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From: Paul on 14 May 2010 12:22 jw(a)eldorado.com wrote: > On Fri, 14 May 2010 06:05:38 -0700, "Jon Danniken" > <jonSPAMMENOTdanniken(a)yahSPAMhoo.com> wrote: > >> Lick your finger and tap it (also while bridging the gap between the tip and >> the shield); you should hear *something*, a thumping, or static, or a hum. >> >> Jon >> > > All these sounds i should be listening for - should come out of the > preamp or out of the computer speakers? > > Bridging the male-female gap between either red or white link or the > other? > > Sorry to be so dumb. > > Duke Your finger tip has a bit of "hum" on the end of it. Wire the preamp to the computer. Wire the computer to the computer speakers. Any signal applied to the preamp input, should now appear on the computer speakers. Listen to the computer speakers - then, press a finger tip against the male pin of the cable plugged into the preamp input jack. The "hum" on your finger, should be amplified by the preamp, and be audible on the computer speaker. It proves there is "path continuity", if you hear something. If there is no change, then something is blocked in the path, such as a bad preamp. You've already tested the computer and speakers, by using a VCR connected to Line In on the computer. So we know that works. Now you have to test the preamp, using a fingertip, to see if the preamp works. Paul
From: jw on 15 May 2010 14:33 On Fri, 14 May 2010 12:22:28 -0400, Paul <nospam(a)needed.com> wrote: > >Your finger tip has a bit of "hum" on the end of it. > >Wire the preamp to the computer. Wire the computer to the computer speakers. > >Any signal applied to the preamp input, should now appear on the computer speakers. > >Listen to the computer speakers - then, press a finger tip against the >male pin of the cable plugged into the preamp input jack. The "hum" on >your finger, should be amplified by the preamp, and be audible >on the computer speaker. It proves there is "path continuity", if >you hear something. If there is no change, then something is blocked >in the path, such as a bad preamp. Here's dumbee again. I did as you describe = I get a hum indeed. So that means the preamp is okay. Whew! Maybe the trouble lies in the phono player. > >You've already tested the computer and speakers, by using a VCR connected >to Line In on the computer. So we know that works. Now you have to >test the preamp, using a fingertip, to see if the preamp works. > > Paul
From: Paul on 15 May 2010 15:07 jw(a)eldorado.com wrote: > I did as you describe = I get a hum indeed. So that means the preamp > is okay. Whew! > > Maybe the trouble lies in the phono player. > I don't have a test for that. To monitor the cartridge, for a 2-3mV signal, would be difficult at best. The only cheap method, is amplifying it with a preamp (as you've already tried). Cheap test instruments can't pick up signals that small. Check that the needle is securely in place on the cartridge. If it isn't properly mechanically coupled, that could be the reason. The vibrations have to be transferred to the magnetic bits to generate a signal. There are many different forms of replacement needles for cartridges. The last one I worked on, eons ago, looked like this. My old turntable had a vacuum tube amp, to give some idea how old it was. http://www.needles4turntables.com/IMG_2068.JPG Paul
From: jw on 15 May 2010 16:48
On Sat, 15 May 2010 15:07:06 -0400, Paul <nospam(a)needed.com> wrote: >I don't have a test for that. To monitor the cartridge, for a 2-3mV >signal, would be difficult at best. The only cheap method, is amplifying >it with a preamp (as you've already tried). Cheap test instruments can't >pick up signals that small. > >Check that the needle is securely in place on the cartridge. If it >isn't properly mechanically coupled, that could be the reason. The >vibrations have to be transferred to the magnetic bits to generate >a signal. > >There are many different forms of replacement needles for cartridges. >The last one I worked on, eons ago, looked like this. My old turntable >had a vacuum tube amp, to give some idea how old it was. > >http://www.needles4turntables.com/IMG_2068.JPG > > Paul Thanks anyway. I think a good way to go is for me to try to find someone with a working vinyl player. I wonder how much luck I'll have with that. Cya for now Duke |