Yamaha M-70 Thread

Discussion in 'Yamaha' started by Bratwurst7s, Jan 17, 2018.

  1. brutal

    brutal YamaHoarder

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    James,

    I've very much enjoyed following your meticulous, detailed, and thorough work and progress. However, I have to say your binding post alignment bugs the crap out of my OCD. ;)

    If it were me, I'd angle them all at 45*. Just saying...

    Cheers!
     
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  2. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Thanks OS441! I have some chrome M3 allen heads but opted for the look of the black oxide ones instead. Kinda silly really, who but one of us would worry about the optics of such a thing.

    MY OCD kept me awake half the night worrying about how to get the bases centered on my improvised spindle so that I didn't file them off-center. In the end the head of the M8 bolt is just large enough to fit in the base and a little jiggling as I tightened the nut made the base self-center because the head of the bold sits on the spot where the inside of the base starts to curve towards the side wall.

    Cheers,
    James
     
  3. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Thanks Brutal! I'll keep the angle thing in mind, and thought about angling all of them but having the A posts vertical is easier for my aging eyes. :biggrin:

    Cheers,
    James
     
  4. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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  5. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Haha, l thought l had OCD problems but l think you guys may have it worse. I like the speaker A binding posts all sitting vertically, easy to access from the top and no doubt the most often used.

    Now, later model Yamaha multi channel receivers they are a PITA when it comes to their factory binding post access.
    [​IMG]
     
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  6. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Yep. My RX-V3900 requires patience. Luckily I don't change things in that system very often.

    Cheers,
    James
     

     

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  7. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    On the meter panel I used Wima MKS2 63v for everything except C511 & C512, 33µF/16v where I used Panasonic FC 35v. Other than a couple with fairly high ESR the old caps all checked fairly close to nominal. C513 took me a little time to find. It's hiding under the lower edge of the right meter block but luckily wasn't hard to change. The board has been re-flowed, cleaned, inspected and re-installed now.

    I didn't change the 4 mylar caps for the simple reason that I missed them and didn't order any replacements. I'll order some and change them when I do the pots.

    Because I'm going to have to go back in and set the ZDR pots after I get a distortion meter I elected to wait on replacing the front meter trim pots. It's not hard to get the panel out and I don't want to have to do the full power test more than once.

    DSC05278.jpg DSC05283.jpg

    Cheers,
    James
     
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  8. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    DSC05284.jpg DSC05286.jpg DSC05289.jpg

    After de-soldering the old light bulbs I ran the wires to my adapter blocks. I drilled 1.5mm holes and passed all of the wires through the holes so that some of the insulation went through. After bending the wires this makes a fair amount of strain relief. Cable ties and a piece of shrink-wrap completed that job. The original wires were not shortened.

    Cheers,
    James
     
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  9. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    DSC05289.jpg

    The lights are now installed and the base plate also. I'm getting dangerously close to turning this thing on...

    DSC05291.jpg

    Cheers,
    James
     
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  10. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    So I got everything ready and puckered up everything that could be and then got serious.

    With the amp on the variac I slowly turned it up and it came alive somewhere around 120v. The meter backlight looks great with the LEDs, and here is a shot of how the meter backlight LED wiring looks...

    DSC05294.jpg DSC05295.jpg DSC05300.jpg

    And one thing that I forgot to mention yesterday. I decided to swap the low power section filter caps back to the 12000µF KMH's. The high power section I left with the 18000µF for now.

    Cheers,
    James
     
    Last edited: Apr 15, 2018
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  11. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Now the SM calls for setting the dc offset before adjusting idle current but out of concern I had the 2 Flukes on the idle current test points for the first power up. I set them with the variac at 220v and then thought about that for a little bit. The mains here actually run at 230v and sometimes climb up to around 236v at night. So I ran the variac up to 230v and re-set the idle current there.

    Setting the dc offset was tricky. Even with the 4 turn pots that I installed the best that I could do was to get them so that they wander from +2mV to -2mv. I'd hate to try to set these things with single turn pots.

    DSC05302.jpg DSC05304.jpg DSC05306.jpg

    Cheers,
    James
     
    Last edited: Apr 15, 2018
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  12. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    So today is a good day. Victory day. After closing it up I took the amp out front.

    After just over 20 years of daily faithful service I took my AX-1090 out of the system. Kinda sad in a way actually. But it's time to move up a step.

    After hooking it up and turning on the system I turned up the CX-1 with no unput to what would be police visit levels to listen for noise. Now I did not deoxit the switches or pots because I wanted to hear how things sound first. Dead silence. No noise at all, not even the tiniest bit. With the case closed and in place the power switch doesn't look so white, more the cream color of the boot. It actually looks better in person than the photos show.

    The 1st cd played was Little River Bands' first effort. First impression, better imaging, another step better clarity, tighter bass. Looks like I have a working power amp. ;)

    DSC05308.jpg DSC05309.jpg

    Being Sunday I was nice and didn't turn it up past peaking at 2 watts. And that is actually pretty room filling. At least I know now that at least half of the meter LEDs are working.

    I think that I'm going to listen to some more music now.

    Cheers,
    James
     
  13. brutal

    brutal YamaHoarder

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    I have an RX-V3800. Still chuggin along after many years in a tight cabinet. However, I do run outboard amps for the main L/R front pair (JBL 250Ti).
     
  14. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Sounds like you have had a win, great work :thumbsup:. Those meter LED's do look great, nice hue and very evenly lit. +1 on the RX-V3900, l have one here also.

    That AX-1090 that the M-70 displaced would be no slouch either l am thinking? What speakers are you running there?
     
  15. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Afaik there isn't much difference between the 3800 and 3900. Does the 3800 have network capability? In any case they are some pretty darn good amps. I tried mine for a short while with 2-channel but it doesn't image as well as the AX-1090 did. So it runs dedicated HT only.

    Cheers,
    James
     
  16. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Thank you very much, I'm pretty happy at the moment, that's for sure. There was a point there in the middle where I was starting to worry but somehow managed to figure it out. The meter lights turned out great, the protection light is just right bet the power button is really just a bit too white/bright. I'm pretty certain that in the end I'll swap in some of the LEDS that Avionic posted about. Or something similar at least.

    The AX-1090 is a very good sounding integrated and has a pretty respectical amount of power for an integrated. But it never imaged as good as the C-50/M-50 that it replaced and for 20 years I've been wanting to get back to separates. Hooking the CX-1 to the power section of the 1090 made a world of difference. Now I'm very happy to have both feet back where I want them.

    Still, it was an odd moment when I pulled the AX-1090 from the system. For 242 months it has been doing it's duty faithfully and reliably nearly every single day. Soon it will have it's own thread when I recap it.

    The speakers are Speakerlab S7's that I bought new in 1993. They have been my main speakers ever since although they have been pretty well modded now.
    http://www.audiokarma.org/forums/index.php?threads/speakerlab-s7s-rebuild.545406/
    They are speakers that I will never part with until they put me in my own cabinet.

    Cheers,
    James
     

     

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  17. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    So what's left to do?

    The power light. that needs to be improved.
    I still have to replace the ZDR and meter trim-pots and do a full power adjustment.
    I don't believe that I'll change the 18000µF caps back to 22000µF. Not because I don't want to but I am worried about their traces.
    The case is in very nice condition optically but there is some tape gum residue on the right side, that has to be removed.
    2 of the top cover screws are messed up from someone that didn't really know how to use a screw driver, it would be nice to someday find replacements for them.
    I will make a master list of at least the caps sometime in the near future and will post it for AK member use.


    Oh. And I have a confession to make. It's only been 24 hours since the M-70 has been running again and I've already been unfaithful to her.
    Yes, it's true.
    You see, today I just paid for an MX-1.

    Cheers,
    James
     
  18. brutal

    brutal YamaHoarder

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    Limited network capability, old DNLA support.

    I prefer to use my Squezebox touch, or I can feed through my Oppo if needed.
     
  19. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Fair enough. I ended up using some orange automotive indicator globe paint to make the M-50 match the C-50, now all good.

    Nice to hear you now have the setup you have been missing since letting go of the M-50, C-50 combo.

    Sounds like another detailed and interesting thread on the horizon.

    Very nice speakers and your thread was an interesting read.

    Ooh she may get jealous, that MX-1 should be a real beast l would imagine. Bet you cannot wait to have a look at the innards of that one.
     
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  20. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    So in addition to LRB I've listened to:

    Mark Knopfler, Golden Heart. (First time that I've listened to this, I like it a lot.
    Chris Rea, Road To Hell.
    Grateful Dead, Working Man's Dead.
    Stephen Stills, Stephen Stills.
    Al Stewart, Past, Present and Future.

    Soundstage is wider, taller and deeper. Clarity is to kill for. With sound level peaking at an indicated 6w that's probably as loud as I want to get with the exception of Friday's. Of course I have 4 ohm speakers so the actual draw is higher than indicated.

    Cheers,
    James
     

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