Sharp SA-606H Vintage Amplifier

The SA-606H is a Stereo Tuner Amplifier manufactured by the Sharp Corporation of Japan in the 1970s. It is a similar model to the Sharp SD-305H, which was another version that had a turntable fitted to the top cabinet. The amplifier power output stage is based on the Hitachi 2SC1060 (C1060) power transistors providing 20-watts per channel (music power output), or 8-watts per channel (continuous power output). For the output impedance, the manufacturer recommends 4 Ω, 8 Ω, and 16 Ω values. The tuner section is a 4-band (FM, SW, LW, and MW) system with AGC and AFC, including three station presets for the FM band. At the front, it has lovely slide controls for volume, bass, tone, and balance, and a switched headphone socket that cuts out the main speakers when listening through headphones. At the back, DIN sockets provide inputs for one tape deck, and one record player, and a slide switch selects between ceramic and magnetic cartridge types for the record player input. There are also sockets for the AM and FM aerial connections. It has a wonderful wooden case with dimensions 474 mm × 127 mm × 318 mm, and the whole unit has 7.5 kg mass.

Review

This is a wonderful quality amplifier made in Japan by Sharp and is a great example that shows how Sharp has always been the leaders of consumer electronic products. I managed to find this old timer on eBay and paid a fiver for it. In recent years, people have been moving on to the multi-channel surround sound receivers, however this amplifier has character and a unique sound quality that will be hard to find. The fact that it lasted all these years is a testament to the good engineering design of that era. All of these old timers deserve some respect for staying in a working condition for so long; hence, I always go out of my way to provide them a good service.

The 2SC1060 are vintage Japanese transistors that would be hard to find these days, however, there might be some sellers on eBay with old stock. This transistor has maximum collector current rating (Ic) of 3 A, with Vce being 50 V, which is impressive for transistors of that era. The great thing about this transistor is that it is a triple diffused NPN silicon construction in a TO-220AA case. This very hardy transistor would be difficult to damage, and probably one of the reasons why these amplifiers have lasted so long. The sound quality of this amplifier is wonderful, and it is as its namesake, which is very sharp. The treble boost is +8 dB, whilst the bass boost is +6 dB, and both are very noticeable.

Price/eBay

'Allo 'Allo! France Calling London

The AM and LW bands sounded clear, and many stations on this band still have good content worth listening if you want to keep up with your French or Italian. The SW band was the most fun to listen though because you can detect some Eastern radio stations with strange sounding music that always sounds good with belly dancers. When I was a young whippersnapper I used to have a valve radio that looked very similar to this and I used to have hours of fun tuning in to distant radio stations. I was always trying to improve the antenna so that it would detect more stations and I was able to listen to stations as far as India and Russia.

On the radio dial there is a list of all the old radio stations such as Budapest, BBC Brussels, BBC Rias, SW Funk, Paris Bremen, Luxemburg, MT Carlo Wien, and many more... The electronic engineering for the radio section is high quality, and the tuning capacitor is the traditional multi-plate construction of good quality. There is a large ferrite rod antenna with coils for all the radio bands mentioned.

The FM stereo reception is good because it uses the Toshiba TA7054P FM radio IC. I was able to detect many distant stations, which was impressive. BBC radio 4 was clear, as this is the radio station I sometimes listen to. The stereo channel separation was very noticeable in this tuner and far better than what my modern surround sound receiver produced.

Reviving the Old Timer

When I bought the Sharp SA-606H it was completely dead. However, I am an Engineer, and we have the technology and expertise to revive anything. The first thing I checked was the fuse in the mains plug, which was OK. The power was certainly getting to the main power switch, and coming out from it, so that was fine. Checking the fuse array inside the amplifier revealed two fuses had blown thereby indicating a short on those power rails. Checking the power rails indicated that it was not loaded down; hence, whatever caused the short was no longer present. I therefore replaced the fuses and the old timer came to life, with all the lights at the front illuminating. It was impressive because this amplifier has these wonderful bright colourful lights similar to a VFD display, kind of like the cockpit instrument panel on a 747.

I decided to check for sound and plugged in some headphones, however there was no sound. It was as quiet as a field mouse. Further investigations with a digital meter revealed that the transformer's secondary coil was producing AC current. This was rectified, and there was definitely DC present. There was plenty of juice in his veins but his circuits were shocked to Hell; he needed a little TLC.

The amplifier board was definitely receiving this DC current so I checked the transistors for shorts and opens. A quick check in-situ revealed that the transistors were fine, but there was nothing showing on their emitters, which is unusual. Hence, I checked the power resistor connected to their emitters, as this is the only other thing that completes the circuit across the rails in a Class A, and sure enough, they were open.

That was a good instinctual call I thought, considering I am working without a circuit diagram! Luckily, I had some recycled resistors of the same period and decided to replace all four to keep the channels identical. I switched the old timer on again, and he began producing a wonderful sound through my headphones; I had the amplifier set to FM radio and it was playing, "It’s Not Unusual" by that Welsh god of music. I then connected some test speakers and it sounded great. The amplifier board also has some presets for DC offset and bias calibration, so I corrected those as well. The presets also needed a good clean with a contact cleaner first and then I adjusted them precisely with pinpoint accuracy. The sliders were crackling -- which is not unusual -- and some good quality contact cleaner sorts that out wonderfully. I liked this old timer so much that I used up a whole can of expensive contact cleaner for all the switches and contacts. Even the PCB received a good clean!

The next day I connected my turntable, and my Sony TC-152SD tape recorder, and the sound quality was very impressive. I had no idea that these vintage amplifiers sounded so great. I will have to keep an eye out for more.

Dust-to-Dust, Old-Timer-to-Old-Timer

Just as I was sitting down to a nice hot cup of Earl Grey and listening to my favourite 60s record, there was a knock on the door, and it was My Friend Father Clarke... As soon as he saw and heard the amplifier, he had to have it, and he would not take no for an answer. I of course received all the blessings of the Church, including a short sermon about how god will look my way this year... Yes, apparently this year is definitely my year. I will be sailing in my own yacht in the Bahamas... Moreover, almost by magic, an act of god you could say, the amplifier was gone! Moreover, so was Father Clarke! Before I had even I decided to let him have it. I figured the old timer going to another old timer was good cosmic symmetry though.

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