Partial Restoration Of Pioneer Two-In-One System Model CK-3
This lovely looking set was received as a gift by one of my friends who was known for electrical/plumbing works. But he manages almost every odd jobs including painting, pressure wash cleaning etc. We know each other from childhood days. He was in Gulf and returned to home town about a few years back. He even repairs Mixie, Fan, Motor etc. but does not take up electronic repair work. That’s how it landed on my table. Knowing me and my background, especially after having provided his electrical/plumbing services in my home, this guy brought it to me only as a last resort that too after hearing recommendation of technicians in and around my town to bring it to me.
When, I pulled him up for this, he told me that he was a bit hesitant to bring such a set, which was not in good shape in front of me, as he was afraid that I might scold him! Strange are the ways of thinking of certain people as it beats all our year long experience of human psychology! Anyhow, the complaint was that it was lying unused for many years and now the power was getting on, but nothing worked. We all know what would happen to a neglected set! He wanted only the Radio section to be working and he did not want the tape recorder section to be set right at all.
After opening and doing a thorough cleaning, I dismantled the set piece by piece and once again cleaned every part of it.
One of the speaker connectors was broken, which I fixed with an externally fit connector later. The set was definitely tampered, as I found that the original Amplifier ICs were missing and two LA4440 ICs were fixed on a separate board and wired very clumsily, with the board left hanging on top of the original board with two pieces of thermocol and paper packing [Both highly inflammable materials near two ICs that might get very hot!]
As you can see from the second picture above, a few of the caps were burst. I replaced all the electrolytic caps on this board as well as on the power supply section, as the values were found way out. Then the Amp board was fixed firmly on the rear cover. After ensuring that the Amp was working very well, I turned my attention to the Radio, as it was completely dead.
I replaced all the electrolytic caps on the board and did a thorough re-touch of the board with fresh solder. Noticed that the three ICs on that section had gone bad, as voltages were not proper at pins. So replaced them and also the crystal. Then the radio section worked very well.
After that, I reassembled the boards back in its original place, and allowed the set to run for several hours before closing it with covers.
Let us have a look at the new speaker connector, and the thermocol pieces with paper removed from the Amp board. And also how I fixed the Amp.
I am providing below snap of a reading of one capacitor to know the extent to which deterioration had taken place, besides the snap of all the parts replaced:
With the replacement of all electrolytic capacitors shown above, the performance of the set was so superb that I had to fight down my temptation to put up an offer to buy!
Mission accomplished with double satisfaction that got doubly qualified to get an entry into the prestigious collection bag! (LOL)
This article was prepared for you by Parasuraman Subramanian from India. He is 72 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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You may check on his previous article on Another Thrilling Antique Valve (TUBE) Radio Service – AIRVOICE 2612
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Arun Kumar
October 14, 2023 at 10:29 am
Simply suuppeerrbb Sir
Parasuraman S
October 14, 2023 at 4:02 pm
Many thanks, dear!
Albert van Bemmelen
October 14, 2023 at 2:00 pm
In these cases I do wonder how such a terrible discarded audio set ever would have been restored to perfection before these ESR meters ever existed? Especially with so many out of spec e-caps!
Parasuraman S
October 16, 2023 at 9:37 pm
We were using analogue multimeter to check the caps, by observing the discharge time. But we had the capacitance meter then, that enabled a check. But removing the cap from the board was necessary. Many thanks for your expert comments.
Waleed Rishmawi
October 14, 2023 at 2:40 pm
good job on the repair but I hope it was wroth it with all these parts replaced. have a blessed day
Mike Retz
October 16, 2023 at 8:32 am
Always enjoy your repair articles. You do a great job on saving the good stuff from the past. Uyi replace tons of caps! You should open a capacitor factory! Lol. That old pioneer stuff is great. That set probably from late 60sor 70s. I had some old pioneer bookshelf speakers that really rocked your socks off! The neighbors hated me,! Look forward to your repair articles! Have a great day and God bless...
Parasuraman S
October 16, 2023 at 9:39 pm
Many, many thanks for sharing your valuable experiences and expert comments! Opening a capacitor factory is a good suggestion! (LOL)
Parasuraman S
October 16, 2023 at 9:37 pm
Many thanks, dear friend!
Yogesh Panchal
October 16, 2023 at 11:31 pm
Good Fix! Sir
Parasuraman S
October 17, 2023 at 11:43 am
Many thanks!