Проверил эту вертушку по стробоскопу, оказалось, что на 33 и на 45 она подтормаживает, на 78, наоборот, убегает. Да и на слух это заметно. В ней стоит синхронихатор, внутри много подстроечных резисторов, но как ее настраивать??? В инструции - китайска грамота. Может кто знает спеца, или сам подстраивал? Соответствующий раздел мануала (снято через файнридер с 4-х страниц...):
Speed Control Board Service
TEST AND ADJUSTMENTS OF ELECTRONICS
1.R210 "TACHO SYM."
-Turn on the unit. Select 33 1/3 speed.
-Connect an oscilloscope to TP 7 (f/u Informa¬tion; y = 10 mV/div; x = 2 ms/div). Use a high impedance, low capacitance probe, since other wise rf interference may be encountered under some conditions.
- Press Start.
- Adjust R 210 "tacho sym." for minimum voltage-step amplitude, <20 mVPP.
2. R 238 "PHASE LOCK SYM." -Turn on the unit. Press Stop.
- Adjust R 238 for 0 V at TP 9 of the board.
3. R243 "SYM.t"
- Connect Jumper 201.
- Connect an oscilloscope (y - 5 V/div,. x = 5 ms/div) to TP 8 on the board.
- Press Start.
- Adjust R 243 "sym.T" for minimum pulse pause.
- Disconnect Jumper J 201.
ADJUSTMENT OFTHE MOTOR AMPLIFIER
4. R 148 "OFFSET ADJ. 2"
5. R 147 "OFFSET ADJ. 1"
6. R 145 "PHASE SYM."
7. R 146 "GAIN ADJ."
- Remove jumper J 202 to open the control loop. A constant de voltage lies at the input of the amplifier (TP 9).
- Turn on the unit. The turntable platter will turn forwards.
- Connect an oscilloscope (y = 50 mV/div; x = minimum sweep) to S4/1 and to S4/2 to the board (0V: pin S4/3).
- Set both Signals symmetrically about their zero-signal levels with R147 "offset adj 1" and R148 "offset adj. 2".
- Set both Signals to an identical amplitude with R 145 "phase sym."
- Set the Signals to 100 mVpp with R 146 "gain adj."
- Connect Jumper J 202!
Speed Control Board
TACHOMETER SIGNAL (PIN S9/1)
The tachometer Signal, fed from the tachometer amplifier in the motor, appears as a sinewave Sig¬nal at the input of the Speed Control board at pin S9/1. The level at 33 1 /3 min:1 lies between 12-13 Vpp.
f» « 142.2 Hz f45 = 192 Hz f78 = 334 Hz
CIRCUIT DESCRIPTION (DETAIL)
TACHOMETER SIGNAL CONVERSION
Z201 is connected as a Schmitt trigger. The sinus¬oidal tachometer Signal is converted to a sym¬metrical squarewave Signal. The negative portion of the Signal is shorted to 0 V by D 203. The sym¬metry is adjusted with R 210 "tacho sym.".
FREQUENCY DOUBLING
Voltage pulses appear at Output 4/Z 202 (TP 1) at twice the tachometer frequency for speeds of 33 and 45 min:1 . At 78 min: ,pulse frequency is identical to the tachometer frequency (input 8/Z 202 = "0"). The duration of the pulses is determined by the RC networks C 204, R 215 and C 205, R 216.
PHASE COMPARISON
Z 203 is connected as a phase comparator. The reference signal (the divided oscillator frequency and signal from 4/Z 202 produce a voltage at 13/ Z 203 proportional to the phase difference be¬tween the two. This voltage is approximately + 7.5 V, upon which pulses of + 7.5 V are super¬imposed, corresponding to either a positive or negative phase difference.
The duration of the pulses is determined by the magnitude of the phase angle.
In the subsequent circuit, a de voltage approx. 7.5 V is subtracted from the Signal of the phase comparator.
The Pulsphase signal is produced at 1/Z 203. It corresponds to the value of the signal at 13/Z 203.
LOOP FILTER
Z 204 Is connected with Output 14 as an integra¬tor. In order to improve run-up Performance, C 207 is shorted during this interval.
Second order low-pass: for attenuating residual
Speed Control Board Service
REFERENCE F/U CONVERTER
The pulses of the reference Signal activate two monostable multivibrators in succession, which produce pulses of constant width: 7/Z 205,10/ Z205.
-7/Z 205 HIGH. Through analog switch 1-2/
Z 207, 7/Z 208 is also HIGH (sam¬ple phase of the voltage on RC network R 240/C 220).
LOW. Through analog switch 1 -21
Z 207,7/Z 208 is also LOW (hold phase of the voltage on RC net* work R 240/C 220).
The analog switch 1 -212 207 is controlled from pin 13/Z 207. It opens during Stop and closes during Start.
-1 0/Z 205 HIGH. Analog switch 10-11 /Z 207 is closed. Approx. 12 V lie on RC network R 240/C 220.
LOW. Analog switch 10-11 /Z 207 is open, the RC network R 240/ C 220 discharges.
-Z 207/z 208 function as a sample and hold Z 209 stage. The voltage on the RC net¬work Is transferred to C 217 during the sample phase and conducted to output 5/Z 208, where it Is held constant, during the hold phase.
A voltage which is dependent on the frequency of the reference Signal appears at output S/Z 208.
TACHOMETER F/U CONVERTER
The f/u conversion of the tachometer signal is performed in the same manner as for the refer¬ence Signal.
Differences:
- Opening of the analog switch 8-9/Z 207 is de¬
layed for Stop uptil the speed is approximately
zero. The motor is thereby accelerated against
the direction of the rotation until It comes to a
stop.
- R 243 "sym.t". Identical time constants for f/u
Converters are adjusted with R 243.
Speed Control Board
SUMMING POINT
The difference of the Signal from the f/u Convert¬ers appears at Output 7/Z 210 and is summed at 2/Z 210 with the control Signal from the PLL Cir¬cuit. T 203 is cutoff during Stop and conducts during Start.
STANDSTILL COMPARATOR 1/2 210
A voltage of approx. -15V lies at 1/Z210. When Stop is pressed, the voltage remains at this level until the voltage at 5/Z 209 falls below a speci¬fied value (approx. 1.5 V). The comparator jumps to approx. +15 V. The f/u Converter for the ta¬chometer signal is switched off with this Signal.
CONTROL SIGNAL
The control Signal Is produced at 14/Z 211.
MOTOR CURRENT LIMITING
Motor current limiting is accomplished with 71 Z 211. If for instance, the turntable platter Is held by hand, C 214 is charged to a level above the threshold voltage of approx. 10V. Output 7/Z 211 jumps to approx. -15V, the gate Potential of T 202 sinks to approx. 0 V, T 202 conducts. The control signal is thereby limited to approx. 3 V.
FORWARD/REVERSE IDENTIFICATION
The forward/reverse identification prevents un¬controlled acceleration of the turntable platter opposite to the selected direction. This function is implemented with two identically constructed tachometer generators, the phases of which dif¬fer by 90° by reason of their physical location.
Function:
Tachometer signal (after conversion into Square wave)atD1 5/Z 213.
Auxiliary tachometer signal (after conversion into Square wave) at Ck 1 3/Z 213.
a) Normal case: Start pressed, platter rotates forward. Q1 1/2 213 remains LOW.
b) Start pressed. Platter is rotated backwards by hand during cueing.
Speed Control Board Service
TEST AND ADJUSTMENTS OF ELECTRONICS
1.R210 "TACHO SYM."
-Turn on the unit. Select 33 1/3 speed.
-Connect an oscilloscope to TP 7 (f/u Informa¬tion; y = 10 mV/div; x = 2 ms/div). Use a high impedance, low capacitance probe, since other wise rf interference may be encountered under some conditions.
- Press Start.
- Adjust R 210 "tacho sym." for minimum voltage-step amplitude, <20 mVPP.
2. R 238 "PHASE LOCK SYM." -Turn on the unit. Press Stop.
- Adjust R 238 for 0 V at TP 9 of the board.
3. R243 "SYM.t"
- Connect Jumper 201.
- Connect an oscilloscope (y - 5 V/div,. x = 5 ms/div) to TP 8 on the board.
- Press Start.
- Adjust R 243 "sym.T" for minimum pulse pause.
- Disconnect Jumper J 201.
ADJUSTMENT OFTHE MOTOR AMPLIFIER
4. R 148 "OFFSET ADJ. 2"
5. R 147 "OFFSET ADJ. 1"
6. R 145 "PHASE SYM."
7. R 146 "GAIN ADJ."
- Remove jumper J 202 to open the control loop. A constant de voltage lies at the input of the amplifier (TP 9).
- Turn on the unit. The turntable platter will turn forwards.
- Connect an oscilloscope (y = 50 mV/div; x = minimum sweep) to S4/1 and to S4/2 to the board (0V: pin S4/3).
- Set both Signals symmetrically about their zero-signal levels with R147 "offset adj 1" and R148 "offset adj. 2".
- Set both Signals to an identical amplitude with R 145 "phase sym."
- Set the Signals to 100 mVpp with R 146 "gain adj."
- Connect Jumper J 202!
Speed Control Board
TACHOMETER SIGNAL (PIN S9/1)
The tachometer Signal, fed from the tachometer amplifier in the motor, appears as a sinewave Sig¬nal at the input of the Speed Control board at pin S9/1. The level at 33 1 /3 min:1 lies between 12-13 Vpp.
f» « 142.2 Hz f45 = 192 Hz f78 = 334 Hz
CIRCUIT DESCRIPTION (DETAIL)
TACHOMETER SIGNAL CONVERSION
Z201 is connected as a Schmitt trigger. The sinus¬oidal tachometer Signal is converted to a sym¬metrical squarewave Signal. The negative portion of the Signal is shorted to 0 V by D 203. The sym¬metry is adjusted with R 210 "tacho sym.".
FREQUENCY DOUBLING
Voltage pulses appear at Output 4/Z 202 (TP 1) at twice the tachometer frequency for speeds of 33 and 45 min:1 . At 78 min: ,pulse frequency is identical to the tachometer frequency (input 8/Z 202 = "0"). The duration of the pulses is determined by the RC networks C 204, R 215 and C 205, R 216.
PHASE COMPARISON
Z 203 is connected as a phase comparator. The reference signal (the divided oscillator frequency and signal from 4/Z 202 produce a voltage at 13/ Z 203 proportional to the phase difference be¬tween the two. This voltage is approximately + 7.5 V, upon which pulses of + 7.5 V are super¬imposed, corresponding to either a positive or negative phase difference.
The duration of the pulses is determined by the magnitude of the phase angle.
In the subsequent circuit, a de voltage approx. 7.5 V is subtracted from the Signal of the phase comparator.
The Pulsphase signal is produced at 1/Z 203. It corresponds to the value of the signal at 13/Z 203.
LOOP FILTER
Z 204 Is connected with Output 14 as an integra¬tor. In order to improve run-up Performance, C 207 is shorted during this interval.
Second order low-pass: for attenuating residual
Speed Control Board Service
REFERENCE F/U CONVERTER
The pulses of the reference Signal activate two monostable multivibrators in succession, which produce pulses of constant width: 7/Z 205,10/ Z205.
-7/Z 205 HIGH. Through analog switch 1-2/
Z 207, 7/Z 208 is also HIGH (sam¬ple phase of the voltage on RC network R 240/C 220).
LOW. Through analog switch 1 -21
Z 207,7/Z 208 is also LOW (hold phase of the voltage on RC net* work R 240/C 220).
The analog switch 1 -212 207 is controlled from pin 13/Z 207. It opens during Stop and closes during Start.
-1 0/Z 205 HIGH. Analog switch 10-11 /Z 207 is closed. Approx. 12 V lie on RC network R 240/C 220.
LOW. Analog switch 10-11 /Z 207 is open, the RC network R 240/ C 220 discharges.
-Z 207/z 208 function as a sample and hold Z 209 stage. The voltage on the RC net¬work Is transferred to C 217 during the sample phase and conducted to output 5/Z 208, where it Is held constant, during the hold phase.
A voltage which is dependent on the frequency of the reference Signal appears at output S/Z 208.
TACHOMETER F/U CONVERTER
The f/u conversion of the tachometer signal is performed in the same manner as for the refer¬ence Signal.
Differences:
- Opening of the analog switch 8-9/Z 207 is de¬
layed for Stop uptil the speed is approximately
zero. The motor is thereby accelerated against
the direction of the rotation until It comes to a
stop.
- R 243 "sym.t". Identical time constants for f/u
Converters are adjusted with R 243.
Speed Control Board
SUMMING POINT
The difference of the Signal from the f/u Convert¬ers appears at Output 7/Z 210 and is summed at 2/Z 210 with the control Signal from the PLL Cir¬cuit. T 203 is cutoff during Stop and conducts during Start.
STANDSTILL COMPARATOR 1/2 210
A voltage of approx. -15V lies at 1/Z210. When Stop is pressed, the voltage remains at this level until the voltage at 5/Z 209 falls below a speci¬fied value (approx. 1.5 V). The comparator jumps to approx. +15 V. The f/u Converter for the ta¬chometer signal is switched off with this Signal.
CONTROL SIGNAL
The control Signal Is produced at 14/Z 211.
MOTOR CURRENT LIMITING
Motor current limiting is accomplished with 71 Z 211. If for instance, the turntable platter Is held by hand, C 214 is charged to a level above the threshold voltage of approx. 10V. Output 7/Z 211 jumps to approx. -15V, the gate Potential of T 202 sinks to approx. 0 V, T 202 conducts. The control signal is thereby limited to approx. 3 V.
FORWARD/REVERSE IDENTIFICATION
The forward/reverse identification prevents un¬controlled acceleration of the turntable platter opposite to the selected direction. This function is implemented with two identically constructed tachometer generators, the phases of which dif¬fer by 90° by reason of their physical location.
Function:
Tachometer signal (after conversion into Square wave)atD1 5/Z 213.
Auxiliary tachometer signal (after conversion into Square wave) at Ck 1 3/Z 213.
a) Normal case: Start pressed, platter rotates forward. Q1 1/2 213 remains LOW.
b) Start pressed. Platter is rotated backwards by hand during cueing.
Изменено: - 18-02-2011 19:33:59
