If the mainspring is slowing the motor down it will also thump to let you know where the problem is. If it is not thumping then it does not have enough drag to be causing the problem.
If the lead screw is bent it will do just exactly what you describe and it will happen at the same spot more or less. You can look down the lead screw as it rotates and see if some errant hand has bowed it. They bend fairly easy. Robert Wright wrote: > Last thought -- listen to a cylinder you know well and wait for the speed to > drop. Back the reproducer up about 20 or 30 grooves and see if it does it > in the same spot, within about 3 or 4 grooves. If so, it's not the > mainspring, or anything other than something the carriage encounters near > that physical location along the feedscrew, whether the contact point of > half-nut to feedscrew, or the shaft the carriage rides along the length of > the playback. Forgive me for speaking out of school, but if it were the > mainspring, it just sems like there'd be no point at which you had reliable > speed. These guys are the experts, but at least give the 30 this > 'repeatable error' test first. > > > ----- Original Message ----- > From: "Ken Danckaert" <kend at lemur.org> > To: "Antique Phonograph List" <phono-l at oldcrank.org> > Sent: Monday, September 01, 2008 3:37 PM > Subject: Re: [Phono-L] Amberola 30 erratic speed > > >> Your problem is in the mainspring. It needs to be pulled and ALL the old >> lubrication removed. 4"0" steel wool and wd40 will do that. Relube and >> put >> the spring back in. That will get rid of the problem. DON'T soak it in >> kerosene or some other short cut to cleaning. The old stuff has got to >> come >> off the spring. >> >> Ken Danckaert >> >> On Mon, Sep 1, 2008 at 12:50 PM, Ron L'Herault <lherault at bu.edu> wrote: >> >>> OK, gang, it is time to tap into the lists' wisdom. I'm working on an >>> Amberola 30. The hook came unsoldered and the reproducer needed a >>> rebuild. >>> Those two easy repairs (the spring was in the case)completed, I tested >>> the >>> phonograph and found that the speed is a bit erratic. It will sound nice, >>> then slow just a bit then return to speed for a while only to slow again. >>> The carriage moves easily and the horn bobbles and rotates as it should. >>> The governor is lubricated and the pad has been oiled. There is no >>> evidence >>> of crud or damage to the governor disk. There were a few teeth on the >>> large >>> hear that had a bit of damage but a bit of judicious filing has cured the >>> noise the damage created, and besides, the speed variation is more random >>> than the cycle of the gear noise. I'm thinking that the mainspring may >>> need >>> to be removed, cleaned and re-lubricated but I thought I might see if >>> there >>> is anything else I missed before tearing it apart. >>> >>> Thanks, >>> >>> Ron L >>> >>> >>> _______________________________________________ >>> Phono-L mailing list >>> http://phono-l.oldcrank.org >>> >> _______________________________________________ >> Phono-L mailing list >> http://phono-l.oldcrank.org >> > > _______________________________________________ > Phono-L mailing list > http://phono-l.oldcrank.org > >
