Yamaha EMX660 Schematic needed

[bnwitt]

I have a Yamaha EMX660 powered mixer in for repair. Channel 5 has signal loss at the line level 1 and 2 jacks but good strong signal from the mic jack. A schematic would really be helpful in troubleshooting the problem. Do any of you fine fellows (or ladies) know where I might get my hands on one?
Thanks,
Barry

[oc disorder]

I was looking a while ago for a similar model.
In Aust Yamaha farm out their manuals to a 3rd party that hire out paper manuals!
I had to buy one from the UK "Mauritron Technical Services ".
Relatively quick download although it cost me $21.18 AUD !
There is a Yamaha EMX3000_E at

www.eserviceinfo.com/downloadsm/25001/Yamaha_EXM3000.html

but thats the only free one I could find.

[Enzo]

Send me an email, Barry, it is a 6MB file

Are you sure it is broken? The 1/4" jacks are not all the same.

The XLR mic ins are all -50dB.
Ch1-4 line ins are -40dB. Characterized as HiZ mic ins.
(Ch 1-4 look to have a 30dB pad that switches in as well to use them as line ins.)
Ch5 line in is -10dB line in.
CH6 line ins are -30dB, characterised as instrument ins.

Aux in is also -10dB.

Of the row of 1/4" jacks, then Ch5 is normally lower gain than the others. And Ch6 should have slightly less gain than 1-4. DOn't assume all the 1/4 jacks are the same, they aren't.

So does the Ch5 5 line in sound about like the Aux in? If so, it is working.

[bnwitt]

Originally Posted by Enzo

Send me an email, Barry, it is a 6MB file

Are you sure it is broken? The 1/4" jacks are not all the same.

The XLR mic ins are all -50dB.
Ch1-4 line ins are -40dB. Characterized as HiZ mic ins.
(Ch 1-4 look to have a 30dB pad that switches in as well to use them as line ins.)
Ch5 line in is -10dB line in.
CH6 line ins are -30dB, characterised as instrument ins.

Aux in is also -10dB.

Of the row of 1/4" jacks, then Ch5 is normally lower gain than the others. And Ch6 should have slightly less gain than 1-4. DOn't assume all the 1/4 jacks are the same, they aren't.

So does the Ch5 5 line in sound about like the Aux in? If so, it is working.

Enzo,
Thanks for the info. I purchased the schematic online and realize now that input 5 and 6 are different dB's as you posted. I can't believe they don't notate that on the panel. There is nothing wrong with this mixer. The user complained about widely varying signal levels across all channels and loud hum in the output. Looks like a trip to the church will be needed to straigthen out his problems as they are not with the mixer. He also had the phantom power switched on but has no phantom power mics. That may be part of his noise issue.

O C Disorder, thanks for the response.
Barry

[Enzo]

Well, the dB levels are not on the panel, but in fairness it does say Hi Z on the mic channels, Line in on 5 and Instrument on 6. And then there is always the owners manual...


It is frustrating when you troubleshoot non-existant problems.

I recall a Yamaha 4 channel cassette recorder that only recorded channels 1,2. SO I looked at channels 3,4 to see what needed to happen for record, went back to that, followed on back to what controlled that, then on to this and that other things, and ultimately I came out the other end to a sensor on the deck. It turned out that it only recorded on 3,4 when a reflective sticker was placed on the cassette itself to trigger that mode.

I had troubleshot the problem completely through the deck and out the other end.

The junior tech I was assisting was all pissed off, but I put it to him that we had just validated out troubleshooting technique. We hadn't done any unecessary parts replacements or anything, we simply went stage to stage troubleshooting.

[bnwitt]

Originally Posted by Enzo

Well, the dB levels are not on the panel, but in fairness it does say Hi Z on the mic channels, Line in on 5 and Instrument on 6. And then there is always the owners manual...

Well, I didn't have the manual but you've got a point on the line in and instrument notations. I glossed over that. I fell for the "This thang is screwed up!" pitch from the customer and didn't listen to my inner voice.

[Enzo]

I have this stack of Yamaha service doc disks. The more recent ones have a contents sheet on the jewel case, but the prior years just had the disk, so you had to play the disk to see its contents. My neighbor/landlord came in a few days ago needing docs on an EMX something, and it just happened to be listed on the back of the first disk I picked up. Thought I was pretty lucky. Now you ask for this model, and it is not on the printed ones, but it was on the first disk I picked up to check. MY karma must be good this week.

I have now started to scan my disks, and making a content sheet for each, so I don;t have to hunt each time.

[bnwitt]

man would I love to have copies of all the discs you've got!

[Enzo]

Oh dear...

I have three cheap bookshelves - the kind you assemble, and are about 6 feet tall. And they hold most of my paper schematics. I have filing cabinets full of old MArantz, Sony, Pioneer, etc stereo stuff from the 70s-80s out in the warehouse too. I did inventory of them a while back. It was a large job. But I do now have a listing. Certain brands I just wrote "many" on the listing. Yamaha was one, because there are SOOOO many models. Fender was another. SLM was one, but I have sicne inventoried all the SLM based brands. But it was a lot of work.

One day I will get these Yamaha disks inventoried. Then one day after that I will put the listing in my word processor. When those days are come and gone, I will have an inventory file, and would be happy to forward such a file. Bit of a large data dump send the contents of the disks.

Plus some of the disks cover keyboard lines like Clavinova and the Disclavier. Probably don't want those.

[bnwitt]

Originally Posted by Enzo

Oh dear...Bit of a large data dump send the contents of the disks.

Enzo,
I think some of us disciples should come to your shop and do this work for you to pass on the legacy.

[Tejaus]

Hello,

I too am having an issue with low gain on a EMX660 but on the mic input for channel 6. It does work but I have to turn the level control up all the way to have any gain. It still won't peg the meter on the main control though and it's not a strong as the other l0-z or channel 5.

The two 1/4" Instrument jacks work fine on channel 6 though. Any thoughts or a schematic would be much appreciated.

thanks

[Enzo]

Hi, read through the thread again, that channel does have lower gain by design.

[Tejaus]

Thanks for the quick reply.

I'm aware of the 1/4" jacks have different input padding, especially the line inputs on channel 5.
What I'm referring to are the specs for the input on the xlr jacks for channels 5 & 6 and the lo-z channels 1-4 showing -50db (with no pad) and the maximum gain for all of the above is 66 db. Shouldn't they all be the same or am I missing something?


From page 8 of the manual:
http://www.yamaha.com/yamahavgn/Docu...o/EMX660_1.pdf

2
MIC, LINE, INST input jacks
These are the input jacks for channels 5–6.
Microphones can be connected to the MIC jacks,
and stereo line level devices (such as synthesizers
or rhythm boxes) can be connected to the LINE
jacks.
The MIC jacks are balanced, and are compatible
with microphones of output impedance 50–
600 Ohm.
The LINE 1 & 2 jacks are unbalanced, and are
compatible with line level devices of 600 Ohm
output impedance. These two input jacks can be used
simultaneously.
Nominal input level is –50 dB for the MIC jacks and –10 dB for the LINE jacks.

INST 1 & 2 jacks are unbalanced, can be used
simultaneously, and their high input impedance
makes them ideal for use with instruments such
as electric-acoustic guitar and electric bass. They
can also be used with line-level sources, such as
synthesizers and drum machines. Nominal input
level is –30 dB.


Specifications

Maximum voltage gain
(PAD: OFF)

88 dB CH IN (Lo-Z) to POWER AMP OUT (CH1~4)
66 dB CH IN (Lo-Z) to MAIN OUT, MONITOR OUT (CH1~4)
72 dB CH IN (Lo-Z) to EFFECT OUT (CH1~4)
48 dB CH IN (Lo-Z) to REC OUT (CH1~4)
56 dB CH IN (Hi-Z) to MAIN OUT, MONITOR OUT (CH1~4)
26 dB AUX IN to MAIN OUT
24 dB TAPE IN to MAIN OUT
66 dB MIC IN to MAIN OUT, MONITOR OUT (CH5•6)26 dB LINE IN to MAIN OUT, MONITOR OUT (CH5)
46 dB INST IN to MAIN OUT, MONITOR OUT (CH6)

[Enzo]

I guess you're right. As I told Barry, it is a 6MB file, send me an email.

[Tejaus]

Thanks Enzo for the schemo. As I suspected it was a bad 470uf/10v electro cap coupling a transistor. Replaced and fired it up and it sounds great. BTW, I found an easy way to restore a rat fur covered piece of equipment. Just get a heat gun like you would use for heat shrink tubing and "go over" the carpet. It gets rid of the fuzz and pill balls making it look alot better. It doesn't take much heat so be careful not to burn or melt it.

Got to love a good meter for finding these bad caps.