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Old 9th Mar 2009, 12:22 pm   #1
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'LIVEWIRE?''s Avatar
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
Posts: 7,307
Question Alpine 7148L Car Stereo digital Tuning Fault

Basically, the LCD Display is totally blank, the tuning 'free runs', by which I means the radio can be heard searching for stions but doesn't stop, and the controls, other than the mecnical waveband switch, have no effect. The +5v supply to the uP is present, as are both the permanent and accessory +12v supplies, but the 4.5MHz Crystal Controlled Oscillator doesn't appear to be working, and the o/ps from the uP to the display are all at zero. Having worked in the car audio trade for over 23 years(1971-95) I am familiar with how digitally tuned radios work, and am beginning to suspect that the uP is faulty, in which case this early 80s stereo is scrap, but I don't have, and cannot find asource for, a service manual, or even a circuit diagram, for this model, so I may be missing something that can be fixed. Anyone know what it might be??
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