The AKAI 1720 model reel to reel tape recorder described in this Manual is quite an old unit - circa late 1960's. As a consequence, the description of the mechanical details - and adjustments thereof - is quite critical. The manual does this quite well. The schematics are also well presented and have detailed PCB overlays. Probably the only negative is that some half-tone detail has been lost from the original manual as it has been scanned in simple B&W.
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Text excerpt from page 36 (click to view)
ELECTRICAL ADJUSTMENT-13/13
3. JITTER CHECK
1) While oscilloscope is kept connected in the same test point as in step2. RF WAVEFORM CHECK, connect the output terminal of an oscilloscope to the input terminal of the jitter meter. 2) Set the VOLT range selector of oscilloscope to 500mV range or below. 3) Play back 2nd track of TCD-782. 4) Check that jitter meter indicates 28.0ns or less.
OSCILLOSCOPE JITTER METER OUTPUT INPUT ns
RF SW Vref
4. PLAY ABILITY CHECK
1) Play back the 3rd , 8th and 13th track of ATD-001. Check that the noise does not occur sound skipping does not occur.
5. LASER CURRENT CHECK
* Do not perform this measurement unless the laser is suspected to be defective. 1) Connect digital multi-meter across the resistor R402(10�). 2) Play back the TCD-782 and check the DC voltage value on the digital multimeter. 3) Calculate the laser current (Iop) by dividing the DC voltage across R402 by the resistor value (R402= 10�). Check that the laser current (Iop) is 60mA or less.
