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Remember the screw I found in there, oh yes sitting in the pins from IC102, and that is a TIP 146, but I still dont get why that would blow all 4 of them.
Collecting Vintage B&O is not a hobby, its a lifestyle.
Help needed, Can i use 1N4148 instead of 1N4448 in position D100/200, D101/201, fast answer appreciated
Søren Mexico: Help needed, Can i use 1N4148 instead of 1N4448 in position D100/200, D101/201, fast answer appreciated
To slow folks, answered.
Hello Søren,
I think you might need reminding at this juncture that you wanted a challenge.
Where I come from the expression is, “When you are up to your ass in alligators, it is hard to remember that your original intension was to drain the swamp.”
Oddities, set-backs, your Beomaster 4400 has it all, BUT you are more than up to the task! And I genuinely mean this….. you WILL succeed in restoring your 4400 and it will mean all the more to you because of the extreme effort required.
I for one am SO thoroughly impressed with your consummate technical skills!
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
After a total of 280 solder points I now finished also the right channel, some 120 components total left and right, I checked every single component after desoldering, I checked every single component before soldering, not only for value, but also placement in the placement scheme, and checking according to drawing. I made 5 pages of notes hereunder transistor values old against new. The TIP 146 Transistors all turned out bad. Only 2 resistors was way of limit.
There are some small differences between placement scheme and the drawing, but following the drawing from the manual onsite showed out to be the right thing for my BM 4400 (early version), I bought a manual from the bay, that came with a recommendation to change 5R176 and 276 to 220 ohms, I will do that. The drawing in the bay manual was the same as the onsite.
Here one productions change, not shown on the placement scheme, but shown correctly in the drawing.
There is no trace to connect the cap and the resistor, they are joined with soldering the pins together in the unmarked hole.
Here component side right channel
Solder side
Tomorrow I'm off to buy a couple of resistors and caps, and then onto assembling, and get the output transistors and cooling elements placed, if the FS leave me alone I should be able to start some tests Sunday
Nice work Søren. Thanks for the detail on the board and the components.
-sonavor
Søren Mexico:After a total of 280 solder points I now finished also the right channel, some 120 components total left and right, I checked every single component after desoldering, I checked every single component before soldering, not only for value, but also placement in the placement scheme, and checking according to drawing. I made 5 pages of notes hereunder transistor values old against new. The TIP 146 Transistors all turned out bad. Only 2 resistors was way of limit.
Love your work practice- way to go !
Dom
2x BeoSystem 3, BeoSystem 5000, BeoSystem 6500, 2x BeoMaster 7000, 2 pair of BeoLab Penta mk2, AV 7000, Beolab 4000, BeoSound 4000, Playmaker, BeoLab 2500, S-45, S-45.2, RL-140, CX-50, C-75, 3x CX-100, 3x MCL2 link rooms, 3x Beolab 2000, M3, P2, Earset, A8 earphones, A3, 2x 4001 relay, H3, H3 ANC, H6, 2014 Audi S5 with B&O sound, and ambio
Went shopping in the morning, got the last resistors and caps, since then I have been trying to get up my spirit to start the finish run, I'm kind of nervous.
Well, onto it, there is nothing we cannot do, but a lot we don't want to do
Søren,
In truth there are many things that we can not do, however rebuilding an amplifier is definitely NOT on your list of impossibilities.
Look at the care you have taken in such an organized manner, all those notes, not to mention ALL those solderings and tests.
It is gonna work!
This is a “P.S.” once your Beomaster 4400 is fully operational, and it absolutely will be, I would like to briefly discuss my Beomaster 4400. I am not talking about it now as not to take ANYTHING away from your riveting dialog and educational photographs.
Thought it would go faster, 4 hours to assemble, now only missing cooling elements and output transistors, the hardest job was to get all the thick wires back in place. Next time I work on a BM 4400, I will start with taking out the transformer and the big caps, and then the PCB 5 it will then be easier to change wires where needed, and easier to get to the solder points for the wires. Tomorrow is another day, keep your finger, and what else you can cross, crossed.
Component side finished
I had to go back to your first page to take a look at what you Beomaster looked like when you got it. Quite a transfomation Søren.
One of my biggest problems was to get it clean, I have never had a unit dirty as this one
Before
After
Got all the output transistors in, be careful doing it, the TIP 142 and 147 are, front view, BCE, on the placement scheme all of them are shown BCE, but some of them on my PCB was BEC, so one will have to cross a couple of wires to get it right, also the TR100/200 is a little dangerous, its mounted face to chassis, but the markings on the PCB shows correct for connecting. Tomorrow the test, with Variac and DBT, I have a bottle of very fine Nicaraguan Rum ready for use if all goes well.
All in
All plugs connected
Søren my friend,
The fine Nicaraguan rum to celebrate is a GREAT idea. It also works in the case more work is needed, God forbid!
Like everyone else on this forum, I am so impressed at your 4400 transformation.
Søren Mexico: I have never had a unit dirty as this one
It's a dirty job but someone got to do it!
//Bo.A long list...
I connected the BM over my variac and dim bulb tester, set the volume to "0", pressed Tape 1, and went from 0 slowly to 110 V at around 80 V the ON light came on, at 110 V I checked the idle current, Right channel OK at 11 mV, measured over the resistors, Left channel I had to adjust from 5 up to 11 mV.
Very happy, shifted to FM and found a station, works, stereo on and balanced. Turned off.
Turned on with Tape 1 again the Variac still at 110 V, the lamp on the DBT came on bright for a second and went to a very light glow.
Turned of again, with the Variac back to "0" started again, vent slowly to 110 V, at around 80 V ON light on, but RL1 (fault switch) also pulls, the DBT shows no light or glow. The 35 V are there before the RL1.
I'm wasted, have been staring me blind at the drawings, tomorrow back to the drawing board, will break the seals on a bottle of cheap rum, maybe that will help me to get a clearer vision.
HELP
Suffice to say I sincerely feel your pain and frustration! (Been there, done that with my BeoCenter 9000 CD player….. but my experience does not remotely compare to your extensive repair efforts.)
When you say you are breaking the seal on cheap rum I do hope you don’t mean Bacardi as it is my favorite.
I hope that HELP will be on the way as most certainly you must be close to getting it right. Keep the faith my friend, you will be victorious.
Hi Søren,
Were you able to get a stable idle current value over time?
What's the DC offset voltage?
Jacques
chartz: Hi Søren, Were you able to get a stable idle current value over time? What's the DC offset voltage?
The first time I powered up, there was no problems what so ever, I could adjust the idle current without problems, it didnt run away like before, I adjusted and it stayed at 11 mV, I then powered off, and after a couple of minutes on again, and then the fault switch was triggered.
What do you mean with DC offset voltage ??
The voltage at the speaker output, which should be close to zero, with volume at zero, and no speaker connected.
chartz: The voltage at the speaker output, which should be close to zero, with volume at zero, and no speaker connected.
Thanks, but I cant measure that now as the RL1 is triggered, will start investigating what triggers the relay.
I'm stupid, stupid, stupid. Found at least 2 caps inverted, I have been checking and checking and at some point you go blind or get confused, stupid.
Off to double check one more time
Oh yes, one 1uF in the left channel, and a 47 uF in the right channel, I'm stupid
Søren, even on production lines do they make such mistakes. You soldered so many components!
Søren Mexico: I'm stupid, stupid, stupid. Found at least 2 caps inverted, I have been checking and checking and at some point you go blind or get confused, stupid. Off to double check one more time
Aaa, thats only human. Happens to best of us too. On the bright side, you didnt blow those caps.
blah-blah and photographs as needed
Søren Mexico: Oh yes, one 1uF in the left channel, and a 47 uF in the right channel, I'm stupid
I have followd this thread since you started it and was very sad when you posted your HELP-message. It was not fair that you shold stumble on the finishing line. The happier I get now when I see you found the errors! Be glad you found them and that nothing serious happened!
/***
http://tinyurl.com/qj9cjsf
Orava:Aaa, thats only human. Happens to best of us too. On the bright side, you didnt blow those caps.
On the ESR I have a difference , the 1 uF, of 1 ohm, on the 47 uF 1.5 ohm. went shopping, have new ones for both. But in 10 min. the soccer game Manchester United- Real Madrid is on, so I ll watch that before continuing.
mexking:Oh yes, one 1uF in the left channel, and a 47 uF in the right channel, I'm stupid Collecting Vintage B&O is not a hobby, its a lifestyle
On the bright side....discovering the source of the problem is better than agonizing over not being able to find what the problem is.
sonavor: On the bright side....discovering the source of the problem is better than agonizing over not being able to find what the problem is.
Chanced the C132/232 and C138/238, checked all the small transistors TR111-120/211-220, same measurement right and left, checked diodes, same right and left.
Started from 0 with the variac and DBT, same sh1t, at 75V the RL1 is triggered, the DBT stays out, Leaving the variac at 110V and powering up, the DBT comes on bright and goes back to a very light glow, the RL1 is triggered. I'm done for today,
A disappointing setback to be sure, but as Nietzsche said, “What doesn’t kill you makes you stronger.” [Was dich nicht umbringt, macht dich stärker]
Frankly, when things go askew in my life, I don’t know that that memorable quote has ever helped me, but perhaps it will you.
Søren, you have come SO darn far, achieved the nearly impossible, you just simply HAVE to be close to solving this Bang & Olufsen riddle.
You’ve got the right equipment and the VERY right engineer’s temperament to resurrect your Beomaster 4400.
I hope you enjoyed your game, especially if you were rooting for Real Madrid.
Søren Mexico: Chanced the C132/232 and C138/238, checked all the small transistors TR111-120/211-220, same measurement right and left, checked diodes, same right and left. Started from 0 with the variac and DBT, same sh1t, at 75V the RL1 is triggered, the DBT stays out, Leaving the variac at 110V and powering up, the DBT comes on bright and goes back to a very light glow, the RL1 is triggered. I'm done for today,
Søren, the dim bulb tester should flash bright, then go to a dim glow if the amplifier is good. It would be bad if the bulb remains bright. As a check, I plugged my Beomaster 4400 into my dim bulb tester and I get the same thing. With the variac set to 120V and the bulb (60W) in the circuit, I turned on my Beomaster, the bulb flashes bright but immediately goes to a dim glow...and my receiver plays fine. In your case, the very first time you tried your receiver, your fault switch didn't trip, right? But now it does? Are you turning the Beomaster on with the speaker selection switches dis-engaged? I typically turn my receiver on with the speaker switches off and the volume at zero. Then I engage one or both speaker selection switches and increase the volume.
Exactly like you, bright and then dim glow, speaker switches off, but the RL1 triggered, The first time I turned on I could adjust the idle current without problems. second time I turned on the RL1 triggered, I changed the caps with the wrong polarity. will desolder and check the TIP 142/147 tomorrow.
Looking at the schematic, the protection relay turns off the positive and negative 35 V rail voltages. It looks like you will have to start at the protection circuit that controls that relay and find what is causing it to trigger. Is it a problem with the protection circuit or is a true problem with the left (or right) power amplifier outputs (that feed the protection circuit). See if there is a DC voltage at the node between R186 and R46 (Left channel). Also check the same node on the right channel - between R286 and R47. Those right and left outputs are what feeds the fault switch circuit so see what those are as you ramp up the voltage on the variac.
Thanks John, will check it tomorrow morning,
I will light a Bhudist prayer candle - then go shovel a pile of ;ate winter snow.
Thank you Bhuda
sonavor: Looking at the schematic, the protection relay turns off the positive and negative 35 V rail voltages. It looks like you will have to start at the protection circuit that controls that relay and find what is causing it to trigger. Is it a problem with the protection circuit or is a true problem with the left (or right) power amplifier outputs (that feed the protection circuit). See if there is a DC voltage at the node between R186 and R46 (Left channel). Also check the same node on the right channel - between R286 and R47. Those right and left outputs are what feeds the fault switch circuit so see what those are as you ramp up the voltage on the variac.
Just checked: Left and right channel the same, going slow to 50V, getting - 8.7V, passing 50V, goes down to 0, at 80V the RL1 connects, and get +1.4V