Vintage Audio
this section covers some restoration work that I did on my vintage HI-FI gear
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Article #1 | 10:00 PM Sunday 03/01/2016

AKAI AA-5210 #2: Introduction

This is one of my two identical amplifiers that I use in my study.

The electrical characteristics of this small amplifier might look conservative at first. But I assure you, it is a true performer. This amplifier came to me with the front face clogged with cigarette smoke. It had a dark golden hue. I tried to wash it as much as I could. Unfortunately some of the letters in the POWER inscription got wiped. Inside it was like new. But the cigarette smoke is omnipresent. This amplifier requires a thorough cleaning of the circuit boards. This could only mean complete strip down of every electronic part. The volume button interrupts a little at about a third of its course. A faint electrolyte smell mixes with the cigarette smoke. Otherwise, it still sings music. And does it well enough for its age.

If you want to see its brother passing through the same restoration process, then check out its page: AKAI AA-5210 #1.

Article #2 | 11:00 PM Sunday 03/01/2016

AKAI AA-5210 #2: Technical Data

This amplifier has the following technical characteristics.

TECHNICAL PARAMETERS
ParameterValue
Continuous RMS power (both channels)15 W + 15 W (8 Ω at 1,000 Hz)
Total Harmonic Distortion<0.5% (at rated output)
IHF power bandwidth (each channel driven at 8 Ω)15 Hz - 80,000 Hz
Frequency Response (at normal listening level)20 Hz - 50,000 Hz
Load Impedance4 Ω - 16 Ω
SemiconductorsTransistors: 23 / Diodes: 8
Power Voltage100 V, 117 V, 220 V, 240 V, at 50/60 Hz
Power Consumption120 W (max)
Dimensions / Weight108 mm (H), 430 mm (W), 290 mm (D) / 7.2 kg

Article #3 | 12:00 PM Tuesday 05/01/2016

AKAI AA-5210 #2: Parts List

I have assembled a parts list for this amplifier. My restoration touches some of the original transistors. Normally the original transistors contribute to the authentic AKAI sound. But modern equivalents are better in any aspects. I am also interested in exchanging the electrolytic capacitors. So this is what you will find listed below.

The schematic value corresponds to what normally can be found in the electrical schematics. The recommended value is what I replaced the former part with. Where I found appropriate, I have chosen a film capacitor replacement instead of an electrolytic. My reasons are reliability in time. Less electrolytic capacitors, less time-ticking bombs.

Descriptions and Parts Listings

The Power Amplifier Block is coded 96-5008 and is located in the bottom-right part of the steel chassis. You will recognize it by the power transistors which are mounted on an aluminum radiator.

Power Amplifier Block (96-5008)
IdentifierSchematicRecommended
1-C12.2 uF / 50 V
1-C1b2.2 uF / 50 V
1-C2100 uF / 50 V
1-C2b100 uF / 50 V
1-C52.2 uF / 80 V
1-C5b2.2 uF / 80 V
1-C7100 uF / 6.3 V100 uF / 16 V
1-C7b100 uF / 6.3 V100 uF / 16 V
1-C91000 uF / 25 V AUDIO
1-C9b1000 uF / 25 V AUDIO
1-C11220 uF / 35 V
1-C11b220 uF / 35 V

The Tone Control Block is coded A5-5029 and is located in the front-center region of the steel chassis, next to the tone shaping potentiometers. For an easy maintenance access, you need to extract this board. Or you could work your way through the bottom of the amplifier chassis after you remove the switches printed circuit board.

Tone Control Block (A5-5029)
IdentifierSchematicRecommended
2-C147 uF / 50 V
2-C1b47 uF / 50 V
2-C547 uF / 6.3 V47 uF / 25 V
2-C5b47 uF / 6.3 V47 uF / 25 V
2-C64.7 uF / 25 V4.7 uF / 50V
2-C6b4.7 uF / 25 V4.7 uF / 50V
2-C1010 uF / 25 V10 uF / 50 V
2-C10b10 uF / 25 V10 uF / 50 V
2-C12100 uF / 6.3 V100 uF / 25 V
2-C12b100 uF / 6.3 V100 uF / 25 V
2-C1347 uF / 50 V
2-C13b47 uF / 50 V
1-C142.2 uF / 25 V
1-C14b2.2 uF / 25 V

The Equalizer Block is coded A5-5028 and implements the Phono preamplifier and the RIAA correction curve. You can find it in the front-right part of the steel chassis, next to the Tone Control Block board. In order to operate changes, you need to extract this board too. Or you could work your way through the bottom of the amplifier chassis.

On this board the capacitors are listed for both channels.

Equalizer Block (A5-5028)
IdentifierSchematicRecommended
3-C1100 uF / 16 V100 uF / 25 V
3-C2100 uF / 16 V100 uF / 25 V
3-C31 uF / 25 V1 uF / 50 V FILM
3-C41 uF / 25 V1 uF / 50 V FILM
3-C52.2 uF / 25 V
3-C62.2 uF / 25 V
3-C710 uF / 25 V10 uF / 50 V
3-C810 uF / 25 V10 uF / 50 V
3-C91 uF / 50 V1 uF / 50 V FILM
3-C101 uF / 50 V1 uF / 50 V FILM

The Power Supply Block is coded A5-5026 and occupies the bottom-center of the steel chassis next to the power transformer. You recognize it by the four rectifier diodes.

For the electrolytic capacitors on this board, you need to order only once.

Power Supply Block (A5-5026)
IdentifierSchematicRecommended
5-C1100 uF / 63 V100 uF / 100 V
5-C2330 uF / 63 V470 uF / 100 V
5-C3330 uF / 63 V470 uF / 100 V
5-C447 uF / 50 V47 uF / 63 V

The construction of this amplifier is straightforward and poses no problems for the restoration.

As always, let me throw a piece of advice. Do not hurry, take your time and do the job once. And do it well.

Article #4 | xx:xx PM xxx xx/xx/xxxx

AKAI AA-5210 #2: Restoration

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Copyright © 1998- Alexandru Groza