I installed one of these piezo cable undersaddle pickups in a guitar and have run into problems. I've never installed one of these before, though they regularly show up as stock installations on guitars I work on.
The is issue is that the pickup seems to be shorting out when the saddle and strings are installed. When I test without the saddle, noise gets sent to the amp. My guess is that the insulation is getting squashed and the piezo element is touching the ground conductor
The braided part of the pickup is longer than the saddle slot. Was I naïve in thinking that I could just bend it through the hole at the end of the saddle slot? Should I have trimmed it to length instead?
Or if you want to use this type of pickup , drill the hole on a gentle slope so the bend is subtle , and as Greg said a blind hole at the other end to take the lump . But that one is probably had it .
But not too shallow an angle, lest you drill into the X brace... I've seen that.
Agreed with all the answers, I used over 10 of them in Flamenco guitars during the past year and they were kind of okay, the best way and clear sound for my experience was like Eric recommended being careful to not compromise any bracing.
Another option is to use the length that you need to fill the bridge groove and leave the rest well fastened inside the guitar if a hole is not an option.
these are very common and can be had from fishman. i dont think its something they advertise but it is available as i have replaced them before. try drilling the hole at a 45 like someone stated. then since it was installed before you can tell which way was facing the strings? if you can, rotate it 90*in the slot where the area that was facing the string is now facing the headstock or the tail. install the saddle with the p/u rotated. if the pickup was grounding out from the string pressure causing a short this will get you down the road, but it really needs to be replaced. sometimes this works, sometimes not, but it is worth a try right? good luck