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Re: New AN1x owner, with mainout L/R problems

Re: New AN1x owner, with mainout L/R problems

2014-11-04 by Daniel Boles

A-ha, now I might have just the ticket. I've become more involved than I ever wanted to in esoteric electronic things like this...

Check muting transistors before the output jacks. In my experience, although this is not much reported online, these can fail often and for the slightest (unknown) reasons. This can then cause distortion, bleed between adjacent channels (on the same muting control line), and possibly other problems. I've fixed 3 synths with distortion (one twice!) by replacing the transistors, and 2 also exhibited some bleed-through before that. None were the AN1x, but I suspect it uses a similar system to mute unwanted audio during power on/off.

The transistors I've seen/replaced for this have been the now-discontinued 2SC2878, specialised for audio muting. They can still be found on eBay - get 10 or so while you can, but please don't hoard them away from everyone else ;-)

The other option I believe is simply to remove the transistors (desolder). However then make sure you don't turn on your speakers/whatever the AN1x is input to until it has been on for a few seconds, otherwise I'm not responsible for damage to other equipment due to possible DC or other noises during power on/off.

Bring back relays, that's what I say........

Let me know how it goes as I'm very interested to hear whether anyone else has the same experience.


Re: [AN1x] Re: New AN1x owner, with mainout L/R problems

2014-11-04 by emma

They are usually jfets and they can fail kurzweils suffer from this problem as does the ensoniq dp4+

Also yamaha used coil contacts switched by a transistor and they can burn out

A good sign is if you get audio from earphones as that circuit has a pre amp and is before the thud circuits


Sent from Samsung Mobile



-------- Original message --------
From: "Daniel Boles db0451@gmail.com [AN1x-list]" <AN1x-list@yahoogroups.com>
Date: 04/11/2014 11:38 (GMT+00:00)
To: AN1x-list@yahoogroups.com
Subject: [AN1x] Re: New AN1x owner, with mainout L/R problems


A-ha, now I might have just the ticket. I've become more involved than I ever wanted to in esoteric electronic things like this...

Check muting transistors before the output jacks. In my experience, although this is not much reported online, these can fail often and for the slightest (unknown) reasons. This can then cause distortion, bleed between adjacent channels (on the same muting control line), and possibly other problems. I've fixed 3 synths with distortion (one twice!) by replacing the transistors, and 2 also exhibited some bleed-through before that. None were the AN1x, but I suspect it uses a similar system to mute unwanted audio during power on/off.

The transistors I've seen/replaced for this have been the now-discontinued 2SC2878, specialised for audio muting. They can still be found on eBay - get 10 or so while you can, but please don't hoard them away from everyone else ;-)

The other option I believe is simply to remove the transistors (desolder). However then make sure you don't turn on your speakers/whatever the AN1x is input to until it has been on for a few seconds, otherwise I'm not responsible for damage to other equipment due to possible DC or other noises during power on/off.

Bring back relays, that's what I say........

Let me know how it goes as I'm very interested to hear whether anyone else has the same experience.


Re: [AN1x] Re: New AN1x owner, with mainout L/R problems

2014-11-05 by emma

There opamps 4750 dual opamp have you checked the psu as if its not working correctly you get distortion on the outputs I had this on my old yamaha an1x wallwart

Ill look at the schematic as I dont see any transistors or jfets in that area you are showing so the muting circuits mogjt be before those

I would get a scope and look at the signal before and after the opamps to see if your getting the correct signals with no distortion thats the only way to see if a opamp is working correctly or not



Sent from Samsung Mobile



-------- Original message --------
From: "mekozbekoz@yahoo.com [AN1x-list]" <AN1x-list@yahoogroups.com>
Date: 05/11/2014 14:29 (GMT+00:00)
To: AN1x-list@yahoogroups.com
Subject: [AN1x] Re: New AN1x owner, with mainout L/R problems


Hi,

thanks for the info, is this what you are talking about...

http://imgur.com/MliwCNx

Re: New AN1x owner, with mainout L/R problems

2014-11-05 by jammie.emma@...

as there are no schematics its hard to see what is doing the muting circuits

all i can see there is several dual opamps and a dac and some custom yamaha asics

there seems to be some dc blocking caps get an esr tester and test them to see if you have any faulty ones

even on the block diagram it shows that the amp output goes to the phones and then muting then outputs

but does not show where the signal from the muting comes from or where it goes
for a service manual its very limiting i will contact yamaha uk to see if i can get a copy of the schematics as i now the main tech and have had many schematics in the past

in the parts list there is only 2 transistors 1 of each type the others are transistor arrays

so it could be those 2 as there are no jfets in the parts list and no relays

but from your picture i dont see and smd or standard transistors

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