Godin transducer fading out ( Check Battery)

Started by eggplant_reaper, November 13, 2013, 11:20:30 AM

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eggplant_reaper

Hi all ~

I've got an older Godin LGX that's recently been acting up. It has the three output configuration (magnetic only, mixed, transducer only) The magnetic output is working fine (both through the solo jack and the mixed), but the transducer output fades from fine to no sound in about 5 seconds.

The transducer output will stay dead until I plug into the magnetic-only jack. This seems to 'recharge' the transducer output so that next time I switch to the transducer, it will again work fine for about 5 seconds before fading out to nothing. (for what it's worth, all string outputs seem to fade synchronously - which seems to indicate this isn't a problem with an individual transducer)

My electronics knowledge is pretty elementary, so I'm a little be unclear of where to look to diagnose the issue. My guess is that it might be a capacitor issue (due to the recharging behavior), but that's a very uneducated proposition. Has anyone else experienced similar issues or have a better idea of where to begin my troubleshooting?

Thanks in advance for the help!

Elantric

#1
Remove the rear Round cover and replace the 9VDC Battery

and remove the control cover and see what manufacture supplied the electronics in your Godin.

If your instrument was made before 2000, its likely to have L.R. Baggs Electronics

If its newer than 13 years old, then it has RMC Pickups electronic's

What you describe might be due to trapped moisture under the piezo saddle. I have fixed this using a hair dryer aimed at the bridge for 10 minutes.
But your mileage may vary ;)

This is what an RMC preamp board looks like


eggplant_reaper

Interesting....

My guitar is a late 90's model, so the LR Baggs seems correct (my preamp is quite different form the one you posted). I'll try the hairdryer method and see what it brings me. Thanks for that heads up.

I'm curious though - what are the mechanisms involved with moisture interfering with the transducer output? Is it an electrical interference issue, or something more physical?

Elantric

#3
QuoteI'm curious though - what are the mechanisms involved with moisture interfering with the transducer output? Is it an electrical interference issue, or something more physical?


LR Baggs saddles are essentially the same as those used in Line6 Variax.

http://www.fullcompass.com/product/341982.html
Here is what they look like


* The single black wire is the Piezo output Signal +
* The entire metal body is the Piezo output Signal -, referenced to the Guitars Ground system.

Moisture can occur if the guitar is played on a hot stage and if your hands sweat, this moisture may travel under the piezo bridge saddle and interrupt  / interfere with the Piezo saddle electrical ground connection. If you are careful, you may remove strings and dis-assemble and carefully remove the piezo bridge saddles from the bridge. Many simply lift right out as the downward tension of the strings at pitch is often the only thing holding the piezo saddle in place.  (Caution: use your phone and Take lots of pics during all dis-assembly / reassembly)  I have used 100% isopropyl alchohol (my secret stash of old Ampex Tape head cleaner ) (Avoid using 80% isopropyl Rubbing alchohol from drug store - too much moisture) and a Q-tip to clean and remove old contamination or trapped moisture found under the saddle,  wait for it to dry ( use a hair dryer 20 minutes max) and then wait a day to be sure all moisture has evaporated.  - then apply a small drop of Caig Dexoxit under the saddle to restore a robust electrical earth / ground connection to the piezo saddle element and put everything back together and this typically restores operation.
 

QuoteThe transducer output will stay dead until I plug into the magnetic-only jack. This seems to 'recharge' the transducer output so that next time I switch to the transducer, it will again work fine for about 5 seconds before fading out to nothing. (for what it's worth, all string outputs seem to fade synchronously - which seems to indicate this isn't a problem with an individual transducer)

Godin guitars with Synth access use 1/4" switching  jacks, I bet this could be fixed by spraying a small amount of Caig De-Oxit contact cleaner into the 1/4" Jacks and then find a guitar cord and insert / re-insert at least 10 times - this process helps knock off any oxidation on the Jack's internal  switch contacts (the only stuff i use) and use a similar "jack cleaning approach outlined in this thread for cleaning 13 pin jacks and plugs

https://www.vguitarforums.com/smf/index.php?topic=3132.0



 

pursue all the above first - if problems continue, then its likely the 14 year old Surface Mount Electrolytic Capacitors have gone dry and lost operation.  (BTW - this is typical fault with all 1980's Casio MIDI guitars
https://www.vguitarforums.com/smf/index.php?action=downloads;sa=downfile&id=72
and other consumer electronics older than 10 years) .These are essential for a steady DC supply current to operate the op-amps on the L.R. Baggs Pre-amp.  Find a local Camcorder repairman   

myksara

I have the LGXT and would try replacing the battery located
on the back of the body.
Not sure if your LGX has one.
Guitars: Ibanez Prestige S5470, Ibanez Jem 7v, Ibanez JS2410, PRS SE Custom24, Cort  Ltd G16, Ibanez RG370Ahmz,
MultiFX: Roland GR55, Zoom 1on, BOSS GT00
Loopers: Digitech trio+, Line 6 JM4
MIDI:, MAudio Axiom24 keyboard, Alesis IO Dock with iPad air 2

eggplant_reaper

@Elantric

Thanks again for the extensive reply. I'll try out the hair dryer tonight and see if that might do the trick. If it does come down to the capacitors however, do you know off the top of your head where I might grab Godin schematics? (I'll be googling it momentarily)

@myksara

Thanks - I wish it were that. Unfortunately my LGX is all passive.

Elantric

#6
Quote
Thanks - I wish it were that. Unfortunately my LGX is all passive.

LGXT/LGX-SA with RMC Electronics provide a Passive Mag PU only 1/4" Jack and a "Mix 1/4" Jack  - ( along with the 13 Pin Gk Out Jack) 

Remove the large round rear cover behind the slider controls. All LGX a 9Volt battery (required when not connected to GK13 pin cable)

Older LR Baggs models employ TWO 9V Batteries   - behind the round cover

eggplant_reaper

Welp - there you have it. I work in IT and I've sworn up and down that I'd always be the guy to check if it's plugged in before I sent for help....

My apologies & sincere gratitude for all the help gentlemen!