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Thorens AD30 4-1/2" Disc Music Box Repair
By Don Caine

Dear JWH,  In response to your quest [090928 MMDigest] for a Thorens
disc musical box repair manual:

> Is there such a thing as a manual or schematic that would help me
> to know how to put all of this back together?  Thanks, JWH

There is, to my knowledge, no Thorens factory repair manual or
schematics for the AD30 4-1/2" disc player mechanism.  I guess I could
write a manual and develop the schematics, but I'd probably loose
a lot of my repair business in the process.

Please note that simply reassembling the mechanism will probably not
resolve the original problem that caused the unit to malfunction in
the first place.  There are, however, several qualified collectors
and repair/service professionals, myself included, who can assist you
in the repair/restoration process of your newly acquired, and now
discombobulated, mechanism.  (Internet Search for "Thorens disc music
box repair")

As the Reuge after-market service and parts provider for North America,
(Reuge bought out Thorens in 1986 and still manufactures the same basic
AD30 mechanism), I import and stock all the necessary replacement parts
as well as over 200 different titled disc tune selections (over 1600
different tunes were made for these machines) at $5.00 per disc.

As I see it, there are two basic options to resolve your dilemma:

1. You may send me, or another technician, the box/mechanism, and at
least one disc.  The cabinet really isn't necessary, but it sometimes
makes it easier to package the mechanism and disc together by leaving
them in the cabinet (box).  One of your own discs is requested because
over the years minor changes were made in these players and not all
discs will play on every machine unless it too has been modified.

(General repair costs run between $90 and $180 for labor plus the cost
of parts and return shipping, handling and insurance fees.)

2. You can purchase individual parts and/or installation instructions
(where available-optional).  Most parts are fairly simple to install
using very simple tools.  However, please note: if the pinion gear
(a white plastic gear that is world-renowned for cracking and breaking
over time) is broken, or the main spring has broken, these problems
generally make the mechanism inoperative and often mask other problems
that exist but will not be apparent until the gear and/or main spring
are replaced and the motor is running again.

I can often talk folks through the repair process and therefore offer
telephonic technical support services at $90.00 per hour with a 1/2-hour
minimum advanced authorization for credit card billing for such services.
I accept all major credit cards.

Please let me know how I may be of further service to you ?

Three notes of _caution:_

1. The replacement comb is the same for all Thorens AD30 4-1/2" disc
players, regardless of age.  However the base to which the comb is
soldered is different in the very old models vs. the newer models.

Therefore, to install a new comb onto an older open clockwork mechanism
one must remove the combs from both bases and solder the new comb onto
the old base.  (See http://www.ThorensAD30.com/ for more details and
photos as well as some good general information about these machines
and the over 1,600 different tunes that have been made for them.)

2. A comb with broken teeth, can be just that or, if the teeth are
broken in the middle of the comb, it can also be indicative of a
problem with the star wheel assembly that plucks the notes on the
musical comb.

Check to see if the block holding the star wheels (that pluck the
notes on the comb) appears to be warped, bowed or cracking.  Also,
look carefully at the alignment of the individual star wheels and
the individual teeth remaining on the comb -- they should line up
squarely center to center star wheel to comb tooth.

Alignment of some teeth and misalignment of others is indicative
that the star wheel assembly has warped and should be replaced, and
(depending on the age of the unit), the swing arm and shouldered
setscrew may also need to be replaced.  (The older, solid one piece
swing arm and shouldered set screw, are not compatible with the current
replacement star wheel assembly).

3. Because of their age and construction design, the AD30 mechanisms
can, and often do, have multiple problems -- related to their age,
oxidation, lubrication, changing atmospheric conditions (temperature
and humidity) and usage -- that are not always readily apparent.
However, on close inspection it may well display symptoms of pending
or existing problems.

In basic order of their frequency of occurrence, those problems often
include, but are not limited to the following:

(a) The nylon release gear (a.k.a. pinion/pignon gear or worm gear --
$30.00), may be cracked or broken.  It connects the main spring driven
motor drive to the speed regulator.  If it is cracked you will hear
a distinctive repetitive "tick... tick... tick..." sound when the motor
is turned on (and most distinctly without a disc in place).  If the
release gear is badly cracked the motor may not run.  If it has broken
and has fallen off its axle, the main spring will wind but will
"release" all of its pent-up energy immediately when the winder is
released.

(b) Comb with broken teeth -- $95.00.  Several broken teeth in the
middle of the comb is often indicative of a warped or defective star
wheel assembly.

(c) Warped or cracked/cracking star wheel assembly -- $120.00.  The
cast block (of metal, pot metal or aluminum) that houses the star
wheels may become cracked and brittle and the gantry swing arm may
snap off, and/or the star wheel assembly block may warp, usually
inward toward the comb.  Thus, advancing the star wheels which, when
they are too close to the teeth, lift the teeth too far upward causing
the central comb teeth to break.  Jammed or stuck star wheels may cause
records not to play or to repeatedly "pop" and "click" as they revolve
beyond the first revolution.  (If the star wheels have not been aligned
prior to insertion of a disc, popping and clicking during the first
revolution may be normal as the star wheels realign themselves.)

(d) The damper rail -- $45.00 -- may have warped, cracked, be out
of alignment or individual dampeners may be bent.  The damper rail is
the thin metal bar with thin flat finger like projections (dampeners)
sticking up between the tips of the comb teeth and the star wheels, and
is located just below the tips of the comb.

Dampeners are designed to stop the teeth from vibrating before they are
plucked again. If damaged or inoperative, it will make the star wheels
difficult or impossible to turn or may make the music sound very twangy
and vibrational.

(e) Broken main spring -- $22.00.  The motor will not run but the
winding key will turn and turn and turn without any resistance or
tension being built up.

(f) The speed regulator (governor) assembly -- $55.00 -- may not be
working correctly.  One complete revolution of the disc should take
19 to 21 seconds.  If more than 21 seconds, the musical tempo will
be too slow; less than 19 seconds and the tempo will be too fast.
If dirty, or out of alignment, the speed may be severely reduced or
there may be a high speed whirring or very fast ticking sound being
made by the governor and or the adjacent stop mechanism.

If you would please call me, with the mechanism and a disc at hand,
I'd prefer to talk you through some simple diagnostics to determine the
operational status of your machine/parts.  Then I can supply you with
all the parts you may need at one time instead of ordering them piece
meal and having to pay multiple shipping and handling charges.

Most sincerely,

Don Caine - Proprietor, The Music Box Repair Shop Unlimited
Lomita, California
tel.: 1-310-534-1557
mbrcu@aol.com.geentroep [delete ".geentroep" to reply]


(Message sent Thu 1 Oct 2009, 11:41:06 GMT, from time zone GMT-0400.)

Key Words in Subject:  4-1/2, AD30, Box, Disc, Music, Repair, Thorens

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