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
Arrived from Alfreton, Derbyshire UK the other day ....
It is suppose to work but obviously I will have to change out the plug and dial the voltages over. Upon inspection I discovered the bass and treble faders were not engaged. So i decided before any powered test to open her up and see what the matter was with the two loose faders. Besides wouldnt hurt to have a look around inside first anyways.
I was greeted with utter filth. Not the worst I have encountered but it is pretty bad.
One of the prongs on the balance slider was missing and another prong on the volume was badly cracked, basically also boken, Very dirty and kind of oily.
The tuning string looks almost brand new and the dial pointer bar was not rusted as they often are. To me it was obvious that this amp had been serviced at some point, The trimmers on the output stage looked like modern piher cermets.. The small number oragne caps still looked good.
The fader lenses had cataracts ! So using my own patented cleaning formula I cleared them up.
much much better
You've got a good cleaning project there, forty years of accumulated grot! My 2000 was the same when I got it - was lovely amp though and sounded great with a pair of 3702s.
A bad one Richard, as bad as my BM 4400 were, have a good time restoring it, we are checking on you, and a vintage thread is very welcome, there are few of us left. good luck
Collecting Vintage B&O is not a hobby, its a lifestyle.
Søren Mexico: A bad one Richard, as bad as my BM 4400 were, have a good time restoring it, we are checking on you, and a vintage thread is very welcome, there are few of us left. good luck
The worst ever for me was the Beosystem 3300. Twice as much dirt plus It had to cleanup all the rotted belt goo and a number of the caps had split and leaked their contents everywhere.
Anyways this is the cleaning solutions used for the project. I like the glass clear over straight ISP because it contains detergents and amonium sulfates which aid in de-oxydizing the component pieces. and it is better on plastics than Hexane. The paint bruch acts as a mop. I pour some cleaner in the small cup and start mopping it all up.
The first mopping turned my clear blue solution black within minutes, The second mopping I was able to mop all the board before it turn black. The third cup Stayed mostly blue with only a the loss of transparency. Then I finish with q-tips.
I had hope that during the cleaning process I would fing the broken prong off the balance slider and I luckily I did.
Can't say for certain if this is the original bridge but is per original spec.
During cleaning further inspections reveled the the tuning sting plate was breaking away at the corners. The backside reveals what appears to have been some work done to the output stage, I can say I am not impreesed by the soldering work.
Way to go, I will try to find and try this kind of cleaner, always stayed with ISP because I am afraid of using not tested liquids. the solder work looks bad maybe you will find some track damage there, and someone also loved heat paste, this type sliders I see for the first time I think it is 5th variant I have seen in B&O, the best are in the BL 5000
Søren Mexico: Way to go, I will try to find and try this kind of cleaner, always stayed with ISP because I am afraid of using not tested liquids. the solder work looks bad maybe you will find some track damage there, and someone also loved heat paste, this type sliders I see for the first time I think it is 5th variant I have seen in B&O, the best are in the BL 5000
Windex or something similar should be fine. The stuff I used is a generic cheaper version. I use Rosin soldering flux prettty much as a rule. But I will always wipe off spatters and excess. After all its a matter of pride, I see thiese stains here and there on the older gear but not in concentration.
OK now for the fix. I bought a two part plastic Kryo based weld kit and decided to go ahead and replace the small electrolyics caps and bridge diode.
I used Fujicon RK high temps because I can. I have Panasonic Nichicons and even some Xicons that would have fit the bill. The diode was replaced with a 200V 2A which is more or less double what was in there.
My solder joints versus the other.
Had a leaker
The glue I used I liked it. a bit tricky but once it grabs it melts the plastic together. Like a weld
Ok basics repairs done and it was time to test. I don't know about the rest of you guys but this is the part I hate the most. The first power on test always give me a very nervous and uncomfortable feeling.
Anyways, it was early Sunday eve and it had been over 24 hours since I has cleaned the boards, more than enough time for the ISP to evaporate. So I plugged it in set the volume down to zero and check for power. 25.4 volts. spec is 26. I decided not to make an adjustment.
Hooked into the right channel load resistors and performed the no load test and got 1.6mv. What ? no way. that can be right I thought . I double check my connections and volt meter settings and it was all good. Decided to check the left channel. 1.2mv. OK. this makes zero sense but the measurements are the measurements and I didn't think my meter was faulty or I was screwing up the tests.
By now I am about read y for the straight jacket but I press on and start slowly trimming up the voltages until both channels were steady between about 10.1 - 10.3. good enough. Let it all ride for the ten minutes and then it was time to play the stereo.
Connected my Redlines and set the volume at about 4 and turned it back on. Sweet music to my ears the sound was warm clear and wonderful. Let it play the radio for about an hour and the sinks never got warm.
The only disappointment was the 4 indicator lamps were out. Another day another project.
Nice work! Nice pomegranate too.
Worst things I've seen were a Citation 16 Harman Kardon amp back in the day, and the Pioneer RT909 open reel when I got it. The open reel had been dormant for years, the owner never used it, and his cat liked to sleep on it, so it was full of cat hair and dander and dust, a total mess. I cleaned it up pretty well, but eventually had to get rid of it as I am hyper allergic to cats, and every time I used it and it warmed up it smelled like cat and I'd get a sneezing fit and a sinus headache. Still wish I had it, but I sold it for 4 times what I paid for it.
The HK amp we got back from a guy we sold it to when I worked in a hifi shop. Only with it it was full of cocaine powder as the guy used to snort it on top of the amp. It had blown the output transistors on one side because he had it hooked to a very low impedance load, parallel connected speakers in a club he was running, lots of them, and it had sensibly kept blowing fuses. He wrapped tin foil around the fuses, and was stupid enough to leave them on when he brought it back in for "warranty" service, which we refused to charge to warranty of course.
Good posts though, great recommendations for cleaning products!
Jeff
I'm afraid I'm recovering from the BeoVirus.
Another great project.
Sigh. I haven't had a B&O project for ages, though I did get a couple Raspberry Pi Plex servers clients going since Christmas.
Thanks for your interest in the project gentlemen.
Another day and a trip to the local electronic supply store and I was able to find lamps near the approximate spec of 12V 30ma and while waiting for my order I spot a pair of 50V 4700uf high temp caps. Why not the originals are 40 years old might as well swap them out as well. So Fix the lamps changed out the load caps and then decided to run the tests again.
The Near Death Experience
So I hook my voltmeter up to first check the power supply voltage all while trying to cook dinner. In the back of my mind I am thinking I should check my photo's to make sure I mounted the two big can correctly, but I didnt. I then turned on the set my meter flash some number and then ... nothing, Tried turning it on again ... nothing... check the cord .. nothing. Then I think you didnt you didnt. A quick look at my photos confirmed the worst. I did it, yes, I did it. I mounted one of the cap polarity backwards.
So now I am just sick. I start examining the circuit to trace back, pull the wiring diagram up and realize that the circuit is fuse at the transformer and also before the mains bridge. So I open the fuse compartment and both fuses are blown. So off I rush to the hardware store to pick up a couple new fuses
Get the fuses installed (I can see why the compartment lid had been discarded on my prevoius set - what a pain to get in and out of). Reverse the caps and pray to Buddha that all will be well.
Elation
I turn the set on and power is back on. I iquickly shut her back down and set up the voltmeter to run the power supply test. Turn the set back on and pull a 24,8 down a bit from yesterday. New caps maybe. But whatever close enought to the spec of 26V I decide to let it ride. I then run my no lad check and they too have driopped a bit from the day before I was pulling about a 9.7 -9.8 still very close to the spec of 10.0mv I decide to let it ride again.
So now is the final test. Play the set. I hookup the Redlines and set the voume to 4 and turn it back on.
Success the sound is wonderful and warm, The light are working and all is well. I rig a makeshoft antennae and tune in the classical radio station and just let it play. two two and half hours and the sinks stayed cool to the touch.
Shut her down . unplugged the unit to let it go cold and went to bed happy.
Tomorrow I will rerun the the test one final time before closing the unit up.
out with the old
In with the new.
If you look closely I traced the outline position of the old lamps so that the new ones would sit in the same place. The have to fit correctly in a somewhat tight space. I position the lamps unsoldered and remounted the board first to insure correct fit and then soldered the lamps
After I pulled the old caps I initially set them aside thinking nothing more of it. But after my small folly I gave them a closer look as if to somehow justify why I would put myself through such heartache. It was then that I noticed one had some kind of gooey resin on it. I scraped the resin off to reveal what can only be described as a pimple or blister. The cap was leaking !!!
Another thing I did was have a look at the Presets compartment. Amazingly in very good shape and still working. I add in a small amount of lithium grease and 4 of 5 were rolling back and forth nice and easy the fifth was a little stiff but working so I preset that one to NPR as I will probably not change it again.
a small amount of new grease
and finally the lights - all shiny and new. The servce manual does not give a value for the dial pointer lamp. It merely refers to it a s "bulb". I am guessing it is also a 12V 30ma lamp but until i can confirm the old one stays,
Ricardo:The servce manual does not give a value for the dial pointer lamp. It merely refers to it a s "bulb". I am guessing it is also a 12V 30ma lamp but until i can confirm the old one stays,
I seem to recall I used a 12V / 30 mA for that as well in the couple of Beomaster 2000s I have. But as long as the old one works, I suggest you leave it alone. The original lamp usually doesn't agree to come out and the glass shatters, then you may need to find a tiny lamp that fits inside the remains.
The bulb circuitry in these Beomasters is somewhat silly and the ratings need to be correct, otherwise the indicators may not work correctly.
--mika
tournedos: Ricardo:The servce manual does not give a value for the dial pointer lamp. It merely refers to it a s "bulb". I am guessing it is also a 12V 30ma lamp but until i can confirm the old one stays, I seem to recall I used a 12V / 30 mA for that as well in the couple of Beomaster 2000s I have. But as long as the old one works, I suggest you leave it alone. The original lamp usually doesn't agree to come out and the glass shatters, then you may need to find a tiny lamp that fits inside the remains. The bulb circuitry in these Beomasters is somewhat silly and the ratings need to be correct, otherwise the indicators may not work correctly.
Pretty much how I see it Mika. I actually have one new dial lamp bulb I bought off Martin years ago but decided since the old still worked -why fix it.
If ever there was "Mod" I would consider doing it would be that circuit. Actually the tuning bars would be left alone but the stereo lamp would be separated then tied to the power indicator lamp. So when I turned on the set the two lamp would both illuminate. Kind of like how it works on the Beomaster 4000. But that's just how I would like it. Personal preference.
I also notice when searching for lamps that there are equivalent leds available at the 12V30ma spec. I was tempted to try that.
Full test. I did a quick cleaning on the woodwork using Milsec. Its dry and sucked it all right in. I will apply some Old Endlish and more wood oil over the weekend.
But for now I will just let it play.
Phono works and so do the tape slots
Flunked testing at about the 8 hour mark. The right channel began to crackle and pop at random intervals. Didnt matter if it was in tape Phono or radio mode. I also swapped out speakers and speaker plugs and switch from speaker 1 to 2,
Moat likely something going on in the output section right channel. Doubt if it is in preamp or in the tone balance contols. nor do I belive it is faulty speaker inputs or anythiing like that. Based upon my interpretation of the circuitry since it is present in radio and tape phono I would most likely start scoping in the outputs section first. That is where I believe I will find the fault.
My plan is to make a continous recording of frequency signals using a software program I have and plug into the tape section and input those signals in the set. Dont see why I would need to add power to the set to do this The signal should be able to migrate thru the preamp and output section, Then I will scope for faults I have a two channel 60mhz scope which should be more than adequate.
An odd arrangement of transistors on the output board. Looks like someone went in their drawer and used what ever was available. Very strage in the placement.
Transistors currently installed ..................................... SpecTR101 ...... BC182B TR201 ..... BC182B BC547B or BC182BTR102 ....... BC182B TR202 ..... BC182B BC547B or BC182BTR103 ....... BC143 TR203 ..... MPS A56 BC547B or BC182BTR104 ...... BC182B TR204 ..... BC182B BC547B or BC182BTR105 ...... factory TR205 .... not verified MPSH 54TR106 ....... factory TR206 ..... not verified BC547B or BC 182BTR107 ....... MPS A06 TR207 ..... BC142 BC212BTR108 ....... MPS A06 TR208 ..... BC142 BC183BAlso listed but not on my board were TR109/209 and 110 and 210 that called for the MPS A06.
Some Pictures
Update transistors currently installed ..................................... SpecTR101 ...... BC182B TR201 ..... BC182B BC171BTR102 ....... BC182B TR202 ..... BC182B BC547BKTR103 ....... BC143 TR203 ..... MPS A56 MPS A56TR104 ...... BC182B TR204 ..... BC182B BC547B or BC182BTR105 ...... BC212B TR205 .... not verified BC212BK TR106 ....... factory TR206 ..... not verified BC183TR107 ....... MPS A06 TR207 ..... BC142 MPS A06TR108 ....... MPS A06 TR208 ..... BC142 no value listed (MPS A06?)I then found another Transistor sheet that makes a little more sense based upon the set I have
Saturday I went to put the scope on it and realized the probe was broken at the BX. New probes are here and I also ordered some new transsisters for the output stage. Looking at the odd arrangements of transissters was driving me bonkers so I closed up the set for the week and continued building my new romper room,
Here is what i suspect. I know that the set has had prevoius service on the output board. the Piher trimmers more than prove that. I believe the tin hats (the bc142's and 143's) are original but several were replaced with the mpsa06 and mpsa56 as are specified in the service manual. I plan to match the two channels replacing the old TI's with new so that both are the same. and then scope.
We shall see this weekend.
This old table worked on a lot of stuff but it is time to give it back to the arts
My kind of table, evidence of hard work. Be careful with TR polarity I have done wrong a couple of times now and without the scope it took me hours to find it, not to speak of getting angry with myself
just wait until you explode a cap Soren !! First time scared the *** out me not to mention all fuzz that flew everywhere
Cant wait
Here is something interesting the output rectifier board on the set is missing the two film caps. Looks to me like the ends have been snapped off. There is a clear line mark on the chassis were the board would have extended out to accomadate those caps.
the set as it is now
How I think is suppose to be ??? maybe it doesnt really matter all that much.
So I placed in some new transistors on the output board and now the channels are a match. Makes me happy. The intermittant cracks and pops still persist. I put the scope on the emitters of TR105/205 TR106/206 and IC101/201. Comparing waveforms from right to left has revealed nothing so far. The waveforms are a match. I played with the voltages settings and timing intervals and it all matches. I will test some more later but for now it is being cleaned - again.
Still a lot of grime and dirt. I also put conductive lube in the switchbox.and sprayed out the speaker dins and input dins.
There is always tomorrow
I re-checked the no load after swapping out some of the transistors.
Conductive lube in the switchbox - what? where ?
Martin
Dillen: Conductive lube in the switchbox - what? where ? Martin
This
Here
The other stuff I will use when needed depending on application
or I could always just empty a 14 oz.can of WD-40 in it.
The lithium grease I could agree to in mechnical assemblies, but the other stuff I wouldn't put anywhere near a stereo."Improves Electrical Properties". By spraying the stuff onto conductors and into switches?:-)Well, if it works for you, then by all means spray whatever suits you, but my experience is that WD40,3-in-1 and nearly all other "miracle stuff" may seem to work wonders right away but rarely do muchgood for very long. Certainly I have spent hours cleaning B&Os that were treated liberally with WD40 and It's amess hard to describe (and remove).None of the miracle stuff will remove any oxidation, dust, dirt and whatever. It may losen something and shift itaround but if it doesn't evaporate completely afterwards it will only add to the mess already in there.Kontakt 60+ is the product I use.It is the "Kontakt 60" contact cleaner (that evaporates completely, - usually overnight) and the + indicatesthat it leaves a lubricant with a very fine oily consistence. I use it (sparingly) for Shadow type switcheslike this, where proper dismantling and cleaning would be next to impossible.It washes off completely using IPA or Kontakt 60 if needed.Martin
It's starting to look like 6TR201 so i have to ask the stupid question. Why ?
This morning after the recommended wait times from the cleaning solutions I began full power tests and adjusted my scope to look for signal spikes. At low volume say about 3-4 the popping and crackle was minimal and infrequent. Much better than it had been. Bringing power up after about an hour or so brought it back and it was just as bad as before.
Ok, so I start scoping the emitters on the output board on the right channel and everyone was spiking. So I start to think what in the signal path would be common to tuner, phono and tape. I have a look at the manual then start looking at tone/balance/volume contols.
6TR202 seems fine but I get all kinds of spike from the emitter side 6TR201 The collector side is clean.. So this is where it get really weird, as long as I keep the probe attached to the emitter on 6TR201 the crackle and pops are stopped. I can still see flash spikes but the sound is smooth. Is the probe acting as a sink in some fashion ?
I let it play with probe attached and the volume set between 4 and 5. I check the display a couple times and the signal had gone smooth and the sound was clear. No pops or crackles for over an hour.
By now the set has warmed itself and so I shut it down disconnected the proble then turned it back on. The pops and cracks were back within seconds. Shut it back down reconnected the probe to the emitter on 6TR201 and the problem faded quickly. Within about 5 minutes the signal was smooth again.
I will replace the transistor and see what happens.
much much cleaner
You cannot measure anything without putting a load on it in some way or another.No matter how good a scope you have, it will always put a tiny (mostly capacitive) load on the circuit.It could easily soften (or eat) a sharp spike.
6TR201; You say, that the signal on the collector is clean. Yes, that's the 26V supply rail.You will have to look at the signal on the base, since this is what controls what comes out of the emitter.If 6TR201 is a BC182 I wouldn't hesitate to suspect it.And if you decide to replace it, I would suggest using BC549B instead because of its position in the circuit - and do itsmate in the other channel the same way for good measure.
Base signal seems ok and yes I am pretty sure they are BC182B at least as far as I can see with my magnifying glass. I thought the actual spec was a BC547B but I will put in whatever you recommend.
there are several BC182 in the output stage 7TR101/201 7TR102/202 etc.. Should they be replaced ?
The BC549B transistors should arrive tomorrow and I will have my answer this weekend. In the meantime I decided to have a look at what is up next.
Should be a simple cap and lamp replacement. I don't remember any other issues with this set but I have not had it in use in 2 or 3 years so who knows and even then it was for a very short time since I suspected as much as I have found already.
One positive is it is not nearly as grotty inside.
Richard,
Impressive, no make that BEYOND impressive work.
Amazing work, bravo!
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Ricardo:One positive is it is not nearly as grotty inside.
Do I recognize a 901, I too have one waiting I will change everything in the output stages
BC547B would also work but when I would choose BC549B it's because of the transistors position inthe circuit and because BC549B has the same specs as BC547B apart from a much lower noise floor.It's a preamplifier/tonecontrol stage, which means that any noise generated here will beamplified a thousand times or so in the following stages.BC182/183 are in my experience particularly prone to generate noise - and occasionally lots of it.BC549B is cheap and replacing is usually an easy job so why not take them all.
Dillen: BC547B would also work but when I would choose BC549B it's because of the transistors position inthe circuit and because BC549B has the same specs as BC547B apart from a much lower noise floor.It's a preamplifier/tonecontrol stage, which means that any noise generated here will beamplified a thousand times or so in the following stages.BC182/183 are in my experience particularly prone to generate noise - and occasionally lots of it.BC549B is cheap and replacing is usually an easy job so why not take them all. Martin
Yes you are right about the cheap part I think it was $4 for 50. I did look at the data sheets did notce the lower values. I suspected as much
Søren Mexico: Ricardo:One positive is it is not nearly as grotty inside. Do I recognize a 901, I too have one waiting I will change everything in the output stages
You are correct.
It is Saturaday morning and it is sunny and the temps are suppose to soar into the low 60's F. No work will be done during the day. Instead I will be out cycling around visiting friends and hangin' out. These days come rare this time of year so I have to take full advantage.
The transistors arrived yesterday so this evening and tomorrow (rain ) I will resume the Beomaster 2000 repair.
In the meantime I was able to sort the 901. For those with keen eyes the previous set of pix revealed a smoke trail at TR20. Indeed the left channel had been overhauled. New transistor trimpot and outputs BC171B was replaced with a BC547B and the Texas Intruments outputs were replaced by ??? I can't find any info on these. They work so I wont mess with replacing. I pulled a couple lamps out to inspect and they looked new as well..
The no load voltages were out of spec for both channels and the current load was off a bit as well. Made my adjustments and let it play for the evening then shut it down. In the morning I rechecked the voltages and they were fine. (ie no drifts). It sounds wonderful with even heat dissipation accross the sink. The only flaw is the tuning lamps are not operating as they should. Should not be to hard to fix. I cleaned it up and rubbed in some Milsec of the wood trim. I am happy with the set so far.
The volume pointer glass fell out and what i really need to know is there anyone out there who can make new ones. I really need one more of these for another set I have.
Enjoyed the beautiful day yesterday, Sat on the porch a bit, took a nice power nap and then went for a late afternoon bicycle ride and got home at dusk. I then replaced a faulty lamp on the BC901 and moved it to a shelf I had set up mated it with a proper pair of Beovox speakers S35. (the good ones). What a marvelous sounding little amp. I really must find a space for it or a good home.
I then cleaned off the beomaster torture table and moved the BM2000 in place for its next bit of service. Repairs completed - as it turns out I believe that all the transistors on board 6 were BC184B. Deosnt really matter i replaced all four. Now in testing and so far the sound is clear. no pops or crackles.
It will remain in testing for at least a couple more days. I hope all that is left is some exterior cleanup. The wood could use some more attention it is really dry and rough feeling in spots and the stain is uneven and a bit faded as well.
Twelve hours into testing and so far everything works fine.
So my question at this point is what should I do about the 40 year old tantalum capacitors. Should I consider replacing them and if so. what would be a good brand of tant to replace them with ?
Also should I replace the remaining BC182B on the output board ?
Came home from work tonight and resumed play testing. I tuned into WOSU classical and and did a few domestic engineering duties and decided it was good enough. It sounds really nice, doesnt get hot, the voltages have been stable throughout the precess. anything else seemed like maybe a "bridge to far". So its done and hopefully it will give me years of good service sitting in a closet collecting dust. Only to be brought out on rare occaision.
As much as I like it the problem is I already have one that only gets used from time to time, The other thing is while waiting for transistors I took on the 901 and discovered how much i really like that little amp. I must find a place for it somewhere.
Anyways I buttoned up the 2000 and gave the exterior another good cleaning and rubbed the Milsec into the woodwork. Later on I will rub some Olde English into it and apply some more Milsec.
My new favorite