-UHZ1C102MPM6UHZ1C102MPM6Aluminum Electrolytic Capacitors – Radial Leaded 16volts 1000uF 8X201$0.94$0.94
647-UVR1C102MPDUVR1C102MPDAluminum Electrolytic Capacitors – Radial Leaded 16volts 1000uF1$0.43$0.43
647-UVR1E470MDDUVR1E470MDDAluminum Electrolytic Capacitors – Radial Leaded 25volts 47uF 5×11 20% 2LS2$0.18$0.36
647-UKL0J102MPDUKL0J102MPDAluminum Electrolytic Capacitors – Radial Leaded 6.3volts 1000uF 85c 10×20 5LS1$0.72$0.72
647-UPW1E471MPDUPW1E471MPDAluminum Electrolytic Capacitors – Radial Leaded 25volts 470uF 10×16 20% 5LS3$0.46$1.38
647-UPJ1C221MPDUPJ1C221MPDAluminum Electrolytic Capacitors – Radial Leaded 16volts 220uF 8×11.5 20% 3.5LS1$0.35$0.35
647-UPW1A102MPDUPW1A102MPDAluminum Electrolytic Capacitors – Radial Leaded 10volts 1000uF 10×16 20% 5LS1$0.53$0.53
647-UPM1A222MHD1CVUPM1A222MHD1CVAluminum Electrolytic Capacitors – Radial Leaded 2200 uF 10V AL-ELKO 12.5X31.5 0.22$1.06$2.12
647-UPA1C222MHD3UPA1C222MHD3Aluminum Electrolytic Capacitors – Radial Leaded 2200uF 16V 20% Low Impedance1$1.19$1.19
647-UHD1V102MHD1TOUHD1V102MHD1TOAluminum Electrolytic Capacitors – Radial Leaded 1000uF 35V 105c1$1.43$1.43