09-01-2021, 07:21 PM
I mentioned this one in the "What did you fix" thread, but since it is a radio (albeit with ICs and transistors) a thread here might be of interest.
The radio is a neat hand-held (7" x 3.5" x 2.5") that covers everything from lonkg wave (150 kHz) to the top of the FM band (108 MHz). No gaps, and various receive modes. Vintage is late 80's to early 90's. Golden age of solid state?
The set was not operable when handed to me by a friend for "a look with no expectations". The speaker clicked when the power switch was operated, but that was all. I have a service manual, and a replacement capacitor kit, and steadily have been working my way through the surface mount boards to change electrolytics, clean up leakage and diagnose problems.
Testing as parts were replaced brought the audio amp back to life, but little else.
The computer and display boards occasionally showed feint signs but were basically unresponsive. This was traced to a feed from the 6 V battery pack via a diode pair package, which had become open circuit or very high series resistance. Making a substitution with 1N4148 devices brought the display and keypad back to life, but no reception achieved.
Last night I spent more time cleaning the board, checking for soldering errors (tiny traces and components) and restored the operation of a DC to DC converter that feeds the oscillator section. Still no reception, but the RF board still needs lots of attention to e-caps. Each one is about the size of a pencil top eraser (or smaller) and the very devil to hold in place and solder with a point-tipped iron, but we are getting there.
Good fun, as always!
The radio is a neat hand-held (7" x 3.5" x 2.5") that covers everything from lonkg wave (150 kHz) to the top of the FM band (108 MHz). No gaps, and various receive modes. Vintage is late 80's to early 90's. Golden age of solid state?
The set was not operable when handed to me by a friend for "a look with no expectations". The speaker clicked when the power switch was operated, but that was all. I have a service manual, and a replacement capacitor kit, and steadily have been working my way through the surface mount boards to change electrolytics, clean up leakage and diagnose problems.
Testing as parts were replaced brought the audio amp back to life, but little else.
The computer and display boards occasionally showed feint signs but were basically unresponsive. This was traced to a feed from the 6 V battery pack via a diode pair package, which had become open circuit or very high series resistance. Making a substitution with 1N4148 devices brought the display and keypad back to life, but no reception achieved.
Last night I spent more time cleaning the board, checking for soldering errors (tiny traces and components) and restored the operation of a DC to DC converter that feeds the oscillator section. Still no reception, but the RF board still needs lots of attention to e-caps. Each one is about the size of a pencil top eraser (or smaller) and the very devil to hold in place and solder with a point-tipped iron, but we are getting there.
Good fun, as always!
I don't hold with furniture that talks.
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