I have started to upgrade my Beovox 5000 MKIII designed for Beolab 5000 (1967-1972).

I am planning the following:

Replace the capacitors in the crossover network

Replace the internal wiring to the bass driver

Replace the external cable

Coat the cones of the midtone- and bass drivers

/Frede

Replace the capacitors in the crossover network

Bipolar capacitors produced for more than 50 years ago are dried out and need replacement.

I will replace the capacitors with some (expensive) MKT film capacitors (metallised polyester film)

I am using some from Bennic and Monacor

Here you can see the old bipolar caps and the new film capacitors.

/Frede

I am going to start the process by replacing these capacitors.

You need to remove the bass speaker and some damping material.

Then you can see the crossover filter.

You can then remove the 4 bolts and careful remove the filter for a more easy restoration.

I don’t remove any wires at this stage.

I only pace the filter at the top of the cabinet and do the work here. I suggest using some protection between the filter and your Beovox 5000.

The process require a few changes to the filter because the new caps are physical much bigger and more heavy.

I will rearrange and I will use hot melt gluing of the caps.

This is the result of the rearranged part for the crossover filter.

The reason for gluing the parts is of course avoiding noise and vibrations.

more to come

Fascinating - I should really do mine sometime! I am not convinced that the bass units in mine are original though - smaller dust caps.

I think yours are original Peter, the MKIII have been sold with 2 types of bass units - one with 'big dust cap' and one with small dust cap'

/Frede

You may well find there is a significant advantage in replacing the wirewound resistors, modern ones are much more accurrate.

If you measure the values of these resistors, you may well get a shock, mine had drifted massively, you might imagine that a drift of a few Ohm isn't much, but when you are dealing with the low values found in crossover netowrks, that dirft can be over 100%.

How do I know, because I did this same exact thing a few years back.

Make sure to refix those chokes too, the glue will be on the way out.

Don't forget to check out the components on the crossover frequency adjustment controls too.

Casdave,

First, thanks for your suggestions, I will certenly check - and remplacer if needed.

This is really interesting.

What was the final result of your restoration ?

/Frede

The sound was pretty dull and lifeless, and this did improve things, however the addition of the cubes made all the differance in the world.Bass seems to go a bit deeper and less boomy.

It was not a massive improvement, but noticeable. Add up all these little improvements and it can make a big difference.

I also did a pair of Type Ks, the cones were gone at te edges, not an easy repair due to them being corrugated paper types. Now sorting these and the crossovers made a huge difference.The bass response is so much better. I would even argue that they sound nicer than the Beovox 5000.

The type S only needed the capacitors doing, but while you have the speakers apart, it is a good time to refinish the wood too. You'd be amaazed at just how grotty the cloth grilles have become.

classic:

I don’t remove any wires at this stage.

I only pace the filter at the top of the cabinet and do the work here. I suggest using some protection between the filter and your Beovox 5000.

The process require a few changes to the filter because the new caps are physical much bigger and more heavy.

I will rearrange and I will use hot melt gluing of the caps.

  

This is the result of the rearranged part for the crossover filter.

The reason for gluing the parts is of course avoiding noise and vibrations.

more to come

Sure looks crowded, I dont see the 3rd coil, is it hidden under the 68 Mu cap, and did you glue the cap to the coil ??

Søren Mexico:

Sure looks crowded, I dont see the 3rd coil, is it hidden under the 68 Mu cap, and did you glue the cap to the coil ??

Yes, the 68uF cap is glued on top of the coil and to the other 68uF cap.

/Frede

classic:

Yes, the 68uF cap is glued on top of the coil and to the other 68uF cap.

If you had to take it out again, wouldn't the glue damage the coil ??

By the way I use transparent silicone for gluing, it takes longer time to set, but is easier to clean of and more flexible when dry, the glue from the heatgun gets very hard.

Søren Mexico:

If you had to take it out again, wouldn't the glue damage the coil ??

Please have a look at the photo of the filter "before" upgrade (2.nd. photo on this thread) - you will see the the "pertinax" washer on top of the coil.

/Frede

classic:

I don’t remove any wires at this stage.

I only pace the filter at the top of the cabinet and do the work here. I suggest using some protection between the filter and your Beovox 5000.

The process require a few changes to the filter because the new caps are physical much bigger and more heavy.

I will rearrange and I will use hot melt gluing of the caps.

  

This is the result of the rearranged part for the crossover filter.

The reason for gluing the parts is of course avoiding noise and vibrations.

more to come

Everything I've read over at diyaudio.com would lead me to believe those two inductors (coils/chokes) are too close together and should be separated to prevent magnetic field interferences.

Rich:

Everything I've read over at diyaudio.com would lead me to believe those two inductors (coils/chokes) are too close together and should be separated to prevent magnetic field interferences.

Here is my 3702 original filter, induktors allso close together.