Sansui AU-D5 Integrated Amplifier Repair
This amp came to me with a complaint that the protect mode is on, and all LEDs on the right channel light up.
As usual, opened the amp and did a thorough cleaning.
Since the main caps were a bit bulgy, as you can see from one of the above pictures, I checked ESRs of all the Electrolytic Caps with Blue ESR meter and found many of them out.
Even the capacitance value was far below the tolerance level. Following pictures are of 9000mfd/63V. (I replaced these with 10,000mfd/100V caps)
So decided to replace all electrolytic capacitors on the board. Changed 56 capacitors totally.
See, how the board looks after replacing the caps:
Did lubrication of all controls and switches with Philips Switching Cleaning Oil (my old stock; this is no longer available). Found that the rotating type speaker connectors were jammed. So, removed it from the amplifier, dismantled each one of them and found cut wires of the speaker inside these. This is a curse with this type of connectors!
Reconnected the Speaker outlets, and reassembled the PCBs, duly connecting all the wires and after visual examination for any possible mistakes, switched it on. It worked perfectly. So, put the covers back. Just see how it started working perfectly well:
Another satisfactory job!
This article was prepared for you by Parasuraman Subramanian from India. He is 65 years old and has more than 30 years’ experience in handling antiques equipment Valve Radio, Amps, Reel Tape Recorders and currently studying latest techs classes conduct by Kerala State Electronics Technicians’ Association. He was a BBA graduate, retired as MD of a USA company and presently working as Consultant Manager, Purchase & IT, in Irinjalakuda Cooperative Hospital.
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https://www.jestineyong.com/stk-ic-tester/
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AccordionTom
October 26, 2015 at 8:54 am
Good job! Thank you for the write-up.
Mark
October 26, 2015 at 9:01 am
Hey Parasuraman, you are a very patient man! That is a lot of capacitors..... I hope the customer appreciates all the work you have done. Thanks for all the explanations of the repair.
Muftah
October 26, 2015 at 12:07 pm
Good work Mr.Parasuraman.
Suranga Electronics
October 26, 2015 at 1:44 pm
success job..
Emmanuel
October 26, 2015 at 2:12 pm
nice job u have done. but the capacitors are much, does it means the decrease in the tolerance value is the cause of the protect light been on permanently?
Yogesh Panchal
October 26, 2015 at 2:29 pm
Good Job sir,
Albert van Bemmelen
October 26, 2015 at 3:22 pm
Good Job Parasuraman! It is always those degrading Electrolytes. Also in most of the defective Power Supplies the cause of Failure.
Petrica
October 26, 2015 at 4:12 pm
Good results Mr.Parasuraman !In many situations these is best solution when a audio device go bad .Change capacitors!
Andre Gopee
October 26, 2015 at 8:59 pm
Great Job and keep up the good work.
Parasuraman S
October 27, 2015 at 6:35 am
My replies:
Many thanks to all my brothers/sisters across the Globe for your supports. It indeed makes a difference!
Electrolytic capacitors have a shelf life. These become bad over a period of time or when not in use for a very long time. The impedance gets affected since the values of these change. Normally, the circuit designs of highly professional equipment is designed to take care of such change in all round tolerances, to make the impedance balancing within the limits. But sometimes, these do happen. The best and healthy way is to replace all electrolytic capacitors in any old equipment. It is not how long we take to repair that matters, but how good we do it! That gives satisfaction and fuel to propel forward!
Robert Calk
October 27, 2015 at 9:49 am
Nice job Parasuraman. Thanks for sharing your repair with us.
I agree with you, especially when it is a device that we really like and want to keep for as long as we can.
imanol
May 23, 2021 at 5:17 am
en mi caso el amplificador no enciende , el protector o se ha roto o le han devuelto los altavoces por corto que lo que aguanta, se abrá quemado la fuente o solo es una reparación simple.
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In my case the amplifier does not turn on, the protector has either broken or the speakers have been returned for short that what it holds, the source will be burned or it is just a simple repair.
Humberto
October 30, 2015 at 8:29 pm
Good repair Parasuraman, another device saved from the dump.
Prashanth Suvarna
March 26, 2024 at 5:01 pm
Have observed your intensive work on SS AU-D5 with lot of interest because have been doing a second round of Rx on the same. The earlier time Opt Tr were blown and had to with on the spk connectors which I changed to more rugged threaded terminal.(Looks& works better) this time too prot mood is on and noticed that there is a wavering voltage of-3v in Rt Spkr. Trouble is it it was there all the time it could have been traced, but it's intermittent nature is foxing me as it is Dc coupled and the culprit could be hiding anywhere in the pwr Amp board. Have taken your to to replace the caps AsAp. Have gotten hold of the diagram, so I may get better clarity on its working. Will keep you people informed. Pz stand by. Have a nice day.