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
Hi guys
My latest plea of help concerns a BS9000 Type2561 i have just been given this as a spares if you can repair happy days. The unit is in pieces at the moment with no visual indication of life, no red STBY zilch. To get deeper into the issue I examined the power input from mains to unit and found the mains relay PCB 5 with no diode D3 to the relay and a burnt flex from PCB5 to 34P16. Buying a new PCB 5 and lead £42!!!!! reconnecting it up to the unit I attempted to power up and it blows fuse F1 on PCB 5 other fuses on PCB 34 are ok. No 5v at PCB 34P16 pins 1-2. At PCB34 P1 pins 1-2 I have 10.2vAC nothing at TR21 I have the schematics but could do with any pointers , I also replaced the bridge rectifier GBU8D same as removed. Any help please
If you have the service manual then it's a question of following the diagram. Most likely a shortened diode or Mosfet. Keep in mind that the psu is controlled by the uP. But first you'll need the 5V. So search the cause of the shortcircuit.
Hi beobuddy
Thanks for your reply, I am pleased to say that I have at last tracked down a dry jiont in the P34 TR10 area so now I have my stable 5V supply. And. A STBY light ! I am going through the diagram bit buy bit. My cause of the Mains relay fuse blowing (100mA) is somwhere in PCB P9 as soon as I connect it to motor controller PCB 35 then it's lights out. I will keep you posted as you were kind enough to respond....Fingers crossed BTW what's uP?
regards Maurics
Dom
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Short circuit mosfets on the motor control board?
You are one very cleaver chappie! that's exactly what it was, also there was a dry joint on the 5v rail to supply the fuse on the relay PCB it's now up and running so now I have two of them!!!! BS 9000 That is thanks very much for the help guys so very much apprechiated... Maurice
Well done! Congratulations
Nicely done!
Did you check any diodes around the Mosfet? Apart from rectifiying they protect the Mosfets. But then again, if they fail it will end up as a shortcircuit.
Maurice: so now I have two of them!!!!
You can never have enough of these icons.
Congrats on saving one more.
Hi All
Hoping for some hints here :)
I also have a totally dead MK1, and I have a few questions.
1. Can I do fault finding with the PCB3 completely out of the unit. Only supplying the 12V to the board, and no other connections ?
2. So far, I have tested it outside the unit. And I have 12V on all LM3578 pin 8's, but they all also supply 12v back on pin 7. Is this normal ?
4. I cannot find 5v anywhere at all, is seems the 5V supply is totally dead.
5. I dont know much about the LM3578, how are they supposed to work, do they need any oscillation input or something I should look at on a scope ?
5. I have the service manual for the MK1, but it is missing the circuit diagram for power supply. There is a block diagram, but it is not of much help. Anyone have the missing diagram ?
6. It states in the service manual, that if 100/120hz is missing, the product will not operate. I would assume that somewhere, even with the board out, there must be 5v to power the std.by / CPU and so on ?
Any helpful tips on where to start is much appreciated. :)
/Weebyx
You should feed the board with 11-20V AC and not DC. You won't measure all the voltages all the time. The processor controls each line.
Beobuddy: You should feed the board with 11-20V AC and not DC. You won't measure all the voltages all the time. The processor controls each line.
I use the trafo from the 9000 as power source. and measure 12vac after the rectifier, after that no voltages anywhere other than the 12vac at the LM’s pin 8?
There is no 5v anywhere near the processor, so I guess that the first 5v line is down. Can you point me to where the base 5v for the processor should be found ?
thanks 🙏🏻
Weebyx: 12vac after the rectifier, /Weebyx
12vac after the rectifier,
I sure hope not!
You should approximately measure 16V DC at the drain of Tr37.
I assume that you've taken out the PCB completely? When not. Take out the big ribbon cable, which leads to the motorcontrol. When the motorcontrol is shortned, then the PSU doesn't start up. But with a defektive motorcontrol the 5V powerline mostly the general fuse (in the 230V section) has blown.
Measure after Tr37 if there is a D22 that's shot.
Beobuddy: You should approximately measure 16V DC at the drain of Tr37. I assume that you've taken out the PCB completely? When not. Take out the big ribbon cable, which leads to the motorcontrol. When the motorcontrol is shortned, then the PSU doesn't start up. But with a defektive motorcontrol the 5V powerline mostly the general fuse (in the 230V section) has blown. Measure after Tr37 if there is a D22 that's shot.
Thanks, and I mean 12VDC ;) Sorry...
Yes, I have the board out completelly, only connected with the trafo and PCB5(which I dont think matters, but i can be wrong).
I will check around TR37.
Weebyx: Beobuddy: You should approximately measure 16V DC at the drain of Tr37. I assume that you've taken out the PCB completely? When not. Take out the big ribbon cable, which leads to the motorcontrol. When the motorcontrol is shortned, then the PSU doesn't start up. But with a defektive motorcontrol the 5V powerline mostly the general fuse (in the 230V section) has blown. Measure after Tr37 if there is a D22 that's shot. Thanks, and I mean 12VDC ;) Sorry... Yes, I have the board out completelly, only connected with the trafo and PCB5(which I dont think matters, but i can be wrong). I will check around TR37. /Weebyx
Just a quick update.
The unit is back to life, but without knowing exactly what I did !! :)
Anyone has experienced something like this ?
Have you checked the voltage lines, which should come up after 2-3 seconds. Check the first main line voltages +12V/-12V /+9V first. They are there a few seconds during the startup routine.
Beobuddy: Have you checked the voltage lines, which should come up after 2-3 seconds. Check the first main line voltages +12V/-12V /+9V first. They are there a few seconds during the startup routine.
I have checked them, and they seem to be there in the beginning, and then fade out, at least if the PCB3 is out of the unit.
How should this be tested with PCB3 in the unit ? I was thinking about removing bottom plate, attach lid and close it manually. Then put it up against a wall so it is easy to measure voltages from the underside of PCB 3?
This way all startup routines should complete without problems ?
I forgot to mention that I also have changed C142/C143, both of these were leaking out the bottom. I did not have 33uF, so they are now 47uF, but same 16v.
But since the unit works 100% after the 3 clicks, I would say that 12 and 9v lines are working correct ? Sometimes I get the single click only, but have not been able to reproduce it consistently.
/Jacob
Can I swap out a mk1 psu with a mk3?
Nope, you can’t.
Appreciate your prompt response