National Panasonic RS-4360 FM level, need help!

Hi guys, just got the NP 4360 few days ago with some issues need you help. The biggest one is the one with FM function. Although the reception is good, the sound come out on FM mode seem quite low. Sound level on AM or Cassette is just right. Also the VU needles move very little on FM mode and I never get the Stereo led lighted.

I would very appreciated any helps or suggestions. Thanks.

How do you know reception is good? Are you saying that it receives all FM stations you would normally expect in your area? Tuners are one of the hardest circuits, especially for non-technicians to troubleshoot. Not only is the theory harder to grasp than simple power line tracing but the equipment necessary to do the troubleshooting are expensive, and specialized that the average bloke would not have.

You can try to swap out the MPX decoder chip, which is the one labeled LA3350 and afterwards, you'll have to readjust the pilot signal level (19khz, easier with frequency counter, or just try for best result by feel). Hopefully that is it. If it's one of the IF stages, let's hope that's not the case because then you are really in trouble. Those two IC's are obsolete and as far as I know, not available anywhere.

Thank you very much for the help.

I thought the reception is good because the sound is clear (on the stations I used to listen), but I'm not sure if the Radio receives all FM stations in the area. Maybe I'll need another good radio to check that, cause I often listen to one or two certain station and do not move the Wheel much on FM - and don't know exactly how many stations are supposed to be heard in this area.

I think after I've confirmed that I'll follow your guide. Hope it is the case. I guess the problem is much worse if even the reception is not good.

By the way, is it difficult to open the radio SuperD? I always feel uneasy to deal with the thing. Not want to break or crack something LOL.

Many thanks.

Edit: I forget to mention that the Signal VU meter also at highest position when I tune to desired stations so that I think the reception is Ok.

No, poor reception might not necessarily be bad. That's because the FM RF amp uses a standard SK49 FET transistor which is still available. If it is weak or broken, you will get little to no reception. After that, there is the mixer and local oscillator circuits. Then there is the IF amp and another one. In other words, there several few stages and a broken SK49 is probably the easiest and cheapest. The MPX chip should still be available. The two IC's in between however are obsolete. Nobody carries them anymore. So the worse case scenario is if either of those 2 Panasonic IC's have failed, then it's just about a lost cause.

In your case, the fact that signal reception meter shows good strength is an indication that reception is good.

I suggest you flip the band selector many times to see if the weakness is from poor connection from the band switch. This model is very prone to oxidized controls and if you are having poor connection in the band switch, then it is possible that not much audio signal is getting through. You know this is the case if flipping the switch makes some amount of difference in the audio (sometimes better, sometimes worse). If you work the switch aggressively and still observe no improvement or even change, then the next step might be to try swapping that MPX decoder chip. I'm not sure I would call it a beginner type job. Opening the case on this model is no more difficult than any other boombox. However, there is no internal chassis so you would have to work on it in the case since only the back cover comes off on this model.