Repair Wharfedale speakers

I have an old pair of Wharfedale speakers which stopped playing any music whatsoever. One is still a bit beeping, while other one is completely quite. One was already repaired few years ago, only capacitors were replaced and that seemed to work. Here is an image of this repaired circuit:



Where should I start? What do you recommend?

 

If we assume the capacitors are the right size, that is a plus, but they are certainly the wrong type. You need non-polar audio grade capacitors. Those are common electronics polar capacitors.

"Polar" simply means they are polarized, which in turn means they have a (+) and (-) terminal. "Non-Polar" means no polarity, and no Plus and Minus terminal.

Also, what is the voltage rating on those capacitors?

Here is a link that will show you want Audio Capacitors look like -

Europe Audio • Cross-over parts

Those rated an Bipolar or NP (non-polar) are the lowest price and lowest quality, but they are also very common in speakers. The Foil, Poly, Mylar, etc... are more expensive, but also better quality.

The quality of that repair does not look the best.

Steve/bluewizard

 

With the volume of your amp turned to low, you could try connecting each speaker driver in turn to check that they are working. Alternatively, check using multimeter.

 

Here is a picture of original cross-over filter. What capacitors and resistor should I get for replacement?

 

The origninal capacitors appear to be bi-pole or non-polar, these are the cheapest kind. They do last quite a while, at least a decade, but the value tends to drift, and they are more likely to fail.

However, the values are clearly marked. It appears to be a 25 MicroFarad and a 4.7 MicroFarad.

The capacitors used in the repair are NOT the right type, and they will not work well. At the link I provided, you can get very low priced non-polar Caps -

Europe Audio • Capacitors types • Intertechnik-Bipolar

Janzen, a very reputable company for audio components, has standard Z-CAPS at a still very low price. Maybe £1 each.

Europe Audio • Capacitors types • Jantzen-Std Z cap

If you want to spend more, you should be able to find some for about £5 each, still very reasonably priced -

Europe Audio • Capacitors types • Jantzen-Sup Z cap

Europe Audio • Capacitors types • Jantzen-Silver Z-cap

Unfortunately, 25 MF seems to be a custom size. 22 MF seems to be the standard size. However, if you combine capacitors in parallel, their values will add. For example, if you put a 10MF in parallel with a 15MF, the total will be 25MF. The 4.7MF is a standard value and you should have no trouble finding one of these.

Any of these linked to capacitors will be better than the replacement Caps you have used.

There are places in the UK that have AUDIO Capacitors, it is just a matter of searching them out. Here is a link to Wilmslow Audio in Broughton Astley, Leicester LE9 6RD -

Wilmslow Audio - Audio Grade Capacitors

At Wilmslow, the SuperSound brand capacitors do come in 25MF (£13.19) and the same brand has a 4.7MF (£3.66).

In Electrolytic Capacitors (also bi-polar or non-polar), these are very low cost. 25MF = £1.62. 4.7MF = £1.11.

I personally recommend some type of Film (polypropylene) capacitor like those found in the other links.

Steve/bluewizard