Fixing a power amp module in a Marantz 2325

Discussion in 'Marantz Audio' started by OP Music, May 12, 2017.

  1. OP Music

    OP Music AK Subscriber Subscriber

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    Hi guys, I'm pretty sure I smoked one of my power amp modules in my 2325 a while back and am looking to replace the faulty one with a new one. I'm not exactly sure where I can find the correct module and correct procedure for replacing the part. I just sent an email to info@irebuildmarantz.com, to see if they could help me out. I'm wondering if anyone here has any helpful insight in to this issue.

    I'm completely new to this vintage audio repair process, however I'm determined to become knowledgeable enough to fix my gear! All help and guidance is very appreciated!

    Thank you for your time and consideration,
    Alex
     
  2. wurlyman

    wurlyman Active Member

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    Can you tell us exactly what you did to the amp?
     
  3. wlhd1610

    wlhd1610 Penny and her new friend Subscriber

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    They are fairly easy to work on.
    We can help walk you through troubleshooting and repair.
    If that doesn't work out then I have several amp modules here that I could send you one and you send me your defective one.

    Bob
     
  4. OP Music

    OP Music AK Subscriber Subscriber

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    I was having a party at my house and one of the wires became disconnected on one of my speakers. I didn't realize this until came in to my living room to find it not sounding right. It sounds very buzzy on the right side. So I tried the L main to R pre-out trick and the right was still buzzy and the left was good. Then I tried turning up the volume and I saw a small flame light up in it and the right went out completely I'm pretty sure. I'm too scared to turn it back on
     
  5. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    If you had flame, there should be some burned parts on the amp board. They may not be the only bad parts, but they are a clue where to look. Can you open it up and take some pics of that board?. If you can't see the board that well, it's not that hard to remove. There is a molex plug and an RCA plug on the bottom edge of the board. If you disconnect those and remove the four screws from the heat sink bracket, the board and heat sink should lift out (if memory serves me correctly. If not, someone will correct me.)
    Steve
     
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  6. rBuckner

    rBuckner Luv 2 Restore Subscriber

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    ^^^ That's right Steven!
     
  7. OP Music

    OP Music AK Subscriber Subscriber

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  8. OP Music

    OP Music AK Subscriber Subscriber

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    Here are some pictures for you guys
     
  9. OP Music

    OP Music AK Subscriber Subscriber

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    Here's something that may interest you guys. Looking at the right side power amp module, there does not appear to be any burn marks-everything seems to be in order there as far as I can tell. However, on the board immediately adjacent to it (facing upwards) there is what appears to be a small burn mark on the board. This is also the area in which I recall seeing the flame appear, so that sort of checks out.

    There are at least 4 missing screws that I have counted inside of the amp thus far. The gentleman that I bought it from told me that the guy he bought it from had it serviced (I think it may have just been recapped idk) just before the gentleman bought it. It was most likely serviced around 8 years ago. Also, you can see in the fourth photo a stray plastic piece that wasn't housing or connected to anything.
     
  10. wurlyman

    wurlyman Active Member

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    By opening your image in a new window and increasing the size to 150% I can see very clearly what you are talking about. That stray plastic piece is the cover housing to the speaker relay, the thing with two white wires and a spring on top. That board adjacent to the amp module is the power supply which creates the DC voltage to run the machine and also houses the speaker protection relay. It looks like you had a fire in the relay which may have blown the cover off and it also burned the brown wire junction J810. I also see a gob of goo on the board next to capacitors C812 and C813 that shouldn't be there. Let's see if the other guys concur with that.
     
    Last edited: May 13, 2017
  11. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    I agree with Wurlyman. There is definitely burned board next to the relay on the power supply board. I wonder if that cap next to the goo failed and started the problem. At any rate, several parts in that area are going to have to be tested, and a new relay will be needed.
     
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  12. wlhd1610

    wlhd1610 Penny and her new friend Subscriber

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    I agree,that relay looks destroyed!
    Pretty crappy previous soldering job on the two adjacent J terminals also.
    You may get away with a relay replacement if it didn't take out the outputs and/or drivers,etc.

    Bob
     
  13. MouseMaster

    MouseMaster AK Subscriber Subscriber

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    The caps on that protection board clearly have overheated. That board should be rebuilt and new main filter caps should be installed to start. Once that's done, dim bulb it and see if it powers up OK. Go forward from there as necessary. I own one of these beasts from new, and it also needs the full treatment.
     
  14. wurlyman

    wurlyman Active Member

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    I don't see any indication that any of those caps have overheated. No bulging tops, no leakage coming directly from a cap; first thing I'd do is remove them one at a time and test them. The cap in C804 does not look correct, it should be identical to C806. They're both 220uF @ 63vdc.
     
  15. OP Music

    OP Music AK Subscriber Subscriber

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    Good eye Bob, that was one of the first things I noticed when I opened it up. Poor solder job on those J terminals, it looks even worse in person.

    I don't see any bulging caps or leakage from caps. The caps in C804 and 806 are identical, may not look it from the picture. Both are 220 uF and 63 V, come with a identifier of: CEW 85L.

    This is something I just noticed though, which seems like it is almost certainly relevant.

    The caps of C804, C806, C805 and C807 all have browning on them, which seems to indicate that they may have been overheated.

    Here's a picture for your reference: (may also be seen in my fourth picture in gallery)
     

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    Last edited: May 14, 2017
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  16. wlhd1610

    wlhd1610 Penny and her new friend Subscriber

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    Definitely not good.
    Rather than screw around doing a forensic autopsy I would recommend a restoration.
    At the very least do the power supply board,amp boards,main filter caps,a thorough cleaning/deoxit of all controls,lamps ,vellum....
    well actually everything,after all a great unit like the 2325 deserves it after 40+ years.

    Bob
     
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  17. MouseMaster

    MouseMaster AK Subscriber Subscriber

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    Looked to me like the sleeves on the caps shrunk from heat. This is on the protection board near the fried relay.
     
  18. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    I wonder if that big cement resistor by those four caps could have caused all of that browning. Maybe the flame came from under it. :dunno:
     
  19. OP Music

    OP Music AK Subscriber Subscriber

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    I am confident that I could do the vellum replacement, led replacement, and I could 3D print a new dial lamp housing if the one in the unit is melted. I'm also sure I can clean all the controls. It's the board work that must be done that I'm not familiar with. Can I fix this myself?
     
  20. wlhd1610

    wlhd1610 Penny and her new friend Subscriber

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    If you can desolder(very important) and solder along with having a decent DVM and know how to use it then yes ,you are well on your way .
    Knowing how to read schematics helps but you should still take"before" pics and make some diagrams of the boards to ensure you place components correctly.

    Bob
     

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