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 satisfactory 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
