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Hello,
I was given a Kenwood KR6030 receiver which plays very, very nice on all functions except FM Stereo.
The tuner works properly by the needle gauge, plays through on FM mono setting but nothing when I flip the switch to FM Stereo.
I don't have schematics so I'm wondering if anyone else had this issue.
I resoldered over 100 points on the motherboard hoping it was just a cold solder joint.
No dice but I do see a Sanyo IC.
Follow Ups:
If you have a schematic and there is a single electrolytic coupling capacitor that gets the signal to the MPX decoder chip it could be open. The signal has to get to the input pin of the MPX decoder chip in order for it to work properly. The MPX decoder cannot produce stereo sound or activate its stereo indicator unless it gets a signal. Your comments indicate that the sound is good and strong on monophonic operation when tuned to a FM station.
If you do not have a schematic for the unit you need one in order to help you troubleshoot it.
You get no sound at all on FM stereo or you get sound but the light doesn't come on and the sound doesnt seem to be in stereo?
Stereo takes a substantially stronger signal quality than mono. What type of antenna are you using?
The signal and tuning indicator show there is a very strong signal and separation.
The FM Stereo indicator never lights. I do get output if the FM Muting switch is in the Mono position.
Other devices play just fine with this switch in Stereo Mode and Mono mode so it's FM Stereo that's the issue.
I'm thinking the stereo detection circuit is now broke. I notice there is a Sanyo IC in the path.
eh?
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
I'm thinking you need to check/clean the stereo mono switch before you conclude something more complicated is wrong. This sounds to me like a switch issue.
Whenever something goes wrong, ALWAYS check the simplest/least expensive to repair possibility first and do these in rank order. USUALLY the most complicated stuff (stereo detection circuit) is fine and its the simple stuff that fails.
Yes, I cleaned the switches with CRC, removed the bottom cover to look for cold solder joints. I resoldered a lot of joints just because I had access at that point.
I've since sold my scopes and audio trace equipment about 20 years ago.
I wish I had it now!
Thank you for the suggestions!
If you aren't driving the FM front end hard enough that might be the only problem.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
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