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  1. Oilmaster

    Sony 2251 and/or 2250 owners thread

    Constant current x resistance = constant voltage = zener
  2. Oilmaster

    Sony 2251 and/or 2250 owners thread

    When a (J)FET is connected like that it becomes a constant current source, combine that with a resistor and a constant voltage drop (like a zener) is created. You might think where is the resistor then? It are the regular diodes in series that have a given resistance at a given current, and thus...
  3. Oilmaster

    Sony 2251 and/or 2250 owners thread

    Indeed, as I mentioned in my thread about 1T243 devices: 1T243-xx40 = TZX11A (10.6V/500mW/1%) 1T243-xx47 = TZX7V5C (7.5V/500mW/1%) 1T243-xx49 = TZX10C (10.1V/500mW/1%) So what is the printed suffix on yours?
  4. Oilmaster

    Sony TAN 8850 amplifier

    Well, that's not entirely true: there is no global negative feedback from output to input stage There is however local negative feedback, from pre-driver stage to input stage, to keep the amp stable and at defined bandwidth. The idea behind that being that if the pre-driver stage is stable then...
  5. Oilmaster

    Relay Matsushita JR2A-DC24V-Y2 substitute?

    Measure up if the distances between the pins are the same as in the datasheet, and you are ready to order.
  6. Oilmaster

    Relay Matsushita JR2A-DC24V-Y2 substitute?

    That's why it would have been a great help to post as well the solder side of the relay at stake, but I read your remark that the board isn't directly accessible. You can see at the PCB layout that there are only 4 holes; so yes a DPST needed. But sometimes a DPDT are available at better price...
  7. Oilmaster

    Issues on Sony TA2000

    Oh that is a b**** problem to diagnose and to find out where.
  8. Oilmaster

    Issues on Sony TA2000

    I double-checked that you had the replacement transistor well positioned, and it looks they are. Since the problem is equal for both channels, and the changes are slim that the same problem happens in both channels at the same board, it makes me think of a "common mode" fault. Some resistors and...
  9. Oilmaster

    Relay Matsushita JR2A-DC24V-Y2 substitute?

    Omron G2R-2A4 for fully sealed version or Omron G2R-2A for non-sealed version You can also buy the DPDT versions of the above and cut off leg 2 and 7 Before any purchase, always check if the leg spacing of your relay is confirmed by the datasheet of the new relays...
  10. Oilmaster

    Yamaha B2 - the "why" and the "how" of a comprehensive rebuild

    The very same reasons why I pulled out of tube amps 20 years ago; an absolute money pit with no guarantees and unstable results. On top of that the tube community is flooded with hardcore subjectivitists, duly populated by folks with a lot of money and near zero technical knowledge; not the...
  11. Oilmaster

    Schematic help required

    Each secondary winding fused at 4A, hence 130VA per winding, which makes for a 260VA peak load. So a 300-400VA transformer with 2x32V to 2x34V secondaries will do as painttoad said.
  12. Oilmaster

    Sony tc-203 sd

    One on sale right now; nothing beats to have original manuals with all colors sharp and clear: https://www.ebay.com/itm/124906543188
  13. Oilmaster

    Searching for new belts for a Sony TC-FX606R

    It's a pretty packed unit. After some testing the headphone amplifier opamp turned out to be faulty and will be replaced later as well
  14. Oilmaster

    Searching for new belts for a Sony TC-FX606R

    Reinstalled and reconnected the whole tray again, and everything works mechanically perfect again, including reverse play :)
  15. Oilmaster

    Searching for new belts for a Sony TC-FX606R

    So after some thorough research, the mechanism of the TA-FX606R turns out to be same as the TC-V7, so i ordered a TC-V7 belt kit including with grease and lubrication oil, as this unit is full of old grease that turned orange/brown. Working on this unit is really easy; the drawer is easily...
  16. Oilmaster

    Another 4558 Opamp Question

    What exact audio unit is this ? I would like to see the full schematics and PCB layouts. Where power rail decouple caps are exactly are connected is critical. Furthermore, from the schematics provided above, there is a -7.5V created from the -15V rail, which means in reality another parallel...
  17. Oilmaster

    Sony TA-8650 power transformer issue?

    I am working on it, had some delays due to various other projects, but soon picking this one up again
  18. Oilmaster

    2017 Sansui Serial Number Database

    BA-1000,225060017,internet BA-1000,225070092,internet BA-1000,225080117,internet BA-1000,225080118,internet BA-1000,225110083,internet CD-10,215110145,internet CD-10,215110070,internet CD-10,225090003,internet CD-10,225090070,internet CD-10,246040067,internet CD-10,246040085,internet...
  19. Oilmaster

    Another 4558 Opamp Question

    Like you I wanted to try out a whole bunch of modern audio opamps in a midrange Sony amp that has a 4458 in a buffer stage and in the tone control section, just to know what potential gains could be. Spent a dozen evenings on the known fora, completely saturated in the end, tons of personal and...
  20. Oilmaster

    JVC A-X9 Output Transistors

    oh that's another default problem in this amp: the power supply of the phono equalizer board. The glue that is used to glue the electrolytic capacitors to board turns acid and corrodes the legs of other components away, creating akward circuit conditions. Furthermore, the original electrolytic...
  21. Oilmaster

    JVC A-X9 Output Transistors

    I had two faulty A-X9 units on my bench; faulty output transistors, or one channel repaired with other output devices, seems to be the theme with this amp. And there is a good reason for it: the original driver transistor are too sensitive to high power output with low speaker loads. And owners...
  22. Oilmaster

    Tracking force sweetspot for a AT-VM95E cartridge?

    So I am finishing a full restoration of a Yamaha YP-D71 table before selling it off, and outfitted the table with a new AT-HS6 headshell and new AT-VM95E cartridge. That combo looks great on this turntable. Full and best possible alignment done using a Bearwald scale, arm height adjusted for...
  23. Oilmaster

    Yamaha B2 - the "why" and the "how" of a comprehensive rebuild

    I deleted my previous postings on the matter as yet another contributor to that theory was far from happy that I shared the method that we jointly developed. As such I cannot permit sharing it again in case somebody copied it in a personal file.
  24. Oilmaster

    Searching for new belts for a Sony TC-FX606R

    thanks :)
  25. Oilmaster

    Sony TA-N7B restoration

    Sure, first they spent between $1000 to $1500 to buy it in Japan and have it shipped, import duties etc, then looking for low cost fix
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