Beolab Penta: how do you get to the crossover PCBs?

[klesolin]

I see them in the service manual, they’re boards 14 and 15. But they don’t really tell how to get to them.

Is it just a matter of unscrewing the foot and the plastic base and then I can slide them out?

I’d like to inspect the capacitors and see if they need replacements while I have them on the bench to replace the surrounds on the midrange drivers.

Thanks

[Glitch]

1. Remove amp
2. Remove bottom plate
3. Remove wires from crossover(s). Wires are color coded and labeled on the crossover.
4. Pull hard.  The boards are held in place by friction (even though it might feel like they are welded in place). The boards slide into slots in the housing. There might be tape on the board to keep it from rattling. Try not to pull on any of the crossover components.

Hopefully this makes sense. Good luck!

Glitch

[Die_Bogener]

 

[Die_Bogener]

Usually the caps in the crossover are not the real problem. I found very often defect broken coils.

[klesolin]

Thank you. I had a look, the caps look OK and so do the coils. The speakers sound fine to my ear.

Do you mean physically damaged coils? How can they get damaged from within the speaker?

[Glitch]

klesolin wrote:

How can they get damaged from within the speaker?

I’ve always assumed that the damaged coils were a result of people pulling their crossovers to check if their coils were damaged. 😉

An alternative (more serious) explanation is that the coils break loose from a hard impact during shipping.

Glitch

 

[Die_Bogener]

Shipping? Yes, that is possible.

Heat? Yes, the glue is not very stable against heat and becomes soft/sticky around 60-70 degrees C. It is not epoxy, it is something like a hotmelt glue.

I think, heat and overload can do this.

Pulling boards? Yeaaah… sure.

But most: i think the Penta was dropped during transport or by running kids/dogs/cats. Most of them had massive damages on the top plate. So there was a very hard impact…

But it can be repaired, it just needs time.

[Author]

Posts