Restored A Liquid Seepage Spoiled AHUJA Power Amp Model DPA770
This Ahuja Personal Power Amplifier was brought to me with the complaint that there was no output, even though the USB/FM was working and it was reading the USB. I opened the set and subjected it to a thorough cleaning, as it was reported to be left unused in a Petrol Bunk for a very long time.
Afterwards when I powered on the set, connecting my external testing speakers, the sound was detected to be coming from the Amp section, but not from the USB/FM or other Mic inputs. Traced the wires and found that the pre-Amp board was fit on its side. Fed an audio signal to the point where the input wire was soldered and found it was not coming out.
On a close inspection of the board with a powerful light, I could notice seepage of some acidic liquid, which had corroded and eaten away the tracks.
On enquiry with the customer, they informed that one of the staff in the Petrol Bunk had accidentally spilled butter milk while taking lunch sitting nearby. Well, as we all know, it is an acidic liquid and that is how the tracks got corroded and eaten away. So, wired it up externally and the audio was working fine when tried. Cleaned the board thoroughly with IPA and looked for any more damages.
I also injected audio signal and checked all inputs. Cleaned all controls using switch cleaning oil. Allowed the set to run for several hours before closing the cover and calling the customer to come and pick up. A job finished quicker than envisaged and satisfaction got added to its collection bag too soon! Here are some more pictures:
This article was prepared for you by Parasuraman Subramanian from India. He is 70 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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