Latest recap and Upgrade amp - Yamaha M-70

Sorry to bring up an old thread...but when you recapped the board shown in the 1st couple of pics did you just recap the 3 there or did you also replace the 4 big ones beside them as well.

I'm replacing the 2 - 1000 mf 100v and 1 - 4700 mf 16v as well on my m-70 and wanted to see if you remember what you used specifically?

Did you replace the one on the power board as well? I forget the # on it off the top of my head...22 something :)

Thanks! And great work
 
brutal said:
Thanks,

1/4" I ordered a 12x12 piece a while back some place online and still have a bit left for two or three more amps depending on size.

Yes, I replaced all the 'lytic caps in the M-70 and the troublesome X2 power input safety caps as well.
Click to expand...

bhuskins said:
Sorry to bring up an old thread...but when you recapped the board shown in the 1st couple of pics did you just recap the 3 there or did you also replace the 4 big ones beside them as well.

I'm replacing the 2 - 1000 mf 100v and 1 - 4700 mf 16v as well on my m-70 and wanted to see if you remember what you used specifically?

Did you replace the one on the power board as well? I forget the # on it off the top of my head...22 something :)

Thanks! And great work
Click to expand...

I replaced all the caps, why would anyone do otherwise?

All the brown caps are Nichicon PM or PW. The gold ones were probably KW.
 
The reason I asked is that it looked like the 4 main caps (C801-C804) are original so I'm guessing you were able to get exact replacements on those?

These are the 18000 mf 80v x2 and 10000 mf 50v x2 ones
 
brutal said:
Time will tell as it breaks in. Bass seems a tad tighter and the damping more in control but that could simply be first impressions. I tried to give it some serious listening time before the recap, but time has a way of changing one's perceptions and it took a little while to finish it all up. Except for Yamaha's poor choice of binding posts, the build quality on this model is pretty great.
Click to expand...

brutal said:
The DSBG is on the front vertically mounted power circuit board where you can't easily spot the issue. You should also have the .22uf X2 cap on the Control 1 power supply board looked after.

I'm still trying to decide if the M-70 or M-80 has the worst binding posts ever... :D It's a shame as they are all such nice sounding amps.
Click to expand...

Nice work Brutal. IIRC, there was some type of legal issue for Japanese power amps and binding posts (specifically 5 way) for consumer gear. That's why all the yamaha and Pioneer (among others) have these goofy designs for "binding posts". However, on the pro gear like the P2200 and PC2002 series, you have the normal regular hex head 5-way binding posts.
 
bhuskins said:
The reason I asked is that it looked like the 4 main caps (C801-C804) are original so I'm guessing you were able to get exact replacements on those?

These are the 18000 mf 80v x2 and 10000 mf 50v x2 ones
Click to expand...

What part of "all" don't you understand? :naughty::bigok:

Panasonic THA caps were not known to be OEM. :D

No doubt, I got them from Digikey, but good luck finding them anymore. I think I still have one pair of 22,000uf 100V stashed away for an M-4 that needs to go under the knife.

Do not question the brutal! :nono:
 
mech986 said:
Nice work Brutal. IIRC, there was some type of legal issue for Japanese power amps and binding posts (specifically 5 way) for consumer gear. That's why all the yamaha and Pioneer (among others) have these goofy designs for "binding posts". However, on the pro gear like the P2200 and PC2002 series, you have the normal regular hex head 5-way binding posts.
Click to expand...

Seems odd considering there is other gear, most notably the MX-2000, MX-10000 that have real BP. :scratch2: I always thought it was more a consumer convenience/cheap ass to produce issue. :D
 
Hahaha...I've been schooled!

I recapped my m-70 today and now it's dead so it's time to recheck everything.

The only part I didn't make a note about was the .22mf 250v x2 cap...does that one matter which direction it goes in? Wasn't sure if there was a - and + or not??? Forgot to take that picture.

One advantage to living 10 min from mouser is getting parts quick :)
 
bhuskins said:
Hahaha...I've been schooled!

I recapped my m-70 today and now it's dead so it's time to recheck everything.

The only part I didn't make a note about was the .22mf 250v x2 cap...does that one matter which direction it goes in? Wasn't sure if there was a - and + or not??? Forgot to take that picture.

One advantage to living 10 min from mouser is getting parts quick :)
Click to expand...

Only polar electrolytic (and old tantalum) caps care about polarity. :thmbsp:

I put films in a common orientation for readability.
 
That's what I thought...can't figure out why my m-70 won't come back to life...no protection no nothing!
 
And no signal is reproduced at any volume? Just the consistently somewhat loud jig pitched whine/squeal
 
So that's what I checked this afternoon and I went back over everything. I got rid of the whining (except for a whining burp it makes when I turn it off.) It's actually dead silent...so silent that it makes no sound at all! Ugh! Relays work, both A & B outputs behave the same. No sound at all volumes. Meters work and it comes out of protection properly. No meter change though at increased volumes.

Anybody have any ideas what to check next?
 
Got the speaker switch in the "on" position with speak A or B selected?
Input attenuators adjusted for the least amount of attenuation?
 
Definitely tried both A and B outputs with speakers On and Off with the attenuators adjusted from all the way down and everywhere in between. Zero amount of sound in all scenarios (except for the burp of noise when I turn the unit off)

Anybody have any idea on what to check/test?
 
bhuskins said:
Definitely tried both A and B outputs with speakers On and Off with the attenuators adjusted from all the way down and everywhere in between. Zero amount of sound in all scenarios (except for the burp of noise when I turn the unit off)

Anybody have any idea on what to check/test?
Click to expand...

Check speaker relay contact continuity-speaker switch continuity--try alternate source input ie. preamp
Start a seperate thread for your amp!

Can you measure DC offset at the speaker binding posts?
 
brutal said:
It's Home Depot "Acrylic", the Lexan was too much but may have held up better.

:D All done with simple handtools and by hand. Six varying grades of sandpaper finishing with 1500 and plastic polish to get that beveled edge. Mostly did it that way because it chipped a tiny bit on the tablesaw without a proper plywood blade. Delrin used for the backing on both the BP and RCA connectors.

The half-dogbone cutout on the Vampire backing plate to clear the screws was the toughest part and didn't come out as well as I had hoped.
Click to expand...
Hi Brutal,

What is the stuff called or what area of home depot did you find the Acrylic? I wanted to ask if you just took out the old plate and just covered it with this nice piece? I have to figure out how to get binding posts off my Nikko Alpha II, I can turn them until they stop but I thought one can just keep turning them but they are not budging.

I am new to all of this and I am trying to find "how to get binding posts off an amplifier" but not luck. I was wondering if I can get the 'better' bigger diameter ones instead of the whimpy old version? I think there is space and when I saw this post I saw the nice work you did...wish I had the skill and know how.

I want to try to get an M70 a guy up here wants $500 CDN for one but I am not sure after I bought my Harman Kardon Citation 19 3 wks ago, I opened up the cover and found a smaller physical cap tied in parallel with the bigger can...so after finding out the new replacements were $265 bucks I could not believe what the cost of things are for vintage stuff...but I was told the rest of the parts if I so choose to replace are very little in cost...thank goodness!
 
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