| The seemingly complicated and
technologically imposing Victrola
Orthophonic soundbox is no different than most sound reproducers in
application, but exceedingly different in execution. It contains
a very thin (.0017" thin) duralumin alloy diaphragm, a needlebar which
is suspended by 14-16 little magnetic ball bearings, and a suspension
"spider" which takes the sound energy from the needlebar and
distributes is evenly to the diaphragm. It has many more parts
than
your standard reproducer, and is much more delicate and
sensitive. Add
to this the abundance of OSBs (Orthophonic SoundBoxes) that are
composed
primarily of the moldable white metal alloy we all lovingly refer to as
"pot-metal." Pot metal is a low temperature pourable alloy
which made
the mass production of small parts casting inexpensive and high
volume. The disadvantage to pot metal composition is that 80+
years
later the metal will exhibit shrinkage and expansion....warpage that
will either self-destruct the soundbox or make its disassembly for
servicing nearly impossible. Should you be fearful of rebuilding one? Certainly not. You should have a basic understanding of how sound reproducers work, LOTS OF PATIENCE, and a good chunk of natural mechanical ability. It seems that everyone in the 21st century has different ways of rebuilding these. Some boasting their decades of experience and technical expertise, others expounding on the scientific principles of the Orthophonic design and attaining an almost "religious" piety in their gospel. I am a self-proclaimed expert. I am terribly cranky, opinionated, and I have incredibly sensitive hearing. Here for you to read I will describe to you how I disassemble, rebuild, and adjust OSBs. If you find this quite lengthy, this is because there is a lot of observation and skill involved. There are special situations and adjustments which rarely come up while repairing any OSB, but those are few and far between. With experience comes skill. The practices and proceedures illustrated below are still a general rough outline of what a phonograph restoration specialist does when repairing one of these. This should offer to you some fair guidance in how I rebuild OSBs for customers and friends. If you decide to tackle the job yourself, or just wondered how in the heck Wyatt does it, this is how: This is a description of a FULL REBUILD, including a subsection on diaphragm replacement using a modern reproduction duralumin diaphragm. Tools and supplies you will need: -large worktable, preferably with a cafeteria sized work tray to catch small parts -needlenose plyers -1.5, 2.0, 2.5, 3.0 mm flat blade screwdrivers -soldering iron, solder -alcohol -Q-tips cotton swabs -razor blade -automotive grease -solder wicking braid (you can get this at Radio Shack) Tools and Supplies you *MIGHT* need: -tube of clear or black GE Silicone-II sealant -propane torch -4" length of Victor Exhibition white gasket material (new) -Devcon "2-tonne" epoxy cement -Dremel tool with small 1/4" grinding wheel and wire brush attachment Procedures will be broken up into a few sections, as not all may apply to your particular repair. Not all OSBs will come apart. Even the early ones made of brass may offer some difficulty due to corrosion or hardened assembly oil, or in rare cases a locking ring on the back flange made out of expanded pot metal. Sometimes things break. Breathe in, breathe out. Find zen. Always be patient. Part I: Disassembly Part II: Diaphragm Part III: Bearings Part IV: Mounting Flange Part V: Testing Part I: Disassembly Remove any needles from OSB, remove needlebar thumb screw. Remove set screws from back flange plate which hold in rubber mounting insulator. Using spread needlenose plyers loosen the back flange locking ring counter-clockwise. This might not always easy. DO NOT USE HEAT TO LOOSEN SEIZED LOCK RINGS. YOU WILL CRACK METAL, DAMAGE INTERNAL PARTS, AND GET VERY UPSET WITH YOURSELF. If you can not remove the lock ring, put a few drops of penetrating oil around the edges of the lock ring and let it work for a day or two. After removing the lock ring, your back flange might come off immediately. If not...STOP! The back plates sometimes stick to the diaphragm gaskets (waxed fiberboard or petrified rubber gaskets) and will pull the diaphragm along with them if removed hastily, damaging the diaphragm. Get your soldering iron, some solder wicking braid, and a small screw driver. You will want to carefully aim the tip of the soldering iron through the face bezel, warming the end of the needlebar where it is soldered to the diaphragm spider. Use your wicking braid to pull the solder away from the joint. You might also want to use your small screwdriver to gently push the spider down and away from the end of the needlebar. They should not be connected. Gently pull the back plate off the face bezel. The diaphragm, if stuck to the gasketry, might come along with it. Even when there is some initial looseness, always be careful and use your eyes to watch what is happening. You do not want to destroy the original diaphragm. If it is still stuck in place, use a few drops of lacquer thinner around the edge to dissolve any varnish or gummy gasket tar which may be adhereing to the diaphragm and/or castings. After getting the diaphragm removed, use your razor blade on a flat surface to *GENTLY* remove any gasket material stuck onto the front and back castings, and the edges of the diaphragm. I emphasize saving the original diaphragms to save the time and cost of replacement. But if the diaphragm is dented and ripped beyond servicability, it will need to be replaced. Part II: Diaphragm cleaning and/or replacement The aluminium "spider" is attached to the diaphragm with crimped fingers which are then sealed with hide glue or thick shellac. Inspect the diaphragm under a bright light and look for holes or rips. Small dents or dings are acceptible for the most part, if they do not have any creases developing around them. Some can be gently straightened with the rounded tip of a lead pencil (with feather light force). If the diaphragm must be replaced, you must remove the spider from the original diaphragm and prepare it to be bonded to the new replacement diaphragm. Although it IS possible to apply the spider to the new diaphragm using the same factory method of crimping the small fingers through the diaphragm, it is terribly labor intensive without access to the original Victor Talking Maching tooling, and it is more than likely that you will damage the new diaphragm in the process. I prefer to use an industrial strength adhesive to bond the spider to the diaphragm. Since we will not be re-using the small fingers on the ends of the spider legs, we will need to cut them off. Using small side cutters (wire snips) you will need to carefully cut the fingers off. Use a small razor blade or a small screwdriver to flake off any remnants of sealing shellac on the underside of the feet. Wet a cotton swab with alcohol and clean the mating surfaces of the feet and on the ridge of the diaphragm where the spider is to be placed. Next, place the spider on the new diaphragm without adhesive. Make sure that ALL feet are sitting FLAT on the mounting ridge. If any are not in contact with the mounting ridge, they will need to be gently bent down until all feet sit flat. Mix your 2-part epoxy according to manufacturers instructions, and apply one VERY VERY SMALL DROP on the underside of each spider foot. Apply to diaphragm. Sometimes this is easier when you hold the spider by one of its legs with tweezers. Make sure spider is sitting flat. Allow to cure and harden for 24 hours. In the meantine, we can work on the needlebar suspension bearings. If your bearings are good, and you have checked that the needlebar is centered in the face bezel, you can re-install the diaphragm with new gaskets. Be careful that you place the needlebar "fork-tonque" end into the spider gently while re-assembling the diaphragm. The diaphragm should be CENTERED, so that when you look through the back plate casting, you can see its rear "cup" centered through the plate. This is delicate work. Please be patient, and do a good job. Part III: Bearings The needlebar of an OSB is suspended and allowed to pivot on two races of 14-16 small ball bearings. On some bearing assemblies, the factory installed rubber damping rings above the bearings to keep them from vibrating in extreme cases. After 80+ years, the rubber will melt into a gum, or harden....thus not performing its duty satisfactorily. One side at a time, remove the bearing covers and inspect the bearings. You will want to use a small screw driver to pick out the hardened rubber (and bearings encased in the rubber!). If your bearings are not rusty or corroded, they can be re-installed. In most cases, the outer races (cups) are secured tightly in the face bezel casting. Sometimes the pot metal face bezel expands, and the bearing race cups wiggle loose....giving the needlebar more reason to vibrate and create distortion. In this case, we will need to bond the race cups to the face bezel to keep them from wiggling. On brass reproducers, the pivot bearings are encased in a steel block which screws to the brass face bezel (from the inside of the face bezel) and these will not need any re-bonding at all. Remove the cups, clean off the inner surface of the face bezel with a cotton swab and some lacquer thinner. Clean outside surface of cup as well. Mix and apply adhesive, and re-install the cups. Bearing re-installation is relatively easy. Replace bearings on ONE SIDE at a time, so that you do not have to go through the small headache of shim aligning the whole needlebar to make reinstallation of both sets of bearings less troublesome. Apply a dab of automotive grease to the inside of the bearing cup, around the pivot bar. This grease will hold each ball bearing in place as you re-insert them, completing the circle of 7-8 bearings needed. If you need to replace the rubber damper, you can cut a small, in most cases 2-3mm thick, slice of small butyl rubber tubing (small windshield washer tubing from your local auto parts store might also work). Place the damping rubber over the bearings, and replace the bearing cover. Notice that if you have a magnetic needlebar pivot and/or magnetic bearings, your bearing cover will be installed "donut side down." With magnetized parts, I do not personally install rubber dampers, but rather put a small drop of tenacious oil on the bearings to keep them lubricated. You may need to swap the Left and Right covers to create a condition where they fit "donut side up" to allow extra space for the rubber dampers. The covers should fit over the rubber dampers with light pressure. If you find yourself forcing them on, then the dampers are too thick, and will need to be cut thinner. Inspect the needle bar under a bright light, and make sure that the needlebar is centered Left-to-Right in the face bezel. If it is off-center, make necessary adjustments to center it, which will most likely mean loosening the bearings on the offending side and re-seating them with a small screwdriver after the adjustment has been made. Pivot the needlebar after all bearings are installed several DOZEN times to ensure the bearings are seated properly. You do not want ANY bearing rattle at all. The bearings should hold the needlebar tightly, but allow the bar to pivot will gentle resistance, but not so tight as to restrict movement over 50%. Part IV: Mounting Flange This is a point of contention with many collectors. Do appreciate that these OSBs were scientifically designed, and part of the design was a mounting flange that acted as a passive insulator to keep the soundbox body insulated from the solidly mounted tone arm, eliminating (nearly) a reflexive condition whereas sound energy fed back to the needle tip, creating distortion - stridency - and record wear. Many modern audio restoration specialists replace the rock-hard mounting flange with a "less" rock hard plastic or rubber material. From my extensive experience with these, I can not approve of this. I have devised my own method of injecting soft silicone into the flange, creating a superior insulator which exceeds the abilities of the original gum rubber that Victor Talking Machine Co installed in the pre-silicone era. We will remove the hardened rubber flange, and replace it with butyl rubber and silicone. Earlier in this exercise, you removed the two small retainer screws from the back flange. This operation is easier with the back plate removed from the soundbox, but can also be performed with the plate in place. Place a small wad of tissue paper inside the opening to protect the diaphragm from debris. If any debris gets into the inner diaphragm chamber, you can shake it out later...but it is a practice to not get ANY inside the soundbox. This operation will require some strength, skill, and patience. Sharpen the end of a 2mm screwdriver so that it is VERY sharp. Chip away the hardened rubber, digging deeper and deeper with every pass. DO NOT USE FLAME (from a torch or otherwise) to melt the rubber, as this will crack your pot metal back plate!!! When all rubber is removed, pull out the brass mounting sleeve with your fingers. The sleeve will be covered in hardened rubber which you can flake off with a wire brush, or burn off with a torch. Make sure the outer surface of the sleeve is clean before we continue installation. Clean inside wall of back plate with lacquer thinner, and a razor blade. The surface should be clean of any old rubber, including rubber dust. Re-installation of the brass sleeve at this point might seem quite daunting, but it is actually easy to install. With a few small dabs of silicone, seat a small ring of rubber tubing (the same white rubber tubing used to rebuild Victor Exhibition soundboxes) in the bottom of the back plate opening. This small ring will hold your brass sleeve center while you inject the silicone from your tube. The brass sleeve should be positioned with the inner alignment pin positioned towards the outside of the flange, and pointing at the hole of the upper flange tightening screw. GE SILICONE-II works the best. Cut a small tip on the tube so you can inject it into the cavity around the brass sleeve. When done, clean off excess with a cotton swab. You may want to wear tight fitting rubber gloves when you do this, as the silicone can stick to your hands. If you are finding the brass sleeve popping up, you may want to apply the silicone in 2 stages. First application about 1/8" deep...........let it cure overnight....then finish the final application the next day. Allow to cure 24 hours before testing. Part V: Testing Now that all the screaming, crying, and whining (from YOU, not the soundbox!) is over, take a breath and realize that you saved yourself about $200 had you sent it to me. Here is our "moment of truth". Put a LOUD TONE needle in your soundbox, and find your favourite Orthophonic recording. Play. The following conditions, explanations, and solutions may apply to you:
This is an ongoing project. Suggestions, praise, and criticism always welcome. |