Re: No LW/MW receive - Sony ST-S311
Well ive had time this evening to set up for more than just a few voltage checks!
The first thing to note, is that the voltages marked on the schematic around the chips - all relate to the receiver being in FM mode! So, I cant go by any of that for what the LA1245 should measure when active!
Ive got a 1233kHz, 1kHz at 70% AM signal being fed into the antenna connection. Ive been able to follow this with my 'scope through the front end filters and to the input of the IC. Likewise, I can trace a signal at the pins for the IF filter, the IF oscillator, and on the output pin, where I have what looks like a pretty distorted 1kHz signal.
I can 'scope that detected signal as far as the input pin of the LA3401 IC, and I believe that chip is working because its the FM subsystem, and FM works.
But, I have to give it a signal stronger than about -35dBm before I start seeing these traces. They are however definitely the injected signal, as they disappear if I tune away.
Anyone know what a typical MW or LW signal level would be at the receive antenna?
Im guessing it would be a heck of a lot weaker than -35dBm! (thats strong even as an off-air feed for a transmitter!)
So, my suspicion is still with the LA1245 IC at present
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