Sansui 800 No FM Reception

Hey AKers. I'm a first time asker, long time lurker, so be nice, but let me know if I'm going about things the wrong way.
Basically, I picked up a Sansui 800 solid state receiver off a fella on Craigslist for cheap, $20. The seller told me that there were a few problems with it, crackling pots and switches, dead lights, and "the FM tuner is funny". Pots and lights have been remedied, and the receiver sounds pretty darn nice on AUX and AM. However, the FM tuner does not seem to be even trying to pull in any stations. Regardless of where the dial is tuned, there is just a steady static sound, like you would hear on any other tuner tuned to a frequency without a station in range. I've looked over the FM and MPX boards, and don't see any obvious problems. The antenna seems to be fine, and I tried a makeshift external dipole antenna and got the same results. The seller was himself a gear nut, so I should have know it wouldn't be a simple fix when he said he didn't "have time" to fix it.
Any advice on where to start with this? I really like the receiver, and am thinking about giving it to my brother as a gift, but I want to get everything working first.

I recently came across my fathers old Sansui 5000a receiver. I know it's not the same receiver, but hopefully the FM tuners are similar. I had the exact same problem, all the boards looked perfect but all I got on FM was static. After searching for about an hour, I removed the cover to the FM tuner, and there is were I found my problem. The axle that has the fins on it sits in a sort of cradle, there are 3 little leads that ride on that axle, one of them wasn't making contact. I simply moved it back to where it was touching that axle, and that fixed it. To find those leads just follow the three metal walls that lead to the axle. I must be honest, I just got started in repairing stereos and speakers, so please forgive my terminology. In fact, this is my first post lol. Hope this helps.

Thanks for the reply! I will take a look at the tuner tonight and see if I can identify what you are referring to. I would be thrilled if this fixes it, but even if not, I really appreciate the info. I'm glad you got the old man's 5000a working. I bet she sounds sweet.

Please see this thread on how to clean a tuner:
http://www.audiokarma.org/forums/showthread.php?t=144163
Do that, clean all the controls and that should fix it.

Thanks to both of you for the info. I opened up my receiver over lunch, and it unfortunately looks way different than Blowedup's. Here are some pictures of my tuner. I can kinda get to the AM tuner, but can't find a good way to get to the FM tuner.

Thanks for posting that link dr*audio, I'm going to re-open this thing and clean it properly. dankwijoti, I had to remove a metal dust cover to reveal the shaft on mine.

What state did this unit come from? Possible lighting storms could have taken out some of the FM front end???

Vigman: I'm not sure where this receiver is originally from. I am in Iowa, and I bought from a guy in Illinois, but he was not the original owner. I imagine it is from the Midwest, but can't say for sure. Lightning is a possibility, but is it likely that the only thing that would get damaged is the FM front end (I have no idea)?

dr*audio and Blowedup: I found that I can access the tuner cap from the bottom of the receiver. All 3 leads were connected, and I even reflowed the solder joints to make sure. I cleaned the contacts as Doc prescribed, but nothing changed. Any other ideas? How would I know if the FM front end were shot as vigman suggested?

If you don't have the service manual, you can get it on HiFi Engine. You have to register to access the file, but it's free.

http://www.hifiengine.com/manual_library/sansui/800.shtml

I just overhauled mine with all new Nichicon electrolytics, Panasonic ECQ's and a few transistors. It sounds awesome! Night and day difference, before and after the recap.

A link to my Photobucket page with the pictures:
http://s551.photobucket.com/user/MartySoCal/slideshow/Old Radios/Sansui 800 Receiver

My FM section is working. Let me know if you need any voltage measurements to the FM boards, etc.

An rf repair like this requires sophisticated expensive equipment to troubleshoot it, along with an experienced technician with rf chops. Where are you located, maybe we can refer you to someone?

Dr Audio is right of course about the knowledge and equipment. Working on tuners and performing alignments etc is a lost art these days. One thing you can check if you have a meter and basic electronic skills is the voltage coming to the front end,aka the tuning capacitor section. I found a few Sansuis thus far including my 5000x where the voltage was sky high going into it because the Zener diode and capacitor that regulate the supply voltage down to 14v was shot. Mine had almost 40v hitting the front end. In my case it friend the first FET and a couple of resistors. If you can locate the input B+ on the schematic for the FM section. Test there carefully. I'll check the schematic when I get to a PC later. If your not 100% comfortable with this type of stuff then do what Doc said and send it to a reputable person close by.

super98lsc said:

Dr Audio is right of course about the knowledge and equipment. Working on tuners and performing alignments etc is a lost art these days. One thing you can check if you have a meter and basic electronic skills is the voltage coming to the front end,aka the tuning capacitor section. I found a few Sansuis thus far including my 5000x where the voltage was sky high going into it because the Zener diode and capacitor that regulate the supply voltage down to 14v was shot. Mine had almost 40v hitting the front end. In my case it friend the first FET and a couple of resistors. If you can locate the input B+ on the schematic for the FM section. Test there carefully. I'll check the schematic when I get to a PC later. If your not 100% comfortable with this type of stuff then do what Doc said and send it to a reputable person close by.

Click to expand...

The other thing that can happen (forgot about power supply issues) is the power supply to the tuner front end (tuning cap assembly) can be missing or very low, caused by a shorted cap on the power supply, a bad solder joint on a regulator transistor or bad transistor, or the power supply may go through the function switch and the switch is dirty. As a last ditch effort you can try cleaning the function switch if you are not comfortable measuring voltages.

dr*audio. Thanks for the help in cleaning the tuner! I seen your post a while back and forgot about it until I pulled out my Sansui 800. It worked great except the stereo lamp would not light, So I followed your directions and the dang thing came on after I cleaned the turner. I have had this unit for years and the stereo light never worked. It works now. :yes::thmbsp: