Hi Christian,

Haha, that archived post of mine was quite a while back (2011).  One of my first Beomaster projects. Seems like ages now. 
To post pictures you do need to adjust the size for the best fit. When I take photos for the forum I try to take one as close as possible to the target information so when I reduce the size it will retain the information. For just adding a photo using the posting options I think around 700 to 800 pixels will fit on most screens. You can go a little larger but then viewers will have to click to expand the image to see all of it. Another option is to upload pictures to a personal folder in your Beoworld profile.  You can then add them to your post from the Insert Media option.  The photos can be a little larger using that method (like maybe 1200 pixels).

Regarding your Beomaster 6000, that is a problem when starting with a non-working unit you acquire from someone else. You don't know where it has been or what has happened with it.

If the Beomaster is not coming on because of its fault detection (and that is what it sounds like) then that trigger is coming from one or both output amplifiers. You need to recap those for sure.  Both output amplifiers can command the fault detection to trigger so you could try and isolate them one at a time but really I would recommend recapping them first. The output amplifiers (L & R) are overdue for the capacitors to be changed so do that first. After that recheck the Beomaster.

Regards,
sonavor 

Hi Sonavor

Thanks for the quick reply

Yes that is a long time since 2011 but you are still in buisness, that's fine.

That was the answer i realy didn't want to hear ;-))

So i have to buy some more caps and trimmers for the amplifier, that may take a while.

It is still not clear for me how you managed the issue with the 74LS74 pigiboard. How can there come out a frequency about 664 Hz when the inputs is 3,975 MHz and 1,75 Mhz?

And how did you manage the fault that the signal from the 74LS74 is gone when connected to PIN 38?

When i seperate the output of the 74LS74 i have a signal like it is frequency shifted (don't know how to discribe,) with square shaped signal about 5Vpp interrupted for a while.

When i put the output back to IC4 the signal is gone.

The schematic in original says the tunerfrequency minus about 10 Mhz goes into the amplifier and divider by 64 and into the74LS93 and from there straight to PIN 38 IC4. So normaly it must be about 1,75 MHz at PIN 38 of IC4...right?

For what the hell did they put this little board with the 74LS74 in there? Did they change the uC?

I don't understand this.

So back to the workbench.

I 'll be back when there is something new.

Best regards

Christian

I´ve rezised the pictures i´ve made...
Here are the results of the german jury with 12 points...😁

Pictures from signals i´ve measured so far with a scope

Piggyboard Input from IC9 Pin 1 to 74LS74 Pin12

Piggyboard Input from IC 6 Pin1 ( TR 1) to 74LS74 Pin 1

Result of Piggyboard Output 74LS74 Pin 9 straight to IC4 Pin 38 not connected. When connected gone somwhere

You can see the different pulselenghts. Maybe it is caused by the different frequencies which are getting together on one D Flip Flop like 74LS74 is!?

Maybe someone is able to simulate this and post the result here...that would be very nice.

Here is a drawing of the wireing of the piggyboard with the 74LS74

Last but not least the RESET in relation to the Vcc 5Volt

and the resulting displaypoints

Hi There

In the meantime i got a simulatorprogram to crosscheck what i've measured at PIN 9 of the 74ls74 (White Wire to pin 38 of IC 4).

It seems to bei the same frequency with the variations like in the Pictures above.

Still it is so that the signal drops to zero when the white wire ist conected to IC4 Pin 38.

Best regards

Christian

Hi there

In the meantime i was on holidays and had to fix some other stuff like my car and a Beogram 4002.

Today i came back to my Beomaster 6000.

I recapped the main amplifier, and was able to align the Noload current and the offsetvoltage.

The amplifier was running about 1 hour in stable condition, no heat, no smell.

I put back together everything and tried to power on the Beomaster.

But there is still the same behavior, shot klick from the relais and P on the right display and a point and zero on the left display

I've aligned the reset circurit once more.

Measured some other Voltages, all seems OK 15 Volt, 6,5 Volt and 5 Volt, even at the relevant IC's

Tried to measure the Crystal frequency, but what is this, no 3.975 Mhz anymore?!

Now I'm searching for a new or used working crystal 3,975 MHz.

Maybe someone who's reading this has one in his workbench and can offer me one.

Thanks for reply

Best regards

Christian

If you are sure that the reset circuitry and the 6,5V are both fine, it could be a dead CPU.

Martin 

As Martin say's,it could indeed be a failed processor chip,it does seem to happen with these Beomaster's,and  sadly,replacement's are now as rare as hens teeth!!!

Various things can stop the upc from running,and it's well worth checking the keyboard,as these can become conductive.We are seeing this phenomenon increasingly with the older kit.It has the effect of shunting one or two of the data control lines around the upc.

Nick

Thank You for the replies.

A dead CPU is not what i expected, because before the recapping of the amp everything around the CPU was working as You could see on the pictures above......

So i give that beast another try and check the Keyboard, hope to find something.

Best regards

Christian

Hi Christian,

Spassmaker wrote:

So i give that beast another try and check the Keyboard, hope to find something.

Did you have any luck with your BM6000? I'm in almost the same situation that you where back then, and curious if you got any further!

Best regards,

Thomas