Bridge pickup electronics problem - 95MJ9169

[fom]

Hello,  I just received my bass earlier this week and I am beyond impressed with the quality of workmanship and playability of the bass.  As luck would have it I am having a problem with the electronics on the bridge pickup.  After several hours of flawless use, the preamp unit started generating random noise, losing all signal from the pickup.  After several minutes the unit went silent.  I have done some basic troubleshooting including verifying that the pickup is working, wire connects are secure into the blend pot etc.  Reading over other posts it appears that the IC may be the trouble area.  The bridge pickup and preamp are working fine.  Any ideas?  How do I order the correct IC for the bridge preamp unit? Also I am really curious why the pickup leads run through a metal tube in the control cavity.  Best regards,  Mike

[mica]

The tube isn't metal - it's a non conductive shielding bead.  
 
If you've got regular Signature electronics, the IC is a TLE2022. You can order one by calling us at 707 5232611. It's easier to change the part by removing the preamp from the bass. Make sure you read how to remove knobs or you will have to send me some more money for a new filter pot.  
 
Was your troubleshooting to switch which preamp the pickups were connected to? You can also switch the ICs if you want to confirm the problem is confined to the IC. Make sure you notice where pin 1 is (marked with a 1 or a circle or a notch) and also where pin 1 is on the socket (marked similarly). Do not rely on the printed markings on the IC for alignment - check for pin 1. If you plug the IC in backwards, it will cease functioning, but it won't harm the rest of the electronics.  
 
If you change the ICs, and the problem persists, I'll need to do some more troubleshooting with you. Worst case: you might need to send the electronics in for testing and repair.

[fom]

Thanks for the speedy reply Mica.  During my troubleshooting I did switch the pickups between the preamps,  the wireless connections are sweet! I did not switch the ICs.  I tried that this morning and can confirm that the ICs are both functional while the bridge pickup preamp remains dead.  I am assuming that the bass has signature electronics,  both modules appear identical,  same code numbers printed on the pot body etc.  When I switched ICs the output and tone controls worked the same with the bridge PU IC installed on the neck PU module.  As I bought this unit used I don't have any build info (I have posted a request when your time is available - super benefit for used purchasers!)  I will followup next week for additional troubleshooting.  Thanks much for your quick support.  Mike

[David Houck]

Just thought I would check; none of the controls are touching the shileding or other controls?  Sometimes if a control is loose, when you turn the knob, the control will move inside the cavity, and possibly short out when touching the shielding or other parts.

[fom]

Thanks for the thought Dave.  The preamp unit was returned to Alembic and has already been repaired and on a UPS truck heading back.  The repair was minor.  I should have the unit back in the bass by Thursday in time for a weekend session.  Service and communication is outstanding.

[David Houck]

Great!