» Electronics » Sound and Acoustics »Finalization of the record player Electronics EF-017 stereo

Modification of the turntable electronics Electronics EF-017 stereo

Modification of the turntable electronics Electronics EF-017 stereo


Records, in addition to some nostalgic charm, also sound very good. Of course, we are talking about players of a fairly high class, allowing you to fully realize the potential of mechanical recording. Mechanical sound recording does not involve the conversion of the original analog signal into a digital code, which implies its simplification. It is clear that at the same time, part of the information is simply lost. Lost, greatly contributes to the natural sound of reproduced phonograms and gives the listener a certain emotional response. Of course, we are talking about a more or less “live” performance and instruments.

But you have to tinker. A decent class vinyl player is a very complex product with precise and therefore expensive mechanics, the pickup reads the microvibrations of the needle sliding along the sound groove and various parasitic vibrations and resonances can play a significant role here, and it is not easy to remove them. Yes, and handling the player and records implies a fair amount of accuracy, caution and imposes some restrictions. For example, you cannot listen to the record again immediately - its resource is reduced. And eternal dust trouble? Uh, what’s there.

Below, an example of refinement in this sense, of a domestic player of the highest complexity group “Electronics EF-17 stereo. " Without granite or glass slabs and other fanaticism, from those materials that were at hand, using a full-time housing.

The player itself is very good - direct drive, hitchhiking with a micro-lift, push-button tonearm control so that it is not put on the track with trembling hands. Cast duralumin “pallet” of the body, soft vibration isolation springs in the legs. The amplifier-corrector is absent, in the sense - the design is not provided.

The player went into a somewhat inoperative state, fortunately, after a simple repair, everything worked. I had to replace several dried electrolytic capacitors and a blown strobe light-emitting diode.

What was needed for work.

Tools, equipment.

Tool kit for radio installation, multimeter. Low power soldering iron with accessories. Electric drill, drill. Handy milling machine came in handy.Construction or special hair dryer for working with heat pipes, several clamps. Squeezer for sealant, "gun" for polyurethane foam. Sharp knife. Device for installation of "exhaust" rivets.

Materials

Acrylic and neutral silicone sealant, masking tape, thermotubes. Polyurethane foam. The wire in the screen is perhaps thinner. A pair of speaker jacks. Solder, soldering flux. Solvent (alcohol-gasoline mixture). Epoxy adhesive, blind rivets. A piece of aluminum corner.



An autopsy showed a very decent construct - neat installation and harnesses, all under varnish. After revitalization, the player was immediately tested in the case, through just the time, the vinyl corrector, which had just arrived, mounted on a live thread. The aluminum “weight” on the axis, pressing the plate, is also intended to reduce a fraction of undesirable resonances, although I did not notice a special difference.



What can I say - in general, not bad, not bad. Immediately, so as not to get up twice, it was decided to slightly modify the design - to dampen the case, where possible, to exclude relay contacts from the signal circuit (opening the circuit when the plate stops, it must be to reduce the background in pauses). At the same time, replace the DIN5 output connector with RCA jacks. Well and on trifles - a power cord, a safety lock block, the ground terminal.

A strong-willed decision was made - to use the standard player case, if possible, damping it. The upper plastic deck was trimmed inside with a layer of mounting foam. A balloon was used without a dosing "gun" - a layer of about 20 mm was obtained. The smooth edges of the panel were covered just in case with paper masking tape, but in general, the measure turned out to be unnecessary - with some accuracy, nothing got to where it was not needed.



The lower, duralumin part of the body, which is much more solid - cast, rather massive. As a matter of fact, all nodes and boards of the player are mounted on it. After dismantling the elements of the player (only the motor remained, it seemed difficult and unnecessary to remove it), the lower part was finalized. The block of the network connector with the built-in fuse has been removed, the unit has been replaced by a powerful integral cord with a plug and a separate block for the fuse on the case. Also, a ground terminal has been added. After marking, small holes were drilled, the hole for the fuse holder was then milled to increase the diameter. Before this - the casing was fixed with two clamps in an upright position, the engine is protected from possible metal sawdust.



After drilling, the “pan” is thoroughly degreased with acetone and coated with a layer of sealant. In general, acrylic - it seemed more suitable, and it costs less, but when it was over, it was covered with silicone, neutral is clear - you shouldn’t use acid, it “eats” aluminum.

Before smearing, with an alcohol felt-tip pen, after trying on elements and knots, the “area” was outlined where my damping could fit. I smeared thicker, but so that the boards and other elements fell into place. I tried on more often, neatly, so as not to peg in the sealant. The installation of the player elements is best done until the sealant has completely cured. Acrylic, after a while it becomes covered with a sort of dry, completely non-dirty crust, but inside it does not harden. In the case of excess sealant, in any place, the installed unit will squeeze out the excess into the free space, organizing itself a sort of orthopedic seat, without even getting dirty.



After assembling the main part of the player, we adjust the top panel, removing the excess hardened foam. It’s a dreary business, but there’s no place to go. With a sharp knife, trying every second to the place of "service", cut off the excess layers, cut out the space for the elements. It is worth remembering that damping is better, the thicker the layer of porous material - do not cut off excess. After the final trimming and installation of elements on the upper panel, we restore and check all connections, check the player’s performance as a whole. After, we assemble the case.



The photo shows that the damping layers of the lower and upper panel of the housing assembly practically close. Here, you can assess the degree of damping - listen to the sound of tapping the player’s body, well, say, with the handle of a small screwdriver. The sound comes out completely deaf, instantly damping, without any “ringing”. And in general, the player began to feel like a kind of monolithic brick.



Finalization of the tonearm assembly. Well, let's get started with a prayer. A responsible node, with fine mechanics. The lift, anti-skidding and hitchhiking did not touch. The tonearm itself, should be as light and tough as possible, should not have resonances at operating frequencies and “ring”. The tube was filled with polyurethane foam, pre-wrapped with paper tape so that later it would not peel off the frozen foam from the outer surface. The pickup holder also got a little hit. After the foam was completely cured, its excess was cut off with a sharp knife, the assembly was assembled. The wiring inside the tonearm tube was replaced by an external one. For her, several pieces of the thinnest, silver wires in the screen in pairs were useful, what is needed. From some kind of sensor. The wiring was fixed over the tonearm tube with thin pieces of thermotube, the ends of the screens were cut and sealed.





In order not to lead wires into the housing, where it will be convenient to install the output signal connectors, the latter are installed on the top panel of the tonearm assembly itself. An open way, so to speak, on a piece of aluminum corner. The corner is attached to the panel with exhaust rivets.

The signal wire from the pickup head, from the stick of the arm comes out already without a screen, for less rigidity, and in front of the connectors, is molded into a sort of Moebius loop to reduce the obstacle to the rotation of the arm. The loop turned out to be quite soft, hanging in the air, touching nothing in any position of the tonearm. Please note - the wires after soldering to the terminals of the connector are secured to the insulation with epoxy adhesive droplets to remove the mechanical load from the solder points, otherwise the wires will quickly break off near the solder joints - they are fragile there, during soldering, solder is sucked into the woven veins by capillary forces and makes these places stiff, and our wires also move. The connection used excluded the standard relay switching the output signal. Practice has shown that no background increase is observed. Apparently, its general, low level is affecting.



In the same photo, one more sort of “modernization” is visible - the used pickup head is slightly heavier than the standard one, so the counterweight could not cope, I had to weight it with two drilled five-ruble coins glued onto neutral silicone sealant - if necessary, they can be removed.



In the transparent, removable cover of the player, a window was cut for the release of the signal cable in the closed state.



I remember listening to the most interesting records all night. Do not come off.

This concludes the description. home "Systems". In general, I am satisfied with the result. The sound of the records varies greatly, from, "almost the same as on the CD", to "close your eyes and Kinchev sings nearby." Indeed, among the collected records there were several unusual copies, the music from which is reproduced extremely naturally.



Description and circuit diagram of the player.
elektronika_ef017_stereo.rar [786.83 Kb] (downloads: 298)
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4 commentary
Author
Thank you colleague. I was curious about the link, impressively. Frankly, I did not look carefully enough for detailed constructive criticism, but we don’t need it either - all entertainments of this kind are, by definition, not rational and practical.The only thing is, if you live in your house and design, operating from small parts, you can see at least the minimum machine park - an hour turning and miniature milling. I myself dream of such a thing.
Guest Pavel
Very worthy painstaking work. Read with pleasure
And here is my vision of finalizing the players. Take a look if you want.
314n.livejournal.com
Author
Thanks. The wires from the pickup, on top of the tonearm, are shielded. The screen is removed only in the flexible part of the wiring. Sufficient flexibility is provided by both a specially formed loop of wires and the type of wire itself. It is extremely thin and soft. The aiming at the correct grounding (reduced to a single point on the grounding terminal, attached to the grounding terminal of the vinyl corrector) is completely absent, even when working near high-voltage equipment. As for damping, pink foam was not yet common during modernization. For the top panel, you can apply other material, no objections. For the tonearm, it seems as if there is no simple and cheap alternative. The mass of material is also important here. In defense of the vibration-damping properties of the foam, I note that it works perfectly. During the fuss with the player, construction and finishing work was carried out in the new apartment. A kitchen sink made of thin stainless steel was damped with mounting foam. It turned out very well - the water does not rattle and does not ring, the sound is dull. Well, the player panel began to "ring" much less, you should knock it on top with something hard and listen to the response. Although I generally agree - in the presence of vibration-absorbing mastics or other similar materials, it is better to use them. The possibility of ignition of the device is very exaggerated - low-current, not remaining unattended, equipped with a fuse.
Guest Vladimir
A lot of work was done by the author. I had some doubts about the damping of the case with mounting foam, since it has poor damping properties and it is combustible, as well as the external wiring of the arm:

1. The properties of the foam after it has completely dried is probably more suitable for elastic deformation, that is, it restores its geometric parameters after its compression, not completely, but it restores, that is, deforming under the influence of the wave and when the pressure of the wave decreases, it returns to its original position and emits a response wave, i.e. It reflects, but does not absorb, vibrations; at the same time, when it returns to its original position, it works not only in the opposite direction to the applied force of the dying wave, but also in all directions. So at a higher frequency, it supports the transmission of vibrations, which can not be said about plastic materials, for example ordinary plasticine, but better vibration-absorbing acoustic material in the form of sheets of vibroplast to reduce vibration in cars, there are self-adhesive options and even completely non-combustible. When a wave acts on it, a plastic vibrational material is deformed, but it does not return to its original position, thereby absorbing, but not reflecting the wave’s vibrations, while there is no wave transmission around itself.
2. Ordinary mounting foam supports combustion very well, in case of strong heating of any radio component, a fire may occur, at least pink or red foam should be used, which does not support combustion, but does this make sense. Polyurethane foam is designed to simplify the installation of structures and eliminate gaps between them to prevent heat loss, but it does not dampen noise, as does foam.
Do a simple experiment! Take a piece of polystyrene foam or a piece of dried mounting foam, but put it on your ear, and on the other side of this piece scratch it with a fingernail or knock. You will perfectly hear the sound from your hand, as if through an earpiece. the sound wave is transmitted with the least loss, which means the vibration will pass almost without obstacles. And now take a block of plasticine or a piece of vibroplast and do the same with it, the effect on the face !!!
Foam in my opinion is directly contrary to the damping goals!

There are doubts about the open wiring of the arm. The author completely brought out the wiring of the tonearm outside, depriving it of a screen in the form of a tube that is grounded through the housing. in this case, interference from extraneous electromagnetic waves is possible, which may lead to the appearance of extraneous noise and background. In addition, the assembly of the output of the wiring from the arm in such a way inexorably leads to the action of a reverse force when the wiring is deformed at the bend on the arm, which will worsen its operation and ruin the anti-skating.

I ask you not to strictly judge, this is just my vision of this “abbreviation” from the point of view of physical phenomena.

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