Fixing Sharp MZ-700

Time to fix the Sharp MZ-700, I have this computer for a while, and it was not working. I decided to fix it. I opened the computer and I found that the power supply was not working correctly. I decided to do the standard procedure, replaced suspects capacitors and voltage regulators. Here are some pictures of the process:

This machine was manufactured in 1982, and it was a very popular computer in Japan. It was used in schools and homes. It has a Z80 CPU, 16KB of RAM, and 16KB of ROM. It has a built-in tape recorder, and it can display 40x24 characters in 8 colors.

Specification Sheet

Processor

• CPU: Zilog Z80A
• Speed: 3.5 MHz

Memory

• ROM: 4 KB
• RAM: 2 KB
• V-RAM: 64 KB

Input/Output

• Keyboard: ASCII keyboard with cursor control keys, definable function keys, and insertion/deletion keys (INS, DEL)
• Display: 40 characters x 25 lines, 80 x 50 pixels (8 colors)
• Printer: Built-in interface
• Cassette Recorder: Built-in interface
• Loudspeaker: Built-in, output 500 mW max.

Graphics

• Resolution: 80 x 50 pixels
• Colors: 8

Connectivity

• Video Output: RGB connector, combined connection
• RF Modulator: Built-in for connecting to a color TV

Power Supply

• AC: 220V/50 Hz, approx. 20W

Operating Environment

• Temperature:
  • Operating: 0 to 35 degrees Celsius
  • Storing: -20 to 60 degrees Celsius
• Humidity: Operating: max. 85%

Dimensions and Weight

• MZ-731:
  • Width: 440 mm
  • Height: 102 mm
  • Depth: 305 mm
  • Weight: 4.6 kg
• MZ-721:
  • Width: 440 mm
  • Height: 86 mm
  • Depth: 305 mm
  • Weight: 4.0 kg
• MZ-711:
  • Width: 440 mm
  • Height: 86 mm
  • Depth: 305 mm
  • Weight: 3.6 kg

Peripherals (Optional)

• Color Printer (MZ-1P01):
  • Colors: black, blue, red, green
  • Print capacity: 80, 40, or 26 columns per line
• Data Recorder (MZ-1T01):
  • Cassette audio compact cassette
  • Data transfer rate (SHARP M-system): 1200 bit/sec

Mother board detail

This model doesn´t have the printer, thats a pity, because it is a very nice printer. I will try to find one in the future.

Under the cassette recorder, there is a small compartment for storing the video system. Open it and ectract the power supply its very easy.

The power supply is lower that the normal that should be 12v

Its a very easy and well designed power supply, easy to repair.

Screens