Guitar Tabs For Beginners

No sounds from B string on electro acoustic classical guitar?

Trawled the net for piezo maintenance info but have found very little! Basically been using my electro classical a lot recently after not playing it for ages and decided to plug it in today, but there is no sound coming through the amp from the B string... All the others have a nice signal coming through, but to get a equivalent volume from the B I have to nearly triple the volume on the amp... I'm guessing its a piezo issue, but not sure how easy it is to check/replace, so if anyone has had this problem or knows the best way to sort it please let me know!

That is unusual for a classical guitar because they are usually set up with a common bridge piece as opposed to individual saddle pieces. The fact that you are getting sound from the G string and the high E sting indicates that it is probably not an issue with the piezo transducer itself but rather a problem with the interface between the saddle piece and the transducer.
Try gently pressing down on the saddle piece next to the B string while plucking it and see if that makes a difference. If it does than try changing that string and making sure that it is the correct tension and tied correctly.
This problem can occur when the string in question is not the same tension as the others. Nylon strings come in different tensions; soft, medium, hard, extra hard. Be sure they are all the same tension. Make sure they are all properly tied around the bridge.
If the problem persists than loosen all of the strings and carefully remove the saddle piece from the bridge. Closely inspect it for any wear or cracks, especially on the bottom edge. It should be perfectly flat. You can run it across a flat file a few times to make sure.
While you have the saddle off, inspect the piezo element that sits underneath the saddle. Check for any obvious wear or signs of damage. Plug the guitar in and set the volume to normal. Use a small screw driver and tap the piezo element very gently, starting at the low E string side and moving across to the high E string side. Try to determine if the volume output is consistent all the way across or if there is a dropout at any point (like at the B string).
If there is no dropout than the problem is not the piezo element. If there is then you may need a new one. This is unusual because, in my experience, when they go bad the whole thing drops out, not just a small segment. If there is no drop out try replacing the saddle and tightening the strings and see how it sounds. If you are still having a problem than you will need to take it into your local dealer and see if they can repair or replace the pickup.
NOTE* If this instrument is still under warranty or if you do not feel up to performing these checks yourself than let your local store do it for you.
Good luck!