I would love to check all the caps and electronic componants but I dont know how to repair electronics,just clean and mechanical and power cords even though the schematics are great and  clear,all I have is a multimeter and tools,but I will clean the controls with iso,and the stereo doesnt use oils or lubes,I will have to get back to you on what I find,hope its not bad,a little worried. 

If the 3 big cans located at the power supply, shows black dust or leekage on only one, change all 3 of them, the red/orange capacitors in the middle you will have to change, they are old and dry, they will fail if not now then in a couple of years. If you can solder its an easy job to change them, just go one by one, on the 3 big ones you will have to mark all the cables going to and from. If your 4000 was playing Ok with the mensioned failures you may be OK with a cap change, but take a look inside and tell us what you find, pics, when I get my spares I will show what I'm doing on this thread.

Martin got a mail, lets see what he recommends.

I finally cracked open my Beomaster 4000,this is what I found,P.S I'll post pics very soon..

I found 20 spider webs, tons of dust, broken bass control tab on the bass switch that lets you control it have of it is gone and my tuner slider came unglued and is no longer attached. I found the original schematic in the lid but no burned looking caps, resistors, diodes, the big 3 Caps look good. Power supply looks good but much theres more dirt on the second circuit board underneath the other two, but I have to remove the bottom of the set still. Trimmers are filthy and I need to test the stereo,but my impressions are is its in nice shape and hasn't been touched in 35 years. Not sure if all the bulbs are burned out yet. Anytips for cleaning the circut boards with out causeing harm to the componants, I used brushes so far but its clinging very well. And the oils for the slide controls is all gummy now what do you use to replace it.

Good to hear that no repairs was made, but change the orange caps they are old and dry, the sliders are fitted with 2 clips each, take them of with all wires attached and carefully bend them, then you can get in from the front to clean, use a bend pipe cleaner and use isoprophylic alcohol to clean, also the PCBs, the tuner slider you can glue back on to the string where it was before, use crazy glue gel or polyurethane.

I'm waiting for my parts from Martin, I'm going to change all electrolytic caps, also the 3 big ones, some trimmers, the 4 output transistors and all lamps, and as in my BM 2400 both bridge rectifiers was bad, I'm going to change these too in the 4000

Just heard from Martin, he will ship my parts tomorrow, so now I'll have cross my fingers, get nerveus and run in circles until I recieve

Got the parts from Martin more than a week ago, since then I had to work for my living , but tomorrow, if my clients lets me, I will start again on the BM 4000, I would like to start now but the fabric selector has ordered me to go with her to eat some normaly dry cooked kind of bird.

Well it got to sunday before I got to it.

I had allready dismanteled everything so I was ready to change caps, lamps and output transistors, did not desolder anything before I got all the parts, and checked that everything was there, I dismanteled the whole front without desoldering anything, to put it together again is a PIB, recommend a flat magnetic screwdriver.

Started with the lamps, first the fieldstrength lamp, took out the baseplate, and then it was easy to desolder and solder in the new one, the other 4 lamps is pull out push in.

Lamps done, I put the front together and started on caps on the output PCB, The PCB is fitted with 4 screws on the back panel, pull out twist and you will see the caps

New caps in

Twisting the output PCB back and forth broke one lead at the solder point, so be carefull

Soldered in again.

 

Went on to the main board, had to put the unit upright to get to solder and component sides simultanius. The output stage I swung aside and secure with a pair of cable straps. To find the right solderpoints I put my working lamp close to the solderside, and from the componentside I could see the siliuets of tracks and the shadow of my finger was put directly to the solderpoint, The BM 4000 has no text on the PCB, at least this one did not.

Old caps main PCB

Main new

As you remember, the old big bad caps looked like this

I desoldered and it looks like this

The middle cap has a lot of leads connected, I desoldered and made notes of what to where, the middle one is a PIB with a lot going to and from. I then desoldered the output Darlingtons and thats where I got to Sunday. More to come.

Good job Søren!

I see that you've (so far) kept the original trimmers everywhere.

Please renew them, they are quite cheap and they could be trouble makers!

The ones in the amp section of course, but also the preamp 47k through which the sound pass!

On my 4400 I had a loss of treble on one channel (Tape 2) because of a bad trimmer (but measured resistance was okay).

I am reluctant to change the tuner ones though, because of à lack of HF generator!

chartz:

I see that you've (so far) kept the original trimmers everywhere.

Coming to it Jacques, way to go yet

chartz:

I am reluctant to change the tuner ones though, because of à lack of HF generator!

When Benny serviced my BM4000 during the summer, he just replaced the entire board, if memory serves.

"When Benny serviced my BM4000 during the summer, he just replaced the entire board, if memory serves."

I am completely against that. No ifs, ands, or buts.

Yes, that is the modern way techs work, and I can even forgive them when there are hundreds of microscopic SMD components, that make troubleshooting a nightmare.

But for heaven's sakes, here we are talking about a 1970's vintage PCB, with big and fat discrete components, easily seen and touched. There is NO excuse under the sun, for not doing proper troubleshooting on the original PCB and finding the one or two bad components, and then replacing them.

Furthermore, if the replacement PCB he put in has not been properly restored with all new caps and some new resistors, I can put money on the fact that you're going to be in for a failure in short order.

Menahem

Didn't get a chance to do anything, clients calling and no rest for the poor, tomorrow morning 5:00 AM I start for McAllen TX, I wanted to go there for 1 year to pick up Bvox flat panel, Bvox 3702 and several other non Beo items, but something allways came between, now the only thing that can stop me is an earthquake or the fabric collector, will be back Monday, and as work is calling it will take time before I get back on the thread.

Got to it yesterday and today, well yesterday I decided to get a computer and internet to my new workplace, so a couple of houers went to get that up and running. To the work, the small caps are done, and I went to get the 3 big caps into place, as the new ones are maller than the old ones, the galvanized stell band that holds them do not fit and I'm out of silicone, I tried to glue them to the galvanized steel angle with my wifes heatglue gun, but no such luck, they seamed to stick to it, but just touching them made them come of again, so to get forward I fitted them with a cable strap, I will fit them properly later with a new steelband and foam strips. The caps on the outside had only each one cable coming to them, but the one in the middle is a SOB, some 8 to ten cables to each peg. The new caps has very small solder pegs so I broke of the pegs from the old ones and soldered these to the new caps before putting them in, this way it was a lot easier. That was it for the Friday.

Saturday: I started getting the big output transistors in place, when I took out the old ones 2 of the isolating pieces (light brown color), between chassis and transistor screw lach, came apart, to pick up the small pieces I used a small pair of pliers and could get to them, but applying just a little force to the plier they just detoriated in small pieces, I had to make isolators of rubber that fitted into the screwholes in the chassis, the 2 other transistors was fitted with black pieces, one broke but I waes able to glue that one with Arleenes allround glue, crazy glue does not ork here.

Got them all placed and all screws in. As you saw in the first pics, the first transistor on the left had bad PCB traces and was repaired with cable strips, I choose to go directly to the solder pegs on the transistor with the cables from the PCB. Double checked all cables and solder points, found one that I didnt like on the transistor PCB board, I put a new cable between the output PCB directly to the transistor peg.

Now onto the trimmers, I dont touch trimmers where I have use oscilloscope or other instruments I cant play , if I can adjust them with a multimeter I change them, so I changed the trimmers for light stregth and light balance and the 2 for the output stage.

Done, after checking done soldering and no loose or forgotten cables, I turned on the power and like Gutenberg I could say "and there was light". With my nose deep down in the BM, my ears open and my eyes flickering here and there, I left it on for a minut or so, turned of again, called up the manual on my computer, it was time to check the no load current, left channel shows some 34.5 mA, no good and cannot adjust it, right channel 120 mA, adjust it down to some 75 mA, leave it on and it increases slowly upwards, after 10 min. I adjust it to 79.8 mA.

Check on the 0.15 Ohm resistors in the left channel, should be 34 volts +-, I get 5 V or something like that.

Thats when the 6.8 earthquake hit us, my Cheif executive office chair started mooving by itself, I took a look at my cuba, it had waves on it, took of my glasses and realized "its an earthquake", my wife was sleeping downstairs and nearly fell of the couch, we both at the same time yelled "EARTHQUAKE", arriving downstairs my wife allready had the box with papers in her hand, I am responsibel for water, flashlight and overcoats, I didn't find the water, but a bottle of aged rum and a coke would do, the flashlight and 2 coats. Its the worst one we have had here where we live (20 years), my house is build on rock and we seldom feel the earthquakes here, but this one got to us. The street lamps was pendeling about 0.5 meters to each side, the quake lasted a little more than 1 minut, I think we got out in about 45 seconds.

So pics pending, and when I get time, start finding the missing laft channel.

Søren Mexico:

"EARTHQUAKE",

As I was reading post's, it was announced on the radio. Even a tremor is  a very unpleasent sensation. I hope you are still rocking to beolabs/beovox and nothing else.

Hi,

No damage then? 

Regarding the big caps, I just inserted high density foam between them and the metal band, which secures them firmly.

Waiting for the photos!

Good job Soren ... I really like my BM 4000 I refurbed last winter. Makes me want to fix the one with the missing left channel sitting in my closet. So much to do soo little time to do it ll,

Eugene:

Good job Soren ... I really like my BM 4000 I refurbed last winter. Makes me want to fix the one with the missing left channel sitting in my closet. So much to do soo little time to do it ll,

Nice to hear from you again Richard, we missed you here, the winter is here again, so heat up the iron and get going, did you stop smoking BTW.

Jacques: Pics will be here shortly, bought a new camara just for this, got tired using my phone and the bad Nokia software.

 

Pics: Cable repair, the tracks was damaged, I think because of to high heat from earlier repair.

New trimmers, I may have to change more, but without tone generator and oscilloscope, how to??

Big caps fitted with cable strap, will do better later.

On the back you see the 4 "new" transistors that Martin provided, with which type can we change them if originals is not available ??

Here the reason why I changed them, the right one in the pic, does not look right and have overall lower resistance than the left one

Front back on nice and clean, all sliders works without noice, all lights works, AFC and channel balance lights work.

Left channel dead, will connect a source to tape in, to see if its the reciever part, if not I will start with the 70 volt supply and go forward from there, as the PCBs are without text its a PIB. I'm so close now I really hope I get this one working correctly

BTW, bought a new Camara just for the Beo pics, always on my workbench and ready to use, and RED so I can find it between all the tools on the bench, Panasonic Lumix DMC S3, recommended.

 

Glad to see the earthquake didn't affect you.

Good luck on the repair - looking great so far.

That's lovely Søren!

You might consider posting with higher res pictures though!

I find it frustrating not to see every detail of your work...

Love your new piccy!

chartz:

You might consider posting with higher res pictures though!

Higher res. in pics, hope its enough.

Today I went after my missing left channel, first I connected my BS 3000 from aux to tape1 in, to check if it was the reciever or the output stages, well, same failure, no left channel, following the drawing I started with the 70 V circuit, same V, L and R, went on crosschecking R to L.

After 1 hour reading drawing, finding the components on the PCB and drinking a lot of coffee I came to the middle of the board, and found this.

Someone changed a resistor in the left output, and it must have gone bad, I will get 4 new ones and change all of them, when done I will continue checking Voltage until the end, I'm glad that the right channel is working, its a lot easier to crosscheck between the two.

Here a top view in higher res. tel me if you want higher Jacques.

And here the front bigger

Hi Søren,

That is an excellent job that is!

Stereo was indeed an invention designed to make repairmen's lives easier!

The new pics let us see more, that's perfect, thanks!