ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Postman called this morning......got to replace the failed 0D2 zener diode, easy enough through the inspection cover underneath.
Blob of thermal paste to keep it cool......
Replaced 2D9 whilst I was in there and secured everything for a test....
With all four diodes replaced and power supplied selector presets P1 through P5 work fine, AUX2 and PHONO also work correctly, however (there it is again) FM and TAPE4 don't, the FM lamp lights and the tuning bar lamps light all the while the switch is pressed but they drop out when the switch is released, TAPE4 doesn't do anything when the switch is depressed.....so not out of the woods just yet, but getting closer.
Peter: https://www.ebay.co.uk/i/253287484307?chn=ps&adgroupid=43920634520&rlsatarget=pla-359427365517&abcId=1063846&adtype=pla&merchantid=113532435&poi=&googleloc=9046778&device=c&campaignid=797602469&crdt=0 I have had the full 6000 system - have to confess not that impressed! CD4 records are the best but have to be pristine and only played on a Beogram as the rear channels are destroyed by high down force styli. SQ/QS records do not have the separation of the CD4 and sound a bit odd if truth be known. I think I gave the records away but will have a look! SQ do have the advantage of playing on any deck with a stereo cartridge and the Beomaster then unscrambles the matrix.
https://www.ebay.co.uk/i/253287484307?chn=ps&adgroupid=43920634520&rlsatarget=pla-359427365517&abcId=1063846&adtype=pla&merchantid=113532435&poi=&googleloc=9046778&device=c&campaignid=797602469&crdt=0
I have had the full 6000 system - have to confess not that impressed! CD4 records are the best but have to be pristine and only played on a Beogram as the rear channels are destroyed by high down force styli. SQ/QS records do not have the separation of the CD4 and sound a bit odd if truth be known. I think I gave the records away but will have a look! SQ do have the advantage of playing on any deck with a stereo cartridge and the Beomaster then unscrambles the matrix.
The longevity of CD4 LPs was very limited with anything but the very best cartridges and tables. I remember my friend had a CD4 capable all in one thing from Panasonic I think, with the table it had you got maybe 2 or 3 playbacks before you didn't have CD4 anymore. The lack of a good way to distribute the music in quad doomed it from early adoption. Not until video surround sound did it come back and then not really for music. But I had always thought and heard that DSOTM was a good use of surround sound, and could believe it but have never heard it. At around that time I made a Hafler DynaQuad kind of decoder box, passive, and played with it. Just like Dolby ProLogic only without the delay, was only moderately interesting so I disconnected it and forgot all about it. I do have a DVD-A surround sound music demo disc that came with my car stereo, which sounds incredible, so the delivery system is there now but no one cares.
Jeff
I'm afraid I'm recovering from the BeoVirus.
Well....the strangest thing! I have no doubt Martin will explain this but I'm completely befuddled. I spent all yesterday evening removing suspect components from the FM network of the electronic switch board and testing each one with no result, hoping for a dry joint I was powering up after the replacement of each component but with no reward, the only odd thing I kept noticing was that the lamp 81L6 was lighting up but only quite dimly compared to all of its peers.....also the emitter voltage of 8TR12 was going up to around 7v when the FM button was held down. So I replaced the bulb with another (sorry Mr Roast) from my cashe of spares and bingo...all is well, on a roll I tested and replaced the TAPE lamp too, it was popped (the hits just keep on coming Roastie) and now that is working fine too, the FM bulb wasn't popped which is the odd thing.......Martin I know you can explain this?
Well, it's a long story - but a bit like Beomaster 1900/2400.
The lamps are an integral part of the circuit, all depending on a certain current flow, both when the lamps are on and when they are "off" (read: conducting less current than it takes to visibly illuminate them).
F.e. in the schematics you posted, you can see that lamp IL6 acts as a pull-up for transistors 5TR5 and 8TR11.
If 8TR12 is off, the bases of both 5TR5 and 8TR11 are pulled up through the lamp.In other words, the lamp is conducting a small current even when off.
In Beomaster 1900/2400 the balance/treble/bass setting illumination lamps doubles as bleeder for
the 15V supply, simply by being fed from that supply.
Without at least one of them (and preferably two), it can be very difficult to get the Beomaster into standby. It keeps popping back on because the15V supply is not bled down fast enough.
Right wattage lamps are essential.
Martin
Martin....that would have taken more lateral thinking on my part to work out than I currently possess.......it just seems so abstract a concept, It had to be something outlandish and cunning on the part of the B&O boys, nothing is ever as it seems.
That's the old girl repaired and fully functioning, she looks a little sorry for herself and this picture flatters her somewhat....I will await the outcome of the potential tuner wheel before I begin the restoration, I think she deserves the time and effort.
Thanks again Martin......your a font of knowledge as always ;¬)
Hi Craig.
I have now got a confirmation that he has the wheel,he demands 300 dkr for it,thats about 40 euro.
If you thought the price is okay he will send it to me during the week.
Henrik.
Henrik
Thank you for arranging this, it's a princely sum indeed.....however without it the Beomaster would never look its best. Please go ahead and request the wheel from your friend, let me know when you receive it and I will arrange payment for you to include shipping cost.
Thanks again and best regards
Craig
Another question for Martin......whilst awaiting delivery of the tuner wheel I have started putting together a list of components, replacing the quiet current 250 ohm trimmers with 25 turn units is a bit of a fiddle, soldering and the extended legs so they will fit is problematic. I have found some bourn 25 turn 1/2w side adjust pots that would fit much better without extending the legs, however they are only 200ohm....the manual says 250ohm 20% which suggests I would be fine to use the 200ohm.......what do you think?
I expect to have the wheel monday or Tuesday,so could you please send me a pm with your name and address.
Thank you...I have sent you an email with my details.
Regards Craig
Craig: Another question for Martin......whilst awaiting delivery of the tuner wheel I have started putting together a list of components, replacing the quiet current 250 ohm trimmers with 25 turn units is a bit of a fiddle, soldering and the extended legs so they will fit is problematic. I have found some bourn 25 turn 1/2w side adjust pots that would fit much better without extending the legs, however they are only 200ohm....the manual says 250ohm 20% which suggests I would be fine to use the 200ohm.......what do you think? Craig
As long as the correct point of adjustment lies fairly near the center value of the trimmer, you can add a 22Ohm resistor to each end ofthe trimmer.If not, just add a 47Ohm resistor at one end as suitable.
Cheers Martin....sounds like It would be just as well to fit the top adjusting trimmers and extend the legs after all, space is tight in there and fitting additional resistors would be just as tricky ;¬)
I could pick up the package today,and i send it to you tomorrow.
That looks awesome......like it just left the factory, thank you for sourcing this for me, I really appreciate your efforts it will mean I have to bring the old girl back to the same condition as the wheel but will be worth it ;¬)
Have a merry Christmas
The wood trim needs some attention......corners all stoved in
The other side is no better.....
need to get the wood filler out and build them back up again prior to applying some new veneer that I just happen to have lying around ;¬)
Sands up nice and sharp when dried.............
started gluing the veneer into place, one side at a time
Preparation is the thing here, the actual gluing takes only a couple of minutes
Had a visit from the postman today, the wheel is great Henrik thank you ;¬) also Mr Roast popped in to collect his BM6000.....such a grand chap! got a second coat of shellac on the cabinet before I got too far down the first bottle, more sanding to follow.
That's about it for the cabinet trim, cleaned up quite well.....
Now that all the Christmas indulgences are at an end I can spend a bit more leisure time more constructively......not that the indulgences where without there charms, in particular the bottles of wine gifted to us by Mr Roast, very nice thank you ;~). got around to replacing the big 10,000uf smoothing capacitor on the previously problematic power supply.
going to start with the power amp....cant believe how much this one has warped over the years, its only the wiring loom that has prevented a short on the solder side of the board against the aluminium support fro the pre-amp. Will glue a Mylar strip onto it when I'm done replacing components.
Extended the legs on the emitter trimmers and put some sleeving on them, not keen on having the legs crossed over and risking a short.
Replaced all the old electrolytic capacitors and fitted the new trimmers, also cut to size and glued into place the Mylar strip to prevent any possible short, I also eased the pressure on the amplifier retaining bracket that I suspected may have been contributing to the alarming bow in the board. Powered up and set the trimmers at 14.3mV and opened a chilled bottle......
Having now re established 4 off S45-2's I decided to run a test of the system before going any further, I had already confirmed that all four channels where now fully functional so wasn't expecting any issues........."however" on connecting my Ipad to the AUX2 input and playing a track or two from Spotify I couldn't help but notice I had to wind up the volume control of the Ipad to get a reasonable output from the BM6000. I confirmed there was an issue by reconnecting the Ipad to Peters BM6000 that is fully operational and found that I only needed around 20% or less volume from the Ipad to get a good output at all four channels as opposed to nearer 80% for the work in progress to provide good sound.....I'm thinking Pre Amp. Will investigate further this evening, my power supply woes may still be ongoing..........
Question for Martin.......
Looking at the circuit for PC6 there is a selector switch SW32 which has 2 positions HI and LO, seemingly when in the LO position this switch provides negative feedback for the amp stage through the resistance capacitance network, and when in the HI position does the same but without going through the RC network, reducing the gain to unity.
What position should this switch be in for normal operation HI or LO....could it be responsible for the loss in gain I seem to have, I'm away from home right now so cant simply test this by operating the switch........
Hi Craig,
the switch is for setting the AUX2 Input to low signal voltages and RIAA equalizing, which means it's a second PHONO in for Moving Magnet pickups or if in HI position for ceramic pickups, without an equalisation. This HI position could also be used for other line level signals (Ipod, CD, Tape IN, TV in...).
Ralph-Marcus
Ralph
Thanks for that, looks like I should have mine set to the HI position for connection to an Ipad, I will check the position of this switch on Peters BM600 too, see if its set differently to the one I'm working on. I think this means that with the HI setting the amp stage wont provide any gain to the incoming signal (unity) but will eliminate some noise?
Well sure enough both units had the SW32 switches set differently, Peters was set to Lo and the work in progress was set to Hi, set peters to Hi and now the amplitude of the Ipad is the same as that required for the work in progress.......another mystery solved with the help of our friends. I feel a mixture of relief and disappointment actually, I was sort of looking forward to tracking down another fault......should count my blessings really ;~)
Tone board posed no problems............
Level Board almost complete......this board is a difficult one to access, best done in stages to preserve one's sanity.
Level board sorted, Pre Amp 50% done........this board isnt a breeze either, always afraid of pulling the single strand wires off from all the pulling and tugging.