Cartridge rebuilder. http://www.west-techservices.com/p1.htm
Sent from my iPad On Jan 26, 2015, at 6:33 PM, Antique Phonograph List <[email protected]> wrote: > I have worked on a couple of these changers, RCA model RP-151. The radio > set that you have, model V-225 was the only set that this changer was used > in. The changer has a number of design deficiencies, and that probably > doomed it from inclusion in other radio set models. There are one or two > people who can rebuild these original RCA "magic tone cell" crystal > cartridges, but I don't have personal experience with them to recommend one. > Perhaps others here can do that. Fitting a more modern cartridge to this set > will pose mechanical mounting problems because of the requirement that the > stylus rotates "against" the record rotation when playing the underside of > the record. This is not insurmountable, but will require some headscratching > and experimentation. Also, newer ceramic cartridges have considerably lower > output voltage than these old crystals, so you will not have as much volume > in playback with them. You may need to add another stage of amplification to > get satis factory output from a newer cartridge. I have an RP-151 that I still need to retrofit like this. > > But you should at least expect to clean the old dried lubrication from this > changer and relube the mechanism. The other problem you will probably > encounter is that the platter speed will not be correct, probably by a lot. > There are two motors in this changer, one reversable 4-pole one that drives > the platter and a second 2-pole motor that drives the changer cycle > mechanism. You can expect that the rubber idler wheels that couple the > platter motor to the platter will be hardened and probably have dents or flat > spots in them that will cause rumble, flutter, wow, and speed problems. So > you will probably need to replace or refurbish these idlers. But the motor > itself will probably not be running at the correct speed. This motor is an > unusual version of a hysteresis synchronous motor that has low torque - I > have not encountered anything like it in any other changers. This is a > split-phase 2-winding design with a phasing capacitor connected to one > winding. Even though this motor is a synchronous design, it is mostly operating in torque-induction mode. It's a very odd application of this design. Consequently, the value of the phasing capacitor is critical in determining the motor running speed. The original value of this capacitor is 1.1 microfarad. This is an oddball value that you will not be able to find as a single unit and you will have to make it up from a 1.0uf paralleled with a 0.1uf cap if you need to replace it. Which you probably will need to do. Also, be aware that this changer uses a tilting mercury-wetted contact switch in a glass bulb that is mechanically activated by the tonearm trip mechanism which switches the cycle motor on and off. This switch will be difficult to replace if it is defective. These are usually good as found, so you may not have a problem with it. > > This certainly is an unusual changer and well worth repairing for "show and > tell" purposes, but you may not want to listen to it regularly as it has > several problems that keep it from being a really good record player. The > platter assembly has very low mass and the unit tends to have flutter even > when fully restored. The teensy platter (it's only as big as a record label) > does a poor job of supporting the record and relies on the record being a > minimum weight to keep the record from tilting on the platter when the > tonearm is tracking at the 35 gram design standard. So it was designed for > use with the prewar record weights of the shellac records of that vintage and > it doesn't work properly with the lighter vinyl records of the later years. > Anyway, good luck with your restoration and let me know if you have further > questions. > > Greg Bogantz > > > > ----- Original Message ----- From: "Antique Phonograph List" > <[email protected]> > To: <[email protected]> > Sent: Monday, January 26, 2015 5:28 PM > Subject: [Phono-L] RCA V-225 > > > I found one of these not too long ago in pretty decent shape, and have been > slowly checking it out. In case you're unfamiliar with this particular > model, it's the one with the changer that can play both sides of a record > without flipping it over (one side at a time, of course), then eject it and > move on to the next disc on the stack. It's a 1942 model, and debuted (or so > I have read) shortly before Pearl Harbor, so there aren't many of them, and > I'm delighted to have found one, though I know it's going to be A LOT of work. > > Right now, I'm trying to figure out what to do about the two crystal > cartridges: They're both dead (no surprise there). The only other > phonograph of this vintage that I've owned had an original crystal cartridge > that was, by some miracle, still good, so I've never had to deal with > re-building or replacing one. Can anyone recommend someone (or, preferably, > several people) who can rebuild these cartridges? (I don't think I'll need > the entire changer rebuilt -- knock on wood -- just the cartridges.) If not, > would you recommend replacing them with newer cartridges? I wouldn't be > opposed to that option, as long as they wouldn't show, but I know that the > needles on newer cartridges are a lot less durable, and I don't want to have > to replace the cartridges more than once. What would you do? > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://oldcrank.org/pipermail/phono-l/attachments/20150126/130d3388/attachment.html> > _______________________________________________ > Phono-L mailing list > http://phono-l.org > > > --- > This email has been checked for viruses by Avast antivirus software. > http://www.avast.com > > _______________________________________________ > Phono-L mailing list > http://phono-l.org _______________________________________________ Phono-L mailing list http://phono-l.org
