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  1. drbacklash

    Marantz 2285b repair in NC

    Both AM and FM reception went out on my 2285b recently (not weak but nonexistent) and I am looking for someone in NC or northern SC to repair it. I live on the east coast of NC between Wilmington and Myrtle Beach. Any referrals? The entire unit was professionally restored about 5 years ago. I...
  2. drbacklash

    Marantz 2285b repair in NC

    I have a beautiful 2285b that was working fine until it wasn't. I'm getting nothing (no signal, no sound, no static) when I select FM so the tuner is suspect. I took the cover off to see if there was something obvious but nada. Everything else works fine except the tuner. My options are to...
  3. drbacklash

    Eleven GX Woes

    I pulled this 50 lb receiver out today to work into my rotation. No problem last time I had it on (2 years). Lights on, relay click and no sound. Flipped the M.A.C. lever and call the fire dept! Opened it up and R48 330 0hm resistor on the right channel side is cooked with smoke damage all...
  4. drbacklash

    AU 717 problems

    I am very careful when I replace components. I draw diagrams, make notes and even tie various colors of knitting yarn on wires to make sure I don't do exactly what I did this time. I did it in stages, over time so I may have been tired or it may have been late at night. Anyway it happened and...
  5. drbacklash

    AU 717 problems

    Many thanks to Lee for being so smart and patient and willing to fix this unit for me. And thanks to Hyperion for his interest in saving this nice piece of gear. You can never be too careful in documenting your own repair work!
  6. drbacklash

    6060 F-2648

    I have a 6060 that has a popping in one channel. The power board is a F-2701 but my service manual shows the F-2648. The manual is for both the 5050 and 6060 so I expect some boarders interchanged between the two units. Where can I find data for the 2701?
  7. drbacklash

    AU 717 problems

    I have now completed replacing all questionable resistors on both driver boards including the Zener Diodes. This work did not correct the problem. The unit still comes out of protection but the DC offset cannot be adjusted. On both left and right channels the readings start at 0 mv and...
  8. drbacklash

    AU 717 problems

    Thanks John, useful information.
  9. drbacklash

    AU 717 problems

    I checked all resistors and diodes again and found some I will replace. I know that you sometimes have to pull a component from the board to get an accurate reading but I figure that if you have to pull it you might as well replace it. Any resistor out by more than 5% gets a permanent...
  10. drbacklash

    AU 717 problems

    Ok, my plan of action is to recheck all resistor values on the driver boards, checks replaced diodes, and then transistors. I sometimes read where the value of components were listed incorrectly in the service manuals. Are there any known errors in the 717 manual?
  11. drbacklash

    AU 717 problems

    Here are the results of the tests: F-2722 right channel driver All connections to F-2721 disabled. With Molex connected, ranges from about 250-280 mv but will not settle. With Molex not connected, increases from 0 to 400 mv and then recycles. F-2721 left channel driver With Molex connected, 0...
  12. drbacklash

    AU 717 problems

    Understood.
  13. drbacklash

    AU 717 problems

    A point of clarification: Looking at the driver board, moving down from the Molex, the pins are numbered thusly: F2721 02 white 03. White 08. Orange 13. Purple 12. Yellow 04. Gray F2722 02. Black 03. Black 08. Brown 13. Green 12. Red 04. Blue So pins 3 and 4 would match up to pins 08 and 13...
  14. drbacklash

    AU 717 problems

    Ok, got it.
  15. drbacklash

    AU 717 problems

    Not familiar with the term output emitter network. Are you looking for voltages at R46 or somewhere else?
  16. drbacklash

    AU 717 problems

    Ok, give me a day or two to test and get measurements. I took the drivers out (again) to test transistors so I will have to put them back in. I'm getting pretty good at doing this now.
  17. drbacklash

    AU 717 problems

    Is it likely that the initial start up power surge affected another component (fusible resistor) on another board (other than driver or power) and that is causing the problem? Just a thought. Also, is there an AK member I can send just the boards to check? For a fee, of course.
  18. drbacklash

    AU 717 problems

    Yes, all the plug/pins on the driver boards and the 4 on the ps board were connected. In fact, I cleaned them to make sure they had good contact. I was wrong on one thing I posted. The offset pots are functional if I connect the mm positive to the driver board test point ( where bias is...
  19. drbacklash

    AU 717 problems

    Thanks Hyperion. I think the problem is related directly to the cold start up without the dim bulb tester but I don't know what component was affected. I measured all the ones I removed and never found a problem. I didn't replace or test any transistors so that will be my next step. Thanks...
  20. drbacklash

    AU 717 problems

    Which transistors should I pull and test first? I will do all of them if I have to but I would like to start with the ones that may be causing the problem I described above. What transistors, if bad, could cause the DC offset to "cycle" from 0 to 400 mv?
  21. drbacklash

    AU 717 problems

    These are the two driver boards after upgrade/changes. Two pics of the F 2721 and one of the F 2722.
  22. drbacklash

    AU 717 problems

    I have pictures to post of both driver boards but can't find any instructions to do so. Why did I use so many metal film resistors? Good question. I knew that the problematic fusible resistors should be replaced with metal film so I assumed that they must be good replacements for other aging...
  23. drbacklash

    AU 717 problems

    This is a continuation of an earlier thread about the 717 not coming out of protection mode but I followed Leestereos instructions on improving the power and driver boards so now I have different problems. Some background, I got this unit a few years ago and cleaned all the boards, replaced...
  24. drbacklash

    Help with AU 717

    Just those two or all of them?
  25. drbacklash

    Help with AU 717

    I have now checked the two driver boards and the power supply and protector circuit boards. All the resistors checked out fine and I had replaced the fuse resistors on the previous rebuild two years ago. I started checking the diodes. I have a diode function on my mm. I left them in circuit...
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