Sony MZ-R90/R91


Name MZ-R90
Manufacturer Sony
Released 1999/10
Device type portable
Recorder Recorder
NetMD No
Hi-MD No
Radio No
Dimensions 78.9 x 17.3 x 72mm (78.9 x 18.0 x 72mm MZ-R91)
Weight 105g (110G MZ-R91)
ATRAC ver 4
Battery "Gumstick"
Battery notes
Sidecar (depr) 1xAA
Voltage 3
Power cable Center positive
Price (launch)
¥46 000
Inputs 3.5mm line in (analog-only), 3.5mm line in (optical multi), 3.5mm microphone
Outputs 3.5mm line out (analog-only), 3.5mm headphone

At the time of their release, they were the smallest recorders with the longest playback time available. The R90 and R91 seem very similar except for the fact the R90 was slightly slimmer/lighter and had a magnesium top cover.

User reviews say that due to power saving drive, it can be slow to start-up/respond.

Common problems for this model include:

  • Cracked flex PCB cables
  • Brittle plastics (especially battery compartment)
  • Shorts due to spilled battery electrolyte
  • Optical pickup failures
  • Original power supply out-of-spec

ATRAC IC is a CXD-2660GA which uses version 4.0 or 4.5 (measurments are inconclusive)

Content adapted from: MZ-R90/R91 Page, Sony Press Release Comparison with Sharp MD-MT831



more photos

more photos

Pink MZ-R91

You can enter the test mode by setting the HOLD switch to on, holding PLAY and pressing the following sequence:

Next, Next, Previous, Previous, Next, Previous, Next, Previous, Pause, Pause

Alternatively you can short the test mode pad shown below:

As you enter the servicing mode you will be in display check mode.

The servicing manual recommends the following steps:

  1. Clear settings saved in device memory (Manual mode - 021 ResNV)
  2. Perform electrical adjustments (Manual mode - 762 through 767)
  3. Calibrate temperature measurement (Manual mode - 014 SetTmp)
  4. Perform automatic adjustment (ASSY11)
  5. Clear clock (Manual Mode - 043 Resume)

Sometimes to pass automatic adjustment you may need to also use manual options 031 for CD and 034 for MO.

The locations of pads for electrical adjustment are shown below.

Example: adjust VC PWN duty (762):

  1. Vol+ - Manual mode
  2. Vol+ 7 times - 700 POWER
  3. Play - 710 PwrChk
  4. Vol+ 5 times - 760 V_ADJ
  5. Play - 761 PwrSel
  6. Next - 762 VclPWM
  7. Vol+/- to adjust voltage between TP915 and GND to 2.500V
  8. Pause to save
  9. Stop to return one level up
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  • equipment/sony/portable/mz-r90.txt
  • Last modified: 5 weeks ago
  • by jdub