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Old 10-15-2017, 10:15 PM   #25
R_J
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Join Date: Jun 2012
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Default Re: Philips FR-740 working but no audio output

On page 78, MFD looks like it should be 0 volts on base of 7253 (power down circuit) and the collector should be +5 volts (amp pd)
A lot of the voltages are marked so make sure they are all ok, the only one I can see that is not right is that {amp lr} line, it should be +5 and its 0 so the main amp ic's are not turned on.
That amp lr line is controlled by one of the output lines of ic7412 (page 34) and that ic takes data in to control the output lines, so something (microprocessor) must not be telling it to turn on pin 6,

Last edited by R_J; 10-15-2017 at 10:23 PM..
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