[Dillen]

Yes, I would suspect the IC before any of the small transistors.
Put a scope to the L/R signals from the IC and you will see.

Martin

[Dillen]

A bad MPX chip wouldn’t be a first.

Martin

[Dillen]

Ralph, nothing seems to be missing in that area.

Martin

[Dillen]

Yes.
Red drops.

Martin

[Dillen]

They are tantals. Tiny drop-like components.
Make sure you get their polarity right or they may go bang.

Martin

[Dillen]

You cannot find new woofers. No modern woofers will match the T/S parameters of the original.
They were custom produced for this speaker – unique to Beovox S80 and S80.2
That’s why we repair and refoam them.

What do you mean by “They came lose”?

Martin

[Dillen]

In the 70s, the white cabinet versions were typically the cheaper ones.
Today, they are often considered to be the most classic and timeless designs and may be
more sought after, perhaps because their “neutral” appearance has a certain minimalism
to it, and they will blend it better in many room designs than f.e. a wrong wood sort would.
Rare? – Well, certain products seem to be rarer in white than others.
Relatively many white Beomaster 1900/2400 can be found, as can the matching Beogram models, but matching white Beocord 1900s and 2400s are far between.

Martin

[Dillen]

1C20 and 1C21 points to C20 anc C21 on module 1.
They are capacitors – not ICs.

Martin

[Dillen]

Sure the problem is in the Beocord? Have you tried with a different amp or a scope?

Martin

[Dillen]

Replace also tantals 1C20 & 1C21 (1uF & 4,7uF).

Martin

[Dillen]

Replace tantal 1C19 4,7uF and let us know.

Martin

[Dillen]

Type number?

Martin

[Dillen]

Reflow the rivet vias. They are found on both the servo and decoder PCBs.

Martin

[Dillen]

How much, and what, was restored/rebuilt?
Capacitors?

Martin

[Dillen]

The short answer is no.
Beocenter 2100 is a very nice system in its own right (and highly collectable as they are getting rare), but it’s not that advanced.

Martin

[Dillen]

It’s the transformer.
Take it out, mask things off, soak it in lacquer under vacuum. Then let it dry in 50degC for 24h.
Fit it back with new rubber mounts.

Martin

[Dillen]

You didn’t tell us where you used the wirewound resistors?

Geoff, are you here, listening?
I wonder if you could find a few words to say about this,
– why, do you think, Bang & Olufsen never addressed any of these, seemingly serious,
issues in any of their passive speaker models and is it, perhaps, something that will
be taken into consideration when you develop and design new speaker models for B&O?

Martin

[Dillen]

xschop wrote:

1. Thank you. You did a fine job yourself, takes Alot of patience. Yes, I painted the frames satin black to match the cones. I rebuilt crossovers with film caps and wire-wound resistors. I also machined and phase-plugged the midranges, as well as foamed the inner baskets frames for ultimate clarity. I’m running them in conjunction with a rebuilt Polk RM-1000 subwoofer and custom tpa3255 amp to match aesthetically. Pure audio bliss.

I find this interesting,
– a few questions if you don’t mind:

Wire-wound resistors – where?

“machined and phase-plugged the midranges”
What is that, exactly ?
Is that the cone shaped thingy? If so, can you tell what improvement this provides?

“Foamed the inner baskets frames for ultimate clarity”
Interesting, – what is the theory behind this?
And do you have any before and after values that would cast light onto what improvement this provides?

Martin

[Dillen]

No relay click when you select a source?
Front panel correctly fitted? – If the bronze forks under the front panel does not grip
each their little pin on the circuit board, the touch fields will not work.

Martin

[Dillen]

Something shorted?
Which transistors did you replace?
How did they measure wrong?
And what did you fit instead?

Martin

[Author]

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