Working on a MC2500...

Discussion in 'McIntosh Audio' started by eiraved, Mar 27, 2018.

  1. eiraved

    eiraved AK Subscriber Subscriber

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    There's a C32 selling for real cheap here. Would that make a good combo with the MC2500?
     

     

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  2. damacman

    damacman Blown and Injected Subscriber

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    Well sure!
     
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  3. eiraved

    eiraved AK Subscriber Subscriber

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    It's only for the garage after all, LOL!
     
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  4. motorstereo

    motorstereo AK Subscriber Subscriber

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    Congrats to you on getting the C32:thumbsup: Hopefully it's an easy fix and that should mate up very well with the 2500's.
     
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  5. tuffstuff1

    tuffstuff1 AK Subscriber Subscriber

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    My garage getting smaller. Congrats on the garage system. The MC-2500 are crazy powerful and make smaller speakers sing with clarity. Be careful though. It's esay to make them go poof! I need a C-32 too. The Yamaha C2-a has an incredible MC phono stage though. Sorry to say. IMG_1643[1].JPG
     
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  6. eiraved

    eiraved AK Subscriber Subscriber

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    Nice system! I see you have a pair of HT-1 speakers up front. I really like mine paired with the MC7150 in my main system. How do they sound with your MC2500?
    Was that rug placed in front so all who see this system can drop on their knees and humble themselves before it? ;)
     
    Last edited: Mar 30, 2018

     

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  7. eiraved

    eiraved AK Subscriber Subscriber

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    I began recap of the 045928 preamp boards shown in the OP. Unfortunately these PCBs don't take well to heat and one of the PCB soldering points broke free from a trace. Fortunately, the cap lead was more than long enough to bridge the gap and I soldered it directly to the next soldering point downstream. Not the perfect fix, but checked with my Fluke and continuity is perfect.
     
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  8. damacman

    damacman Blown and Injected Subscriber

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    OK . . . now we have three AKers with garage systems with a pair of MC2500s - how freakin' crazy is that?

    I feel left out . . .
     
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  9. eiraved

    eiraved AK Subscriber Subscriber

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    We're starting a trend here!
     
  10. eiraved

    eiraved AK Subscriber Subscriber

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    I'm been getting over the flu for the past week and haven't been able to do any real work on the amp. I figured I'd do the Rich Andrews mod for lowering the noise floor which involves relocating the overheat switch and re-routing the fan and overheat switch wiring. It's not difficult to do, although reusing the philips screws required the use of a 90 degree ratcheting screwdriver. Rich recommends replacing the philips screws for hex head screws, but this fancy little screwdriver eliminated the need for that.
     
    Last edited: Mar 30, 2018
  11. eiraved

    eiraved AK Subscriber Subscriber

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    Original wire routing:

    IMG_8736.JPG
     

     

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  12. eiraved

    eiraved AK Subscriber Subscriber

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    Modified wire routing and relocation of overheat switch.

    IMG_8740.JPG
     
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  13. eiraved

    eiraved AK Subscriber Subscriber

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    Fancy screwdriver used:

    IMG_8741.JPG
     
  14. damacman

    damacman Blown and Injected Subscriber

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    I gots one of those! Rich just up and disappeared one day ... yet another with a pair of MC2500s. That makes FIVE here that I know of - you three, him, and @paulvo ...
     
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  15. Velocityboat

    Velocityboat Super Member

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    I did it on the cheap with closed end wrench and screw driver tip. Wish I had that tool when I did it twice.
     
  16. eiraved

    eiraved AK Subscriber Subscriber

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    I just received the VTL5C9 and VTL5C3 LDRs, which will replace the original CLM6500 and CLM6000 LDRs. Funny, but just today I read on a MC2255 restoration thread where the VTL5C9 can be used in place of both the CLM6500 and CLM6000. :mad:
    Does anyone know if there are any issues with using the VTL5C3 as a replacement for the CLM6000? I've already purchased 4 of them to replace the originals. If no real issues, then I'll use them.
     

     

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  17. c_dk

    c_dk Addicted Member

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    The 6000 and 6500 have a few differences......mainly the off resistance.

    I have seen lots of 6500s fail in the muting mode but have never seen a 6000 fail in the PG circuit. I am sure they must but I just have never seen a PG circuit not work on the bench.

    I do believe the clm6000s do fail in the SoundTechnology 1701 I use and at some point will be testing replacement devices in it.

    I do believe in some C34s I have seen the 6500 replacement used for both muting and PG in the headphone amp circuit.
     
  18. eiraved

    eiraved AK Subscriber Subscriber

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    Thanks for your insightful response c_dk! According to the schematic, there should be a CLM6000 in place on the preamp input board 045928 for amps with s/n CS1001 - CS2849. This amp came with a CLM6500 installed instead, but someone had been inside this amp before me. Since there's not a big history of CLM6000 failure on McIntosh equipment, I'm just going to follow the schematic.
     
  19. eiraved

    eiraved AK Subscriber Subscriber

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    I removed the Mode/Input PCB, disassembled the switches, cleaned the dirty contacts and reassembled them. I also replaced the capacitors as well.

    IMG_8745.JPG IMG_8744.JPG IMG_8742.JPG IMG_8743.JPG
     
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  20. eiraved

    eiraved AK Subscriber Subscriber

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    Preamp input PCB recap and LDR replacement is complete, ready to reinstall! I cleaned off the old flux from the solder to prevent any conductivity issues. I also reflowed the molex solder joints, and removed both IC's, applied DeoxIT to the legs and carefully worked them in and out of the board several times to remove any oxidation which may have been present.

    IMG_8746.JPG
     
    Last edited: Apr 7, 2018
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