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If the problem becomes persistent and on all sources, then you may have a problem with the PCB 2 Control board in the Penta.
Specifically a transistor BC 337-40; it switches the Penta on and off dependent on an incoming signal. There are more detailed
articles on the old forum that describe how to replace the transistor and where it is exactly; you would need soldering iron skills.
The BC 337-40 transistor was readily available 3 years ago when I suffered the issue.
See https://archivedforum.beoworld.org/forums/t/42040.aspx but there are more and better articles in the old archived forum(s).
Keep your fingers crossed that your transistor is not failing – unless your issue was a one off problem caused by a signal source problem.
I would speak to Steve at Sounds Heavenly; he is very helpful regarding all sorts of connection cables. He can be contacted on this site or on the Sounds Heavenly website where cables for a variety of brands, including B&O, are available.
I can see your reasoning for a DIN to Phono adapter cable (as I have a 5500, but Beolab Pentas) – that type of cable is available from Steve. He may be able to advise a better method though, so it would be worth messaging him.
Both sets of sockets will accept standard 2 pin DIN plugs to allow non-B&O (or) B&O speakers to be connected, as you require.
The 4 pin sockets carry the 2 pin loudspeaker signal (as in the 2 pin DIN plug) plus the extra 2 pins carry data for Beolab speakers
which have an LCD display indicating the source and volume.
The 3 pin sockets, as mentioned above, can be connected for an MCL system to allow multiple sets of speakers to be connected.
There are further documents in the archived forum which show cable wiring for the 4 or 3 pin sockets’ use.
Good luck finding any 4 or 3 pin B&O DIN loudspeaker plugs; they are very, very rare to find.
An interesting cause of the fault though, which is very useful to know. Switch cleaner/lubricant use as preventative maintenance might well be worth doing on the (pair of) Penta control board(s).
Would contact switch cleaner sprayed into the switches (when the control board is out of the Penta) be sufficient without resorting to physically dismantling the switches ? I’d be interested to know the level of corrosion in the dismantled switches.
The BM5500 can drive two sets of speakers (actually more) from the two pairs of speaker outlets. Both outlets (pairs) will take the 2 pin DIN plugs to drive two pairs of passive speakers or two pairs of Beolab Penta or both active and passive (pairs of) speakers.
If you connect a 4 pin DIN type plug to speaker 1 outlet Speakerlink you can drive Beolab Penta 1,2,3 and get the display data on the Beolabs. If you connect a passive speaker, e.g. Beovox Penta to speaker 2 then both pairs of speakers will be driven as well. Mute will only work on the main speaker 1 pair.
If you connect a 3 pin DIN type plug to speaker 2 outlet you can connect via an XTra speaker box a remote pair of passive speakers (or even a chain of XTra boxes). The datalink information goes down the 3rd wire so you can connect Beolab Pentas to the XTra box and get data display on the main Beolab Pentas and the remote ones.
For you, I would suggest making up the 4 pin DIN cable (difficult to buy and you will have to source or “manufacture” the four 4 pin DIN plugs). Beolab Pentas will be driven by the amp in the speaker – very little output comes from the BM5500. If passive speakers are connected, they are driven by the BM5500 and will need higher current cable.
Have a good read of “Beolink Master Control Handbook”. Try not to get too excited about the capability of running 2 sets of speaker in different rooms. I have a BM5500 with Beolab Penta 2 out of speaker 1 and an Xtra box driving Beovox Pentas out of speaker 2.
For cables, you can always try Steve at Sounds Heavenly but the 4 pin and 3 pin DIN plugs (made for B&O) are almost impossible to obtain (although I have been lucky on ebay once in a while).
Here is a refurbishment service on eBay:
https://www.ebay.co.uk/itm/295320288254?hash=item44c275fbfe:g:isQAAOSwfzJeQIWC
I have not used it myself, but you can read the feedback for the specific work you require.
I’ve had this with Penta II, 6622, but it’s the same issue for 2s and 3s.
See the archive forum at:
https://archivedforum2.beoworld.org/forums/p/17590/153806.aspx#153806
https://archivedforum2.beoworld.org/forums/p/45751/330229.aspx#330229
As I wrote in the archived post:
“The transistors TR3 and TR4 are on PCB 2, the Control board which, as you say, is the front panel. So 2TR3 and 2TR4 refer to (PCB) 2 TR 3 and (PCB) 2 TR 4. The transistors you have identified on the board are the ones to change. TR3 failing is a common fault and can also be the cause of a Penta always being green and not going into standby (red).”
Good decision. When you get your Beovox Pentas refoamed, I am sure you will appreciate the sound from the system.
If it is just the refoam of the mid-range units, then it is a straightforward job that you could do yourself. I’d rate it as “easy” as there’s no soldering involved just the need to be methodical and to label the wires and connections as you go. There is no need to “shim” the centre cones and methylated spirits will remove the old adhesive when used with a No. 17 knife blade.
It is helpful is you can connect each speaker to a source just to check the tone is OK as it checks the surround and cone are centred.
You can purchase foam surrounds and I would recommend the glue as well from various companies. I have replaced 2 sets in Beovox and Beolab Pentas with surrounds from the Netherlands who produce very good fitting surrounds. Don’t forget to order the backing rings that go between the back of the speaker and the surround into which they fit.
If you require more work, say, crossovers then that does require soldering skills and is more difficult. There is plenty of information on the archived forums.
There is/was a service on eBay offered as well – you buy the service and send your panels of 4 speakers in for refurbishment.
Aside from playing a record, you have the alternative of sending the MMC4 away; some of the companies that refurbish B&O cartridges will also provide an examination report. After a report, you can decide to refurbish or not. Refurbishment can be to standard MMC4 or various upgrades of stylus and/or suspension. Both examination and refurbishment are chargeable, of course, but you need specialist tools to examine the stylus and also the suspension mechanism. Have a scan through these forums for “MMC4”.
That’s what I did – refurbishment of MMC4 to standard. Well worth the cost (and wait).
Excellent work in providing the schematic.
I’ve had to repair an LC1 after it stopped working by replacing the BTA06-600T. Whilst it now functions, the maximum brightness is now limited so the schematic will be very useful in troubleshooting the problem.
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