I currently run a BeoCenter 9300 with a pair of Penta 1 (SL to PL adaptors) and have an odd issue.  On one penta the display, amp, woofer, and tweeter seems to work just great just the midrange seems not to be working (did test sweeps to isolate midrange output to no avail).   On the other the display works just fine but the amp turns on for about 3 min then powers off and no sound ever comes through the speakers, but the display remains on and updates the info just fine while the amp is off....  they both turn off when the 9300 is turned off...   now I do have a BeoCenter 9000 that I also tested the pentas with and the same issue occurs...  any suggestions? and the suggestion to get penta 2s/3s isn't much help.

If the midrange units are not working, I would suggest a problem with the cross over - the Penta is a powered speaker rather than active so have a passive cross over above the amplifier. The other problem sounds like the protection circuit switching on - what colour is the light on the amplifier? 

Have you tried plain speaker link? In the short term, you could even try just using them passively - the amplifier unbolts and you could have these serviced - you could also try swapping them over to see if you could isolate the fault. 

Nice car by the way! TR3 ?

the amp goes from off (red) to on(green) then to off(red)  the amber light does not come on.   any suggestions for the midrange?  ies examples/diagrams?

and yes... it's a 1957 TR3.. good eye.

As I recall there are 2 boards that together make up the crossover (it's quite complicated in there). One board does bass/treble and the other does midrange. The midrange one is connected to the base/treble board by a couple of wires so it sounds like the midrange board may simply have become disconnected. It would be worth taking the base off the speaker and seeing if there's anything loose in there.

That's a possibility, but if the connectors were last off at the factory, they are very tight and should not get disconnected by themselves (you're more likely to need pliers). Worth checking though, as the midranges indeed rely on just those two wires between the boards.

If the condition of the midrange drivers themselves is unknown, try putting a flashlight on the fabric as shown on the attached picture, and peek if they have any of their surround foams left... still, they are connected as two series pairs, so at least two of them would need to already have a damaged voice coil to mute them completely.

The other speaker has an amplifier fault and needs service - it's anybody's guess what the exact problem is without going in there.

ok I just re-foamed the midrange speakers so I know they are fine... they worked great before re-foaming... and did work for a time after...   but now... nothing.  My weekend project is to completely review the wiring with the service manual, pliers, ammeter, soldering iron, etc handy just in case there is some issue with it...   I will also take a look inside the amp to see if visually there is an issue... any other ideas? so should I post more (with pictures) this weekend if I find something out of order...

Oh, you should've said up front that you have been in there already. Pretty sure it is a connection problem then, at least for the non-operational mid unit.

I'll leave fiddling with the amp itself to somebody who has actually been inside of one

ok upon exploring the amp a bit (in the one that wasn't playing); there was a blown fuse so I will replace that tomorrow.  All caps look good and test out, each an every resistor was tested and also ok.  Removed both boards inside tower and tested each component and it looks good.  Had to re-solder a couple of wires to the DIN connector but that was simple enough (yes I made a note of location and got it right). Reconnected all the wires and "sealed" the tower.  I will replace the fuse, re-assemble the amp, and add it to the tower tomorrow and hopefully that one will work out.   As per the other tower.. I will take a look at it tomorrow and hopefully it will work out as well.

I imagine the connection simply was disturbed to the midrange but you clearly know what you are doing. Hope it all works! Pleased to say my GT6 convertible is tucked up in its garage! About 8 inches of snow here!

hrmm upon checking everything I did run into one issue... only one issue.. for some reason the 5A 250V fuse on the amp blows on one of the towers..  when I try and isolate the issue I cannot seem to trace it to anything.  any ideas?  it happens as soon as I plug it into the wall..  and yes the voltage here is adequate for the power rating for the amp.   

snow...  yeah I moved down to Texas from Massachusetts about a year ago and really really glad that I did...   no snow.. but still a bit cold... the odd thing though..   I still keep the car in Wisconsin, just seems to work better for me.. 

ok everything all fixed.. I also picked up a pair for penta 3s!!  thanks much!!