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Dead 2275?

Discussion in 'Marantz Audio' started by tmccullough, Jul 5, 2018.

  1. tmccullough

    tmccullough You are who, who you are

    Messages:
    1,171
    Location:
    West Deptford, NJ
    Greetings all!

    I've had this 2275 sitting in my garage for maybe nine years now. I bought it when I was under the illusion that I was going to restore it, despite having the most rudimentary of tools and soldering skills. Lack of time and other priorities never let that happen. I've hit my "piss or get off the pot" moment, and reclaiming space is something I need to do.

    While cleaning the contacts in my Pioneer SX-1080 yesterday, I opened it up again to inspect, take some pictures, and change the fuse in the back. When plugged in and turned on, there's nothing - no lights, no sound, no relay click. I didn't think unloading a can of DeOxit on the unit was a good use of DeOxit at that stage.

    A couple things I noticed which could be a big part of the issue. First, someone hacked the power cord, and replaced a section of it with a polarized plug. I'm far from an expert, but I think this could be at least part of the problem. Second, the cap for the fuse holder doesn't appear to actually screw down to the fuse slot - there's no threading on the cap. This may not be an issue, but I am not sure since I don't have any prior Marantz experience. I've included a bunch of pictures from yesterday in the event the folks in the know have other suggestions.

    I'm not adverse to putting effort into some basic fixes, but I suspect this may be beyond my skill set. I've read these units sound great, and frankly would like to hear myself. That said, I need to figure out if it would be worth restoring (objectively better than the SX-1080), and what that might cost. If it matters, the rest of my system is a Technics SL-1100 turntable, and JBL L100t speakers.

    Appreciate any suggestions/comments/advice.
     

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  2. wlhd1610

    wlhd1610 Penny and her new friend Sponsor Subscriber

    Messages:
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    First ,build or buy a dbt(dim bulb tester)
    Get yourself a DVM
    See if you have power at the unswitched and switch outlets on back while plugged in.
    A polarized/non polarized plug has nothing to do with it as long as the plug/cord is ok.

    Do you have power at the fuse holder wires?

    Basic stuff to start out with.
    It's 110 volts so work safely!

    Bob
     
  3. Steven Tate

    Steven Tate AK Subscriber Subscriber

    Messages:
    2,956
    Location:
    N. Richland Hills, TX
    You won't find many on the Marantz forum who would say any 2275 is not worth restoring. The 2275 is a beautiful unit with enough power for most speakers and just sweet sounding. It doesn't have the power of the SX-1080, but I think you would find the sound very appealing. If you don't feel you can do a full restore and don't want to spend the money for an expert restoration, sell it as a unit for repair so someone can bring it back to life.
     
  4. Oerets

    Oerets AK Subscriber Subscriber

    Messages:
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    Location:
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    Get an Ohm meter out, then with the unit unplugged do a few tests. Start at the plug checking the repair. One wire at a time check the path into the receiver. One side will go to the fuse. You can test the fuse holder with the meter also. Plus the power switch is a known cause of problems.
     
  5. tmccullough

    tmccullough You are who, who you are

    Messages:
    1,171
    Location:
    West Deptford, NJ
    These are all things I can do. I never bothered to make a DBT, but since I have most of the components, I guess I can get on that.

    I have a DMM, with various probes/clamps. I'd be checking AC voltage, yes?
     
  6. highvoltage_

    highvoltage_ Addicted Member

    Messages:
    5,144
    Not yet. Check for continuity of the AC path starting at the plug and working your way in. You mentioned that you plugged it in and nothing happened. To be sure that nothing is really happening (as in there's no short and smoke would soon appear if there was), build the DBT first. Then plug the unit into the DBT outlet and turn on the DBT. If you get a bright light then the unit is acting as a short circuit. At that point you will need to dig deeper.
     

     

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  7. EastPoint

    EastPoint Factory Code No. 4200 Subscriber

    Messages:
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    Location:
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    Build the dim-bulb tester, set that up. Buy the correct fuse cap and replace that (there'll be one on eBay). Make sure the fuse is good. I wouldn't be surprised if the issue is with the fuseholder. Check the cord like everyone said.
     
  8. tmccullough

    tmccullough You are who, who you are

    Messages:
    1,171
    Location:
    West Deptford, NJ
    Fuse cap is ordered and I'll be shopping for the remainder of the DBT supplies I need later today.

    After reading some of the restoration threads, I feel empowered, but since I lack all the proper tools (have some, not all) I suspect it may be less costly to have the work done for me. I guess we'll need to figure that out together.
     
  9. Dingman

    Dingman Do you know where your towel is? Subscriber

    Messages:
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    Location:
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    I'm betting that end of the fuse isn't making connection due to the busted cap.
    Do as these guys say - DBT!
    As they've said - it's a good unit. Take your time, ask questions here and you'll get it.
     
    rBuckner likes this.
  10. wlhd1610

    wlhd1610 Penny and her new friend Sponsor Subscriber

    Messages:
    2,592
    Location:
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    Give it a go first with the basics.
    Maybe it’ll be a simple fix to get this great unit up and running and you’ll feel good doing it yourself!

    Bob
     
  11. tmccullough

    tmccullough You are who, who you are

    Messages:
    1,171
    Location:
    West Deptford, NJ
    DBT is assembled and I believe functioning properly. I didn’t realize the bulb would not illuminate without something else drawing current. Had I thought about it more thoroughly, I’d have known (electronics was my least favorite part of physics). I’ll fire things up either tomorrow night or Saturday and see what I turn up.

    Thanks for the guidance so far. I know this is putting the cart before the horse, but I recall a thread in which people were posting pics of their gear without wooden cases. Someone had an amazing looking powder-coated Marantz. I think if this gets up and running, I may give that some serious consideration.
     

     

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  12. highvoltage_

    highvoltage_ Addicted Member

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    Here's probably the simplest diagram I could find that explains the concept of a DBT (there are no switches, to keep it simple). In effect, if the unit being tested looks like a short circuit the bulb will light up, otherwise it will be dim. If the light comes on brightly then the bulb is dissipating power and protecting the short circuited unit from burning a component (or two or three).

    images.png
     
    Last edited: Jul 7, 2018
  13. EastPoint

    EastPoint Factory Code No. 4200 Subscriber

    Messages:
    4,675
    Location:
    Milwaukee, WI
    A dim-bulb tester is one of the most useful tools when working on vintage gear. It’s up there with a multimeter.
     
    catrafter, wlhd1610 and highvoltage_ like this.
  14. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

    Messages:
    12,857
    Location:
    Duvall, Washington
    Resurrecting stone dead gear 101.
    AKA, Starting to work on an unknown unit.

    You should start with a dim bulb test, but we jumped ahead.

    Since you went full line power and it's stone dead, we start there.

    Side note, IF it has a dead short and the AC cord and fuse holder had enough proper connection, the fuse would have blown.

    THIS UNIT; Cord is suspect, fuse is suspect, fuse holder is suspect.
    Use lowest ohm setting and test fuse, touch each end of the fuse with probes. IS IT GOOD?

    Use AC setting and test AC getting into unit. touch one probe to each end of power line where it connects inside.
    BE CAREFUL! It's best to cover the probe tips with insulation (shrink tube, tape, …) all the way to the very tip to avoid accidental shorts.
    IS 120AC getting through the funky cord? YES/NO? (either way, replace that cord).
    IF you have AC at the end of the cord, check to see is AC is getting through the fuse holder. IF the fuse holder can even be assembled. YES/NO? (Either way, replace or repair the fuse holder.
    You probe one AC line at the cord connection and probe the connection on the fuse holder (both, you should find 120AC). If not, the cord probe may be on the wrong wire.
    ONCE 120AC is getting through the fuse, move to the AC coming out of the transformer.
    The transformer output lines come in pairs of the same color wire. Probe them in pairs where the connect and you should find AC voltage of some value.
    Once you have AC confirmed coming out of the transformer, then we move on to the DC system at and after the bridge rectifier and the big filter caps.

    You can check for good DC system initialization at the big filter capacitors.
    Hook the negative meter probe to the chassis and use the positive probe to test the connections on the filter caps.
    IT'S DC, change your meter setting.
    The filter caps are connected to make a positive and negative rail system.
    One positive and one negative on the caps are connected together and to chassis ground. (common, 0V plane).
    The connections NOT connected to the chassis should have a large positive DC voltage on the positive terminal of the proper capacitor and a large negative voltage on the negative terminal of the other capacitor (like 50-60-70V large, I don't have the spec handy).

    Once you have good DC at those caps, you should have some sort of life in the unit.

    The next target in the power path is the power supply. That should provide the 35V that every Marantz I ever touched uses.

    Once you get the lights on (so to speak). Then either the relay clicks or not.
    No click? A messed up amp is the suspect.
    A click? Things may be so-so. Then we can check sound (since you deoxit it, bad sound would indicate bad parts).
     
    Steven Tate, Aaron99 and thxdave like this.
  15. tmccullough

    tmccullough You are who, who you are

    Messages:
    1,171
    Location:
    West Deptford, NJ
    Thanks for the advice so far. Waiting for the NOS fuse cap to arrive and will test then. I bought new fuses so even if the fuse was bad I have replacements.
     
  16. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

    Messages:
    12,857
    Location:
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    I scavenge fuse holders but you can get complete new ones at RadioShack and other hardware places.

    If you paid more than a couple bucks or live in hardware wasteland, you took the spendy OEM road.

    But, there are many variations to common holders so in the long run, you probably took the easy road.

    I have boxes full so I can dig to match.
    Sometimes I just save the caps and fuse.

    A junk pile is a happy place.
     

     

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  17. tmccullough

    tmccullough You are who, who you are

    Messages:
    1,171
    Location:
    West Deptford, NJ
    A3C768A7-7C6C-459F-88F7-890F4B796CBD.jpeg

    OK, so now that I’m not traveling and have a good fuse holder assembly, here’s where we are:

    1. Hooked up to DBT after replacing fuse. Light shines brightly.
    2. Check VAC at the plug - Reads 2.13.

    It’s entirely possible I’m not reading this properly. The Fluke manual says I am connected the right way, but I’m by no means an electrician. I can learn though.
     
  18. avionic

    avionic " Black Knights " Subscriber

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    Not going to be any AC unless the unit is plugged into the wall via DBT.
     
  19. tmccullough

    tmccullough You are who, who you are

    Messages:
    1,171
    Location:
    West Deptford, NJ
    It was. DBT plugged in, switched on. Receiver plugged into DBT, switched on. Lightbulb burns brightly.
     
  20. highvoltage_

    highvoltage_ Addicted Member

    Messages:
    5,144
    If the bulb is bright, your unit has a short somewhere.
     

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