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

AKAI AA-5210 #2: Introduction

This is was 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.


The following articles are not to be treated as do-it-yourself tutorials on how to fix, restore, rebuild, or improve the unit in cause. This was not my initial intention. But you can consider this whole content as a general guideline, should you decide to launch into such an adventure.

The entire documentation is just a reflection of my work and I cannot be held responsible if you damage your unit, or even harm yourself in the process.

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

AKAI AA-5210 #2: Technical Data

This amplifier has the following technical characteristics.

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. I don't believe that transistors actually contribute to any specific sound signature. 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)
IdentifierSchematicRecommendedMouser Number
1-C12.2 uF / 50 V647-UFG1H2R2MDM
1-C1b2.2 uF / 50 V647-UFG1H2R2MDM
1-C2100 uF / 50 V647-UKZ1H101MHM
1-C2b100 uF / 50 V647-UKZ1H101MHM
1-C52.2 uF / 50 V647-UFG1H2R2MDM
1-C5b2.2 uF / 50 V647-UFG1H2R2MDM
1-C7100 uF / 6.3 V100 uF / 16 V647-UFG1C101MPM
1-C7b100 uF / 6.3 V100 uF / 16 V647-UFG1C101MPM
1-C91000 uF / 25 V AUDIO647-UKZ1E102MHM
1-C9b1000 uF / 25 V AUDIO647-UKZ1E102MHM
1-C11220 uF / 35 V647-UFG1V221MPM
1-C11b220 uF / 35 V647-UFG1V221MPM

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)
IdentifierSchematicRecommendedMouser Number
2-C147 uF / 50 V647-UKZ1H470MPM
2-C1b47 uF / 50 V647-UKZ1H470MPM
2-C547 uF / 6.3 V47 uF / 25 V647-UKZ1E470MPM
2-C5b47 uF / 6.3 V47 uF / 25 V647-UKZ1E470MPM
2-C64.7 uF / 25 V4.7 uF / 50V647-UFG1H4R7MDM
2-C6b4.7 uF / 25 V4.7 uF / 50V647-UFG1H4R7MDM
2-C1010 uF / 25 V10 uF / 50 V647-UFG1H100MDM
2-C10b10 uF / 25 V10 uF / 50 V647-UFG1H100MDM
2-C12100 uF / 6.3 V100 uF / 25 V647-UKZ1E101MPM
2-C12b100 uF / 6.3 V100 uF / 25 V647-UKZ1E101MPM
2-C1347 uF / 50 V647-UKZ1H470MPM
2-C13b47 uF / 50 V647-UKZ1H470MPM
1-C142.2 uF / 25 V2.2 uF / 50 V647-UFG1H2R2MDM
1-C14b2.2 uF / 25 V2.2 uF / 50 V647-UFG1H2R2MDM

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)
IdentifierSchematicRecommendedMouser Number
3-C1100 uF / 16 V100 uF / 25 V647-UKZ1E101MPM
3-C2100 uF / 16 V100 uF / 25 V647-UKZ1E101MPM
3-C31 uF / 25 V1 uF / 50 V FILMN/A
3-C41 uF / 25 V1 uF / 50 V FILMN/A
3-C52.2 uF / 25 V2.2 uF / 50 V647-UFG1H2R2MDM
3-C62.2 uF / 25 V2.2 uF / 50 V647-UFG1H2R2MDM
3-C710 uF / 25 V10 uF / 50 V647-UFG1H100MDM
3-C810 uF / 25 V10 uF / 50 V647-UFG1H100MDM
3-C91 uF / 50 V1 uF / 50 V FILMN/A
3-C101 uF / 50 V1 uF / 50 V FILMN/A

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)
IdentifierSchematicRecommendedMouser Number
5-C1100 uF / 63 V100 uF / 100 V647-UKZ2A101MHM
5-C2330 uF / 63 V470 uF / 100 V647-UKZ2A101MHM
5-C3330 uF / 63 V470 uF / 100 V647-UKZ2A101MHM
5-C447 uF / 50 V647-UKZ1H470MPM

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 | 10:00 AM Monday 06/01/2018

AKAI AA-5210 #2: Restoration

I have already restored it's sibling which means that I already have the restoration plan in my mind. Everything should be straightforward.

I am not going to repeat myself regarding part numbers and replacement component markings. In short I have used the exact same parts as for the first AKAI AA-5210 that I have been working on.

General Considerations

Working on this unit exposes you to electrical hazards. There are lethal voltages inside.
Severe accidents and possibly death by electrocution might occur. I am qualified and skilled with electronics and I have been doing audio gear repairs for over 20 years. If you lack experience, please take these articles as just a knowledge base. Do not attempt to repair something that you cannot handle as there is a high chance of doing further damage while also possibly suffering accidents.

Good tools are a must for a quality restoration. I use eutectic soldering alloy and a temperature-controlled soldering station equipped with various tip shapes. I a standard and a precision desoldering pumps and desoldering wick in various widths. To clean the flux, I use isopropyl alcohol and high purity acetone.

Empirically, I found that working with a temperature of exactly 300 °C is safe for these vintage printed circuit boards. I have never lifted any pads and I never wait more than a couple of seconds with the hot tip on any pad. While working on the chassis, I use between 360 and 440 °C. Flux fumes are extremely toxic and should be avoided at all costs.

Every replacement part is brand new, from a reputable manufacturer, ordered from the U.S.A., Japan, or Germany. In addition, I only use parts that are suitable in specific circuit sections, after inspecting and comprehending the original schematic diagrams. Last but not least, I have years of experience backing up my choices and actions.

96-5008 Power Amplifier Board Restoration

Here is the board before the job.

And here it is after servicing.

A5-5029 Tone Control Board Restoration

This is the board before the service operation.

And here it is after servicing.

A5-5028 Equalizer Board Restoration

Here is the board before the job.

And here is the board after working on it. Note the transistors mounted in reverse. This is due to the modern parts having mirrored terminal disposition.

A5-5026 Power Supply Board Restoration

Here is the board prior to restoration.

And after the job.

This concludes the restoration of this unit.

Article #5 | 01:42 PM Monday 19/02/2018

AKAI AA-5210 #2: Impressions

So how does it sound? Like its twin brother.

In the end I parted ways with this amplifier once the Sansui AU-7500 took over my dual amplification rig in my study. In addition, a superb little amplifier like the AA-5210 should be playing music instead of waiting in a corner. It is still in the family, though. These days, my wife's brother in law owns it.

Overall I declare the restoration a success.

your help matters

Please note that all the work presented herein this site is non-commercial. This is my hobby and I am doing this in my spare time. Through this page I freely share my knowledge with you. But if you like my work, please consider helping me buy a transistor or a capacitor for my projects.

Thank you!

Copyright © 1998- Alexandru Groza