[amsat-bb] Help needed for my FT-736

ab4ab@aol.com ab4ab at aol.com
Tue Aug 31 15:19:44 PDT 2010


Hi,
My FT-736 suddenly lost all audio (apart from the scanning beep). Looks 
like the Q06 opamp in the AF Unit failed and shorted out the 1Ω,1/4W 
resistor (fuse), 13.8V at the supply side, 2.4V at pin 5. Could also be 
that the 2200μF cap. is shot. I can hear low level noise and signals 
using an old AF amp. connected to the J02 AF in plug so the rest of the 
rig incl. the TX appears fine. Any hints how to cure this sick baby 
will be appreciated. Searched for a NEC μPC2002H replacement but no 
joy. Found  a possible solution at:
http://diyaudioprojects.com/Chip/DIY-TDA2050-Hi-Fi-Chip-Amplifier
where the data sheet includes a Single Supply Typical Application 
Circuit, Fig. 3 in the pdf file @:
http://diyaudioprojects.com/Chip/DIY-TDA2050-Hi-Fi-Chip-Amplifier/TDA2050-Datasheet.pdf.
Any feedback is welcome, guess Yaesu does not carry any spare boards or 
spare parts for this old rig.
Thanks and 73 de AB4AB
Ben




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