Super manual it contains all the things you need to service your Marantz 2100.
Text excerpt from page 61 (click to view)
4.
Tracking Balance Measurement 1) 2) 3) Connect the oscilloscope to test points TP-TE and TP-VC. Playback the second track of TCD-782 and press the PAUSE button. Check that the traverse waveforms of the oscilloscope are up and down symmetrically.
OSCILLOSCOPE
OUTPUT
TP -TE TP -VC
5.
Playback Check 1) Playback track numbers 3, 8 and 13 of ATD-001 and check that noise or sound skipping does not occur.
A 0V B
A=B
VOLT / DIV: 100mV TIME / DIV: 1ms
6.
Laser Current Check * Perform this check only when the laser is faulty. 1) Connect a digital multimeter across the resistor R541 (10 ohms). 2) Playback TCD-782 and check the DC voltage value of the 3) 4) digital multimeter. Check the SPEC VALUE specified on the label of pickup. Calculate the laser current (Iop) by diving the DC voltage value across R541 by the resistor value (R541 = 10 ohms). Check that the laser current (Iop) is SPEC VALUE ± 10 %.
