Revived Yet Another AKAI AJ500FS TWO-IN-ONE SET
I request you all to see the following link, before reading this article further, as this case is a result of that article published by Jestine Yong.
https://jestineyong.com/revived-an-antique-akai-stereo-cassette-recorder-aj-500fs/
One of the readers, who had a similar set, living in a city which was more than 1000Kms away from my town, got in touch with me and sought whether I could attend to it. Considering the cost involved in his bringing this all the way from such a long way and also his age, I suggested that I would fetch someone known to me in the nearby area to attend to the set. Though I suggested a couple of names, the referred techies were reported to be disinclined to accept the job. By this time, Covid set in and time passed by. As somehow, I liked this person after my telecons with him, one day I asked him whether he could get his set serviced. As he replied in the negative, I requested him to arrange bringing it to As his relative’s son was studying in a city which was around 50KMs away from my home town and as they frequently visited him, it was arranged to be brought to me through him during one of his visits.
The set was brought to me on a prearranged day by him engaging a taxi that increased the cost of transportation to a high level. I was amazed to see the kind of packing that was done in a suitcase to enable carrying it in the flight without any damage and the user manual meticulously bound and preserved! I could immediately sense the passion the customer had on this set and that made me ready mentally to do a thorough job to the extent possible. I played the set in front of the person who brought it and listened to the very loud crackling noises which could not be controlled by volume potentiometer. I switched it off and kept it aside for taking up on the next priority. As the set is exactly same as the one repaired by me earlier, I am including only the pictures relevant to the works done which are different.
The first picture above show the bound user manual preserved by the customer. The set can be easily dismantled by removing five screws from behind, taking away the knobs from the front and by ejecting the cassette door, and then taking away the front and back, before which we need to detach the speaker wires from the board. The main board was fixed on to the dial cord unit which could be removed by taking away two black screws under the cabinet and two inner screws on both front insides which are hidden from view. The set was clean inside saving my time. But the board was soaked in some sort of sticky oil, which was the result of someone trying to lubricate the controls and switches using unsuitable oil. In all probability, some edible oil might have been used. The dirt and dust that got collected made it further sticky. I applied IPA spray liberally and used brushes wherever possible to remove this sticky substance which could definitely cause a short or an effect of capacitance in the wrong place. As I found dark patches of these in the legs of AN7145H Amplifier IC and the three pin DC connection, I removed them and as suspected these could have caused the shorts which made the incessant sparkling sounds when the set was switched on. It was evident that the set had gone for service elsewhere, might be many years back. Considering the age of the set, a service done in it was obvious.
But, what worried me was the extent of tampering or damage done to the set and crude methods employed for easy finish of the works. I am sure many of you might also feel the shiver in the spine like me when we see a set opened and serviced by some other, many times by unscrupulous hands! Anyhow, I was already half deep in the work and decided to go ahead and finish it with efforts put in unsparingly! Let us have a look at the conditions observed:
From the third picture above, you would notice a wax covering also. The oil had melted it in many places and this also had got mixed up with the dirt and dust to make the cleaning process most difficult! I used a small screw driver and peeled off all such wax coverings and used CRC 2-26 spray liberally to melt the wax sediments and wiped with tissue paper wherever it was possible. The board was thickly populated with components and interconnecting wires, which looked very crude for such an internationally reputed company from Japan! This made cleaning and even reach for replacing components most difficult! But my repeated and determined efforts to clean could make it better. On checking the health of the capacitors, I found many out of range. So, took up the replacement of these capacitors one by one. I think there were around hundred or more of them. Some of the caps were difficult to reach and locating the legs on the PCB side was also time-consuming and strainful. Then removed the IPLS board vertically fit and the RF board fit inside a metal case for replacing the electrolytic caps. It took many hours of work for two days!
The picture of the IPLS board what you see on the top is before replacing the caps. (This is a method that was in vogue during the cassette days. When the extra switch on the tape mechanism is pressed along with the play, the sensor circuit looks for gaps between the two recordings and turns the play mode on! Please see this link for a brief detailing of this: https://audio-database.com/AKAI/player/gx-f90-e.html ). The last picture above would show you how crammed the PCB was and look at the caps located under the wire mess! Does not it have the look of a dense forest? You can then imagine the ordeal that I have had to undergo for replacement of these caps! After finishing all these works I did a thorough retouching of all the boards: Mother board, Power in board, Mic control board, graphic equalizer board, IPLS Board, RF Board, Motor connection intervening board etc. Then refit the removed boards, before which I lubricated the controls and switches very well. The band switch of the set was very long with several legs and firmly fit on the board. I applied CRC and later transformer oil inside the switch and rotated it back and forth many times to do a self-cleaning of the contacts, which had the wrong oil sticking to it. All these laborious and time consuming tasks took many hours of work on several days. After ensuring that there were no man made shorts and rechecking that all capacitors were fit observing the correct polarity, I applied power and noticed that the DC fuse of 1.6A was blowing and traced it to an internally shorting on/off switch. The tar like black substance might be shorting the switch inside. I removed it after making futile attempts to clean it even using IPA, in the process of which a few more fuses blew! In order to remove the switch from the array, we have to gently lift the metal lugs of a rack that holds the switch in place and position, unsolder the pins and lift it out. Then if we lift the end of the spring out of its slot and turn it in opposite direction, it would come out. Then the white portion that enables on/off (depressed and released positions) could be lifted out from the top.
Then the spindle holding the metal contacts could be slid out. We need to be more careful not to spill the contacts if the switch has multiple connections. Following pictures would be more helpful to follow the narrations. The first picture would show the switch array assembly. The second picture would show you the lugs that hold the switch in correction position and place, which is marked with arrows. Please also look at the dark substance stuck inside the contacts.
I kept the entire unit soaked in terpentine oil for a few hours, then took it out, sprayed IPA liberally and gently cleaned the inside and and also pressed the contacts tight enough to make a proper contact. Reinserted the spindle, put back the white locking mechanism in its slot, put the spring back in its position and checked the connections using an analogue multimeter. The contacts were proper and did not show any signs of shorting at the time of pressing and releasing. Refit the switch back in its array and gently bent the locking lugs. We cannot remove these too often as it might definitely break because of the strain. After replacing the switch, applied power and found that the fuse did not blow any more and all switches functioned very well. Then selected the radio section and tuned the stations by manually turning the gang and found that the reception was good. Gave an input signal to the Phono and found that it was also making proper contacts and worked well. I allowed the set to work for several hours on Radio and Phono in and repeatedly pressed all the switches on and off, turned all the controls left and right to ensure that these were clean.
The band switch, nevertheless found to be missing proper contacts occasionally but repeated rotations made it working. I did not venture removing this long switch with several pins for fear of damaging the PCB and sometimes PCB might even break when we try to take it out. We need to realise that the natural wear and tear coupled with abuses made such as using wrong oil for lubrication can all affect smooth performance of any set. There are limitations for restorations whenever mechanical parts are affected as most of these custom made parts are no longer available in the market.
Then turned my attention to the tape mechanism. One of the belts was in a bad condition. One leaf of a leaf switch was found broken and the previous mechanic had done a make shift arrangement by bending the remaining stub down and using a sponge stuck to the knob to push it down when pressed. The method used was really innovative but crude. I removed the leaf switch, took out one leaf of another switch that I had with me and cut it short to fill the remaining length and soldered it on the stub. Then fit it back in place along with the protecting mica sheet, which was shaped well to cover the switch but not to cause an obstruction when the cassette player switches are pressed. Unless we study the methods used by the designer which always vary and many times are very unique, we cannot carry out repair works.
So, I was happy that each such problems gave me an opportunity to learn! Here are some relevant pictures, which would speak for itself:
After replacing the belt and doing lubrication of all its moving parts taking care not to spray it on the pinch roller, play & erase heads and belts, I pressed all the switches several times to enable self cleaning. Then fixed the mechanism connecting it from outside and used a head cleaning cassette and ran it three times as suggested in the guidelines printed on the cassette. Let us have a look at the cassette, as it might be news to many new comers:
The tape is a mild abrasive that cleans the pinch roller and both beads. It is a very good tool for cassette deck repair work. In fact, I had almost forgotten of it and chanced to look at it only when I searched for cassettes to play! This was definitely a lucky customer, indeed, and of-course very deserving too because of his passion in preserving such an antique set bought in the 1980s!
It was working very well and the output was very pleasing, especially in the audio wide mode. I aligned the head using a master cassette and selecting the stereo mode and using headphones. The two electret mikes were also connected temporarily from outside. Then used a blank cassette for recording a song from the radio as well as voice. The recording switch had to be pulled manually while doing this as the mechanism was kept outside. The output was also amazingly superb! But the rewind and fast forward was sluggish and sometimes it got stuck too. The mechanism stopped working if we pressed any of the IPLS switches, as it got overloaded. As that was the same case with other cassettes too, I realized that it meant dismantling the mechanism! Thus, another series of restoration attempts were carried out, including wrapping a piece of flat rubbet belt. When I dismanled the capstan wheel assembly and the supply wheel assembly, I saw that the previous technician had already tried his level best to compensate for the loss of thickness of the rubber rings on the wheels. He had used threads wound on the wheels to push the rubber rings slightly out for proper engagement. Let us have a look at some pictures, without the help of which, many might not follow my narrations:
The last picture what you see is a piece of some tape stuck somewhere by the previous technician, which fell off when I disassembled the capstan wheel section. I resorted to pasting a rubber piece on top of the capstan gear wheel to compensate the loss of rubber on the engaging wheels. I found that the supply wheel was scorched deliberately to enable contact with the rubber wheels (see picture third from last) . Since it was for the rewind, it won’t make a problem as only the playing path should be free from any friction and wobbling. The collection might get affected.
Anyhow any patch work done in any mechanically moving parts would have its own side or after effects, which the user might have to put up with. Let us remember one thing, that any experiment such as this one can be tested only after putting everything back and trying it out and if it did not work, we have to once again dismantle and try other tricks. I had to do such assembly at-least about 9 to 12 times! I even dismanled the supply wheel assembly fully and the capstan gear wheel assembly for cleaning it of dust and sediments of oil. You all can imagine how much of work this set was taking out of me!
Luckily something I did on the capstan gear wheel helped me find resolve the rewind and fast forward problems. I had used a black gum for pasting the rubber, which I had to peel off later because of the strain and subsequent sluggishness found. But that gum served as a good enough rough coating to enable proper contact of the rubber wheels on to it when REW or FF switch was pressed. Thus what looked like an eternal problem got solved by once again sheer luck of the customer. But the IPLS functions did not work as it was too much of a load for the mechanism. The moment that was pressed, the rotation slowed down instead of going fast indicating that something was obstructing. I advised the customer not to use it for fear of once again rendering the mechanism defective probably permanently.
I played several cassetes using FF and REW options and also did recordings. Then assembled the boards back and ensured that all screws were put back in its place and the set was back to its legs once again like before. Continued my tests and kept the progress reported to the customer by way of picutres, audio messages and videos, which of-course were very well appreciated.
Mission accomplished with a lot of sweat, heart burns and mental pressures, which caused an impregnated satisfaciton make a loud entry into the collection bag! (Work started on the 16th of April, 2025 and finished on 26th of April, 2025)
- PS: A couple of times the 5.6 Ohms resistor got burnt instead of the fuse and I had to replace that too. I remembered it only when I saw the final picture of components replaced!
- PS: This customer, who is a qualified engineer himself paid me almost double the amount charged as I had kept him updated with the various stages of work done through videos and audio messages with pictures from time to time. If we make the customer realise how much of work we did on a set, a few of them would be like this, but others might not hesitate to pay our bill without a remorse afterwards! I had such over paying customers in the past too!
THIS IS MY 600TH ARTICLE AND I THANK JESTINE YONG AND ALL OF YOU FOR MAKING THIS POSSIBLE!
This article was prepared for you by Parasuraman Subramanian from India. He is 74 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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Albert van Bemmelen
December 20, 2025 at 6:41 pm
Your 600th article was a long and interesting read with many problems you successfully were able to fix Parasuraman! The transformer oil you used to oil the switches must have been new to me, just like the mentioning of the IPLS function board.
In the past when cleaning cassette-recorders with alcohol and cotton swabs I also used this electronic (230VAC plug) cassette head demagnetizer. Which they say fix high frequency audio problems. That demagnetizer can still be bought and seen here
Parasuraman S
December 20, 2025 at 8:32 pm
Many thanks for your expert comments, sharing of valuable experiences and lead for purchase, dear Albert!
Mark J
December 21, 2025 at 5:29 am
Congratulations on your 600th article. Like I said before I always enjoy your articles. Thank you for sharing.
Parasuraman S
December 21, 2025 at 9:59 am
Many thanks for your continued encouragement and support, dear Mark!
Philip
December 21, 2025 at 5:54 pm
Double-thanks for the two-phase sister radio repair articles, Eng. Parasuraman. In the repair articles I seriously took note of the switches fixing. Switches are such a considerable silent failure point. All in all, the repair was superb, and the lesson exellent, and the advice couldnt have been more elaborate. Though the initials such as IPA should better simply be expressed as 'electronics cleaning argent' for purposes of free-flowing article. I cant thank you enough for the six hundredth repair article. Thats no mean feat. That can happen nowhere else but at Jestine Yong caring blog where I feel most privileged to be always in 'class'. Its an honour for me to interact with highly regarded engineers and master repairers of repute. And for you Eng Albert, your valued prompt comments that deserve to be emulated will never go unnoticed. Your time and again noteworthy responds too should be clocking in the neighborhood of six hundred. To every one else, many thanks, and Merry Christmas and a happy 2026 year !
Parasuraman S
December 21, 2025 at 10:08 pm
Many, many thanks for your wonderful words of encouragement and suggestions and valid comments! Wish you too all the very best!
MP
December 21, 2025 at 6:21 pm
By the grace of God I too hope that in the course of the year 2026 I'll come up with an article here, be it as it may that incompetence is written all over me.
Parasuraman S
December 21, 2025 at 10:09 pm
Many thanks! Eagerly look forward to your contribution!
Adam S
December 22, 2025 at 5:51 pm
Another superb repair and warmest congratulations on number 600, Parasuraman. I look forward to many more in 2026!
Parasuraman S
December 24, 2025 at 2:56 pm
Many thanks for your encouraging comments!
Yogesh Panchal
December 23, 2025 at 4:31 pm
Good Reviving of antique Device! Sir
when we see device is opened by the person who does not know technology our mind struggle to find some perfect words for that guy($$$***&#%!@?$$###). as you told you feel the shiver in the spine.Such people spoil the work to such an extent that the other person has to struggle despite the possibilities of reviving it.
Parasuraman S
December 24, 2025 at 2:58 pm
Yes, very true, dear Yogesh Bai! Many thanks for your comments!