hi!

i bought a faulty bm6000 quite a while ago over ebay, and gave it a secod try now for bringing it back to life. it seems the microcomputer got stuck and doesn´t reset. so the reciever doesn´t go to stand by, but shows weired info on the display; after 2 or 3 seconds the amplifier protection circuit is activated and the display changes, but doesn´t go stand by.

until now i replaced all the capacitors, some of the transistors ( the ones involved in voltage-regulation) plus transistors, the variable resitor and the diode in the microcomputers reset circuit.

result so far: the powersupply delievers all the correct voltages, but the microcomputer wont reset and the poweramplifier still switches off the unit.

for the poweramplifier, i think, the problem could be the variable resistors for offset and no load current, but no matter, whats going on in the poweramp, the beomaster should go into stand by, when connected to the mains.

i tried to calibrate the ic reset circuit following the instructions in the service manual, but i failed to get the 2,6V over R90, but as i haven´t got an scope, it could be caused by my slow multimeter. depending on the position of the R89 i measured either 4,5V or  0,2V, but no values in beteween.

my guesses vary from the ic has left this world to i haven´t got the right equipment to calibrate the reset.

it´s a shame, as the 6000 is a relly nice machine and i´ve got already a beogram 6006 and a becord 8000 waiting for the right partner.

anyone any ideas?

any help very much appreciated!

have a nice evening

jens 

Make sure you have a clean 5V supply. A bit hard to do without a scope but an AC voltmeter should tell you if
there is any ripple to disturb the processor.
Next, check the zener diode D6, this is where the 2,9 V should be found. R90 should hold 3,5 - 3,6V.
The voltage on the processor pin 39 is also interesting since this is the actual CPU reset point.
Anything lower than apprx 2,5V will halt the CPU.

The processor could of course be dead but it is rare to see.

Martin

hi martin!

as far as i can see, the power supply should be o.k. 

i had 4,6V at pin 39, then i replaced  d6, now i have 0,1V at pin 39.

voltage at d6 is 4,9 V, which is obviously too much. so i will check around the reset circuit. 

i already replaced tr5 and tr6, but nothing changed. 

thanks for your help!

greetings from munich!

jens

p.s.: my beogram 6006 runs perfectly with your tachodisc, which i bought on ebay! thanks for this ! 

2D6 is a 2,7V zener. If you have 4,9V across this diode, it's either dead or of a wrong type. Are you sure you mounted a 2,7V zener diode ?

0,1V on pin 39 keeps the processor halted, 4,6V sounds more like the correct voltage here.

Good job on the mounting and thanks for the feedback on the tachodisc, greatly appreciated !

Martin

i double checked the zener, it´s a 2V8 zener bzx.

but when i put the old one (the original b&o) back in - surprise,surprise all the voltages went back to  their former values.

so i´ve got 2,9V over D6 and 4,6V on ic pin 39.

but unfortunatly still no reset and no standby.

Probably a dead processor then. A scope would tell if any activity is found anywhere (keyboard scan etc.) but there probably isn't any.

Martin

hi martin!

i guess the ic is no longer available?

it´s a shame, that after all the work and the new parts, i have to give up. 

thanks for your help!

jens

first of all, hello everyone. i am new on this forum, and... please forgive my eventual language mistakes

jens_m, for your problem, i am sorry but i do not know the answer at this moment :( but, maybe you can help me....

i also have a BM 6000, and i have it for a long time. it was perfect until some stupit did some repairs at the electric cables on the street and connected my house to a 380 voltage. a lot of my electric stuff was damaged, and the BM6000 was also plugged, and now is dead. it's problem is the primary supply transformer, the little one that is sealed. i have a lot of supply transformes, but i do not know the correct voltage for it at this moment, and i do not know wich one fits. it has 2 voltages on the exit. one of them is 15V (the ic2 is a 78-15 supply), but i can not figure the other one, because i have no repair manual for it :(. so please, can you tell me vhat voltages delivers that voltage transformer? AC, and DC on the main capacitors c1 and c10.

i'd be greatfull if you can help me, and .... and, maybe if i can bring it to life, i can help you with some mesurements on mine if you want to compare to yours. DO NOT give up with it, it is a wonderfull amplifier.

nic

Please guys, don't give up too easily. You know why we have the Beoworld forum ? - Namely so that people can help eachother ...

nic, welcome to Beoworld !

The transformer; Why do you think it is dead ? If the mains fuse keeps blowing check the capacitors on module 16 (the low voltage power supply inside the cooling tower) and the rectifier(s). I've seen the two large board mounted capacitors short circuit quite often. A full capacitor kit is available but a single cap can also be arranged. I may also have a good used transformer in stock if you need. Is your Beomaster 6000 a 220/240V version ? Check for the part number sticker on the transformer if it's still present - something like 8013258.

The processor; I am not sure if B&O still can supply this part, worth asking I suppose. They do surprise occasionally. If not, I will be happy to help you look for one.

Martin

hi nic!

the two voltages on the transformer should be 10VAC and 20VAC according to the repairmanual. after the rectifier it should be 10.5VDC at c1 and 24VDC at c10. after a regulation circuit the 10.5V go down to 6.5V (plug p41 position 1) and the 24V go down to 15V (plug 42 position 5 and 6).

i suppose, you´ve checked the fuses on pcb 11 (the small board close to the transformer).

i hope the overvoltage did not destroy any ics.... 

good luck for your work!

jens 

hi martin!

thanks for your support!

i´ll check B&O, if they still have the processor.

have a nice evening!

jens 

dillen and jens_m, thanks a lot!

the transformer is dead, I am sure of that. I tried to measure it and the primary is blown... it is a 220-240v model

tomorrow I will search one with the correct voltages or buy one, and I'll try to bring the BM to life. i also have the tape - beocord 8000 but this one is ok because I did not use it for a very long time, and it was not plugged.

I hope nothing else is blown, but no matter what, I'll try to repair it. if this works, maybe i can help you wih some measurements for your problem...

@dillen: the problem is that I live in romania, too far away from you... and I think I can find one to fit. if not, I'll make one :D the sticker is no longer there, and i do not know why.

I've sent parts to California, South Africa, Chile, New Zealand, Iceland, Mexico, Hong Kong, Alaska and Greenland. Romania is not that far away but if you prefer to search for a suitable replacement or even make one yourself rather than grabbing an original part, that's OK with me.

Martin

I think it's alive. I tried with one transformer vith 10 an 17V on AC, and the BM went on stand by.... now... I think I can repair the original transformer. it had a metal plate on the inside.... now, i can see a rubber tube with a wire inside, that is blown. I'll try to upload a picture...

@dillen: thanks a lot, if I can't repair the original, I'll ask you for one, because the one I have, does not fit in the space :( the only one problem is for the transport... I'll ask someone how can we do, because I do not know....

got an answer by b+o the last week, that they do not stock any more spare parts for the beomaster 6000, so they don´t have the processor anymore.

perhaps you have got any other sources fo rthe ic, martin?

greetings

jens

I can't promise anything but I will definitely look for one.

Martin

hi martin!

thanks alot for helping!

jens

hello again...

It's a long time since my beomaster is workimg again, but now I have another problem with it :(

the freqvency display is not working well; it displays some random numbers, but, the radio is working well... I'll try first to change some capacitors, but ... with some schematics I think I'll go faster :D the second problem is that the radiator is overheating in the left side, or at least I think that, because I did not verify that until now, but... the amplifier is working fine. still... I think it's not normal...  Any help is wellcome.

thanks :D

dj01fad:

the second problem is that the radiator is overheating in the left side

Probably the amlifier no load current and offset trimpots.  They go bad and need replacing/resetting, this is what causes the amplifier to run too hot. While you're in there you should replace the electrolytic caps too. Ask Dillen, he can supply a cap kit with instructions and probably the right trimpots too!

The service manual, available to gold and silver members, can help you with the adjustment of the trimpots.

Good luck!

hello again!

the problem is still there, but i think i know how to fix it, but.... without a schematics is very hard. so... can anyone help me with that? i need a schematic for the entire unit, if anyone has it. plus... some wires were broken and i need to know if i put them back well..

thanks a lot

If you upgrade your membership to silver schematics are freely available. Worthwhile and you help the site too!

Ok, but... how can I do that? I will search tomorrow the forum to find out...

click on main site above and there should be a link on the main page..

ok, I found it. the problem is that I don't have any bank account, and I will not make one (I don't like banks). I'll think about how can I send the money....

How on earth do you manage without a bank?!

Give 9Lee a message I am sure he will be able to arrange some method... I highly recomend gold membership if you can as you will be entered into a very good prize draw!