View Full Version : Yamaha M85 and M80 - any difference??


lixaudio
10-27-2009, 05:39 AM
This one for Yamaha experts.
I'm trying to fix Yamaha M85 power amp and only got the service manual for M80. Whatever I check is there. Are there any differences between them?

LIX

dkelley
10-28-2009, 12:59 PM
about 5 I'd say

dkelley
10-28-2009, 01:00 PM
but seriously folks...

hang on I'm looking for a c-85 service manual. might have one, might not, worth looking...

dkelley
10-28-2009, 01:02 PM
dang, nope, same as you, c-85 manual, c-80 service manual, never the twain shall meet.

although one would think they'd be very similar...

audiozaz
10-28-2009, 01:28 PM
I know that the M-40 and M-45 are in order a year appart, and the M-45 is 5W stronger. The M-40 also does not have the LED power meters. Other than that, pretty similar machines.

That could be the case with the M-80/M-85. A small power difference only I'd say and a year appart. But they both have the power meters.

az

PacificStereo
10-29-2009, 10:44 AM
There's one huge difference. The M-80s were legend for living up to their name and blowing up. The M-85 is vastly more stable.

audiozaz
10-29-2009, 10:45 AM
There's one huge difference. The M-80s were legend for living up to their name and blowing up. The M-85 is vastly more stable.

Hehe, that's good to know!

az

dkelley
10-29-2009, 12:16 PM
There's one huge difference. The M-80s were legend for living up to their name and blowing up. The M-85 is vastly more stable.

I didn't know that, classic quote there, LoL :-)

whoaru99
10-29-2009, 12:24 PM
There's one huge difference. The M-80s were legend for living up to their name and blowing up. The M-85 is vastly more stable.

Huh? Must be a California thing, you and SoCal Sam.... ;)

My two 80s have been flawless since they left the factory sometime back in the early or mid-80s.

GlobalWarming
10-29-2009, 01:18 PM
Huh? Must be a California thing, you and SoCal Sam.... ;)

My two 80s have been flawless since they left the factory sometime back in the early or mid-80s.

:lmao:

I do know about SoCalSam dislike for Yamaha but PacificStereo is new to me; thank you for enlightening me:D

brutal
10-29-2009, 03:54 PM
M-85 has a button to turn off the meter display.

[edit for accuracy] C-80 has "DAD and AUX" where the C-85 has "CD and VIDEO" and flat black v.s. shiny glass over the selection indicators, but I've other "runs" of the C-80 that has "CD and VIDEO" and glass, so go figure. They're updated versions of the same gear.

Internally, they're pretty much identical.

M-80's are older and therefore potentially capable of (though not guaranteed) a higher failure rate if they haven't been serviced. The glue holding the two 1000uf 100V caps on the main board corrodes everything around it and if not attended to, will cause havoc. I have FOUR and only one has ever had any issues and that (slightly weak channel) was corrected by replacing ONE little squiffy cap in the path of destruction of that nasty glue.

Do we really have to have this M-80/overheating Yamaha discussion weekly? Sheesh.

whoaru99
10-29-2009, 05:25 PM
I think it is destined to be for eternity. :sigh:

lixaudio
10-29-2009, 06:17 PM
Ok guys, thanks.
I was only asking about differences, it wasn't meant to be about overheating and other problems and yes, the M85 on my desk had serious problems because of the glue under the two condensers - corroded everything, lost the ground too. I found only few different resistors values so far and probably strangely added 47R on some transistors. Now I'm waiting new 2SA1169 to come, until then I'll work on some other older pieces.

LIX

avionic
10-29-2009, 06:34 PM
Huh? Must be a California thing, you and SoCal Sam.... ;)

My two 80s have been flawless since they left the factory sometime back in the early or mid-80s.

:lmao::lurk:

Lastplace
10-29-2009, 08:13 PM
The glue holding the two 1000uf 100V caps on the main board corrodes everything around it and if not attended to, will cause havoc. I have FOUR and only one has ever had any issues and that (slightly weak channel) was corrected by replacing ONE little squiffy cap in the path of destruction of that nasty glue.


Could somebody please either give a location or post a picture of the two 1000uf 100V caps?

PacificStereo
10-30-2009, 12:27 PM
I think there's some confusion here... I don't hate Yamaha products at all- I was a factory tech for them, and most of our products were very good!

The M-85 is essentially an M-80 with all the service bulletins and changes applied- whoaru99, it's very possible that you have late-production M-80s, which would be fine.

My initial comment wasn't intended to ignite some new controversy- was more of just a passing thought.

lixaudio
10-30-2009, 02:12 PM
Thanks Pacific Stereo, M80 with changes applied, that would make sense.
For Lastplace and other courious - the two 1000uF condensers are the two in the centre of the main pcb. You can see the photo of the pcb before cleaning and without the two condensers.

LIX

elgato8905
10-30-2009, 02:18 PM
I think there's some confusion here... I don't hate Yamaha products at all- I was a factory tech for them, and most of our products were very good!

The M-85 is essentially an M-80 with all the service bulletins and changes applied- whoaru99, it's very possible that you have late-production M-80s, which would be fine.

My initial comment wasn't intended to ignite some new controversy- was more of just a passing thought.


Damn... That argument was put to bed quickly.:thmbsp:

brutal
10-30-2009, 02:21 PM
Yup, that's the culprit. One of those 220pf 6.3V caps right there was also the squiffy one that dropped one channel output about half. I replaced those also, a few zeners in that area and a couple of those 1/8w resistors and a 3.9K 2w(?) nearby. I also de-soldered the ground busbar there and polished it up, coated with lacquer and re-installed it. Sings like a champ now again.

brutal
10-30-2009, 02:22 PM
I think there's some confusion here... I don't hate Yamaha products at all- I was a factory tech for them, and most of our products were very good!

The M-85 is essentially an M-80 with all the service bulletins and changes applied- whoaru99, it's very possible that you have late-production M-80s, which would be fine.

My initial comment wasn't intended to ignite some new controversy- was more of just a passing thought.

What are said SB'? Curious minds want to know.

dkelley
10-30-2009, 02:32 PM
What are said SB'? Curious minds want to know.

I suspect it's stuff I've heard such as overheating with low impedance loads, failing caps, cold solder joints, arcing around certain components. all of which is likely very rare and not something that is m-80 specific (I've read of that with my m-70 and iwth other yammy gear from that period, but then I've read of that or worse with some carver gear and so on.... so it's not imho a reason to stay away from any of their gear).

that's assuming that I'm on the right track with the SB stuff guesses...

cheers,
Don

rushfan
10-30-2009, 03:14 PM
Do we really have to have this M-80/overheating Yamaha discussion weekly? Sheesh.

Maybe we could alternate HPM-100 bashing with M-80 bashing - a two week rotation, perhaps?

dkelley
10-30-2009, 03:36 PM
Maybe we could alternate HPM-100 bashing with M-80 bashing - a two week rotation, perhaps?

LoL

I didn't know it was so common a thread :-)

my m-70 hasn't overheated yet with lots of use over the past while. same with my c-70 (another person's c-series peramp does have an ongoing heat thread all it's own LoL).

PacificStereo
10-30-2009, 08:30 PM
It's been a very long time, guys. There were service bulletins that we distributed to authorized servicers, and then there was all the stuff that we knew about in the lab that no one else knew about (except Japan). I recall that there were a number of things we would do to M-80s that came into the lab for repair to improve stability, and I also recall that these changes propagated into the M-85.

What those changes were would probably have to be extracted by a licensed hypnotherapist. ("You are feeling very relaxed, Pacific. Very relaxed...")

dkelley
10-31-2009, 01:12 PM
It's been a very long time, guys.

....

What those changes were would probably have to be extracted by a licensed hypnotherapist. ("You are feeling very relaxed, Pacific. Very relaxed...")

LoL - I understand :-)

bhebbel
01-23-2011, 03:09 PM
While web surfing I stumbled onto Technical Bulletin No. 66H, 3/15/1986 for serial numbers below 2401. It recommmneds replacing five parts on the circuit board.

I'll publish it on the site but I have to credit John from analogalley.com for the bulliten. I have no relationship or affiliation with the guy. I just used a bunch of Search engines to see if I could find the mythical Bulletins. I picked up a M-80/C-80 on ebay for $200. the M-80 has one weak channel so I started looking for info to fix it. Apparently John used to own a audio repair business but he closed it because so much of the new gear is more or less disposable (according to John).

I don't know how many Tech Bulletins were published on M-80's but no one seems to have them unless Brutal, Avionics or Merrylander have a secret stash of documents.

I have a decent Yamaha-a/d/s collection and audiokarma has been a great info source. This may not be the Dead Sea Scrolls but if I can contribute something worthwhile, at least I can help someone else.

I suggest that this should be included in the Yamaha doc's page on the site.

bhebbel

Susurus
01-25-2011, 08:05 PM
I suggest that this should be included in the Yamaha doc's page on the site.

Yes, very cool. Along with your avatar of course... :yes:

reneborg
01-25-2011, 09:58 PM
Yes, very cool. Along with your avatar of course... :yes:

Seeing bhebbel's avatar after reading the Back Alley Pub post about how looking at boobs increases your life span makes me think the stars are aligned on this ...
:banana:

PacificStereo
01-26-2011, 10:34 AM
Wow, that's a nice find. Yep, that's one of them.

bhebbel
01-28-2011, 04:10 PM
No audio system is complete without a good pair of headphones. I do not have a pair of the over-the-ear model shown in the Avatar in my house. Those are very rare, very heavy and were highly modified by the original owner.

I did have a nice pair a few years ago but my ex-wife kept them as part of the divorce settlement. I told her "I paid for them dammit, I should be able to take them with me!" She told me "I'm not giving them back! Why don't you find another pair out on that audiokarma site!"

I sent out a few requests but my posts kept getting rejected by the moderators. I guess I was asking for to much so I'd be happy with something smaller-maybe some in-the-ear models.

If anyone out there could recommend a nice set, I'll check them out and see how well they fit. Listener fatigue is a HUGE factor with headphones so finding a pair that you want to keep for life can take you a long time before you are really happy again!

I suspect that audiokarma is primarily a male subscribership but if there are members of the other gender out there that think that I seem like a perfectly reasonable man with an interesting outlook on life, send me a message!:music:

I should warn you that I do like large speakers and I do think that they belong in the living room!

Back to the original subject-I'll keep poking around to see if I can find other tech bulletins. I think I jsut got lucky. I did ask Brutal if a comparision of the parts list and the schematics of the M-80 vs the M-85 would enable someone to make the uprgrades. He thought the differences were great enough that this might not work but I'll compare them over the weekend and give you my thoughts. I am not a technician nor will I pretend to know that much once the cover comes off so whatever I discover should be validated by folks like Brutal, Avionic, Pacific Stereo or Merrylander.

brutal
01-28-2011, 04:27 PM
No audio system is complete without a good pair of headphones. I do not have a pair of the over-the-ear model shown in the Avatar in my house. Those are very rare, very heavy and were highly modified by the original owner.

I did have a nice pair a few years ago but my ex-wife kept them as part of the divorce settlement. I told her "I paid for them dammit, I should be able to take them with me!" She told me "I'm not giving them back! Why don't you find another pair out on that audiokarma site!"

I sent out a few requests but my posts kept getting rejected by the moderators. I guess I was asking for to much so I'd be happy with something smaller-maybe some in-the-ear models.

If anyone out there could recommend a nice set, I'll check them out and see how well they fit. Listener fatigue is a HUGE factor with headphones so finding a pair that you want to keep for life can take you a long time before you are really happy again!

I suspect that audiokarma is primarily a male subscribership but if there are members of the other gender out there that think that I seem like a perfectly reasonable man with an interesting outlook on life, send me a message!:music:

I should warn you that I do like large speakers and I do think that they belong in the living room!

Back to the original subject-I'll keep poking around to see if I can find other tech bulletins. I think I jsut got lucky. I did ask Brutal if a comparision of the parts list and the schematics of the M-80 vs the M-85 would enable someone to make the uprgrades. He thought the differences were great enough that this might not work but I'll compare them over the weekend and give you my thoughts. I am not a technician nor will I pretend to know that much once the cover comes off so whatever I discover should be validated by folks like Brutal, Avionic, Pacific Stereo or Merrylander.

Well, couple things. I believe around these parts headphones are often referred to as "cans." :D

The other thing (cause I was taught you're not supposed to number your lists unless there's more than two things) is that the "upgrade" would also entail a button and circuitry(?) for the meter off switch on the M-85 (and now that I think of it, a new faceplate). I thought I was clear on that? Pacific Stereo has been pretty clear on this before, in that he recalls 3 SB mods that bring the M-80 up to M-85 "standards." Without that meter button though, it's still an M-80, just less prone to annihilate so many parts when an output goes short.

I suppose there is a thirdly sorta kinda thing. VERY much appreciate that SB mod being posted here and I plan to take my perfectly working M-80 under the knife to make the mods. If it ever does drop another output, this should save some upstream parts from releasing the magic blue smoke. I may even took a long hard look at the M-60 circuit to see if it also could use the mod, although someone more qualified than I - and nothing against anyone else here - but say the circuit guru ecluser, takes a look and makes a recommendation.