Andy Green wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Somebody in the thread at some point said: > |> I have suggested a refinement on the second approach: short the small > |> capacitors. Add big caps outside the shielded unit - there are places > |> with room. But don't put wires from the caps into the shielded > |> unit. Connect them to the headset plug instead, and break the plug's > |> normal connection to the circuit board. This approach won't pick up any > |> more buzz than the headset based solution, or the current bassless > |> setup. And you can use any headset you want. > | > |> The big question is - is it safe to short those small capacitors? Or > |> will that have other side effects, such as draining the battery or > |> disturbing sound on the built-in speaker? > > There are a couple of 1K resistors to 0V that will then connect directly > ~ to the amp outputs all the time before the new DC blocking caps you > will add back in. But thanks to some recent patches by Mark Brown on > andy-tracking, we should keep the amp turned off more often. > Can these be safely removed? Are they there just to make sure the capacitors slowly drain, so you don't get a pop when plugging something in?
Or do they have other purposes as well? > |> Another question - is a single big capacitor enough, if it is put into > |> the ground line instead of having one cap for each of the stereo > |> channels? Or will that wreck stereo sound? One could then use a even > |> bigger cap. > > You'd need to do both channels; the one with the unchanged cap will > sound the same as always otherwise. You misunderstand. I did not propose to do only one channel. I planned on shorting both the small caps. Then, instead of one big cap on each of the stereo lines: LEave the stereo lines connected as-is. Break the ground line (which is common to both channels) and insert a single big cap there instead. Slightly less work, and perhaps a bigger capacitor will fit. (It'd probably have to be bigger too, as the two channels often enough have the same signal.) > > |> There is lots of easily accessible room next to the battery, above the > |> SIM card. > | > | I'd love to see a good answer to those questions. Currently, it's > | unusable as an MP3 player and that's an important use for me (if > | I could use it as an MP3 player, I'd carry it with me that much more > | often, which would in turn increase my use of it). > > Lifting the can and meddling with the caps is nontrivial. Somebody did > give this plan a go on the list about 6 months ago and reported some > success though. But I don't recommend considering it unless you are in > an experimental frame of mind and can deal with the fiddling and risk > involved. I understand that it won't be trivial. Maybe not for me. But if openmoko creates a standard procedure for this improvement too, then I can have an electronic repair shop do everything in one go - both buzz and bass fixes. That will cost me less than having the fixes done separately, even if both fixes together may cost a bit more than buzz only. I hope to ship the phone only once, the repair guy will need to open it only once... A mass fix will be especially cheap - a good technician doing identical fixes on a big stack of phones won't need much time on each. It seems like pulster might set up something like that - but they surely need a procedure, before they can train someone for the job! I hope some thought goes into this for the gta03. Sound output from a phone obviously has low power, but it should be as hi-fi as the sound chip allows. Ideally, a balanced output that don't use (or need) caps. One can play uncompressed wav files, and use a high-quality headset or connect to a regular stereo system. Openmoko could have sound enthusiast customers, as well as linux enthusiasts. Helge Hafting _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community