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Beomaster 8000 Restoration

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dahiyas
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dahiyas posted on Tue, Oct 13 2020 5:47 AM

This weekend I started on trying to restore a Beomaster 8000. 

Couple of issues before I started -

1. Three buttons missing on the panel - Martin found the replacement buttons in his dungeon and sent over the same.

2. The system has the standby light on but does not come out of standby.

3. The volume dial makes a scratching sound when turned. Looks like something is out of alignment.

So last 2 weeks were spent reading all Beomaster 8000 related messages to prep for the project. Rudy's (Belover) detailed blog was really helpful to get started.

I will also do a complete recap while trying to fix the above issues.

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sonavor
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Sehrbug:

Hi, there, sorry for jumping on the thread, I have just finished recapping BM8000 since it was completely dead, 

All the functions are working, but no sound and reservoir capacitors are measuring 105VDC. 

any suggestions?

Are you meaning that the Beomaster 8000 begins in Standby mode when you plug it on and you can switch to the various music sources okay?

If that is the case do you hear the power relays RL1 & RL2 engage and can you measure +-55 VDC on the output amplifier rails?

Did you check for sound via headphones?

Also...It would be better if you create your own thread.

-sonavor

 

dahiyas
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dahiyas replied on Sun, Nov 29 2020 12:14 AM

Sonavor - I did not see the standby issues come up again today. I will later remove amp for another Penta and try the balance functionality.

Thanks 

------------------------

Meanwhile - I have another project at hand.

The MS150 showed up - only 50%. Two speakers two separate packages. Shipped together. Both reach Atlanta local hub and then 1 delivered @ home today Angry. Looks like they were too big for the delivery van Wink.

AND for the one that reached, the tweeter and midrange speaker box got ripped from the front frame and I can imagine the box along with the weight rolled around inside the frame and the PCB got pulled by the wires. As a result the PCB has a crack right in the middle. Not too bad I think. Should be able to recover. (Could not post pictures due to site issues). I will keep my fingers crossed on the second one.

Maybe I'll start another thread for this.

 

sonavor
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Darn...you are running into quite a flurry of issues on this project.
I can't imagine how the midrange and tweeter assembly could get ripped away from the frame but the MS150 crossover board does mount to the back of them. You must mean that tweeter/midrange/crossover assembly got pushed into the cabinet from the front. I hope that doesn't mean the metal mounting clips for the assembly broke any of the frame. Maybe all of the mounting clips were not installed (or not installed correctly).
Examine that carefully as you may need to file a damage claim.

When you get a chance you need to post some photos including the inside. I wonder if everything inside is complete.
If you haven't already, check out my old Beovox MS150 forum posts. It is from 2012 but they will give you an idea of what you should see inside.

-sonavor

dahiyas
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You can say that again Sonavor...

UPS is giving me a helping hand here. The other speaker was to show up today and didn't get delivered. The UPS hub is about 10 miles from my house. Is has been sitting there for about 72 hrs now..the status shows EXCEPTION. Either they broke it completely or some UPS guy is enjoying the speaker right now Big Smile

dahiyas
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dahiyas replied on Thu, Jan 21 2021 11:34 PM

Finally am back on the project.

On the positive side I fixed the unresponsive tuner dial. Replacing the OP240A fixed the issue. (same as the volume sensor module - https://beolover.blogspot.com/2018/02/beomaster-8000-repaired-rotary-volume.html). 

Added Beolab 5000 speakers to my collection.

So the BM8000 works well .....only when it works. Issues -

1. There are times it wont come out of standby..pulling out power and plugging it in again fixes the problem. Takes couple of retries sometimes.

2. When it does come on, the keys/dials become unresponsive after couple of minutes. and the first indication is that the display characters start displays random pattern. Music continues playing without any issue but I cant use the keyboard and the displays have random characters. Also can't put system in standby. Only way out switch off power and start again.

3. A new symptom I am seeing is that in standby, there are times one one of the bars on the frequency display flickers or the source indicator display will come on...This is all random. Again, when this happens the keypad is unresponsive. power cycle gets it back to normal.

So for the CPU and Display boards, I have changed all the connectors. Checked the via's.

Looks like the CPU board is still the issue. 

Any other suggestions ?

 

sonavor
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Some Beomaster 8000 units can be real beasts to work on. Others work great all of the time.
Fredrik (Mohawk on the Beoworld Forum) produced a replacement (bare) board for the BM8000 display board earlier this year. He also recreated the output amplifier PCB.

A month ago I sent him a spare BM8000 Microcomputer Board that I stripped the components off of...and I wished him good luck on his journey to create a replacement PCB for that. Hopefully he will master that board as well and we will have a good option for these troublesome Beomaster 8000 units.

When I have come across a problem such as yours I have the luxury of a spare, fully working Beomaster 8000 I keep opened up in my workshop. That allows me to easily try out other boards, cables and various components. If you get completely stuck I might have you send me your suspect boards and I can test them in my bench unit.

Some of your issues sound like possible connection issues to (and from) the Beomaster control panel. Do you have the remote control for the Beomaster and does it also have the same problem controlling the Beomaster?

I may have asked you this before but have you measured the DC voltage levels on the components involved with your problems?

-John

dahiyas
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Thanks Sonavor..Yes !! I did see the post about the new PCB. Am sure many folks will be waiting for that one. 

Initially, the 5v regulator/capacitor were an issue. Replaced those and 5v problem was fixed. Now it's stable at 4.9v. Other than that only other thing I checked was the voltage for display PCB, which was ok.

I did try a Beomaster Terminal remote. The system only responds to the remote when not in "hang" state. Which is again pointing to the CPU board being a problem. 

I will recheck the CPU board.

And continue to wait for the new PCB.

 

Thanks Sonavor.

 

 

 

 

dahiyas
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Thanks Sonavor..Yes !! I did see the post about the new PCB. Am sure many folks will be waiting for that one. 

Initially, the 5v regulator/capacitor were an issue. Replaced those and 5v problem was fixed. Now it's stable at 4.9v. Other than that only other thing I checked was the voltage for display PCB, which was ok.

I did try a Beomaster Terminal remote. The system only responds to the remote when not in "hang" state. Which is again pointing to the CPU board being a problem. 

I will recheck the CPU board.

And continue to wait for the new PCB.

 

Thanks Sonavor.

 

 

 

 

dahiyas
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Thanks Sonavor..Yes !! I did see the post about the new PCB. Am sure many folks will be waiting for that one. 

Initially, the 5v regulator/capacitor were an issue. Replaced those and 5v problem was fixed. Now it's stable at 4.9v. Other than that only other thing I checked was the voltage for display PCB, which was ok.

I did try a Beomaster Terminal remote. The system only responds to the remote when not in "hang" state. Which is again pointing to the CPU board being a problem. 

I will recheck the CPU board.

And continue to wait for the new PCB.

 

Thanks Sonavor.

 

 

 

 

sonavor
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Perhaps the crystal oscillators for the clocking of the microcomputer board are not working correctly.

-sonavor

dahiyas
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Looks like I we may have found the culprit. 

I was checking on the crystal oscillator X2 (the one on the left) and trying to see how to take it out. I poked on the 3 vias right above x2 (with a plastic spudger). And decided to try one last time before removing the CPU/Display boards. The system came out of standby on the first attempt and I tried on/off combination many times - worked fine. Connected a source and let the system run for about 3-4 hrs..No issues since then. Looks like everything works the way it should.

I think the vias were the problem (which you and Martin had pointed out right at the beginning). There was one right under the top of X2 which I had not touched earlier. I guess the poking fixed something.

Now the question is - since the unit is open, should I just put 3 jumpers for the vias or just leave everything as is. 

dahiyas
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dahiyas replied on Thu, Mar 18 2021 10:29 PM

I am back on my project after a long break. 

So I did end up putting the jumpers. The system has been playing well for the last 2 months. I haven't put the screws as yet as there are 2 issues:

1. Even when the speaker volume is set to 0, I can hear the music from the speakers. Even though its low, its there. In fact, I continue to hear the volume for couple of seconds after the system is put in standby. Volume offset ? I did replace the trimmers on the tone control board but didn't calibrate the trimmers as per service manual instructions. Could that be the reason ?

2. No sound on Radio. Initially I thought that the issue was I didn't have an antenna and that's why I couldn't hear anything. I just hear hiss but cannot tune to any station. The hiss comes only from left speaker when in stereo and from both when in mono. Maybe I have messed up the cable connections? I have no idea if the Radio function was working before I started on the project.

I realized this issue today by accident. I just got a BM6000 and when I checked the radio there, it worked perfectly fine. It picked up stations without any issues. (The fact that freq display does not change is subject for another thread and already documented on the forum)

Any guidance on the above challenges ?

 

dahiyas
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Over the last month I did figure out and fix another issue.

FM Issue - some progress. I figured that there was no sound from the speakers when FM was set to Auto Tune. But when I switched to Manual Tuning, I did get audio but only on the left speaker. If I switched to Mono both the speakers worked fine. Also confirmed that PCB 2 was not the issue by swapping left and right outputs (p10). I did get output from left. Past posts indicated 3IC202 (AD 10/278) could be the culprit and sure enough replacing 2IC202 fixed the problem. (I waited 5 weeks for the IC to show up). So now I have sound from both speakers in stereo but only if set to Manual Tuning.

For Auto Tuning, still no sound. The speakers go completely silent. 

Any inputs ?

 

Thanks !!

 

 

 

Dillen
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Check the "Signal condition" signal (Anode 2D6). It may be constant low.

A bad 2IC3 or 1IC2 would be my guess.

See also my post from april 7th):

Recent repairs - (beoworld.org)

Martin

dahiyas
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I will check the two ICs. 

Thanks Martin.

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