The radio was purchased after a quick power up test that produced healthy
loud white noise and all displays lite up, however when the radio was
powered up back at home the audio was dead. While all displays appeared
to working well the S meter was showing full deflection.
While
using a sniffer amplifier to probe the input pin 1 at IC5 (uPC2002v
audio amplifier chip) it was noticed that there was goo around the
base of electrolytic capacitor C104.
C104
a 470uF electrolytic capacitor had catastrophically failed blowing the
capacitor’s electrolyte material out the bottom of the capacitor and
onto the PC board. The C104 capacitor was replaced and all the
electrolyte material was cleaned from the board which had reacted with
green PCB mask causing the mask to be completely deteriorated from the
area under the capacitor and leaving exposed copper after
cleaning.
There
is reasonable concern that the electrolyte material would have
ultimately corroded the copper PCB tracks.
With
C104 replaced and all the electrolyte material cleaned, related
electrolytic capacitors C99 and C101 were also replace as a mater of opportunistic
preventive maintenance while the board was out..
