Manley MONO VARIABLE MU LIMITER / COMPRESSOR 5670 MODELS - Manual (Page 10)

SERVICE ADJUSTMENTS
A METER (FRONT PANEL TRIM) - Set in Limit Mode
1. The LIMITER COMPRESSOR is factory calibrated and you should not re-adjust
these trims unless you have re-tubed the unit or you suspect that the unit is in need
of a "cal". The unit will need to be warmed up for at least an hour to adjust any of
these trimmers. AC power fluxuations can affect the meter calibrations.
2. With no signal or gain reduction - adjust the trimmer for a GR meter reading of
"0". You may have to adjust again if you go further with these trims.
3) There is a mechanical adjust on the back of the meter to set the rest position
counter-clockwise (power should be off). This should align to the furthest line past
"12" or fully counter-clockwise on the marked scale.
B. This adjusts internal balance and lowest distortion:
NOTE: This unit has been factory set for the lowest THD and optimum AC balance.
It is recommended that this control be reset only after changing 5670 tubes.
Because of
high voltages (400 DC volts) in the unit and the necessity of having the unit "ON" while
adjusting , we recommend that these procedures be done by a qualified technician with
the right tools. We don't want to get our customers shocked. We need you.
1. Adjusting this control adjusts the current draw of the 5670 cathodes.
2. Set a multimeter to read DC volts.
3. Connect a good DC voltmeter to the two 500R resistors (brown, black, brown,
brown, green) near this trimmer. The sides of the resistors to measure are not joined
to the middle ground trace.
4. Adjust the small trim pot until the VOLTMETER nulls to zero.
5. Alternatively use a distortion meter, 1kHz oscillator, 2 dB of gain reduction and adjust for
lowest distortion through the unit.
C COMPRESSOR ZERO
1. Step "A" must be checked and OK first.
2. Switch to COMPRESS with no input or gain reduction.
3. Adjust for "0" on the meter.
D METER CAL
1. Supply the unit with 1kHz tone and use an extenal meter at the output to measure
the output level in dB or AC volts.
2. Turn the THRESHOLD to read 6 dB less output level or 1/2 the voltage as seen on
your external meter.
3. Adjust the meter cal trim for 6 dB shown on the front panel meter.
4. Check & Repeat steps A, B, C, D because of interaction of the trims.
These are factory presets. These should only be altered after a re-tube.