Юность

Combo Organ

The Юность is a solid-state combo organ made in the Soviet Union. The name is most often transliterated to English as "Junost", but the most accurate would be "Yunost", since it is pronounced "yu", rather than "ju" as in the famous "Juno" synthesizers from Roland. The name itself means "Youth" in Russian, and was a common Soviet brand of keyboard instruments, televisions, record players, and cameras, among other devices. This particular type of instrument was manufactured between 1965 and 1971. Many of the Soviet components inside have dates printed on them, so based on the latest dates, my instrument would have been assembled in 1971, the last year of production. Things that distinguish the Юность from other combo organs include a thick and robust metal chassis with distinctive styling, seven control knobs with numbering but no labeling, and an unusual key switch design.

I have found two documents on the Internet about this instrument, both in Russian and both of which I have transcribed and attempted to translate, as presented near the bottom of this page in the Downloads section. Based on these documents, it's clear that throughout its production, there were various changes to the design of the Юность, such as different types and quantities of output connectors, different transistors, different internal power supply voltages, and whether or not the vibrato speed knob is included.

Features

  • 60 slightly smaller-than-normal keys (C to B / 5 octaves)
  • completely polyphonic (all notes can be played at once) analogue tone generation
  • vibrato depth & speed potentiometers, with the latter located on the underside of the instrument
  • additive octave synthesis, with registers 16', 8', 4', and 2'
  • 1/4" output jack
  • two methods of being powered:
    • 127V or 220V AC input (selectable through the fuse holder), using a hard-wired cord with IEC Type C plug
    • 12V DC from a battery, using two banana plugs

Trivialities

  • 14 single-sided PCBs, of the phenolic paper type, using all through-hole components
  • 146 transistors in total, of the following germanium PNP types:
    • 144....МП39 (on generator boards)
    • 1........МП41 (on vibrato board)
    • 1........П217А (on power supply board)
    Note that my unit has had various generator board transistors replaced in the past with МП40, but normally all would be МП39. Transistor types vary; see notes in "Hardware" section, and the schematics.

Repairs

This example of a Юность was found on eBay, listed by a seller in Voronezh, Russia. From the pictures alone, it was clear that it had not been well-treated, but it was nonetheless listed as serviced and working. Having tried other means of acquiring a Soviet keyboard without success, I decided to take a chance on this unit. It arrived a total of 54 days after shipment (a reasonable time from Russia, I've found), in a minimalistic box without packing material. Luckily, being the metal-bodied beast that it is, it survived the shipment with only minor damage: a bit of paint had flaked off, and the left "cheek" piece was slightly bent. Here is the box prior to opening:

Naturally, it was taken straight down to the studio after being removed from the box, and the top cover was removed.

The Юность has two options for its line voltage, which are 127V and 220V AC. Having come from Russia to Canada, the line voltage had to be changed from 220V to 127V, which was easily done by pushing the fuse holder inwards and rotating it. Of course, the true line voltage here in Edmonton is 120V, but this difference is not significant enough to cause any issues.

Once powered, the first problem noticed was the absence of vibrato. No matter what vibrato depth or speed selected, no vibrato would be heard. Having a look at the vibrato board, I noticed that it had two electrolytic capacitors that had not been replaced, despite all other electrolytics having been replaced by a previous technician. These were changed with high quality Nichicon and Panasonic equivalents. Soviet electrolytics are in metal cans, which makes them look somewhat like transistors, though with markings such as "30мкф 15в", i.e. 30 microfarad 15 volt. They also have their year of manufacture printed, in this case 1969 and 1970.

This did not fix the dead vibrato, though. The real issue was that the vibrato oscillator transistor, an MП41 (germanium PNP), was defective. Since I didn't have any germanium PNP transistors at first, I substituted the common 2N3906 silicon PNP type, which allowed the oscillator to run again. I decided, however, to use a proper NOS Soviet part, which was found from another Russian eBay seller quite inexpensively. Note that the replacement part has a manufacture date of 5/1985, while the original is 3/1970.

Another problem noticed was that certain keys would produce loud "popping" noises when first pressed, as well as after they keyboard had been turned off. This suggested a DC bias being placed on the key contacts, which I intially though may be from leaky capacitors, but was actually caused by bad connections between the movable reed contacts of these keys and the bottom stationary contacts (held at ground potential) when the keys are unpressed. Without being connected to ground, these develop a DC bias. Cleaning these contacts with paper soaked in isopropyl alcohol, and in stubborn cases using a dental pick to slightly abrade the contacts solved this problem.

Another issue was a nearly dead 2' register on the 2nd-highest B key. The problem here was a 24kΩ resistor that had gone open. This was replaced with a typical 22kΩ carbon film equivalent. Note in the image below how the original Soviet parts are green with printed values instead of color codes, and how some have flat radial leads instead of round axial ones.

There were also some minor mechanical issues. Mainly, the felt under some of the highest keys had come unglued and moved so that it was no longer cushioning the bottom of these keys when pressed. This was easily fixed by moving the keybed outwards (after removing the screws underneath) and applying a little PVC-E glue. The "nameboard" felt also had detached in some places and required re-gluing.

The Hardware

Since much of the hardware was discussed in the above repair section, this section will mostly be dedicated to showing some of the aspects of the unit that did not involve any repairs.

Firstly, here is the bottom of the unit. Towards the upper left in the image, the vibrato speed knob, power switch, and permanently attached power cord can be seen. Below those, the fuse holder/voltage selector and the 12V battery terminals are located in a recessed area. A thick cast metal frame is mounted to the bottom that features four large threaded holes for mounting the legs, which unfortunately were not included with the instrument (same with the original volume pedal). Towards the right side is the output, which in the case of my unit is a single 1/4" jack.

Having a closer look at the area of the vibrato speed control, I wonder if the original knob has been replaced; it certainly looks like it. In any case, according to the servicing description (see Links section), not all examples of Юность have such a control.

The power plug is of course a two-pin IEC Type C plug typical of Russian electronics. A very simple travel adapter is used to allow it to connect to a Canadian NEMA-1 outlet.

The Юность can also be powered from a 12V source (such as a car battery / "аккумулятор"), connected with two banana plugs to the sockets near the fuse holder.

Taking four knurled screws out allows the top cover to be easily removed. Inside, have a look at one of the tone generator boards (the "B" in this case), about which a number of interesting details can be noted. For one, the transistors are mounted upside down with small plastic insulating caps, and plastic insulating sleeves on their leads. I am honestly not sure the reason for this style of mounting. Near many of these transistors, an unusual type of component can be seen: the cylindrical ceramic capacitor, which in this case are orange and all have a capacitance of 6800 pF (note that the schematic lists 1500pF). There are also a large number of point-contact germanium diodes present, some of which have clear bodies, and others of which appear painted black for some reason.

In fact, the types of parts used varies considerably between cards, and some parts have clearly been replaced at some point, especially transistors.

The power supply is to the left of the vibrato board, when looking from the front. The most interesting thing to note here is that in both schematics that I've found, the power supply is shown as being -12V DC (negative since all transistors are PNP), with two power transistors in a darlington pair for voltage regulation. My unit's power supply has only a single power transistor of a different type than in either schematic, with a 9V zener diode (Д810 instead of Д813), resulting in a power supply voltage of around -9.3V.

On the back of the unit, there is a builder's plate, which lists the model, serial number, part number (?), and price. The original price listed is 500 rubles, which was a fair amount of money considering that an LP album typically cost around 2 – 3 rubles at the time. By the way, don't try to clean this plate with a damp cloth, since the ink is slightly water-soluble; luckily this was noticed quickly.

Also on the back is a plastic strip bearing the instrument's name and held on with two screws, behind which are the tuning potentiometers for the 12 master oscillators. These can be turned with a flathead screwdriver. I didn't take any pictures, but it's pretty easy to figure out; when looking from the back, the rightmost adjusts "C", all the way to "B" on the left.

The Sounds

The sounds of the Юность are fairly typical for transistor combo organs. For example, it may be nearly indistinguishable in sound to certain Farfisa or Vox models.

I have made a video of the instrument showing some of the basic sounds, which can be seen here:

Downloads

As this is a Soviet instrument that as far as I know was never sold outside of the Soviet Union, virtually all information about it is in Russian. I have found two Russian documents about it: the original owner's manual including schematics, and a servicing description from a book that includes different schematics. Since these are in image form, I have made an attempt to transcribe and then translate them into English. Both sets of documentation are presented below.

Links

If you notice any errors or have additional information that you would like to add, please contact me!


Last Updated: 9/26/2016