LA-4 and LA-5: 
Amplifier upgrades, user tips, modifications and experiments
updated July 2014
LA-4
LA-4
LA-5
 
 
WHAT TO REPLACE

The signal goes through only THREE capacitors in both versions of the LA-4.  In the blackface version, these are Tantalum and rarely fail.  In the silver version, these are often Electrolytic and should be replaced.

The most likely components to fail in vintage gear are the Electrolytic Capacitors.  There are easy to spot on the Blackface photo, where there are five 'gold-ish' AXIAL capacitors.  In the upper right corner is black power transformer.  Just below are the two power supply filter capacitors (C14 and C15), secured to the chassis with a white plastic wire tie.  Too the left of them are two smaller capacitors (C16 and C17) and another (C7) is on the other side fo the output transformer and is veritcally oriented.

In the center Silver LA-4 image, C14, C15 in nearly the same location, but the case style is now RADIAL.  C16, C17 and C7 are AXIAL.

That said, finding high quality AXIAL capacitors is more difficult because RADIAL is the preferred case style. The best way to retrofit RADIAL caps is to use one of the existing holes and then drill another hole that matches the lead spacing on the capacitor.  

When requesting replacement capacitors, RADIAL caps will be shipped.