Problems with Sanyo M9990L

Hi, only FM radio works! The other 3 radio bands don't. I've had it apart and have sprayed contact cleaner in each of the buttons, with no results. Also, the cassette player doesn't work. Despite all the problems, I love this box, and listen to it daily. The speaker system is fine, FM band works perfect, and FM Stereo sounds superb. The clock and dial lights work. Plus the box is in near perfect condition cosmetically. I really can't understand how FM band works but the others don't. It would be really nice to get this fantastic looking and sounding box fully working as it should!

FM and AM are very different and one band dead when another band is fine is not uncommon. In fact, this seems to be a very common problem with Sanyo's in particular, or perhaps it's just because I have a lot of Sanyos.

Radio problems are very difficult to trouble shoot but if you really want to fix this radio, then I suggest you pick up a copy of AM/FM Stereo System Troubleshooting by Robert L. Goodman.

Also, a signal tracer will be an invaluable tool because you can trace a circuit all the way back to where there is a problem. Of course, a service manual or schematic is almost essential to do it well. Most likely, I'm guessing a bad diode. SW bands have more in common with AM than with FM and may share a diode someplace. This may be why the AM + SW is dead.

However, since your cassette player is not working and you haven't fixed it yet, I am guessing that this will be too technically challenging for you to tackle yourself since the cassette deck is probably the easiest repair for a beginner to tackle with respect to boombox issues.

Superduper said:

FM and AM are very different and one band dead when another band is fine is not uncommon. In fact, this seems to be a very common problem with Sanyo's in particular, or perhaps it's just because I have a lot of Sanyos.

Radio problems are very difficult to trouble shoot but if you really want to fix this radio, then I suggest you pick up a copy of AM/FM Stereo System Troubleshooting by Robert L. Goodman.

Also, a signal tracer will be an invaluable tool because you can trace a circuit all the way back to where there is a problem. Of course, a service manual or schematic is almost essential to do it well. Most likely, I'm guessing a bad diode. SW bands have more in common than FM and may share a diode someplace.

However, since your cassette player is not working and you haven't fixed it yet, I am guessing that this will be too technically challenging for you to tackle yourself since the cassette deck is probably the easiest repair for a beginner to tackle with respect to boombox issues.

Click to expand...

Superduper said:

However, since your cassette player is not working and you haven't fixed it yet, I am guessing that this will be too technically challenging for you to tackle yourself since the cassette deck is probably the easiest repair for a beginner to tackle with respect to boombox issues.

Click to expand...

Actually, I've took apart and fitted belts to many of my boombox decks, but I haven't tackled this one yet. I actually took the box apart because the tuning knob was loose, and I had to get inside to tighten the nut. I tried to clean the tuner buttons at the same time. I ignored the deck because I wanted to tighten the knob, and make the radio bands work before I tackled anything else. Thanks for the suggestions for diagnosis btw, I will look into them.