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Yamaha EM-80 troubleshooting Single-Channel Preamps
Old 28th July 2014
  #1
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Yamaha EM-80 troubleshooting

Just scored this little guy at a garage sale for next to nothing. The exterior seems to in perfect condition so I was surprised when I got home and plugged a mic in and got no output to the headphones.

I set the input selector to mic as the manual indicated. The power light turns on but not sure anyone is home. Possible issues?
Old 28th July 2014
  #2
It's a low-power PA mixer. Have you tried the L & R speaker outputs? If the pilot lamp lights, the fuse is probably OK. Have you checked to be sure the line voltage selector is set for your local line voltage?

If you get nothing from the phones and speaker outputs, it may have a damaged power amplifier. Try connecting the "Monitor Out" jacks or the "Rec Out" to the line inputs of a mixer or audio interface to check for signals. If there is no output on the "Monitor" or "Rec" outs and no output on the phones of power amp channels the mixer may have a blown power supply. If the Monitor and/or the Rec outs work, it may just have a blown power amp, and still be usable as a line mixer.

It's a very simple little PA mixer. The owner's manual is available here.
Old 28th July 2014
  #3
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johnnyv's Avatar
Oh my goodness, That is classified as Vintage I would think. I actually know someone who still gigs with one and I always give him a hard time about it. They are not very good sounding and most likely that one is just dead in the water. Even if it was working every pot will make scratchy noises etc.
It was worth a shot and I my self would have taken a chance for $10.
Sell it on Ebay as is for $20 Ha ha...

Old 28th July 2014
  #4
Quote:
Originally Posted by johnnyv View Post
Oh my goodness, That is classified as Vintage I would think....
I've always wondered what the definition of the "dividing line" between "Old Junk" and "Vintage" is.
I have a basement full of what I like to consider as "Vintage Gear", but that's certainly not what my wife calls it.
Old 28th July 2014
  #5
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Lotus 7, thanks! The monitor out it working well and it has a pretty snappy little reverb. Glad I snatched this little guy up. Question, worth getting the power amp looked into? I'm assuming it's a pretty simple piece of gear to repair.
Old 28th July 2014
  #6
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Oh and Johnnyv, thought you might get a kick out this: Yamaha EM-80 troubleshootingYamaha Em 80 4 Channel Mixer Power Amp with Spring Reverb EQ Vintage Unit | eBay

Someone is trying to get a lot more than $20, haha.. This guys is price is twice everyone else's btw.
Old 28th July 2014
  #7
Quote:
Originally Posted by Kevincompton View Post
Lotus 7, thanks! The monitor out it working well and it has a pretty snappy little reverb. Glad I snatched this little guy up. Question, worth getting the power amp looked into? I'm assuming it's a pretty simple piece of gear to repair.
You might try panning an input to center and and checking each power amp output channel separately. If both power amp outputs are dead (probably the case since you weren't getting anything on the headphone output) it may be a power supply fault. If just one side is out, it's more likely a defective part on that channel. Unless you have a schematic and circuit tracing skills, it's probably not worth opening it up and trying to fix it. Certainly not worth the time a qualified tech would take to troubleshoot and repair it.

There's not a lot you can learn by simply looking at it inside unless you find some leaking capacitors and/or burned resistors/diodes/ transistors. If it was an old RCA OP6 mic pre or a vintage LA2 compressor, there would be value in investing whatever amount of effort and components it would take to fix it.

Unfortunately a Yamaha EM80 is not quite in the LA2 class.

I'd consider it a nice little dynamic mic or line mixer with a spring reverb and forget the power amp exists.
Old 28th July 2014
  #8
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Ya I'm on board with that, I just wanted it for a line mixer anyways. The pots are a little dirty so I'm gonna get a quote on getting it 100% but odds are it will be as is since i got it for a steal anyways.
Old 24th April 2016
  #9
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Output devices

Yamaha has a long history of making their own IC chips that they use in their gear. I do know that mixer speaker outs use a monolithic output chip. I'm not sure if the hp gets its signal from the sp-out but it could be the case that the sp-out IC is dead. Check the line outs to see if you have signal there.
Old 6th October 2016
  #10
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Hey guys, I'm having a weird issue, I first tried inputting a stereo test signal into all the line inputs from my computer and computer monitor, both set to output in stereo, and It outputs in mono. When I tried it from my phone, it only outputs the left channel. Any ideas?
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