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Beomaster8000 repair/resoration

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ALF
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AUS
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ALF posted on Thu, Mar 21 2019 8:53 AM

greetings ALL 😁

I decided to start a new thread with my new donor-unit BM8000 - this time in the correct forum !

this donor unit was purchased as a parts-reservoir but turned out in very nice cosmetic condition.

so I took a close look and noticed all boards were recapped, the displac is fine....well, so far so good.

further testing reveiled there are issues:

Plugged in it shows the StBy dot.

turning on, no relay clicking while the display comes on.....hmmm ?!

checked the power supply board....all associated transistors have tested fine off-board, all caps are in the correct way, all connector joints have been reflown.....?!

next thing I noticed the small heatsink with the 3 voltage regulators is getting VERY warm....?

next thing : with no relays energized I can measure the 15V and -15V regulator which should only be possible

when the start-up circuit gives the “green light”.

5V should be present at Pin14 / 9IC4 during STBY mode and going down to ‘O’ when ON is achieved....no, it remains at about 25mV

meaning: the BM according to this is actually out of ST BY !!

5V are only present at the 5V regulator when I disconnect P76 of the processor board ?

a faulty processor 9IC4 ??

I did change the two 2MHz crystals (as suggested as a precautional measure by Beolover) after removing 

both uPs for safety reasons......! No change !

I disconnected the keyboard in case the on/off key is stuck and used the remote to turn off/on  the BM....

no luck here either 😡

disconnected P51 and 50....no change.

well, what am I missing here ?

and this is only unexpected work at the donor-unit while waiting for those speaker switch replacement to

continue work/repair/restore on my original BM8000 project...😳

guess help is badly needed here 🙄

All Replies

chartz
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Burgundy, France
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chartz replied on Wed, May 22 2019 9:28 PM

Incredible! Phew!

Jacques

ALF
Top 100 Contributor
AUS
878 Posts
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ALF replied on Thu, May 23 2019 12:59 PM

Well,

there is still the BM8000 donor unit........probably another high-speed project ?

Not sure yet how much effort is necessary to bring it back to life....we’ll see

and if, no doubt there will be posts 😁😁 and in between the odd relaxant   🍷🍷

ALF

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