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  1. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    That makes sense. I went ahead and ordered a couple. If that doesn't get everything back where it should be, I'm sure I'll be back. Thanks for your help guys!
  2. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    I'm starting to think that TR601 and its counterpart, TR602, are both at different states of failure. Swapping them may have fixed the negative voltage leak, but I finally realized that I cut off the expected voltage listing when I tried printing off a portion of the schematic (woops!). I...
  3. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    Yeah, that does make sense. You know what? I went back and double checked the measurement on the emitters of TR601 and I got a positive value. Then I remembered that I switched them from one channel to another, so I checked the other one and it's negative. I'm waiting for the capacitors to...
  4. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    Yep, I still have about +60V on the base and emitter of the main output transistors on one side. *sigh*
  5. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    Hmmm.. I've had that one pulled before and tested resistance. Right now, in circuit, I get 100k and climbing. If I reverse the dmm leads, I get 0.L. I may try swapping it with TR604 first just to confirm. Maybe it's only leaking under load
  6. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    voltage at the wiper of R601 = 23.91V voltage at TR601 emitters = -21.20V Voltage across R613 = 38.4V voltage at TR601 input base and feedback base - To be honest, I don't know for sure which is which. I would assume that the left-most side would be input and the right-most side, feedback...
  7. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    Collector of TR607 is +60.2V R611 Shows a voltage drop of almost zero (it fluctuates upwards of 10mV, but always goes back down to zero after a second or two). When I power everything off and test the resistance on it, I get 15.58k ohms
  8. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    I almost planted one once, but I'm far more of an audio nut than I gardener, it seems. That's where I was looking too. I've already replaced TR605 with a new generic and just now swapped out D601, but I'm still getting about 58V on the base / emitters of the main output transistors for this...
  9. KilgoreCemetery

    Technics SA-5760 Receiver No Output

    At first, the protection relay would click on and off sporadically and I was able to trace the problem down to the driver board having voltage spikes in the signal path of one channel. The board mounts vertically, so I had this bright idea of removing it and putting it in the freezer for a...
  10. KilgoreCemetery

    Kenwood Receiver Heating Issue

    I did finally get around to setting the idle current! The supply voltage is now up to 49.3V! Thanks again for your help, Ylli. This thing sounds way better now too.
  11. KilgoreCemetery

    Kenwood Receiver Heating Issue

    If you don't mind me asking, how did you come up with the 15K resistor solution?
  12. KilgoreCemetery

    Kenwood Receiver Heating Issue

    Ok, I tested a few of the 13k resistors and found one at 13.5k. Popped it in and we now have sub-400mV adjustment with room to spare. It hasn't really warmed up yet, but the lowest measurement I've gotten is 311mV. At 390mV, I'm getting 21.30V on the collector of Q4 and none of the output...
  13. KilgoreCemetery

    Kenwood Receiver Heating Issue

    I ended up looking at the service manual for the Kr-77. It's not identical, but it is similar. I have a whole mess of 13k and 24k resistors. Also, I have a KR-4400 that I can pull parts off of. I'll have to check the specs, but it has the same type of VR's.
  14. KilgoreCemetery

    Kenwood Receiver Heating Issue

    Hmm.. well, I started by spraying all the trim pots with some deoxit and working them back and forth a bit. I realized that the resistance on VRe2 had a sweet spot in the middle and higher resistance on both ends of a full rotation. Now the resistance changes gradually. If I set VRe4 back to...
  15. KilgoreCemetery

    Kenwood Receiver Heating Issue

    The lowest I can get it to go with VRe2 is 496mV before it starts climbing back up. If I get VRe4 involved, I can get it down to 447mV. That gets Q4 collector voltage up to 16.29V
  16. KilgoreCemetery

    Kenwood Receiver Heating Issue

    Yep. I totally goofed that up. The top of this receiver is really clean-looking, the bottom is a point-to-point mess where they only had 4 different wire colors to choose from. Let's try that numbering system again: R212: 91.9 mV R213: 101.3 mV R112: 13.6 mV R113: 13.9 mV The transistor...
  17. KilgoreCemetery

    Kenwood Receiver Heating Issue

    I apologize for the discrepancies. Some of these values are from before I replaced the capacitors. Also, as the heat builds, some of them change quite a bit. Whenever I spend a significant amount of time checking voltages and stuff like that, I have a small fan that blows on the heat sink to...
  18. KilgoreCemetery

    Kenwood Receiver Heating Issue

    These kept dropping gradually even after the receiver had been on a couple of minutes R112: 91.9 mV R113: 101.3 mV R212: 13.9 mV R213: 13.6 mV Q2: C = 43.6V, B = 21.36V, E = 20.81V Q3: C = 20.77V, B = 0.555V, E = 13.2mV Q4: C = 14.67V, B = 0.684V, E = 95.2mV Q5: C = 43.6V, B = 15.42V, E =...
  19. KilgoreCemetery

    Kenwood Receiver Heating Issue

    I've been trying to figure out this Kenwood KR-70 receiver. The guy I bought it from said that the volume drops to zero after you run it for a while and, although it hasn't done it to me yet, there are some other signs that something is wrong with the receiver. There's one power transistor that...
  20. KilgoreCemetery

    Marantz 2015 Receiver Distortion

    You and me both. I can't believe it didn't just shoot sparks the first time I powered it up. It wasn't even drawing much current and with just the headphones, you never would have guessed there was anything wrong.
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