Beomaster 8000 display issue

8 replies
spassmaker
Offline
spassmaker
Bronze
Posted January 19, 2021 at 20:57 GMT
#2212745

Hi to all technical specialists.

After a complete refurbish of a BM 8000 incl. new LED's for the Displays I can clearly see that the lower display for Balance is reacting parallel to the upper display for volume.

Just only a little bit but even in a bright day visible.

I' ve checked the displays twice, all  LED's are in the right direction and the masks have no chrome coating which could make some short circurits.

Already changed all LED related resistors to a higher value and the LED driver IC's are exchanged too. 

The lower display is still visible but all LED's are dimmed as  expected. 

All other displays work as expected.

I've already refurbished 3 of these Beomasters and used always the same type of LED's without any problem

My suggestion would be the PHASE 1, 2 and 3 transistors or the LOGIC 1,2 and 3 transistors.

Maybe I'm on the wrong way and someone has had the same problem, like a comment on Beolovers website shows, regarding the display refurbish.

Look here down in the comments:

https://beolover.blogspot.com/2012/05/beomaster-8000-display-brightness.html

Any advice is welcome.

Stay tuned, Kind regards Christian

 

 

 

 

 

K(
Offline
krais (archived2)
Bronze
Posted January 20, 2021 at 11:52 GMT
#2212746

I've had the same issue on my BM8000 project, see: /forum/imported-unmapped/taking-on-the-bm8000#post-2210944

 

The issue was resolved when I replaced the board connectors between PC8 and PC9, so it's most likely a connection issue.

spassmaker
Offline
spassmaker
Bronze
Posted January 20, 2021 at 14:56 GMT
#2212747

Thank you for your advice, I will check the conectors.

Hope to find something.

😎

Kind regards Christian

spassmaker
Offline
spassmaker
Bronze
Posted January 21, 2021 at 07:53 GMT
#2212748

Hi again

Yesterday i rechecked all traces from the plugs to their desired points on both boards, all ok.

The plugs and sockets where already desoldered and resoldered as I make this process always during a refurbish.

I soldered all contact pins even they where looking good without any corrosion.

Poked with a small tip to the contacts while the amp was on, nothing.

Finaly I exchanged all transistors relaiing to the Phase 1,2 and 3 as I remember TR 14 up to TR 19. Nothing changed. Still the same glimming of the lower display.

😭

Today I try to renew the darlington transistors from the LOGIC  amd will look what happens.

My sugestion is that there is a kind of overlap in the LOGIC circurit or the PHASE circurit.

After changing the LOGIG darlingtons I will grab my oszilloskop and have a inspection to the signals.

The story goes further.

I'll be back 😐

Best regards

Christian

 

spassmaker
Offline
spassmaker
Bronze
Posted January 24, 2021 at 14:30 GMT
#2212749

Hi dear members

Last days I spent some time with measuring some signals of the Beomaster 8000

I´ve seen nothing suspicious maybe I´m a little blind ;-))

So have a closer look to the signals shown as 

Collector TR 15, 17 and 19

 

 

Anode D 11,13, 15

 

 

PIN 1 Display 1

PIN 9 Display 2

 

Don´t let me stand in the rain please ;-))

 

Thanks for advice

Best regards

Christian

L(
Offline
leeshep (archived2)
Bronze
Posted January 24, 2021 at 18:28 GMT
#2212750
The dim “reflections” in the lower balance screen of the volume is completely normal. Mine does it too. Hardly noticeable when the screens are put back together with the filter in the glass.
spassmaker
Offline
spassmaker
Bronze
Posted January 24, 2021 at 19:50 GMT
#2212751

Hi Lee

Did you refurbish the displays or are they still original?

Have had the 4 BM 8000 two were visible two were ok, used always the same LED´s.

Thanks for reply.

Best regards

Chistian

L(
Offline
leeshep (archived2)
Bronze
Posted January 25, 2021 at 11:58 GMT
#2212752
Yes mine have been rebuilt with new LEDs. It had the same “reflection” with the old LEDs too.
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