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Marantz Superscope R340B problems with the FM

daveyh

daveyh

Super Member
I have a Superscope R340B that all functions work except the FM. Well the FM works, but I can turn up the volume all the way and hardly hear the stations. The stereo light works and goes on and off while tuning into the stations but all channels are weak. Antenna is connected. AM is strong. Aux and phono both work. Both channels work on right and left. All switches and controls cleaned more than once. Anyone have any experience with these or know where I should look in the unit?
 
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Fixed!

How did I do it? I downloaded the datasheet for the 14 pin MC1310P Stereo Decoder IC located on the FM tuner board. I turned on the unit and I used my homemade signal tracer and I placed the tip on each pin slowly as not to slip. I noticed on pin 2 it is labeled input. I did have sound. I also had sound on pin 3 labeled Audio Amp Output. There was no sound however on pin 4 and pin 5. I unsoldered the chip and placed a 14 pin socket in it's place. Then I looked up the datasheet for a replacement. NTE has one which is a NTE801 but I only had a HA1156. The replacement for the MC1310P and the HA1156 are NTE801. So, I used the HA1156 IC and it works! Sounds excellent. Stereo lamp works as well as full power in both right and left channels. Hope this helps someone else in their quest to repair the same type of problem on the Superscope. :music:
 
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