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AM-FM Stereo Tuner KT-880F and KT-1010F (TRIO-Kenwood)

[Outline] [Front view] [Inside view] [Trouble-shoots]

Fig.1 KT-880F ( top ) and KT-1010F ( below ). How are they identified?

• PLL discriminator for FM det.
  Kenwood called the cirquit DLLD ( Direct Linear Loop Detector ).
• DCC ( Distortion Corection Circuit ) for FM mode.
• THD = 0.009@1kHz stereo.
• IF band selector for FM band ( KT-1010F ).
• RF sensitivity selector for FM band ( KT-1010F ).
• IF band width controll for AM band ( KT-1010F ).

Trouble	Cause	Repair
No audio signal output ( both ). Any SW didn't work( both ). Display nothing( KT-880F ).	A chemical capacitor after +5V AVR IC (7805) was shorted.	Replaced the shorted capacitor.
Always lock apart from 100kHz from the station ( KT-880F ).	Detune of secondary discriminator for tuning system.	Adjust the secondary discriminator to the center of the required frequency.
Any SW didn't work and the FLD segments are all on ( KT-1010F ).	The memory back up capacitor on 5V line is shorted.	Replace the memory back up capacitor