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
Thanks Mika!I thought that one should be able to use some silly little resistors to build one's own attenuator.40 pounds for the Rothwell gizmo isn't excatly cheap, but on the other hand it's probably well made, which my own gizmo probably will not be.When I measured the voltages by the way, it was a mess. Not until I used a high quality multimeter did I see that perhaps the values of the CD wasn't that high, but rather around 0,4V, or up to 0,4V. With the DAC I could adjust the output so that it stays below 0,2V.What is the normal output supposed to be in the line out of a CD?Does impedance play a part in this?
Now something different, which fellow Beomaster 1000 fans may find interesting. An article from the Swedish magazine Populär Mekanik, from 5th of May 1965. A short review.My translation to English below.
For the music lover:Beomaster 1000Wonderful news for music lovers - a compact fully transistorized combination of HiFi-stereoamplifier and FM-radio with many uses.The highly selective FM-radio sectio: enlarged FM-band (up to 108 Mc/c). 3-time(?) variable capacitor and 4-stage middle frequency amplifier with 4 limiters. Automatically sucks in FM-stations and locks them at the best setting. Built in FM-antenna.---Special indicator for station setting. Prepared for coming radio-stereophonic broadcasts over one station, designed so that a B&O multiplex-unit (sterodecoder) can be connected to a multipole built in connector.Equipped with a "Beacon" indicator lamp, which lights up when the reciever is tuned to a station that broadcasts FM-stereo. This indicator lamp also lights up when set for playing stereorecords or stereotapes.---Constructed in accordance with the international I.E.C.-standard for oscillatorradiation, so that by using Beomaster 1000 one does not risk disturbing the neighbour's radio- or TV-reception.The amplifier section, over which both stereophonic and normal records can be played, has a very powerful output power of not less than 2x15 watts. The speaker switch can direct 2 pairs of stereophonic speakersystems, for example a pair in the living room and another or several set of speakers in other rooms.Separate, powerful bass- and treblecontrols. Balancecontrol for correct "stereophonic sounddistribution" when playing stereorecords or tape.Physiologically compensated volumecontrol, which gives full balance in the whole tonal area at all levels. Very low distortion, thanks to the transistorized, transformerless amplifier. Separate treble- and rumblefilters. Pushbuttonswitches for the following connections: FM-radio, FM-automatic, taperecorder, and gramophone 1 and gramophone 2. Low power consumption.---Beomaster 1000 is constructed for connection of external speakers, for example the groundbreaking B&O pressurechamberspeakers.
Not sure if someone still follows this thread, but here is an update on my Beomaster 1000. It took a while, but capacitors, zener diodes and a few new old stock AC128 transistors (found on ebay) was bought. Yesterday I exchanged 11 capacitors, one zener diode and the AC128-3, which had been replaced by someone with a silicon transistor that was fried. I also made my own heat sink for the transistor, which you can see as a little copper "star". Not sure if that was really necessary, if those transistors get that hot, but it originally was mounted in a sort of heat sink, that now seems disfunctional, so I thought I should make some sort of heat sink, it was a fun project. The Beomaster now works and plays beautifully! It's connected to a pair of Beovox 2702 and a pair of Wharfedale Denton from about 1970. Superb sound! This machine is a jewel.I am amazed that the capacitors still seem to be working and have retained their values. They are like 50 years old. I was going to replace ALL capacitors just for the hell of it, to have it back to factory new condition, but now I hesitate, is it necessary? It sounds great as it is.
Sure we follow! Nice work and glad you like it. I had mine (the later black version) for a long time before actually trying it out properly, and was surprised at how good it was.
All the electrolytic caps might be better replaced, but if it works & sounds good now and you don't mind opening it again if need arises, I would probably just button up the receiver and enjoy it.
Plastic film/foil caps and ceramic caps don't usually age at all, so there is no need to replace them unless they are physically cracked.
--mika
Thanks Mika!
There are some caps in the schematics labeled PE, and some other like ceramic, these usually have lower values and high voltages. I have had some problems locating replacements for these and also heard that they don't age like electrolytics. But there are quite a few electrolytics that should be totally aged now, or so I thought, but I haven't found one that was severely bad, after 50 years. But I still wonder if perhaps their performance has deteroriated somewhat, although the F values are still within spec (this is the only value I can measure), and what would be gained from replacing them..? I may just button it up and enjoy it! I paid 190 kronor for this Beomaster, that is like 20 euro, then another 20 euro for components. That is absolutely amazing for this sound quality, I love it! The front rail of the radio scale is still broken and I am looking for a way to solve this, maybe construct something. If anyone has a clue of how to solve this I am eager to hear!Next project is to wake up a black version Beomaster that is waiting in my storage room. Would be so interesting to compare them. Have anyone compared the black and white version in sound impression?
I only have the black version so no!
Funny you should mention you want to fix a black one, I for one would like to find a white one - possibly white, not yellow...
Now what about that Beogram eh?
Jacques
Yes, looking for a nice Beogram!Was not in a hurry for the plan was to restore the Beomaster first, but now it's time to find a Beogram too. You recommend the Beogram 1000?I have never owned a gramophone and know very little about it's mechanics. Where do you find spares, like needles and spares for example for the "drive train"?I saw that there were a couple of white key Beomasters on sale on French ebay lately. You are located in France I believe. I also saw a couple on hifishark.com advertised in France. If you find one and start to restore it, I would love to follow your restoration.
I have a question that I find very interesting and would be happy if someone could bring light into this matter.In another thread I found this quote by Martin:Now is not the time for me to tell you that the large filter capacitor can explode. Don't ask me how I knowor how far I wasn't from the Beomaster...I like to replace it with a 2200uF 50V component in all Beomasters of this type. The rectifier is properly dimensionedand will have no problem at all with the somewhat higher rush-in current plus it will give a slightly better filtering (and agreatly reduced risk of explosion).The two output series capacitors can also be replaced with capacitors of the same type. The originals will have passedtheir sell-by-date by now and it will give a much needed kick to the damping factor which in turn means a muchbetter control over the low frequency (bass) range. You will like this, I know. In fact I did just this, replaced this big cap with a 2200uF 50V. I also replaced the two output series capacitors, with 2200uF 25V (Nichicon KA Audio Series). These are slightly over spec. I know the +/-20% rule. But how far off can we go in F value. I could not find close enough values for some components. Are there some places in the circuit where we must be more careful to be close to original compared to others? For example, in the schematics is the capacitor 905, it's a 125uF 16V, close to the zener diode and the AC128 I replaced. For this I didn't have a close value, I used a 220uF 16V (Nichicon FG Audio Series). Aware that this was 76% higher I tried it anyway. Now I don't know for sure what this capacitor does, but it seems to be involved in power supply. Soon I plan to replace several caps in the amp section - some are originally 1,6uF while I plan to use 2,2, and there are many more 125uF caps in this section, but dare I replace them with 220? What would you do?I know you could put them in parallell and so, but now the question is about overspec value on a single cap. I also want to stay within the same range, that is Nichicon audio series and Elna Silmic, so that limits my choices somewhat.It works fine now though, with what I have replaced so far.Another question, do I need to upload photos to Media library to be able to attach them here?Thanks so far for all the help you have given! I enjoy this forum tremendously.
It's next to impossible to give a secure handrule for replacing no-longer-available component values, besides the+/- 20% "rule". Upping the capacitance of caps in certain positions will give a problem rather than an "upgrade".However, for most electrolytic capacitors, it'll be alright to grab the next higher capacitance value.Well, as long as we talk about filtering and decoupling capacitors, anyways.From 125uF to 220uF is quite an amount. I would recommend 150uF instead (which is not a standard value, butcommonly available regardless).The output series capacitors can be upgraded a little more freely than other caps, it will give a betterdamping factor, which you may (or may not) hear as a slightly tighter bass response. - But the originalvalues were perfectly adequate already.
In most cases:1,6uF -> 2,2uF80uF -> 100uFetc.Will be perferctly acceptable.Martin
Thank you Martin.I see. I will really try not to stray too far away from the original values.Perhaps I could get away with the 220uF instead of 125uF this time because it is a filtering or decoupling capacitor (I am not quite sure what). But for the amplifier section I was sceptic, so I have ordered 150uF Vishay/Sprague capacitors. One could perhaps use a 100uF and a 33uF together, but that seems messy.There was also one case where I could not find a 50uF 40V capacitor so I ordered a 47uF 50V, but that I assumed was close enough even if I avoid lower values.I have no intention to try to "upgrade" the design, actually I really want to avoid it, my ambition is to restore it as close to original as possible with high quality components.
The work continues. Today 25 capacitors were replaced. I think that was all electrolytics in the amplifier section, except those 125uF mentioned earlier.It still works. Being a complete amateur I am glad I could do this.
The sound is different from yesterday, but maybe because the caps are new and need a few hours. There is more clarity at high frequencies but the lower end is still the same. Odd thing is that at low volume there is a bit less treble than at higher volumes, when increasing volume treble also increases slightly. I hope this is not an issue because some of my caps were out of spec..There is a "brrrr" sound from the transformer (sometimes disappears for a little while).I used IPA to clean switches. Then something called PRF 7-78, its a contact spray I was recommended at the Swedish store Kjell&Co, for using with electronics. It is supposed to clean and leave a protective "oil film". Is this really good? It leaves a greasy film where sprayed. After using it on the switches, particularly the Radio source switch - I ended up with no reception at all. Then switching a few times and it came back. Just wonder if this spray is really good or if you sensible guys use only IPA?Oh yes, I have another question for you who still follow my project, how come my other Beomaster 1000 have excellent FM reception even without antenna, while this one has very weak reception (almost nothing is heard)? I read somewhere that Beomaster 1000 has a built in antenna, but that must surely have been an error?
It died! There was a mystery component, a capacitor that did not exist in schematics, at least I think so. A 125uF/16V capacitor. After exchanging this it just makes a "wowowowowo" sound.. I don't think its because of this component, I changed it back to the old one - to no use. I have done all I can, very sad that it worked earlier and sounded great and now it doesn't work at all..I didn't use the power switch, just plugged the cable in and out (keys not connected and didn't want to stick things down in there), perhaps this caused some power surge that destroyed a transistor or something..? Nothing should have been shorted, no things left could have caused damage.. I have no idea what happened.I am very sad..See photo for mystery component if you are interested.
Come over to me with it.I have about 2-3 weeks line right now, but will have a look at it when I canChristian
My re-capped M75 are my precious diamonds.
My saviour!Tack.
I really wonder what happened today..
Beomaster 1000 has no built-in antennas.You didn't use low-ESR capacitors - did you?That could explain both the change in sound and eventual motorboating.
Martin
No built in antenna, I thought so. Quite sure I read it somewhere but of course investigating the matter in my own machines made me conclude there was no such thing.No I didn't use low ESR capacitors. They were all Nichicon audio grade, KA or FG series. These are not specially low ESR I believe, and should fit these applications.The change in sound is quite subtle, not so obvious. I don't think it is necessarily for the worse, except perhaps that treble/bass ratio changes a little bit depending on volume.The motorboating sound was a change for worse for sure, in fact it's completely unusable now, it's not subtle - it's possibly speaker damaging bad. Maybe something with the transformer, it did make a sound like a bumblebee before.
Check that you got the polarity correct for all caps." treble/bass ratio changes a little bit depending on volume" I suppose is the built-in Loudness you can hear.
Yes, I should have got the polarities right, I am quite sure. Also it worked and played beautifully for a while.I had done all work for the day and sat down with a cup of tea, very satisfied with myself. Then I started to think about that "mystery capacitor", and realized I probably had made a mistake. This was while the Beomaster was playing (some bossa nova I think). This capacitor was not marked correctly in the schematics, and I had misunderstood it and put in a much higher F and V capacitor. Though it played so beautifully I decided to replace it with a more suitable cap, because perhaps this was the reason the radio was odd and the mystery cap seems to be involved with the radiosection. I put a more suitable cap in there instead, and then tested it - all that came out was "wowowowoo". I put back the original cap (125uF 16V), not really thinking it would make a change - which it didn't - still "wowowoo". This little operation couldn't possibly have cause the problem I think..That was a long story - in short - it worked perfectly and then it stopped working for a reason I can't understand. The built in Loudness, it's a step towards putting it back in original shape that I could hear this more clearly suddenly then.Does all Beomaster 1000's have built in Loudness?
The built in loudness has a perfect match with Beovox 1000 in sensititvity and and caracter.I would never modify a beomaster in such way
Jeppe: Does all Beomaster 1000's have built in Loudness?
Does all Beomaster 1000's have built in Loudness?
Yes.
Thank you Christian and Martin.I didn't mean the Beomaster's Loudness should be modified in any way, I don't want them modified. Just meant that the restoration may have brought the built in Loudness back to life, because it seems there was a difference here before and after my "restoration". Sometimes perhaps a restoration becomes a modification by necessity when you can't find original parts, but at least I intend to not modify it.Perfectly paired with Beovox 1000's.. How sad I missed an auction on tradera.com yesterday of a white Beomaster 1000, a Beogram 1000 and a pair of Beovox 1000. Went for 675 kronor (approx 70 euro).Felt like now that I have 3 Beomasters (and Christian is kindly helping me with two of them), I couldn't find a reason to buy another one, not at the moment at least..But the Beovox 1000's, they're good you say..?At home now a white Beomaster is paired with Castle Kendal speakers, the original version hand built in England in about 1971. Restored by Andrew in the UK, who I again really recommend! It's the third pair I buy from him. https://www.anapeachloudspeakerrestoration.co.uk/Power handling 40W they say, larger speakers than the Beovox 1000's, but the match is really good!Below is a photo of them after restoration and while being restored. Not only cosmetically, but internal wiring and capacitors were replaced, and a new pair of drivers to better match the originals (which had been replaced).I was afraid these would be too big for the Beomaster but it doesn't seem so. Do you have any experience of non-original pairings with Beomasters?
I have run nearly all my speakers (Beovox 1600 to M70) with the BM 1000 no problems what so ever, also some non B&O 4,6 or 8 ohms no problems
Collecting Vintage B&O is not a hobby, its a lifestyle.
Thank you Sören.What do you guys think of the built in Loudness? Generally I don't like loudness, so it scared me a bit when I heard that the Beomaster has an "automatic loudness". Mostly, where there is a Loudness button, I prefer it off. On some machines, like my Tandbergs, I think it is too much, overblown. On the Beomaster though, I get the impression it is more subtle.Does other, more modern Beomasters have this too?
I don't like that loudness thingy either, but I can live with this one if used with the correct speakers. Not bad at all.
Martin will tell you he's a loudness man, on the other hand.
It's not bad at all, this loudness thingy!Do you or someone else know how it works - does the circuit have a fundamental design that makes it work like it had a built in loudness, or is there actually a separate loudness circuit in it?If the last alternative, do you know where in the schematics it is..? I am very curious about this loudness thing.
It's a filter using a tag on the volume control.Many people are scared of filtering in general, but that's because they never actually tested their own ears (these people usuallyget VERY surprised at the result).It's a matter of taste - and perhaps habbit - but it's a fact that what your mind will pick up from the music will be quite far from linear ifyou are not using Loudness.Having said that, depending on the choice of speakers, the Loudness in Beomaster 900/1000/1001/1200 etc. could be felt as excessive.
That's what I heard clearly after the "restoration", the workings of this filter. On the unrestored machine this is less obvious. Bear with me hear, and I hope you don't find me annoying. But I hope this could be of interest also for other fans of the Beomaster 1000 out there who wants to keep their machines in perfect shape. What I was thinking was if there is a possibility that I may have changed the character (or level) of this filter when I replaced capacitors in the amplifier section. I don't know how this filter works, or which parts in the schematics is responsible for it's operation - but say it's one or several 1,6uF 25V capacitors, of which there are several, that I replaced with 2,2uF 25V, then maybe this could be the case..?Another thing I am curious about, is if the later models 1001 and 1200 also have built in loudness..
Of course a change in capacitor value(s) will change the filter characteristics, but in Beomaster 1000 thecomponents related to the loudness is fitted physically on the volume potentiometer and none of them are electrolytics soyou won't have changed any of them.
Beomaster 1001 and 1200 also have built-in loudness.
Thanks Martin for advice on loudness and capacitors.Today I encountered another problem, something very easy (or so I thought), and now I feel like a moron..Just wanted to replace the lamps below the radio scale. Now, I have never had a Beomaster 1000 where these works, but they are supposed to light up when you switch on power, right?With fresh new lamps that Christian kindly gave me, there is still no light. I measured the connections with my multimeter, and I got the impression that there is no current to the lamps. Isn't this very odd??The old lamps seems to be ok. Something else is the problem. Fuses seem alright, but that couldn't have been the problem anyway, taken that the Beomaster now works and currently playing Roberto Menescal - Bossa Zen, with a warm, full, lovely sound.Anyone have an advice for this amateur?
There's a separate fuse for the dial light lamps that doesn't power anything else. The fuse holder is often corroded so your problem might be simply that.
Also, the bulbs are connected in series so either they will both work or both go out at the same time. If the fuse is OK check the lamp sockets. The power to the lamps is AC so switch your multimeter accordingly.
EDIT: sorry, they are actually connected in parallel in BM1000 so likely the power to the lamps is out.
Thanks Mika!Contact spray on the fuse holder didn't help but I'll do a more thorough cleaning. That must be the problem. AC, I see, I got some odd readings, wasn't sure which, that explains.I'll try that and get back with a success or failure report.Want to say thanks again to all you who have helped me so far! - for your endless patience and your quick replies to my silly little questions. This forum is fantastic. I am amazed with the level of knowledge you have, with even the smallest little details.
Thanks Mika for help with the lights!It now lights up beautifully. New fuses and cleaned fuse-holders. The lamps didn't light up at first, when I measured if there was any current to the lamp holders with my multimeter they suddenly did light up and continue to do so.The Beomaster is now playing Cannonball Adderley - Somethin' Else, it seems to have been made for this music, plays it so beautifully.
soD8eJeppe.
Its playing now, you can come and pick it upI have a slight dyslexia. I have trouble of following long threads and long emails.So I have not read all the posts here.
The problem was driver transistor to the regulator, the one you replaced and most likely the problem is your own cooling invention
The cooling solution you have done is the cause.The AC128 was shortcut, and did not provide proper level to the power transistor, which made power transistor to level out way to high voltage.
( based on how it looked like when I got it there is also a speculative reasons that , due to eventual capsel leakage it was short cut with your cooling solution , to the cables in the surrounding )
There is a reason why the orginal colling design is as it is.The coppar plate rounding must round around the transitor perfect.
The way to to it is to desoilder the entire package of both transistors and the colling plate.
Dillen wrote some where, I cant remember, "lots of strong coffe and good coockies helps"
Now there were more problems. the PCB layout had loosen from one pin, because of not proper earlier demounting, which of course broke when I repaired, so I had to make sad solutions.So , the only thing I can teach you is that there are no short cuts, do it right ;) ;) ;)
Beoworld servers didnt allow me to upload images this night, so link is bellowsoD8e
What I did is I took out the entire package, tried my best to restore the rounding of the coppar, to my best and inserted a new AC128 and filled it with silicon paste to hopefully compensate for the not perfect rounding..Sombody had wrinkled out the coppar rounding so it was crinkled, not easy to get perfect.Keep the orginal, think orginal.
Christian Christensen:Dillen wrote some where, I cant remember, "lots of strong coffe and good coockies helps"
The cookies has to be Danish
Thank you Christian!!!I did try to be so careful when I made the heat sink. I even used thermal paste between the copper "cage" and the transistor. But I see, it didn't work. I was pretty sure myself that it would disperse heat enough, then perhaps it was shorted. I was thinking when I made it - "I hope the outer part of the transistor is properly insulated, otherwise I am screwed"..So the AC128's actually get hot enough to need a proper heat sink. I wasn't sure of that either.Even with Danish cookies and strong coffee, to remove that heat sink and fix it and put it back must have been lots of difficult work! Looking forward very much to testing it and comparing it to the almost unrestored white Beomaster 1000 that I also have.
. Sören, As we can buy danish coockies in Sweden, beoing is easier in this country compared to other countries
I am investigating the possibility to remake a few pieces of that front rail that holds the radio scale, between the keys, on the Beomaster 1000. It seems they often break. On one of mine it is broken, and I want to replace it. Now checking if they can be 3-D printed or molded. It seems it can be done. Anyone here who is interested in having this spare part? In the photo is a typical broken rail.
I am still working on my Beomaster 1000's..Now I have to bring the black Beomaster back to life myself. Christian pointed out that this is actually a germanium version, although it is black. I thought it was silicon, so that I could compare them.. But a nice surprise sort of. Now however I am left to try to fix this germanium equiped Beomaster myself. I have changed all the capacitors. When I started it up after the recap there was only a sound going "wowowowo.." from both channels and a thin smoke pillar from somewhere. I have checked that the capacitors are all properly put in place. I have checked what I believe is the vital resistors, and the zener. I suspect a transistor in the power stage somewhere. It is probably the same fault as the earlier white BM1000 (which is now under Christians care), which had blown a AC128. Now the question is - how do you search for faulty germanium transistors?I know how to measure silicon ones. But these germanium transistors give the oddest readings, they are all over the place and I don't know how to check if they are alright or not!How do you guys do it on your germanium machines?
Jeppe:Now the question is - how do you search for faulty germanium transistors?I know how to measure silicon ones. But these germanium transistors give the oddest readings, they are all over the place and I don't know how to check if they are alright or not!How do you guys do it on your germanium machines?
Germanium transistors are quite "bad" compared to silicon transistors - for example, they may have a large reverse leakage current that can mess up simple multimeter diode tests. Regular cheap multimeters with a hFE range may fail as well.
The best option would be a real transistor tester, if you do enough work to justify the cost - I haven't looked in a while, but I would expect that you could find a cheap but useable one from China nowadays. Or perhaps even build a small test bench:
http://tagboardeffects.blogspot.fi/2012/08/germanium-transistor-tester.html
(theory for this more extensively here:http://www.geofex.com/Article_Folders/ffselect.htm)