Nice find. Thanks for posting this information.

-sonavor

hi there, i notice you've had a lot to do with these. i've pulled the other apart to recap and note that someone has marked the PCB with GR and BR for the cabinet wires - but this did not correspond with how it was actually connected. are the markings correct?

http://i86.photobucket.com/albums/k91/mpwdhc/crossover_zps9vbygvlg.jpg

also, i presume the "bank" of wires to one side of the board are all negative, and the ones scattered around are positive? if so, the mid is reverse polarity...

I've only restored two (of my MS150 sets) so I am not what I would consider an expert by any means. One day I will have time for the third.

It is always best if you label cable ends and their respective board mounts before removing them.  On the Beovox MS150 crossover board the terminal someone previously marked as BR was for that reason.  BR is for brown and is the positive terminal. GR is for gray and is the negative terminal.

I haven't looked inside an MS150 since 2012.

Per the service manual ...

The bank of wires you refer to .... black (b), yellow (y), blue (bl) and white (wh) ... are connected together and to the gray (GR) negative terminal.

The black (b) also connects to the woofer negative terminal.
The yellow (y) also connects to the midrange1 negative terminal.
The blue (bl) also connects to the midrange2 negative terminal. 
The white (wh) also connects to the tweeter negative terminal.

The red (r) connects to the woofer positive terminal.
The orange (or) connects to the midrange1 positive terminal.
The green (gr) connects to the midrange2 positive terminal.
The violet (v) connects to the tweeter positive terminal.

sonavor wrote:

I haven't looked inside an MS150 since 2012.

Per the service manual ...

The bank of wires you refer to .... black (b), yellow (y), blue (bl) and white (wh) ... are connected together and to the gray (GR) negative terminal.

The black (b) also connects to the woofer negative terminal.
The yellow (y) also connects to the midrange1 negative terminal.
The blue (bl) also connects to the midrange2 negative terminal. 
The white (wh) also connects to the tweeter negative terminal.

The red (r) connects to the woofer positive terminal.
The orange (or) connects to the midrange1 positive terminal.
The green (gr) connects to the midrange2 positive terminal.
The violet (v) connects to the tweeter positive terminal.

An additional note:

On my link, the first pair that I restored were an early model of the MS150 (with the rosewood veneer on the back) and looking at the photos I have of that one, the wire color coding is different from the service manual I have. The service manual color coding I listed above matches the second MS150 pair and the MS150.2 pair. You can see the three different crossover boards

thank you. though the board had been marked, given the inexpert nature of the work performed in the past, i thought i'd try to be certain they were marked correctly. certainly the wires as found didn't match the markings. The big mid range toilet roll was dislodged, and one of the windings had detatched from the crossover. the dome mid range was also reverse polarity. 

after some listening, it became clear the speakers - one "original", the other with new caps and mid dome - were unbalanced. the original unit had very forward mid and high and little bass by comparison to the repaired speaker. i always felt they lacked bass, but that this was a symptom of the little tube amp. id always enjoyed the clarity of the mid range so was a bit disillusioned by the prospect of losing it. 

the only choice was to recap the other one and suck it and see. i don't know which was the biggest influence - rectifying polarity issues etc, or the recap, but the difference is huge - and i always thought they sounded great, anyway. very pleased. and after a night of listening to them, the replacement mid is definitely the correct one. i may buy a spare to stash away, either for these or the S80.2s.

thank you. though the board had been marked, given the inexpert nature of the work performed in the past, i thought i'd try to be certain they were marked correctly. certainly the wires as found didn't match the markings. The big mid range toilet roll was dislodged, and one of the windings had detatched from the crossover. the dome mid range was also reverse polarity. 

after some listening, it became clear the speakers - one "original", the other with new caps and mid dome - were unbalanced. the original unit had very forward mid and high and little bass by comparison to the repaired speaker. i always felt they lacked bass, but that this was a symptom of the little tube amp. id always enjoyed the clarity of the mid range so was a bit disillusioned by the prospect of losing it. 

the only choice was to recap the other one and suck it and see. i don't know which was the biggest influence - rectifying polarity issues etc, or the recap, but the difference is huge - and i always thought they sounded great, anyway. very pleased. and after a night of listening to them, the replacement mid is definitely the correct one. i may buy a spare to stash away, either for these or the S80.2s.