Home |
Search |
Today's Posts |
#1
Posted to rec.audio.pro
|
|||
|
|||
[OT]? Replacing 1/4" jack on amplified acoustic guitar.
I have a Takamini Classical with a preamp/effects unit
built in. I plugged in a cheap cord, and the tip came of into the jack, which is a metal completely enclosed unit. I don't see much hope of retrieving the offending piece of metal, so the amp has remained unused for quite a while. I ordered a replacement jack that was supposed to be a direct replacement, and indeed, it looks just the same. I soldered the new jack on with care. I made nice clean joints and everything looked great. Now, the effects unit is supposed to power on when you insert something into the phone jack. This fails to happen now. I tried fresh batteries, but no luck. The audio jack is wired to a stereo 1/8" phone plug that plugs into the effects unit. I unplugged that phone plug and tested tip/ring/sleeve, which all tested good going out the the 1/4" jack which I stuck a TRS cable into for testing. There are no shorts, and the tip and ring connect distinctly to their counterparts at the 1/4" end. But the effects unit will not turn on. What does it expect to see? Normally, I can plug anything into the 1/4" jack, and its presence turns on the unit. Now, no dice. I'm wondering what to try now. What is it that normally turns the effects on? I wonder whether I shorted the wrong pair in the jack by having that rogue tip stuck in there for so long. Thanks, Toby --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
#2
Posted to rec.audio.pro
|
|||
|
|||
[OT]? Replacing 1/4" jack on amplified acoustic guitar.
"Tobiah" wrote in message
... I have a Takamini Classical with a preamp/effects unit built in. I plugged in a cheap cord, and the tip came of into the jack, which is a metal completely enclosed unit. I don't see much hope of retrieving the offending piece of metal, so the amp has remained unused for quite a while. I ordered a replacement jack that was supposed to be a direct replacement, and indeed, it looks just the same. I soldered the new jack on with care. I made nice clean joints and everything looked great. Now, the effects unit is supposed to power on when you insert something into the phone jack. This fails to happen now. I tried fresh batteries, but no luck. The audio jack is wired to a stereo 1/8" phone plug that plugs into the effects unit. I unplugged that phone plug and tested tip/ring/sleeve, which all tested good going out the the 1/4" jack which I stuck a TRS cable into for testing. There are no shorts, and the tip and ring connect distinctly to their counterparts at the 1/4" end. But the effects unit will not turn on. What does it expect to see? Normally, I can plug anything into the 1/4" jack, and its presence turns on the unit. Now, no dice. I'm wondering what to try now. What is it that normally turns the effects on? I wonder whether I shorted the wrong pair in the jack by having that rogue tip stuck in there for so long. Thanks, Toby I know of two ways that 1/4" jacks are used to switch power. The most common is to have the battery (or other) power negative side wired to the ring or a T/R/S jack, and the return/ground/chassis wired to the sleeve. The battery's negative terminal sees an open circuit with no plug in place. When a T/S plug is inserted, the ring and sleeve of the jack are are connected by the sleeve of the plug, completing the power circuit. Much more rarely (I've only seen it once), there are switch contacts that are closed (or opened) when the plug is inserted. These jacks are normal [sic] in patch bays, but rare in guitars. This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com It's not an email. Clueless advertising for Avast doesn't instill confidence in their protection. |
#3
Posted to rec.audio.pro
|
|||
|
|||
[OT]? Replacing 1/4" jack on amplified acoustic guitar.
I found out more. I examined the old jack, and found that I
did not get an exact replacement. Here is a photo of the old jack: http://tobiah.org/jack.html There are three tabs coming out of the center, one of which is connected to the tongue coming off the barrel. The new jack has only the the top two connectors coming out of the barrel, along with the tongue. I soldered the shield of the cable to the big strain-relief tongue, and the R/L to the other pins from the center. I still can't figure out what the inside wiring is like. I tried connecting a stereo plug to the jack and shorting pins here and there, but nothing will turn on the amp. Thanks for any help. Toby I know of two ways that 1/4" jacks are used to switch power. The most common is to have the battery (or other) power negative side wired to the ring or a T/R/S jack, and the return/ground/chassis wired to the sleeve. The battery's negative terminal sees an open circuit with no plug in place. When a T/S plug is inserted, the ring and sleeve of the jack are are connected by the sleeve of the plug, completing the power circuit. Much more rarely (I've only seen it once), there are switch contacts that are closed (or opened) when the plug is inserted. These jacks are normal [sic] in patch bays, but rare in guitars. This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com It's not an email. Clueless advertising for Avast doesn't instill confidence in their protection. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
#4
Posted to rec.audio.pro
|
|||
|
|||
[OT]? Replacing 1/4" jack on amplified acoustic guitar.
I got the offending plug tip out of the jack by
slamming it on the desk many times. Put that jack back into the guitar, and I'm all working again. On 6/7/2014 11:32 AM, Tobiah wrote: I have a Takamini Classical with a preamp/effects unit built in. I plugged in a cheap cord, and the tip came of into the jack, which is a metal completely enclosed unit. I don't see much hope of retrieving the offending piece of metal, so the amp has remained unused for quite a while. I ordered a replacement jack that was supposed to be a direct replacement, and indeed, it looks just the same. I soldered the new jack on with care. I made nice clean joints and everything looked great. Now, the effects unit is supposed to power on when you insert something into the phone jack. This fails to happen now. I tried fresh batteries, but no luck. The audio jack is wired to a stereo 1/8" phone plug that plugs into the effects unit. I unplugged that phone plug and tested tip/ring/sleeve, which all tested good going out the the 1/4" jack which I stuck a TRS cable into for testing. There are no shorts, and the tip and ring connect distinctly to their counterparts at the 1/4" end. But the effects unit will not turn on. What does it expect to see? Normally, I can plug anything into the 1/4" jack, and its presence turns on the unit. Now, no dice. I'm wondering what to try now. What is it that normally turns the effects on? I wonder whether I shorted the wrong pair in the jack by having that rogue tip stuck in there for so long. Thanks, Toby --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
#5
Posted to rec.audio.pro
|
|||
|
|||
[OT]? Replacing 1/4" jack on amplified acoustic guitar.
On 08/06/2014 20:15, Tobiah wrote:
But the effects unit will not turn on. What does it expect to see? Normally, I can plug anything into the 1/4" jack, and its presence turns on the unit. Now, no dice. I'm wondering what to try now. What is it that normally turns the effects on? I wonder whether I shorted the wrong pair in the jack by having that rogue tip stuck in there for so long. The unit will probably be looking for a short circuit between two normally open internal contacts caused by inserting the jack into the socket to turn on. One simple way to do this has one side of the power supply connected to one of the contacts, with the supply current passing when they are closed by the plug being inserted. If these contacts have been bent out of shape or otherwise damaged, they will not short together, so the unit won't power up. You need to open the case and check these contacts, which (and it's a slim chance) may be in the form of a microswitch which is operated by inserting the jack. The *really* cheap and nasty way has a contact on each side of the sleeve connection, and the operating current passes through the sleeve from side to side. Not hard to fix once you get in. You might even find it preferable and possible to install a proper switch if there's room, or if you run it off a wall wart, just wire it to be always on when the power's connected. -- Tciao for Now! John. |
Reply |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
stereo earphone plug "widens" jack: how to fix (replace=impossible) | Tech | |||
166XL Compressor - Advanced Fingerstyle Guitar and Strummingw/acoustic guitar | Pro Audio | |||
FA; Jack Darr Book "Electric Guitar Amplifier Handbook" | Marketplace | |||
FA; Jack Darr Book "Electric Guitar Amplifier Handbook" | Vacuum Tubes | |||
Weird results with Acoustic Mirror reverb on acoustic guitar | Pro Audio |