Yamaha M2

Discussion in 'Yamaha' started by jdsalinger, Feb 10, 2018.

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  1. jdsalinger

    jdsalinger Well-Known Member

    Messages:
    715
    Location:
    KCMO
    I just landed an M2 and C2a. Just what I was looking for to drive my L1290's. The M2 is dusty and has evidence of being dropped (bottom panel has a warp from the inside out :eek:). Removing the top panel...sure seemed like it was the first time that had ever been done. :thumbsup:

    I had to replace bulbs and the power switch is failed closed, so I need to use a power strip temporarily.
    Sounds like those are very common issues though. I found a thread with a replacement switch from Digikey when the time comes. https://www.digikey.com/products/en?mpart=P197EESB&v=141 or I may be able to find some correct Alps switches.

    I did all of the adjustments from the service manual (idle current, power voltage, dc balance) except for level indicator.

    Deoxited the pots (hard to reach, but it's done now) and the power and speaker switches. Blew dust from the boards as best I could with keyboard cleaning duster spray. I was going to re-grease the power transistors, but I was only able to reach the transistor covers on one set. I think this is a job that will need to wait until I'm ready to disassemble for a recap. But, I was able to check some of the grease that had squeezed out of one transistor and it was still pretty fluid, not dry. I think we're OK.

    I'm a bit concerned about the OBS Toshiba power transistors. If anyone would be so kind as to share a source for authentic ones, I'd sure appreciate it. ( although I realize that's like asking a fisherman where the honey hole is ) Nothing wrong now, but I'd like to stock up before the NOS runs out.

    Also, I haven't been able to find any PN for the 22,000uF filter caps. Caps seem to be OK. During voltage tests, the caps dropped about a volt per second after shutdown. Seems OK to me, but I don't know for sure.

    Any other PM I should do to this beast?

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  2. OMGCat!

    OMGCat! AK Subscriber Subscriber

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    2,166
    Location:
    San Diego, CA
    This is a good link
    http://marantzhallo-fi.blogspot.com/2016/12/jims-yamaha-m-2-power-amplifier-ns.html

    Really it's up to you how far you want to go. It's approaching 40 years old so a full restore wouldn't be a bad idea but they seem to be bulletproof so just touching up the various adjustments might be all you need.

    The M2 is on my list of stuff I want to get eventually. I've got a C2a to pair it to and everything.
     
  3. avionic

    avionic " Black Knights " Subscriber

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    Last edited: Feb 10, 2018
  4. stoutblock

    stoutblock If it sounds good, it is good... Subscriber

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    I ran a C-2 with an M-2 and L1290s for a while. A most excellent combination!
     
  5. 808_state

    808_state Active Member

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    331
    That power switch may unstick itself. My B-5's switch got stuck and then unstuck itself a couple months later.
     
  6. jdsalinger

    jdsalinger Well-Known Member

    Messages:
    715
    Location:
    KCMO
    I have to say that the switch lamp colors are ugly....but I like 'em. They have that "dawn of the PC age" look.
    I was just a pup in kindergarten when this thing was built, I guess, for me, it's a connection to a simpler time before PC's, internet and cell phones.

    Odd that Yamaha chose a tiny red LED for the C2a and the jumbo lamp-lit buttons for the C4.

    Impressive sound stage that it has, and most likely it is due in large part to the C2a, but listening to some jazz (MJQ I think) and I could sense that the drums were behind the bass. Never really experienced that with SS before.

    Thanks Avionic.
     

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