Any guess what is wrong with my amp??? (1 Viewer)

[SteveSpoon]

Hello:

I have a Yamaha M-80 amp (250 watts into 8 ohms, 50 pound amp)which I use for driving my main speakers in my antique collection of componenents. Other components are C-80 preamp, GE-60 equalizer, T-80 tuner, PX-3 turntable, Nak RX-505 cassette (I know, I know, but I still like the old stuff!!) deck, dbx 222 noise cancelling thing a ma jiggy (actually works really good!!), Panasonic DVD RV-65, DSP-E492 pro logic thingy, and a JVC Super VHS VCR......speakers are JBL CF-120's, small AR surround speakers, and a BIC (the big one!!) center channel speaker. Have a Dayton 12" DVC still in the box along with a 250 watt Parts Express plate amp awaiting assembly, but for now, getting by with a very cool Jensen 12" 100 watt noise maker sub.

Anyway, after all of that, the problem with my amp is that the right channel doesn't get as loud as the left channel. I've switched the RCA patch cords going into the amp with no effect. The problem definately lies with the right channel.......it is only about 60-70% as loud as the left channel and the red LED output meters on the amp support what my ears are telling me. No distortion, just not as loud as the left side.

I bought this amp brand new way back in 1985 when I was stationed over in Germany. Never in a smoking environment and always handled with kid gloves. Has been a great amp. I have friends that say "Steve, get rid of all that crap and get a high-end receiver"...... I just can't seem to part with my "dinosaur" stuff.....reminds me too much of when I was young!!

Any ideas what's wrong with my amp is appreciated. Thanks.

Steve

 

[DanaA]

Does the amp have level controls (maybe in the back) for each channel? Sorry, if that's not it, but it's the only guess I'm able to make.

 

[SteveSpoon]

Here's what it looks like. Hope the link works.

http://www.retroaudio.ru/others/ampl...a%20M-80.shtml

Steve

 

[DanaA]

Didn't notice any level controls on the back. Can't see what the two knobs are for on the front right. Sorry, I'm stumped. Any of the experts around???

 

[SteveSpoon]

The two knobs on the front will adjust the individual output to the speakers. Both work fine and are turned all the way to the right.

Guess it's off to the Yamaha shop and see what he can come up with.

Steve

 

[Robert_Gaither]

I'd recommend checking the caps (one might of sprung a leak), where the fuse seats (pull these out and clean the contact points), and check any parts of the amps interior for any kind of scorching. Of course this should go without saying but unplug the amp first (playing at very low volume, this will help discharge the caps).

 

[Chu Gai]

With your setup, you need to confirm that is in fact the amp since you've got a bunch of components in the signal chain. Simplify your setup as much as possible. Remove the equalizer, the DBX, and maybe just use the preamp and tuner or preamp and DVD player. Listen again. If its the same to your ears, you need to confirm what your ears are hearing. I'd consider running a test tone (or even FM noise) and measuring the voltages going to both speakers with a multimeter. If they're different it's MAY be issue with the amp. If they're the same it's either the speaker on that side or something to do with your room and how you've place your speakers.
Got to do a little more detective work on your part.
BTW, nice stuff! Specs on that Yamaha put a ton of equipment that's out there that goes for up in the mid to high thousands to shame. But being as I'm a generous person, I'll take it off your hands for $50, you pay the shipping

 

[Voltmeter]

SteveSpoon:
I might be able to help you with this. I had the same problem once. There is a balance control on the C80 preamp, it is located on the bottom of the unit in the front directly under the volume/flatness control.
I hate to admit it but I did not know this existed until I had the problem. The balance control is very hard to notice.
I hope this works for you. I still have my M80 and it is still top of the line compared with other amps today.

See Ya,
Voltmeter

 

[Mark Romero]

I have an M80 and an M85 and they will stay with me forever.

 

[avwemet]

I am just posting this in response to Steve original post,and i'm sure he had that issue taken care of long ago.Anyways,knowledge is always good.To begin with,Steve should have done a process of elimination first to find out the source fo the problem.It could be his EQ,preamp,amp or RC cables most likely.All three units has some sort of balance control,make sure they are all set at 12 o'clock(the EQ especially can carry up to two different bal control,depending on the unit,turn knop and a push knob)If that had fail,then i would investigate the RC cables,maybe a bad one is in the bunch,defective on one side.I would bypass most of the stuff and start with CD,into Preamp into Amp and see what happens there,if the problem still exist.I just save alot of time.