Macintosh LC 475

This machine was given to me after having sat in storage for something like a decade. I think it was stored in a wood shop as it was covered in a fine layer of sawdust in addition to being very dusty on the inside. Yellowing on the case was moderate and internally there was a mess of leaky electrolytic capacitors as is becoming increasingly more common as Macintosh computers from the 90's age.

I attempted a boot in it's original state but I got nothing but static as a startup bong and no video on the screen. The video was caused by a dead clock battery but it was time for a re-cap anyhow so I decided to do a full restoration job from top to bottom.

Capacitor Lists

Motherboard

Qty	Designation	Value
9	C35,C36,C101,C103,C127,C128,C129,C149,C150	47uf @ 16V
2	C136,C137	100uf @ 6.3V

TDK Power Supply

Qty	Designation	Value
3	C5,C52,C55	1000uf @ 10V
1	C8	8.2uf @ 50V
2	C53,C54	270uf @ 25V
1	C56	56uf @ 25V
1	C60	47uf @ 25V
1	C8	270uf @ 10V

In addition to the recap I cleaned and re-greased the floppy drive, which was fairly stiff. The case I put through the dishwasher for a good clean followed up by Perifractic's air-bright technique in the hot summer sun to de-yellow the case. I have to say, after three days the case looks very much better!

Finally I upgraded the RAM from an 8MB SIMM to a 32MB SIMM for a total of 36MB RAM and swapped out the 68LC040 for a full 25MHz 68040 to round out the restoration. Boots like a dream! Last thing I'd like to do is buy a couple of 512KB VRAM SIMMs so that I can display thousands of colours at 800x600 or 640x480. Currently I can only do so with 512x384 with the default dual 256KB models. Hopefully I can find a good deal!

Oh yea, in order to get video, I plugged in one of my 3D printed battery adapters. See the link to that page below.

Benchmarks

All benchmark tests happened on System 7.6.1 using the SCSI to SD controller using Speedometer 3.23. HDD scores aren't included as the SD adapter can't reach the full speeds of the SCSI controller on the LC475.

68LC40 @ 25MHz P.R. Results (Uses Mac Classic as 1.0): CPU: 15.871 Graphics: 15.613 Math: 31.811 Performance Rating (OLD PR): 14.804 Performance Rating (NEW PR): 8.678 Benchmark Results (Uses Mac Classic as 1.0): KWhetstones: 285.714 39.138 Dhrystones: 19230.769 19.737 Towers: 18.909 QuickSort: 17.758 Bubble Sort: 18.409 Queens: 18.320 Puzzle: 22.457 Permutations: 21.018 Fast Fourier: 26.503 F.P. Matrix Multiply: 27.841 Integer Matrix Multiply: 24.200 Sieve: 23.362 Benchmark Average: 23.138 No FPU present. No tests were run. Color Tests (Uses Mac II as 1.0): Black & White: 4.967 4 Colors: 5.287 16 Colors: 5.444 256 Colors: 5.539 Color Test Average: 5.309

68040 @ 25MHz P.R. Results (Uses Mac Classic as 1.0): CPU: 15.727 Graphics: 16.116 Math: 101.184 Performance Rating (OLD PR): 21.829 Performance Rating (NEW PR): 8.821 Benchmark Results (Uses Mac Classic as 1.0): KWhetstones: 1428.571 195.694 Dhrystones: 19230.769 19.737 Towers: 18.909 QuickSort: 17.166 Bubble Sort: 18.837 Queens: 19.083 Puzzle: 22.457 Permutations: 21.018 Fast Fourier: 123.589 F.P. Matrix Multiply: 127.196 Integer Matrix Multiply: 24.200 Sieve: 23.362 Benchmark Average: 52.604 FPU Tests (Uses Mac II as 1.0): FPU Fast Fourier: 10.733 FPU KWhetstones: 4000.000 5.600 FPU F.P. Matrix Mult.: 11.025 FPU Test Average: 9.119 Color Tests (Uses Mac II as 1.0): Black & White: 4.954 4 Colors: 5.251 16 Colors: 5.433 256 Colors: 5.530 Color Test Average: 5.292

Current Specifications

Processor: 25Mhz 68040
FPU: Built-in
RAM: 36MB, 4MB on motherboard plus 32MB 72Pin 70ns DRAM SIMM
HDD: 16GB SD Card on SCSItoSD 5.0b card.
Floppy: 1.4MB Superdrive
Internal Expansion: LC PDS Slot (populated with PDS ethernet card)
External Expansion: DB-25 SCSI, ADB, DIN-8 RS-422 Serial x2, Audio-In, Audio-Out, Mac VGA 15pin
Battery: 3.6V Lithium
Gestalt ID: 89
Production Dates: October 21, 1993 - May 1, 1994
Original Price: $1085 USD
Size (HxWxD): 2.9" x 12.2" x 15.3"
Weight: 4kg
Part #: M1476
OS: 7.6.1 (currently installed)

Links

3.6V 1/2 AA Lithium Clock Battery Replacement
Retrobrighting with Just Sun?

Last Updated September 21, 2019