View Full Version : KEF Reference Series Model 104aB Crossover help

11-19-2010, 09:22 PM
A capacitor is blown. It says:
3.3 MFD
50V L.L.
Where could I get a replacement?
Also, there are 2 things on the board that look corroded (see attached pic). They look this way on the other speaker, too. What are they, and if they need to be replaced, where could I get those?

11-20-2010, 04:51 AM
The two corroded looking components on the crossover are resistors. The one between the capacitors on the top of the pic is a 3 Ohm and the one in the bottom, next to the red coil is a 1 Ohm one.

These resistors tend to look ugly but still work fine. The looks aren't important here.

On the other hand, the capacitors tend to look great (unless they are blown) but drift badly. I repaired a pair of KEF Calindas and had the problem that one tweeter didn't produce adequate sound level. After examining the capacitors, discovered that all had drifted, half of them more than 100% from their nominal values.

For some reason, these ELCAP capacitors with values ranging from 1 ~ 15uF are the ones that drift most on KEF crossovers. Don't forget that these crossovers are more than 30 years old.

What I did is the following:
1. Invested on a $35 LCR meter to be able to measure inductors, capacitors and low value resistors.
2. Remove each component from the PCB using a soldering iron and then measure it. You can't measure in-circuit.
3. Replace components that have drifted too much from their nominal values (>15%). Typically what has drifted will be well beyond that threshold. IIRC, a 5uF capacitor on the Calinda was measuring 3.5uF.

Where you source capacitors depends on where you are. Parts express is a reputable retailer in the states, and Falcon Acoustics is long specializing to KEF products. Capacitors don't have to be from a specific brand. There are several different types and materials ranging in prices from a few cents to a few $ or even more. I wouldn't spend more than half a buck for each component and replace with what is closest to the nominal values.