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
Hum, HUM, no more, checked the 35 VDC, was down to 27 V, checked my power lines, one phase was down to 100 V, another phase was stable at 115 V, changed to that one.
Now playing with test speakers connected, but not sufficient volume, normal listening level at 3/4 at the slider, my BM 4000 reached that level at 1/3.
Stereo separation good with a good FM station, output TIPs Temperatures at 25 *C . But 5TR2 at 78*C, I dont like that.
Collecting Vintage B&O is not a hobby, its a lifestyle.
Very hot here too. I remember discussing this with another member...
Jacques
Connected CD to tape1, no problem, but same low volume level, and I get the hump in the speakers turning on and off. Turning off, first like a click in the left speaker and then a hump from both.
When you say the DBT is bright...you mean it stays bright the whole time? What wattage bulb are you using?
No its OK now, it was probably the low incoming power, now connected without the DBT, but I'm still fighting low volume level and speaker sonnds turning on and off
You mean a thump with you turn the speaker switch on and off?
Sorry, I didn't read all of your previous post. I sometimes get the thump on my Beomaster 4000 and 4400. I would like to fix that if possible but what I do is always start with the volume all the way down, turn on the receiver, then the speaker switch and finally adjust the volume. I do the reverse when turning off the Beomasters.
The "thump" is normal at switch-on, and switching off will have the woofer diaphragms move a bit too!
Have more or less the same in my BM 4000, but I'm still fighting the volume level, should be a lot louder, running small speakers. 4 ohm.
My 4400 also has a loud thump through the speakers when turned on, a characteristic that I don’t really appreciate. There is a soft one when it is turned off.
Jeff
Beogram 4000, Beogram 4002, Beogram 4004, Beogram 8000, Beogram 8002, Beogram 1602. Beogram 4500 CD player, B&O CDX player, Beocord 4500, Beocord 5000 T4716, Beocord 5000 T4716, Beocord 5000 T4716, Beocord 8004, Beocord 9000, Beomaster 1000, Beomaster 1600, Beomaster 2400.2, Beomaster 2400.2, Beomaster 4400, Beomaster 4500, Beolab 5000, Beomaster 5000, BeoCenter 9000. BeoSound Century, S-45.2, S-45.2, S-75, S-75, M-75, M-100, MC 120.2 speakers; B&O Illuminated Sign (with crown & red logo). B&O grey & black Illuminated Sign, B&O black Plexiglas dealer sign, B&O ash tray, B&O (Orrefors) dealer award vase, B&O Beotime Clock. Navy blue B&O baseball cap, B&O T-shirt X2, B&O black ball point pen, B&O Retail Management Binder
The volume level:The line switch works, volume, treble, bass, balance works, but loudness does not give any difference, and the high and low filter neither, so there may be something around there going wrong. On the other hand I have 1.6 V coming out at TP 107. I'm afraid of going onto the amps again, the PCB is so crowded that I may short something.
I have all the power feeds a little on the high side, 35 V = 36 V, 24 V = 24.9 V, so that should be OK and the volume is the same right and left.
The BM has been running for some 2 hours, without problems, the components temps. stays stable.
I'm going to take my siesta, when I start again I will find something.
Piaf: My 4400 also has a loud thump through the speakers when turned on, a characteristic that I don’t really appreciate. There is a soft one when it is turned off. Jeff
Loud is bad, probably your caps, mine is not loud, but I thought someone had a solution, but do as Sonavor, volume down, speaker off, and then turn off.
chartz: The "thump" is normal at switch-on, and switching off will have the woofer diaphragms move a bit too!
In a way it is good to know that it is “normal” to have that initial thump rather than another issue, but it is annoying.
Søren Mexico: Piaf: My 4400 also has a loud thump through the speakers when turned on, a characteristic that I don’t really appreciate. There is a soft one when it is turned off. Jeff Loud is bad, probably your caps, mine is not loud, but I thought someone had a solution, but do as Sonavor, volume down, speaker off, and then turn off.
Well I can just add that to my list of issues. When I say loud, I don’t mean LOUD, it is pronounced.
Piaf:In a way it is good to know that it is “normal” to have that initial thump rather than another issue, but it is annoying.
It may have something to do with that these BMs does not have a standby function, my BM 2400 does not make these sounds and it comes on and off from and to standby.
Correct. Nothing to worry about.
Søren Mexico: Piaf:In a way it is good to know that it is “normal” to have that initial thump rather than another issue, but it is annoying. It may have something to do with that these BMs does not have a standby function, my BM 2400 does not make these sounds and it comes on and off from and to standby.
None of my other Beomasters make this sound, not the 2400 or 4500, and certainly not the BeoCenter 9000.
I had simply assumed that the thump was one of a “collection” of oddities my 4400 suffers from.
Should you be interested I have started my own thread [not wanting to interfere with your terribly interesting thread] to determine if my 4400 is safe to use in the “North America” category and titled “Operational Safety.”
Jeff, your Beomaster 4400 is fine...
chartz: Jeff, your Beomaster 4400 is fine...
Hi Jacques,
Well that response really put a smile on my face because previously you agreed with Halmstad who said not to use it.
Martin says that I am probably safe to use it, but then Peter commented, not so fast, as he wasn’t sure that is what Martin meant.
Now I am really confused.
Søren Mexico: No its OK now, it was probably the low incoming power, now connected without the DBT, but I'm still fighting low volume level and speaker sonnds turning on and off
So was the problem on the fault protection being off due to applying power up slowly using the variac?
chartz:Correct. Nothing to worry about. Jacques
sonavor: Søren Mexico: No its OK now, it was probably the low incoming power, now connected without the DBT, but I'm still fighting low volume level and speaker sonnds turning on and off So was the problem on the fault protection being off due to applying power up slowly using the variac?
Yes, the low 15 V feed also activates the fault switch, and it stays connected until the power is of or below 40-50 VAC. Also with 1 channel (P11 or P!2) disconnected it activates, comes to that, yesterday I had a power blackout, when the power after a couple of hours, 1 phase was down to 100 VAC, or just under, result: there was only 26 VDC on the +- 35 VDC, so the whole time we were working on something we couldnt solve. But now we know.
Will start again in a few minuts, I want to find out why I dont have full volume..
Rich: chartz: Correct. Nothing to worry about. Jacques I'm not so sure. That thump on my BM4000 scared the heck out of me when I had a 4" Fostex full range hooked up. The driver moved a good half an inch during the thump. With the bullet proof 10" woofer of the M70 no big deal, but that Fostex isn't designed to move that far. I won't use it with the BM4000 again.
chartz: Correct. Nothing to worry about. Jacques
It scared me too, now I just find it annoying. However unlike you I am running S75 and S120.2 speakers, neither of which are going to be bothered by that thump….. plus as Sonavor says, just turn the volume way down and we won’t be bothered.
I have been checking voltages on the PCB 5, where is the muting and silent tuning, but no luck all voltages OK, the low volume must be something that has to do with both channels, as I have same volume in both channels. Only thing I found is no light in the lamp for the signal strength meter, I have 16 VDC there. Have to wait for some expert advise from the forum.
But I must confess, I'm a little proud of that I got this BM working as far as this, biggest job I ever done in this, for me, new world.
The time I used for it, is the time I use for installing 2 pcs., 6 color, 32 tons, printing machines.
Yes, that was definately a big one and good work. I am not sure what the problem is offhand regarding the lack of power. Since it affects both channels could it be a power supply problem? What about through headphones? Is there enough volume for you to tell that the sound is good? Did you make sure the Ambio switch works and is turned off and did you try the speakers in both speaker connections?
Ambio switch works, power supply feeds all + 0.5 to1.2 VDC, tried both speaker connections, with different speakers, did not try headphones, All plugs and jacks on the PCBs was cleaned one more time, but no difference, filters and loudness switches do not work, I may have to get at the PCB8, PIB. I´m sure switches work, but they give no effect.
Can you tell if you are getting a stereo signal?
sonavor: Can you tell if you are getting a stereo signal?
Stereo light is on when tuned to stereo station, sound changes when mono switch is activated
Piaf: Martin says that I am probably safe to use it, but then Peter commented, not so fast, as he wasn’t sure that is what Martin meant. Now I am really confused.
What?
We were talking about another situation and another Beomaster, weren't we?
Here we were discussing the switch-on thump!
chartz: Piaf: Martin says that I am probably safe to use it, but then Peter commented, not so fast, as he wasn’t sure that is what Martin meant. Now I am really confused. What? We were talking about another situation and another Beomaster, weren't we? Here we were discussing the switch-on thump!
I am sorry, I must have confused you. We have a similar amp with a thump when turned on.
Søren Mexico: I have been checking voltages on the PCB 5, where is the muting and silent tuning, but no luck all voltages OK, the low volume must be something that has to do with both channels, as I have same volume in both channels. Only thing I found is no light in the lamp for the signal strength meter, I have 16 VDC there. Have to wait for some expert advise from the forum. But I must confess, I'm a little proud of that I got this BM working as far as this, biggest job I ever done in this, for me, new world. The time I used for it, is the time I use for installing 2 pcs., 6 color, 32 tons, printing machines.
Søren,
My heartfelt congratulations on your well earned victory. I never doubted that you would get it right, but like you, I was surprised that it took so darn long…… but that only makes the triumph sweeter.
Søren Mexico: Stereo light is on when tuned to stereo station, sound changes when mono switch is activated
I'm not sure what to tell you to try next Søren so I'll just throw some things out there. I would suggest getting a hold of an oscilloscope to check the audio analog signal at left channel pre-amp stages: TP100, TP101, TP120 and TP107. Also at the right channel TP200, TP201, TP220 and TP 207. That would show if the audio signal is the same. As you know, the Linear switch bypasses the bass, treble, loudness and filter circuits between those points so monitoring the audio signal through that part of the amplifier while using the volume and linear switch might tell you something. Could there be a problem with the switches involved not making good contact? Could the overload light not be working and the Beomaster is actually in protective muting mode? Do you have an 8 ohm speaker you can try? Have you tried just headphones yet? Did you say the +24 VDC rail voltage checks out fine?
Sorry if these are things that you have already tried but I am trying to think of things that are common to both channels.
I'll go at it tomorrow, but as I dont have an oscilloscope, I can only check voltages through the systems, will start at TestPoint 100 and go through to TP 120. I was thinking about the muting function, but yesterday I was around there and checking the voltages around there, they all shows near the volts on the schematics, the overload light works, it came on 1 or 2 times when I was fumbling around. Will make a list with the TP values, maybe that can help us.
Very odd, the low output being the same on both channels. In lieu of an oscilloscope do you have a signal generator that you can use to input a constant sine wave of a set voltage so you can use you DMM to check the AC levels? Or a cassette or mp3 file with a fixed tone you can use to detect as it goes through the amp? Right now my bench is full with the audio tester project assembly right now...otherwise, I would open my BM 4400 and take some measurements you could compare to. I do have my 4400 connected to two speaker systems though - S75's and a pair of CX-100 with a Cona. Playing it today I saw that in both cases the volume is at a good listening level with the volume slider at 30% (3). The S75's are listed as 4-8 ohms and the CX-100/Cona are listed at 6 ohms. So there is definately something wrong if you have to go up to 70% volume (and still have a low level). I went back and re-read where you said your tone controls and balance work. There is something wrong if you can't notice Loudness. The filters are a little harder to tell. You can probably tell easier using headphones. If those aren't working, what about Linear? If you turn up the Bass and Treble all the way, then turn on Linear to you hear everything go flat?
sonavor:Very odd, the low output being the same on both channels.
Very odd indeed, I'm reading the schematics again and again, and dont see anything obvious that can explain it, the muting seems to work as when I am tuning from station to station, I get first white noise, then silence, then white noise and then the next station. Liniar is working, I will chack with headphones for the filters, Loudness is NOT working, On my other BMs its easy to hear the difference, on this one there is non.
The speakers I use for tests has been connected to all my BMs without problems, I can connect my S45s (2 way) 8 Ohms, but I doubt that this will make a difference.
As for the filter and loudness contacts, I doubt that all of them will fail, and in both channels, as all the other ones are working flawlessly, I have worked them on and off, a hundred times or more, no reactions what so ever.
There is a table in the manual, where the volts are shown with muting on/off, AFC on/off and so on, will check these first thing.
I was hoping to see some comments from the other experts, but no such luck. Maybe they are just holding their breath.
I am for one holding my breath, yes.
If the 'linear' switch works as it should, defeating tone controls, then I do not get what's wrong. Since you took out the main PCB, perhaps you forgot something... P13? Missing cap on PC8? Mmmmm...
Sorry I cannot help.
Jacques, you are into my line off thoughts about it, and I have been checking and rechecking the connections, will go through it one more time, and if I do not find anything today, next thing is to get at PCB 8, and P13
If you get through all the mechanical (switch) testing without the problem being found then I guess that takes us back to the problem being in the amplifier circuit. Can you increase the idle current a little and see if that has much affect on your output? I take it you have gone back and reviewed the output amplifier transistors? What about all the new trimmers you installed? Have you adjusted any of those (like one of the tape inputs) to see if they improve the output?
Is there a way to separate (cut) the signal path from pre-stage to power-stage. If so, do that and introduce an external signal (line level, like an external pre amp) source to the powers stage. Then you could verify if the power-stage is working properly or not and thereby isolate the problem to either the power-stage or the pre stage/tone volume control.
//Bo.A long list...