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  1. ViperZ

    Tannoy HPD 385A tweeter diaphragm replacement options

    Hi all, I bought a pair of Tannoy Berkeley with HPD 385/A in them, and one tweeter coil was repaired (now it is lower impedance compensated with resistor in series). I would like to replace the diaphragm with a coil, and Lockwood looks like the best replacement avaialble on the market. I also...
  2. ViperZ

    Velodyne ULD-15 subwoofer repair

    Yes, I have the schematic. It is surprisingly complicated for a subwoofer. 2 microcircuits and 3 matched colour-coded transistors in the preamp.
  3. ViperZ

    Velodyne ULD-15 subwoofer repair

    As much as I appreciate this post, sure, point me in the right direction then... I always do enough research on previous posts before making a new thread. This amp has been in my house for close to 20 years, working like a champ after my last repair on it. So yeah, hence my post.
  4. ViperZ

    Velodyne ULD-15 subwoofer repair

    The driver surround was replaced less than 5 years ago. It is not rattling sound, it is an audible hiss/noise - can be heard from about 1-2 feet with no sound playing. The sub itself works fine when sound is applied.
  5. ViperZ

    Velodyne ULD-15 subwoofer repair

    Hi all, I am going through my system repairing minor issues, and finally got to this Velodyne ULD-15 Series II subwoofer amplifier from 1985. I repaired it probably close to 20 years ago and it has worked great every since in my system. Last year I noticed that the subwoofer got a little...
  6. ViperZ

    Replacement Power Switch P227EE2B20A is end-of-life

    Just saw this thread. Checked my stash, I still have a couple of the ones, which are obsolete. These ones should work great, thank you for finding them.
  7. ViperZ

    Rotel RA-1412 strange preamp problem

    Interesting timing. I just picked it up a couple of hours ago. Apparently cause of the issue was an intermittent ceramic capacitor on a power rail for the preamp board.
  8. ViperZ

    Avery's "First" Maker: The TA-800

    Dave, thank you again for taking your time to find and share this circuit. I will hopefully be picking up my TA-800 today, and will start making parts lists and making plans to restore and modify it. Regards, Eugen
  9. ViperZ

    Avery's "First" Maker: The TA-800

    Thank you, Dave. I see 100-Ohm screen stability resistors on the output tubes; 10-Ohm 1% resistors on cathodes. Is there recommendation on wattage for both? Screen stability I guess 1/4-watt will do; would the same work for cathode current sampling ones? For individual bias pots - your schematic...
  10. ViperZ

    Avery's "First" Maker: The TA-800

    Hi all, is there a marked-up schematic available to show where to install and the values of: 1. Screen Stability resistors, 2. Cathode current sampling resistors 3. Individual bias controls I am supposed to pick up a very tired TA-800 soon and it will need a total overhaul. Thank you.
  11. ViperZ

    ADC Accutrac 4000 repair

    Yeah, I read that whole thread. Luckily for me, both my chips, control and memory, are working fine. I wish that guy posted gerber files for PCB along with his code and parts list. Would have been a full replacement package for those with failed controllers.
  12. ViperZ

    ADC Accutrac 4000 repair

    No, I don't have the orb or the remote, and they seem to cost a pretty penny. Yes, there is an adjustment for the tonearm sensor sensitivity level. You will need ADC proprietary mirror insert, or you can improvise.
  13. ViperZ

    ADC Accutrac 4000 repair

    Thank you! I'm trying to source the stylus. The person who was helping me had one, but he is on vacation. I'm in no hurry for now. Spent an hour and a half sanding and polishing the dust cover, glued a crack in the back... it will need another round of polishing later, but looks presentable now...
  14. ViperZ

    ADC Accutrac 4000 repair

    I think I am done. I tried to adjust the run-in position and rest position perfectly, but there is not enough adjustment, since they both use the same mirror. It is not a big deal, as everything works now, arm gets into rest position / cradle, just off from the very end of the hook by ~4mm. I...
  15. ViperZ

    ADC Accutrac 4000 repair

    Thank you, Dave. I love working on unusual or unique gear, have a pretty good collection of it too. I will definitely look at the Optonica table, sounds like fun. (holy cow - a separate arm wand for the sensor was used - https://www.ebay.com/itm/224052239648) Right now I took the whole thing...
  16. ViperZ

    ADC Accutrac 4000 repair

    I think I got it... I just lifted the tonearm by about half a millimeter or so, and no more sticky clutch... LOL. Maybe clutch plate got magnetized over last 40+ years; I have seen this thing in jukebox relays, which have "stick" function, but would stick longer than needed after 50+ years (and...
  17. ViperZ

    ADC Accutrac 4000 repair

    I just watched voltages on SW2 and clutch coil. The moment the tonearm gets to the blank space between tracks, voltage off the clutch is removed. SW2 also loses voltage fraction of a second after tonearm starts moving down, way before tonearm swings inward. So microcircuit does react absolutely...
  18. ViperZ

    ADC Accutrac 4000 repair

    So looks like this position is a tiny bit too much.. since the same mirror is responsible for shutting everything off when the arm reaches the rest, my arm does reach the rest, but doesn't go back into the hook cradle by ~1/8". Anyway, this is fixable... Now that the arm is able to reach the...
  19. ViperZ

    ADC Accutrac 4000 repair

    Whoever was screwing with this table definitely made a total mess. One adjustment screw on the brake wheel was loose (it is hard to get to it without total disassembly like I did). The moment I undid the one tight screw, I pushed the wheel and it almost popped into this position. It was about...
  20. ViperZ

    ADC Accutrac 4000 repair

    Thank you... slowly but hopefully surely. Yes, it does use specialized LMA1 (or LMA3) cartridge with the provision for sensor to be installed on top of it, and cart/stylus have a hole in the front to allow for sensor beams. I don't want to take it apart another time, so will take some time...
  21. ViperZ

    ADC Accutrac 4000 repair

    Two wires are for the sensor, but it is not needed to check brake and clutch. I took everything completely apart, had to do it to get to brake wheel screws. Will try to go over everything I can before rethreading and resoldering those tiny wires again. You can see the stick where the imaginary...
  22. ViperZ

    ADC Accutrac 4000 repair

    I should have mentioned that lol. Yes, these photos are all 'before' photos when I originally disassembled all the arm control assembly and discovered that someone stuffed it with grease. I cleaned it all with alcohol properly. I take a ton of photos all the time, but somehow did not take a...
  23. ViperZ

    ADC Accutrac 4000 repair

    I looked at someone else's brake wheel position, and it is very similar to mine. Weird that all of my lead-in and cut-off positions are so far off... maybe that's why adjustment is supposed to be done at 1/32" at a time...
  24. ViperZ

    ADC Accutrac 4000 repair

    So brake wheel assembly procedure step that I am looking at: - rotate the Brake Wheel until the edge of the braking surface and an imaginary line drawn through the center of the bushing aligns itself with the edge of the port hole in the control box housing. Here is the photo of my tonearm at...
  25. ViperZ

    ADC Accutrac 4000 repair

    I read the brake assembly replacement section in the service manual yesterday night, it explains how to set it up after new brake wheel is installed... I can see that my brake is off, but not by much. It does make sense to take everything apart again and rotate the brake wheel to match the setup...
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