Hitachi-HMA6500-pwr-sm维修电路原理图.pdf
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1、SERUICE MATUA1 SPECIFICATIONS Continuous RMS power outpul Harmonic d istortion (both channels driven) (at rated output) lat 1 12 rated output) Power bandwidth (lHF) (at 1 l2 rated output) Frequency characteristics (at 1 W output) I nput sensitivity ( j mpedance) Damping factor Channel separation Slg
2、nal-to-noise ratio (lHF, A network) Speaker impedance Power supply Power consumpllon Dimensio ns Weight English Deutsch Franqais 50 watts per channel min. RMS, at 8 ohms from 20 Hz Io 20 kHz, with no more than 0.02% total harmonic distortion. 55 w/ch + 55 w/ch (8 ohms, 1 kHz, T.H.D . O.O2%l 53 w/ch
3、+ 53 w/ch (4 ohms, 1 kHz, T.H.D .0.02%l Less than 0.02% Less than 0.003% 5 Hz-60 kHz (8 ohms, T. H. D. 0.05%) DC-1OO KHZ 1? dB (DIRECT COUPLING) 5Nz-100 kHz 1? dB (CONDENSER COUpLtNG) 1 V (SO kohms) 50 (1 kHz, 8 ohms) 80 dB (1 kHz, 8 ohms, input shorted) 115 dB 4-16 ohms (A, B), 8-16 ohms (A+B) AC 1
4、20 V 60 Hz, - 120 v l22O V 1240 v 50/60 Hz 22OW or 320 VA (AC 120 V) 430 W (- 220-240V1 435 (W) x 153 (H) x 306 (D) mm 11-118 (wl x 6-1132 x 12-1116 Dl 9.4 kg (20.7 lbs ) No. 159 Specif ications and designs may be changed wlthout notice for improvement STEREO POWER AIhPI.ITIER Febru aryI 979 RadioFa
5、ns.CN 收音机爱 好者资料库 t Sinusdauerleistung ( R MS) Klirrfaktor (beide Kanle betrieben) (bei Nennlelstung) (ei 1 12 Nennleistng) Leistungsbandbreite ( I HF) (bei 112 Nennleistung) Frequenzgang (bei 1 Watt) Eingangsempf ind lich keit ( I mpedanz) Dampf u ngsf aktor Kana ltrennung Geru schspannu ngsabsta nd
6、 (lHF, A-Netz) Lautsprecherim pedanz Netzspan nu ng Leistu ngsauf nahme Abmessu ngen Gewicht SOWKanal *SOWlKanal (g Ohrn;20 Hz -20 kHz, Gesamtkl irrfaktor 0,02%) 55 W/Kanal + 55 W/Kanal (8 Ohm,.1 kHz, Gesamtklirrfaktor O O2%l 53 WlKanal + 53 W/Kanal (+ Ohm,!. kHz, Gesamtktirrfaktor O,O2%l Wen iger a
7、ls O ,02o/o Weniger als 0,003% 5 Hz - 60 kHz (8 Ohm, Gesamtklirrfaktor 0,05%) Gleichstrom-l00 kHz 1 Oa (Oiret Chassis ground Fig.4 The is because the POWER MOS FET is in the source case, and in order to maintain the capacity between FET and the radiation fan, stability deteriorates by this, so the F
8、ET is isolated from the chassis using a resistor of 47 ohms. Accordingly, be careful not to cause an output by touch- ing the Q lead wire of the speaker to the chassis or dis- charge the electrolytic capacitor during servicing, since this may cut the lead wire of Rl or R2 and introduce nolse. 5q . W
9、oshcr _kl) -4- . Precautions on troubleshooting and replacing parts (1) When the stabilized power circuit and the peripheral parts of Q701 and Q702 (D106, R752, R753 and their peripheral parts) are replaced, the adjustment of the input/output DC may drift, so be sure to check the input/output/ DC vo
10、ltage. (2) Since grade of hrs is specially classified into - fo. Q701 and Q702, replace them match- ing the proper grade with the proper channel. (3) Since the socket for transistor use is used for the socket of the POWER MOS FET, polarity is indicated as B, C, E. Match it to the indications shown i
11、n Fig. 5 when replacing the POWER MOS FET and when checking. . Gautions on checking the voltage (1) Oscillations may occur depending on the voltmeter HITACHI HMA-6500 used when checking the gate voltage at FET 701 L/R. If this happens, measure the collector voltage of Q704 LiR as it is at the same p
12、otential as FET 701 L/R. The protection circuit may operate when checking the collector voltage of Q706 L/R and the base voltage of Q707 L/R. In this case, change the measurement position and measure the voltage between the respective electrodes. Gate (G) Fig. 5 (2) ADJUSTMENT . Adjusting idle curre
13、nt Perform adjustment with no signal and with the speaker switch turned OFF. Remove the wiring , shown in Fig. 6 and connect the side of the DC ammeter to the drain side of the FET and the O side to the main amp. PWB. Next,adjust R75 lL and R75 lR on the main amp. PWB. so that they are both 150mA. A
14、ttached the wiring , as they were, after adjust- ment is completed. IEI|OZR FETTOZL Fig.6 o Adjusting the input DC Insert the shorting pin to the input, set the DIRECT COUPLING/CONDENSER COUPLING switch to CONDENSER COUPLING, turn the speaker selector switch ON, and turn the powet switch ON with no
15、load for more than about 8 minutes before performing the adjustment. To adjust Lch, connect the side of the DC arnmeter to 13 terminal of the main amp. PWB, and the Q side to 14 terminal. To adjust the Rch, connect the side to l5 terminal, and the Q side to 14 terminal. Then perform the adjust- ment
16、 using R152L or R752R respectively for a zero reading (within t 0.5V) with the 3mV range. (Fig. 7) o Adjusting the output DC Be sure to perform this adjustment after the input DC adjustment is completed. Insert the shorting pin in the input, set the DIRECT COUPLING/CONDENSER COUPLING switch to CONDE
17、NSER COUPLING, turn the speaker selector switch ON, and perform the adjustment with no load. Fig.7 Perform adjustment using R753L or R753R after con- necting the DC ammeter to the and Q sides of the speaker A terminals of Lch or Rch for a zero reading (within +5mV), with the l00mV range. (Fig. 7) Ad
18、justing the meter Adjusting the meter sensitivity Adjust sensitivity of the meter after zero adjustment is completed. With no load applied to the speaker ter- minals, connect the audio oscillator to the input terminal (INPUT) to feed in a signal of lkHz. In this case, adjust the input so that the Lc
19、h pointer indicates 1W. Then adjust R955R so that the Rch pointer also indicates lW (Fig. 7). o (1) FETT02R Fig. 6 -5- HITACHI HMA.6500 CHECKING THE OPERATION OF When the output circuit is repaired by replacing the power MOS FET, etc., perform an operation check on the ASO (Area of Safe Operation) d
20、etection circuit and the speaker protection circuit. 1. Operation check of the ASO detection circuit for the power MOS FET Connect the audio oscillator to the INPUT terminals with the speaker terminals unloaded (speaker : dis- connect). Set the frequency of the audio oscillator at lkHz and adjust th
21、e level of the input signal so that the voltage at the speaker terminals is approx. 5V rms. Under these conditions, short-circuit the speaker termi- nals of the channel to which the input signal is applied using a lead wire, etc. If this short-circuit makes the ASO detection circuit operate, no outp
22、ut appears at the speaker terminals even if the lead wire used for short- circuiting is removed. Next, turn off the power switch and, after approx. 10 sec., turn the power switch on again. When out- put comes out of the speaker terminals, this indicates that the ASO detection circuit is operating no
23、rmally. 2. Operation check of the speaker protection circuit Make sure that the relay operates(a click sound is heard) approx. 4 seconds after the power switch is turned on with the speaker terminals unloaded (speaker: discon- nect). ACvolmeler 0scilloscope Fig. 8 o Phenomena and remedy when the pro
24、ection circuit operates THE PROTECTION CIRCUIT Next, when a resistor of approx. l0 kohms and2 dry cells (1.5V) are connected in series to R902 on the audio printed wiring board and the jumper wire , the relay turns off within I sec. When the dry cells are taken away, the relay operates again. Next,
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- Hitachi HMA6500 pwr sm 维修 电路 原理图
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