Yamaha A-1 Natural Sound Stereo Amplifier Shipped from Japan Maintained Adjusted

509 YAMAHA Yamaha A-1 maintenance adjustment product. After the maintenance, Yamaha sound is revived with the sound stability in all bands as well as the clearness and omission of the sound, as well as the stability of operation, and it is a finish that makes you feel the musicality. Panel front part there is a line scratch of about 10 mm/0.40 on the left side of the sealing panel YAMAHA logo, top edge part. It seems that the passable state is maintained without large scratches, rubbing, discoloration, etc.

Bonnet: Aged scratches, rubbing, etc. Due to use can be seen on the top, left and right side parts.

Operation knobs: Main volume control knob small mark on side, other control knobs and levers are in no problem with no scratches, rubbing, etc. Since the hinge for opening and closing the sealing panel on the front of the panel was damaged, it has been repaired. A lock magnet is attached to prevent the panel from opening when the panel is closed. Please refer to the second photo.

Since the rust and corrosion progressed on the rear terminal part, it was replaced with a good RCA terminal on hand. It looks good and the connection is good. The RCA terminal of the signal input section is designed so that it can exhibit 100% of the signal transmission capacity connected by exchanging it with a good product. MC, EQ amplifier, tone amplifier, driver amplifier, power supply, protector circuit are replaced with the following contents.

Small and medium signal transistors 29 pieces Small and medium capacity high sound quality electrolytic capacitors Nichicon Muse, FG, etc. Replaced power transistor Complimentary 2 pieces same as original (Sanken). AC fuse 1 DC fuse 2 Exchanged.

Speaker protection Protect relay 1 piece for maintenance finished product. Tone bus adjustment volume Replacement of parts that are good for hand-held. Installation AC power cable tie band installation. Perform the following measures as a circuit stabilization measure. (1) Re-solder the deteriorated parts of the main amplifier and control amplifier parts to repair solder cracks due to aging deterioration. (2) As signal transmission stabilization measures, each input selection switch PHONO, TUNER, AUX, TAPE (SOURCE, PLAYBACK) MODE switching. Contact cleaning, tone (ON-OFF switch), main, BASS, TREBLE VR contact cleaning. (3)Output relay Replaced with a non-defective product that has been maintained because the degree of wear of the attached relay has advanced.

(4) Re-apply heat dissipation silicon to the power transistor and heat detection transistor, and clean the heat sink. (5)Clean the board to prevent current leakage from the control, driver amplifier, and power supply leakage. (6)Cleaning inside and outside. Equalizer amplifier, DC midpoint potential adjustment of driver amplifier, power supply voltage adjustment, bias current adjustment.

With the above maintenance and adjustment, it is in a good and stable operation state with no sound interruption or gutter. The presence of noise from the power circuit noise due to the measuring instrument, the leakage from the input circuit due to volume reduction, and the noise from the EQ and control amplifier to the power amplifier output. The output waveform by the oscillator signal input, the left and right output balance (oscillating waveform, listening), TONE (BASS TREBLE). We have confirmed the normal operation of the mode switch, TAPE MONITOR: SOURCE, PLAYBACK, speaker ON-OFF and DISC switch ON-OFF.

Immediately after maintenance Check the operation by continuous power output for 12 hours, check the output by bias current and offset operation log, and then check the normal ringing status for a week for 5 hours each day with a power-on test. Power frequency: 50Hz / 60Hz.

Size: (W) 435 × (H) 117 × (D) 381mm. Weight: 15.8Kg/34.83 lbs. The overall condition seems to be reasonably good given the age.

Amplifier body, instruction manual copy will be. There is no original box or other. It is a used product. Please inspect images for condition reference.

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User instructions are mostly written in Japanese. Electronics voltage is 100V (+/- 10%) no problem for USA or Canada. Now, for countries with 220240V please use a step down transformer.

Listing and template services provided by inkFrog. The item "Yamaha A-1 Natural Sound Stereo Amplifier Shipped from Japan Maintained Adjusted" is in sale since Wednesday, April 22, 2020. This item is in the category "Consumer Electronics\TV, Video & Home Audio\Home Audio\Receivers & Amplifiers\Amplifiers & Preamps". The seller is "japantreasures" and is located in Tokyo.

This item can be shipped worldwide.

Brand: Yamaha
Model: Y112/4.22(65K/1180)20kn416103412A/150NDP
MPN: Does Not Apply