I purchased a Sony STR-D311 stereo it turns on won’t pickup radio stations and all I get is white noise?
Hi John,
Okay, the tuner pack is probably getting B+, but either the Vt line isn't working, or the LO out isn't functioning.
Are you an experienced audio tech accustomed to tuners? DO you have any test equipment you would need for this work?
-Chris
Okay, the tuner pack is probably getting B+, but either the Vt line isn't working, or the LO out isn't functioning.
Are you an experienced audio tech accustomed to tuners? DO you have any test equipment you would need for this work?
-Chris
I do audio work on radios and cbs the side I usually build guitar amps. No all I have is a multimeter and signal generator
I assumed you had an antenna connected.
Okay, so you know what to do. Check your IF out in the tuner pack. I think you'll only have power, control signals and audio plus ground out. You'll be working in the tuner pack. Also check the charge pump is outputting a tuning voltage to the varactors.
Okay, so you know what to do. Check your IF out in the tuner pack. I think you'll only have power, control signals and audio plus ground out. You'll be working in the tuner pack. Also check the charge pump is outputting a tuning voltage to the varactors.
What kind of voltage should I look for? When I open it up I’m gonna check all solder joints first then checking voltage
Hi John,
Classic tuner packs used commonly 9, 12 or 23 VDC for top of band. That is varactor dependant. I have seen 3V3 supplies lately, so probably a step-up. If it isn't detecting a VCO output it will lock high or low.
My trick is to disconnect the VT line and feed a variable power supply in Start low and see if it can manually tune in low stations. now of course they may have added to the mix today. It is possible that unless the up locks to the VCO it may mute. All you can do is monitor the IF signal to see if it tunes in that case.
Common things that killed these circuits were coupling capacitors, typically short allowing DC through that would either drag the circuit down, or bias the input too high. Caps could also short in the charge pump. Now this is today, so maybe a different issue has cropped up. Occasionally a prescaler chip could fail. These are all likely on the chip today, no separate chips - hence no access to some signals.
Classic tuner packs used commonly 9, 12 or 23 VDC for top of band. That is varactor dependant. I have seen 3V3 supplies lately, so probably a step-up. If it isn't detecting a VCO output it will lock high or low.
My trick is to disconnect the VT line and feed a variable power supply in Start low and see if it can manually tune in low stations. now of course they may have added to the mix today. It is possible that unless the up locks to the VCO it may mute. All you can do is monitor the IF signal to see if it tunes in that case.
Common things that killed these circuits were coupling capacitors, typically short allowing DC through that would either drag the circuit down, or bias the input too high. Caps could also short in the charge pump. Now this is today, so maybe a different issue has cropped up. Occasionally a prescaler chip could fail. These are all likely on the chip today, no separate chips - hence no access to some signals.
I did a visual on the inside of the radio and it looks like it was never touched as far as component replacement.
Hmm, does it look like some outputs were replaced?
Look to see if anything else was disturbed that could account for your current problem.
Look to see if anything else was disturbed that could account for your current problem.