Yamaha M-80 outputs ?

I recently got a Yamaha M-80 amplifier in need of repair.I have ordered the service manual.I know a few here Have repaired these before.A quick check reveals one channel is blown.So where do I get outputs that I can be sure are not fakes.Lets see ,just from memory the drivers are 2sc2773 and 2sa1169 ,outputs 2sa1216,2sc2922.Also is there any advice from someone who has worked on one of these before as to other things to watch for?Its in excellent cosmetic condition.Has 1 scratch on top and thats about it.Heard alot of good things about this amp,and I am anxious to try it with my Quantum 3s.Thanks

Roger, get the phone number from their web site www.bdent.com and call them, As far as genuine and subs they have never steered me wrong.

Rob

The M-80 is one of the more complex repairs to do. In addition to replacing the outputs with matched groups, you need to check literally scores of driver transistors, pre-driver transistors, steering diodes, bias transistors and miscellaneous resistors. If you miss one part that was weakened or killed from the prior failure, expect the amplifier to blow out again.

As much as possible, try to use the exact Japanese part numbers. Otherwise, you may have stability (oscillation) problems.

Fred Longworth

Thanks guys.

Fred are you recommending a whole sale diode and transistor replacement?Would this be money well spent.Outputs look to be expensive (lots of them).I want it to kick AXX the first time around.Right now it blows 1 10amp fuse on power up .Just a quick multimeter check shows at least 1 output and 1 driver are shorted.

The M80 typically requires over 20 parts when the amp shorts. 4 outputs, 2 drivers, 2 pre drivers, 4 zeners, 2 protect transistors, emitter resistors, and other fuse resistors, and a bias transistor. It is not DIY.

Undaunted

I got the service manual ,and have done some familiarizing myself to the layout.One odd thing I noticed is some transistors #117 118 113 114 all have a resistor actually tied to 1 leg and then soldered into the pcb.2 legs are soldered straight to the board as usual,the 3rd is folded up the front and has a resistor soldered to it then to the board,(both channels are like this )Not on the schematic though.Looks like it may be easier to remove the whole main output section to make it easier to check everything.I am not a novice ,but I am not a seasoned pro either.I believe I can get her going with patience and time.Parts are available,B-dent,Consolidated elect,and Acme Electonics ,and amps lab have what I need .Diodes and zeners look pretty standard.It will have to be a component by component check ,match it to good right channel and give it ago.I only see 1 burnt resistor ,r134 ,so it may not be too bad.Wish me luck and maybe I can post some pics as I go.

The sound quality of the M-80 is worth the effort.

She lives.

I built me a light bulb variac and fired her up.25,40,60 ,100 watt bulbs.All seemed well.I checked voltages on left to right channels under the 60 and 100 watt bulbs and found them the same.So i ventured to full powerup.Went off without a hitch ,set the bias and let her cook awhile.Hooked up my cheap test speakers and all is well.I replaced all the outputs in the left channel as well as drivers and predrivers.The bias transistors and 4 zeners and 2 diodes,and a couple resistors.All in all about 24 parts.The outputs I got from b-dent which were very helpful.I will post some pics soon.I will hook it up to one set of my Quantum 3s for a test run this weekend I hope.

Good, I always find the guys at BDent to be very helpful that's why I steer folks their way. Now I just pick up the phone, give them my customer number and it's "Hi, Robert, what cane we do for you today?" I get everything in two days.

Rob

Nice going Roger! The M-80 is sweet. It was my first amp (bought new) and it's still powering my main system.

Give me hope I can get mine going.

Congrats Roger...What type of trannies were recommended to you, NTE?? Japanese replacements..just curious.

Original.

Sankens.The 2sa1169 is replaced by 2sa1494 and its complimentary 2sc3858 5 bucks ea from bdent.com Nice high power audio outputs.They had nearly every piece I needed .Still do not know why the drivers had a 47 ohm resistor tied to collector of each one.I put them back like original ,both channels are the same .Works great.

Far out and good job.
I'm listening to my M-80 playing Black Sabbath right now.

Unbelievable.

I hooked the m-80 up to a set of Quantum 3s.I am using the Yamaha CR-3020 as a preamp with it. This is a very powerful revealing amplifier.Drives the big Quantums to unbeliavbly loud levels and never breaks a sweat.I have not been able to get the protection to trip on it yet.It will not outdo my brystons but they are in a league by themselves at 500 watt mono blocks.It still outdoes any other amp I have had at the same output per channel.Has that clean Yamaha sound with brute power to control the watkins woofers with ease.Another fine example of Yamaha Technology.