Recent content by sonavor

  1. sonavor

    (another)Yamaha C-70 Project

    Unfortunately, I disassembled and cleaned the SW-104 switch assembly years ago, before I did the full restoration of my C-70. I didn't take any photos at the time but it wasn't too difficult of a task. Just take your time and go slow during the disassembly. If you do the disassembly, take...
  2. sonavor

    Another MX-1000 refurbished

    Very nice work and thanks for the good photos.
  3. sonavor

    I don't have any Yamaha C2a preamplifiers for sale at the moment.

    I don't have any Yamaha C2a preamplifiers for sale at the moment.
  4. sonavor

    dbx 14/10 Equalizer - Replacing Battery for the Static RAM

    My dbx 14/10 Equalizer stopped recalling saved settings recently. I had a similar problem a while back with my dbx 20/20 Equalizer. While the dbx 20/20 has a battery compartment in the back which is easily accessible (for its two AA batteries). The dbx 14/10 does not. That is because the dbx...
  5. sonavor

    (another)Yamaha C-70 Project

    Back to this C-70. After replacing the bridge rectifier the C-70 played music continuously for just over ten hours with the top and bottom covers removed. That was so I could check it periodically for any problems. There were no problems so I moved on and put the C-70 cabinet back together...
  6. sonavor

    (another)Yamaha C-70 Project

    The lamp in the fixed arm of the Beogram 8002 (and their BG400x, BG8000 turntables) serve as light sources for an optical sensor that detects if a record is on the platter. An empty platter produces a pulse signal that the circuit used in reading the sensor reads. That is important because the...
  7. sonavor

    (another)Yamaha C-70 Project

    Yes, I have had my fair share of "oops" moments. I share your concern about why the rectifier device failed but I haven't been able to find a source for that yet. As I just posted, those wire wrap terminals are tight and don't have any wires that could touch the "live" heatsinks. I am also not...
  8. sonavor

    (another)Yamaha C-70 Project

    Hi Dr. Ear, I think that image that you are seeing as a bare strand of silver wire is just a reflection in the photo. I had checked all of the power supply connections very thoroughly when I finished and first powered the C-70 on. Here is a better angle of that terminal with the white wire...
  9. sonavor

    (another)Yamaha C-70 Project

    I left the C-70 playing music through some headphones for ten hours (and still playing). The cover and base of the cabinet have been off on this leg of the test but here is a look at how hot the power supply components get when power is on these units. Here is the C-70 happily playing...
  10. sonavor

    (another)Yamaha C-70 Project

    Eagle Eyed Avionic was right on about the C-70 full bridge rectifier (D521). I pulled it out of the C-70 and measured its leads to each other. The minus lead was shorting. I had a spare D521 1B4B41 rectifier from a C-70 parts unit to swap out for. All four of its leads measure as you would...
  11. sonavor

    (another)Yamaha C-70 Project

    No. I was wondering if something like that was happening too but after rechecking connections the problem is still there. That makes sense as well because the amplifier went through performance testing without any problems and nothing moved so I believe some component had to have failed.
  12. sonavor

    (another)Yamaha C-70 Project

    The joyful sound of this restored C-70 was short lived. The owner had to deliver the preamplifier back to me the next day as it would no longer power on. It operated for a couple of hours then powered off. Back at my workbench I quickly found that the 1A, 250V fuse, F501 had blown. I decided...
  13. sonavor

    (another)Yamaha C-70 Project

    Tonight I hooked up the Yamaha C-70 to a QuantAsylum QA401 Audio Analyzer for some performances tests. I like using the QA401 quite a bit. I started out with their original QA400 then migrated to this new model for a slew of new features they added. I use the QA401 to measure and check my audio...
  14. sonavor

    (another)Yamaha C-70 Project

    Thanks. I want to get a new oscilloscope one of these days but the ones I want are a little expensive :-)
  15. sonavor

    (another)Yamaha C-70 Project

    Okay, thanks for that information. However, I already setup for it and want to document it so I can reference the next time. I know I made these measurements on my own C-70 but that was a few years ago and apparently I didn't save my notes. Here is the test setup for the C-70 service manual...
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