Integrated Amplifier
1981
The RA100 is the simplest - but also by far the smallest - amplifier from the 1981 series, if you don't count the midi components. This was possible by packing the power amp part into a hybrid IC and using a toroid core transformer. Of course, a hybrid IC is nothing a high-end Hifi fan would want to see in an amp...
2x40 Watts RMS, 2 pairs of speakers (clamps and DIN connectors), high-pass filter, mono/loudness switch.
Magnetic phono/Aux/Tuner/Tape (DIN only), 4 x speaker (DIN plugs resp. clamps)
(taken from the user's manual)
| RMS Output Power: | 2 x 40 W |
| Peak Output Power: | 2 x 60 W |
| Rated Impedance: | 4 Ohms |
| Intermodulation Factor: | < 0.1 % |
| 250 Hz / 8 kHz, 4 : 1 | |
| Transmission Range: | < 10 Hz ... > 40 kHz, +/-1.5 dB |
| Power Bandwidth: | < 10 Hz ... > 50 kHz @ K=7% |
| Dampening Factor: | > 35 @ 40 Hz |
| Input Sensitivity/ | |
| Impedance/ | |
| Overload Immunity @ 1kHz: | 200 mV / 470 kOhm / 26 dB for tape |
| 200 mV / 470 kOhm / 26 dB for tuner | |
| 2 mV / 47 kOhm / 32 dB for phono | |
| Outputs: | 1.0 mV / kOhm at tape rec |
| headphone 8 - 200 Ohms | |
| 4 speakers 4 - 8 Ohms | |
| (2 x room A, 2 x room b) | |
| Controls: | balance: +0 ... -50 dB |
| treble: +/- 12 dB at 15 kHz | |
| bass: +/- 17 dB at 40 Hz | |
| Deemphasis TA Magn: | according to IEC/DIN 45546 and 45547 |
| Noise Filter: | 6 dB per octave, 6 kHz threshold |
| frequency | |
| Voltage Ratio: | > 67 dB at 50 mW, sh. 6 (eff.) |
| Channel Separation: | > 55 dB at 1 kHz |
| > 35 dB at 10 kHz | |
| Input Separation: | > 70 dB at 1 kHz |
| General: | |
|---|---|
| Components: | 4 integrated circuits |
| 15 transistors | |
| 6 diodes, one rectifier | |
| Power Requirements: | 220 or 110 volts AC at 50/60 Hz |
| Fuses: | secondary: 2 x T6.3 A |
| Dimensions: | 435 x 56 x 250 mm (W/H/D) |
As I already mentioned, the RA100 uses a hybrid module for the power amp section. In this case, it is a STK465 from Sanyo. These modules seem to have a finite life time and/or are sensitive to overloads and shorting. A quite common failure is that one of the final transistors in the push-pull gets shorted, leading to an output driven with either +30 or -30V...in contrast to some hybrids known from Technics amps, the DC protection is outside the hybrid, therefore does not fail in the same moment and your speakers stay alive ;-)
These days, it is extremely difficult to buy a replacement hybrid amp. The last source in Germany I knew dried up a year ago. Since typically only one channel breaks, you may think of assembling two 'half' hybrids, but that is difficult with the space constraints in the RA100.
I've been told that there is a source in USA
http://www.datadart.com/al/alindex.htmthat still has some in their stock. Furthermore, there seems to be a compatible module named 'NTC 1345'.
| Mechanical Parts | ||
|---|---|---|
| 1 | front panel | 339 132 115 |
| 2 | knob guide, 3-fold | 339 222 113 |
| 3 | mains knob guide | 339 222 112 |
| 4 | side mask for front panel | 339 232 120 |
| 6 | push button | 339 229 110 |
| 7 | holder for push button | 339 222 111 |
| 8 | spring for push button | 339 202 108 |
| 10 | decorative ring 30 mm | 339 272 108 |
| 11 | decorative ring 17 mm | 339 272 109 |
| 13 | volume knob | 339 222 109 |
| 14 | control knob | 339 222 114 |
| 15 | mains knob | 339 222 115 |
| 17 | cabinet, top part | 339 152 108 |
| 21 | socket holder | 339 872 110 |
| 23 | angle for mains switch | 339 827 106 |
| 24 | mains switch rod | 339 827 107 |
| 29 | bottom plate | 339 132 121 |
| 30 | foot, cpl. | 339 062 107 |
| 31 | felt foot, rear | 339 062 109 |
| 32 | foot fixing plate | 339 062 111 |
| AF Amplifier Board | ||
| 35 | AF amplifier board | 339 337 122 |
| IC401 | IC STK465 | 339 575 266 |
| IC701 | IC TA7317P | 339 575 265 |
| T301/302/304/305 | transistor KTC732 TM-GR | 339 556 505 |
| T303/1303 | transistor KTA970 BL | 339 556 435 |
| T501 | transistor KTC22360 | 339 556 437 |
| T502 | transistor KTC950Y | 339 556 436 |
| T701/702 | transistor MPS9630K | 339 556 429 |
| T703 | transistor MPS9680T | 339 556 430 |
| D001 | diode KBPC602 | 339 529 292 |
| D502/503 | diode ZPD-18 | 339 529 294 |
| D701-703 | diode 1N4148 | 339 529 034 |
| D704 | diode 1N4001 | 339 525 013 |
| C501 | Al-El. Cap. 4700µF/35V | 339 588 040 |
| R396/397 | var. res. 100 kOhm, bass/ | 339 502 119 |
| treble | ||
| R398 | var. res. 100 kOhm, balance | 339 502 118 |
| R399 | var. res. 100 kOhm, volume | 339 502 117 |
| R407/1407 | res. 0.22 Ohm/3W | 339 537 107 |
| RY | relay | 339 360 106 |
| S1-4 | push button assembly | 339 442 112 |
| S5/7 | push button assembly | 339 442 114 |
| S6 | switch | 339 442 111 |
| S9 | switch | 339 442 113 |
| FU501/502 | fuse 6.3A | 339 570 070 |
| Equalizer Board | ||
| 36 | equalizer board, cpl. | 339 337 123 |
| 37 | DIN socket, 5 contacts | 309 672 801 |
| IC351/1351 | IC HA12017 | 339 575 311 |
| L351/1351 | coil 5.6 mH | 339 347 121 |
| 40 | speaker switch-over, cpl. | 339 337 125 |
| 41 | LED mains indication | 339 337 117 |
| 45 | headphones socket | 309 671 967 |
| 46 | loudspeaker socket | 339 540 139 |
| 47 | clamp socket for speaker | 339 550 107 |
| 48 | mains switch | 339 442 115 |
| 50 | mains transformer | 339 312 110 |
| 51 | power cord | 339 482 106 |
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