Fender Princeton 112Plus Jacked-up Input Jacks

Worn input jacks are the bane of players and the bread and butter of amp technicians everywhere.  The Unbrokenstring Crew is ready to Slay the Bane and get this wonderful unit back on the air!


Most commercial equipment manufacturers sell their gear world-wide.  The European Union (and other areas of the world) have stringent requirements regarding electrical isolation of the consumer and any electrical parts of the equipment, including the grounded chassis.  Thus, synthetic insulative materials are pressed into service for input jacks, although the longevity of that material is nowhere near the longevity of steel.  Such is the world we live in.


We’re taking a quick tour of the rest of the front panel.


These jacks aren’t in much better condition.  The synthetic material just degrades over time.


We’re documenting some connections here, so that we can disconnect them to remove the amplifier and then get them properly connected during reassembly.  The reverb tank lives in the bottom of the amplifier cabinet.


More documentation, and a little Tech Porn!  Loudspeaker connections are shown here.


The circuit board is typical of Fender gear from this era.


These screws hold the output module to the heat sink and thence to the aluminum cabinet of the amplifier.


Oops, I did it again!  A little tech porn, this time the high voltage fuse which protects the high voltage transformer.


I believe that this is the date when this amp was built.


With the circuit board free from the chassis, we have our objective in sight!


Here is a quick view of the other front panel jacks.


Here are our new jacks.  Next, all the nuts holding the controls will be reinstalled.  I have spared you the details of replacing the jacks and the soldering and all that.  If you want to see that process up close and personal, check out the Gallien-Kreuger jack repair in an earlier blog posting.

Here’s Jacob doing a checkout:


This unit is 100% electrically.  New knobs are on order, but I’ve returned this amp to the owner as-is.  Later, I made a trip to his place to install the knobs and audition the amp.  As it turns out, he is quite the Jazz Cat and is really enjoying this amp.

Thanks for checking out my blog post!

David Latchaw EE