Fender Acoustasonic active circuit current bleed problem

[huntgl]

Hello again :-)

I've just bought a used Acoustasonic Telecaster which has an active circuit that controls both the magnetic and piezo pickups. I noticed immediately that if I leave a battery plugged in, the circuit drains (9.5 volt battery drops to about 7.5 volts over 15/20 hour period). The circuit is supposed to be activated when you plug in a cable, and the stereo jack has contact switch on one of the rings to facilitate this. I have read elsewhere that it is usually a jack failure that causes this type of problem, but I would love to know if there is a way that I can test this jack to see if it has failed and is causing the bleed. Is a simple test with a multilmeter possible?

Cheers,

Gary.

[newey]

Yep. There are actually a couple of different ways to test this. First, your output jack should be of the TRS variety ("Tip-ring-sleeve"- also sometimes called a "stereo jack"). The tip and sleeve are the usual two connections to your guitar's electronics, while the "ring" terminal is the one used for disconnecting the battery when no cable is plugged into the jack.

So, to test it, disconnect the cable and also remove the battery. With your multimeter, check to see if you have continuity between the ring's lug and the tip's lug, then check from the ring lug to the sleeve lug. You should not have any continuity with either of those tests (in other words, your meter should read infinite resistance or "out of range").

You can also test with a battery in place, checking for voltage across the jack with no cable plugged in (shouldn't be any), but the above method is probably easier.

[huntgl]

Ok, I just tried that, but one of the leads has now broken...

There are 4 lugs on this jack, one to the tip, one to the sleeve, one to the ring and one to the switch which connects/disconnects to/from the tip prong/spring. The switch one has never been soldered and it was wired as follows:

White wire to the ring lug
Red wire to the tip lug
Yellow and Black to the sleeve lug

Looking at the manual for this guitar here...

Manual

...common sense seems to indicate that the Black and Yellow should not have been wired together, and that the Yellow should go to the 4th, switch lug. As it is the yellow that has now broken, I think it may be time to solder it to the unused lug :-) The circuit board seems to clearly indicate this, no?

[JohnH]

Im not sure we know how this should work! These boards are not just simple analog preamps but have digital circuits. The full versions can be programed by usb!

That means that it may be controlling power by digital logic rather than simple battery disconnection. So what to expect at the jack could be different. Id suggest getting it back how it was and measuring curent flow from the battery with and without jack plugged in.

[sumgai]

hunt,


Yes, your surmisal is correct - the Yellow wire should never have been soldered/connected directly to the Black wire's terminal on the jack. Someone blew it big-time at the factory.

Contrary to the standard TRS type switching, which basically requires that a bone-stock standard guitar cable be used to turn the internal circuitry on, this model can do stereo. A standard cable won't let that happen of course, but digital control means that both the mag and piezo signals appear at the tip of the cable. If a stereo cable is inserted, the unit still turns on, and the digital controller detects that second, separate output, thus going into stereo mode.

Nice rig. Treat it right, and you should have a near jack of all trades for a long time.

HTH




sumgai

[huntgl]

It does seem to be clearly marked in that manual, so I did wonder if it was a factory ck-up ;-)

It actually has a switch on the battery holder where you can choose stereo or mono, so that ties in with your description of the circuitry controlling the signal and not the jack itself.

Thanks for all of the replies, they really are appreciated :-)

The soldering iron is primed and ready...

[sumgai]

Gary,


I think you'll find that, since you can't do stereo over a standard (mono) cable, that switch is meant to override the circuitry sensing a stereo cable has been plugged in. IOW, you can opt for mono out of both "channels", instead of piezo out of one channel, and the mag pickup out the other.

Many of today's "acoustic" amps can handle stereo just fine when using a stereo cable, but the problem is, without at least one extension speaker, the stereo effect is lost, just a couple of feet away from the amp. In some rooms, one can stand back from this kind of amp, and hear a "warbling" effect - this is where one channel's sound is interacting/interferring with the other channel's sound. That interference causes a nodular cancellation effect, exactly like what we call the 'quack' tone on a Strat (or other three-pup guitar). But in a reasonable sized room, this can be disconcerting, so adding the Mono option allows the player to overcome that possibility, thus making his/her playing more attractive.

HTH

[huntgl]

Well I've just rewired this, and now there is no signal at all.

It was really tricky to re-wire as the leads are very short and there's hardly any room to manoeuver at all. I'm going to disconnect everything tomorrow and start again with a new jack as this one seems very cheap to me. It's very loose and the sleeve spins freely, which I'm pretty sure shouldn't happen. The problem I have is finding a replacement for these types of jack as they don't seem to be that readily available. Switchcraft don't do one to my knowledge, and the only brand that I've found that makes one is Lumberg, but their one has a sort of plastic ring on it which I believe will cause problems when fitting it back in the jack slot...

[huntgl]

Ok, here's the latest.

I've tracked down a Switchcraft jack and wired this as it was wired when I got it: red to tip, white to ring, yellow and black to sleeve. The guitar now works, although there still seems to be a pretty drastic drain somewhere. With the lead removed (which supposedly cuts the circuit) I connected one half of a new battery to the circuit, then connected multimeter leads to the unconnected half of the battery, and the other circuit connection. It's giving me a readout of 9.2 volts, and this reading counts down quickly: 9.19, 9.18, 9.17 in under a second a step. There's clearly a drain somewhere, and I'm no expert, but that seems like a pretty big drain to me...

This guitar has 2 circuit boards in it: the Aura board which is the digital acoustic guitar simulator, and another one which controls the blend of the two pickups.

It all looks very daunting at this stage, so if anyone has an idea where to start I'd be very grateful...

Many thanks again :-)

[JohnH]

It sounds like you may be putting the meter between battery and guitar, but on a voltage setting? If so, the idea should be to set it to read DC current.

Connect battery negative to guitar negative, as usual
Meter set to maybe 200mA DC current setting
black lead to guitar positive
red lead to battery positive

The guitar should work in this arrangement, and you can read current (probably several milliamps), and get the reading when its on, and then also when it should be off. Hopefully, the current would drop virtually to 0 when off. If you see that, move to a lower current setting to check it.

cheers
J

[huntgl]

Thanks, John. I'm getting a reading of 17.6, both on and off. This is on the 200ma setting.

[JohnH]

Feb 6, 2015 1:38:42 GMT -5 huntgl said:

Thanks, John. I'm getting a reading of 17.6, both on and off. This is on the 200ma setting.

Well, that's a credible current draw in mA for 'on', which should be good for maybe 20h playing? But it confirms what you found that its just not switching off at all! Do you have any info about how it is supposed to work? And is there any warranty? I can only think of ugly work-arounds right now. (Add a switch, or a jack with another switch in it)

[huntgl]

I have posted on another forum and have contacted some other users to see how their jack is wired. Although it didn't work when I connected the yellow wire to the 4th lug on the other jack, it may be because that one is faulty, and if I try it on this new jack it might work. I'm not going to do that until I hear back from another user, as solering this thing is fiddly and I don't want the new jack to be a mess of solder after countless attempts.

The user guide says that the mono/stereo switch on the battery box is simply that. If you use a mono cable you switch it to mono, and vice-versa for stereo, so it seems the circuit is a little less intelligent that I and sumgai thought.

By confirming that the current draw is normal, I can at least rig it up and simply take out the battery after playing, but I'd really like to crack this, as well as possibly fit a switch that allows me to bypass the circuitry when the battery dies, thereby allowing me to use the neck pickup passively. It's very busy inside the guitar as the service manual shows, but I'm sure there'll be a way somehow...

[huntgl]

Well here's the latest...

I emailed Fender expecting nothing in return, and lo and behold a very friendly guy there has a spare board and pre-wired jack in his spares box which he is putting in the post to me, gratis!

Faith in humanity = restored :-)

[aliko]

Hello every one, 


Just bought a new acoustasonic telecaster. My problem is with this stereo and mono switch. When i use mono switch both pickups works just fine, but when i switch to stereo, acoustic pickup doesn't work. Tried with new cables and different mono and stereo jacks, didn't help at all. Is there any one had same issues? Thanks for your help!

[newey]

aliko-

Hello and Welcome to G-Nutz2!

Fender has made a number of different guitars called "Telecoustic". For example, the manual that huntgl linked to above is for a guitar without a soundhole, and with a magnetic pickup in the bridge position, and it doesn't appear that his had a stereo/mono switch. So, we may need further info on your particular model to find out how this thing is wired. I searched Fender's website for an owner's manual, etc, but came up with nothing.

First, without any pictures or a wiring diagram, I'm hesitant to suggest something so obvious, but does this guitar require the use of a stereo cable for the stereo function? If it is indeed brand new, the owner's manual that came with it should tell you this.

Next, if this is indeed a "new" one, is it still under warranty? If so, that should be your first solution.

[aliko]

Thank you for your help.
The guitar that i'm talking about is fender acoustasonic telecaster. It's came out on 2010. My tele made on 11 may 2011. Yes it has mono and stereo switch back of the guitar and came with stereo Y cable. Unfortunetly i bought 2nd hand and no warranty.

When i search from internet i found that it works both way like mono and stereo mode. In mono mode you can just use one standart mono guitar jack and get the acoustic and electric pickup from the same cable but, can't use saparate amplifiers! In stereo mode with stereo Y cable you can use 2 amps, 1 cable for electric the other cable for acoustic guitar amp. 

My problem is, i can  use the mono mode. In stereo mode i can't get the acoustic sound. I did try another stereo Y cable but didn't work, not a broken cable nor input jack problem. Can it be a fabriquation problem?

Here is the wiring diagram.


support.fender.com/service_diagrams/telecaster/014-4500A_SISD.pdf

Thank you,

Ali.

[newey]

You're right, I meant "Acoustasonic", not Telecoustic. But my point about different versions still stands. The link you provided is the same as the one huntgl posted earlier, and unless I'm completely blind, I'm not seeing any stereo/mono switch.

If you've eliminated the cable as a potential source of the problem by swapping it for another, then logically the fault must lie either:

• In the wiring to the output jack(likely at the "ring" connection.)
• In the wiring of the mono/stereo switch, or
• On the circuit board itself

If it's #1 above, it's probably easily fixable by you. If it's # 2, then it's probably fixable by you unless #2 and #3 are the same, meaning that the stereo/mono switch is part of the circuit board itself. (Again, I'm not seeing the stereo/mono switch you describe, so I can't tell if it's a separate switch or not

If it's number 3 above, it's probably unrepairable by you unless you are quite experienced with desoldering and soldering circuit boards.

[aliko]

I checked the cable and the output jack with the digital meter, looks clear. As you said maybe the mono-stereo switch it self. Hope not the circuit board! The switch behind the guitar near the (left side) battery door. It's very small switch, if look carefully you'll see!

[newey]

So, is that mono-stereo switch separate from the circuit board?

The fault must be somewhere "downstream" from the switch, since the mono set-up works fine.

[aliko]

Yes you are right, it is switch. I'll try to unplug the stero mono switch cable, than will try to manually contact the pins. Hope It'll work. If it works don't wanna change the switch, will solder the cables stereo  mode! 

[huntgl]

Have you taken the two circuit boards out to look at them at all? I took both out and checked for broken connections etc and it's a pretty easy job to do. The battery box too for that matter. The thing I noticed with mine was the amount of wood dust in there as the guitar is hollow. I can't believe that this could cause any sort of electrical malfunction, but I cleaned the boards off nevertheless.

[aliko]

Yes, i did open up all the components. Battery door and circuit board, front plate, and checked all the cables and connection too. Unfortunately the problem seems to be on the circuit board it self. But i did solve the probelem.

First i disconnect the 2 cables coming out from the neck magnetic pickup wich gets in to a board. (cables are coming from magnetic pickup and goes to volume and tone pot and then goes to board!) and soldered them to directly to output jack. Needed to disconnect one cable (white cable coming from the board to out put jack).

And the problem solved. Good thing is with this connection if youre battery dead you can still play with magnetic pickup. Normally with the orijinal wiring you can't use magnetic and acoustic pickup when the battery is dead. Anyways, i'm very happy to found the solution, can't use the stereo mono switch but no need to ! Works like i'm in the stereo mode now.(Which was not before) And i love both sounds, acoustic and electric fantastic guitar for me!

Thanks for your help again!  

Ali.

[huntgl]

Success at last!!!

I received the replacement pre-wired board from Fender, and rather than install the whole thing, I thought I would just disconnect the jack and connect that to my board. The jack on my guitar was an open frame stereo jack with switch, but the Fender one is an enclosed jack with 8 separate lugs, so a completely different looking animal. After wiring it in, everything works perfectly as it should :-)

Hopefully the experts will chime in here, but it seems like the previous owner had replaced the jack, and the standard stereo TRS jack wasn't enough for this circuit board. With the enclosed jack having 8 lugs, it would seem to me that they are very different, although I'm just a layman. Are they very different?

Ali,

What sort of jack have you got installed, an open frame one, or one of these enclosed types with 8 lugs?

[aliko]

Hey Huntgl, 
I didn't chage the input jack at all, just solder in a different way, separated the neck pickup wires from the circuit board. The original input jack i believe, enclosed types with 8 lugs.



Ali.

[newey]

The enclosed 8- lug jack is a switched- type jack. A regular TRS (i.e., "stereo") jack simply disconnects the connections when no cable is plugged into the jack. With the switched type, with no cable plugged in, one set of two lugs is active, and inserting a cable then switches from those lugs to another set of two lugs. It's sort of like a DPDT switch and a jack all in one. So, the 8 lugs break down as a set of two for the tip, a set of two for the sleeve, a set of two unswitched for the ring, and another set of two switched for the ring.

You will see these used as headphone jacks, so that stereo speakers (with separate grounds) are on when no headphones are inserted, but the stereo output is then switched to the phones when they are plugged in, disconnecting the speakers. I'm using one in a stereo Tele project (which has unfortunately been languishing on the workbench for a couple of years now!) so as to avoid problems from using a common ground for both stereo channels. I'm guessing that's the reason Fender uses one in these guitars as well.