Adcom-GFA5802-pwr-sm维修电路原理图.pdf

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2、MatchedFETsandServiceManualCorrectionsModel#:GFA-5802Bulletin#:GFA-5802-1The GFA-5802 Service Manual notes on page 4 that anumberof the MOSFETsintheamplifier are matched to ensure properperformanceFor repairs requiring replacement ofthese parts, equivalently matched parts must be used. In ordering t

3、hese parts, theseprocedures must be followed.Failureof0169,0171,0176, 0178,063or073For repairs requiring replacement ofanyoneof the transistors in input pair0169and0171,cascade pair0176and0178or second differential pair063and073,bothtransistorsinthe pair must be replaced. That is, if0169fails, both0

4、169and0171needto be replaced. Order both and specifyMatchedwith the part number.FailureofanyoftheIRF244outputtransistorsThe category of the output transistorsisidentified by a letter written on the bottom of thetransistor. The markings will appearinone of two ways.1)As a single or double repeated le

5、tter. (Example MorBB.Note:BandBBare differentcategories).2)Asasequence of letters separated by a dash. (ExampleAD-AAorTB-O).When ordering replacements, indicateMatchedwith the partnumberand theexactlettercodewritten on the transistor. The replacement parts will be of the same category.Note: there is

6、 no quality difference between transistors of different letter categories.Transistors of category CC are not better than those of categoryD.It is only important thatthe output transistors are of the same categoryforproper operation.GFA-5802Service ManualCorrections1)On page1,change step 4 of theBIAS

7、ALIGNMENTprocedure fromThe reading across these resistors should average33mVand all should be between23mVand 43mV.toThe reading across these resistors shouldbe amaximumof33mVandallshouldrangebetween18mVand33mV.2)On page 3, change the062,63, 73 part description from *Matched IRF961 0 to*Matched IRF9622 and the part number from 33009610 to 33009622. IRF9610s will bereplaced with IRF9622s. These will be providedinmatched pairs as described above.ES 8/RadioFans.CN 收音机爱 好者资料库