This Mac nearly had me beat! It fought hard but I got it in the end.

In this video I repair a Mac 512k motherboard with an unknown RAM expansion card on it. In part 1, we looked at two Mac motherboards with unusual RAM expansion cards. The Mac 128k motherboard worked, but I left the Mac 512k motherboard for another video. This is that video! Figuring out what was causing this motherboard to not boot and display video issues required me to study schematics and try to understand the architecture of these early Mac machines, and it paid off!

Part 1:    • Mac motherboards with cool 3rd party RAM b...  
Part 2: This part!

-- Video Links

ROM Matrix:
https://docs.google.com/spreadsheets/...

Sad Mac Error codes:
https://tinkerdifferent.com/resources...

Macintosh 128k technical documentation:
http://bitsavers.informatik.uni-stutt...

ROM Disassembly:
https://www.bigmessowires.com/rom-ada...

PicoRC:
https://github.com/dekuNukem/PicoRC/b...
https://www.tindie.com/products/dekun...

Adrian's Digital Basement Merch store:
https://my-store-c82bd2-2.creator-spr...

Support the channel on Patreon:
  / adriansdigitalbasement  

Adrian's Digital Basement (Main Channel)
   / @adriansdigitalbasement  

My GitHub repository:
https://github.com/misterblack1?tab=r...

-- Tools

Deoxit D5:
https://amzn.to/2VvOKy1
http://store.caig.com/s.nl/it.A/id.16...

O-Ring Pick Set: (I use these to lift chips off boards)
https://amzn.to/3a9x54J

Elenco Electronics LP-560 Logic Probe:
https://amzn.to/2VrT5lW

Hakko FR301 Desoldering Iron:
https://amzn.to/2ye6xC0

Rigol DS1054Z Four Channel Oscilloscope:
https://www.rigolna.com/products/digi...

Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
https://amzn.to/3adRbuy

TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
https://amzn.to/2wG4tlP
https://www.aliexpress.com/item/33000...

TS100 Soldering Iron:
https://amzn.to/2K36dJ5
https://www.ebay.com/itm/TS100-65W-MI...

EEVBlog 121GW Multimeter:
https://www.eevblog.com/product/121gw/

DSLogic Basic Logic Analyzer:
https://amzn.to/2RDSDQw
https://www.ebay.com/itm/USB-Logic-DS...

Magnetic Screw Holder:
https://amzn.to/3b8LOhG
https://www.harborfreight.com/4-inch-...

Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
https://www.ebay.com/itm/14-16-18-20-...

RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
http://www.retrotink.com/

Plato (Clone) Side Cutters: (order five)
https://www.ebay.com/itm/1-2-5-10PCS-...

Heat Sinks:
https://www.aliexpress.com/item/32537...

Little squeezy bottles: (available elsewhere too)
https://amzn.to/3b8LOOI

--- Instructional videos

My video on damage-free chip removal:
   • How to remove chips without damaging the c...  

--- Music

Intro music and other tracks by:
Nathan Divino
@itsnathandivino