Am Sa 29. November 2008 schrieb Andy Green: > Somebody in the thread at some point said: > |> I think I understand. I built one 10 F capacitor into the adapter (at the > |> mass), so the problem with the headphones should be fixed. I also > measured a > |> 1,59V current at the capacitor when plugged in and silent. Sound is > good as > |> before. > | > | It's beginning to sound very appealing. I was very disappointed to > | discover that my FR is unusable as an MP3 player (and I'm not demanding: > | I usually find 64Kb/s Vorbis files good enough for such a use). > | > |> Unfortunately, the internal speaker sounds really bad now (distorted). > |> So I think i'll remove the silver again and find somebody who can help > |> me with the soldering... > | > | Hmm... why does it distort the interal speaker? > > With the caps the transducer experiences -~1.5V .. +~1.5V worth of > deflection "down" and "up"; without the caps it experiences 0 .. ~3V > worth all "up". So it's physically unable to deflect enough linearly I > would think.
Please note the internal speaker isn't connected via the 1uF capacitors. See "SPK LOCATION:41XX" page6 schematics GTA02. So shorting them will not directly cause a different DC-offset situation on internal speaker, and shouldn't make any trouble for it. A short to GND when applying the silver-varnish on the other hand might cause the distortion you have heard. I won't recommend shorting the DC-blocking capacitors. A decent rework/fix comprises finding a place for 2 100uF, and then connecting these in parallel to the 1uF, preferably by by shielded two-wires-cable. If these big capacitors are located outside can, I strongly suggest to place a ferrite bead directly on the hole where the cable enters he can, to block RF from entering the can (homebrew buzzissue). BTW: be aware you easily may destroy headsets or speakers by applying DC for prolonged periods of time. Strongly deprecated. cheers jOERG
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