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Late Beogram 4002 and the 4004 (Types 551x and 552x), which have DC platter motors instead of the earlier synchronous AC motors usually suff...

Tuesday, December 27, 2016

Beocord 9000: Power Supply

 Moving on to the Beocord electrical problems I started with the power supply.  The power supply in this unit was having problems. I wasn't measuring +24 VDC on capacitor C1.  At first I suspected the rectifier board so I pulled it and examined the supply capacitors (C1, C2 and C3).  Here is the rectifier board in the Beocord 9000.





























Here are the C1 through C3 measurements.





































I decided to swap some parts with other Beocord 9000 units I have on hand. This Beocord's rectifier board worked fine in another, working Beocord unit I have so the board is fine. That led me to the transformer. Sure enough, the transformer was the problem.
At first I thought the transformer was defective so I started checking other Beocord 9000 units I have...both working and non-working. I found another one with a non-working transformer and compared the Beocord serial number to the one I am working on. What a surprise! I had another Beocord 9000 unit that was an assembly line mate to the current Beocord I am working on. What are the odds of that? After all of these years these two meet up on the same workbench.





































The transformer turned out to be a non-issue as I remembered the transformer assemblies have an internal 250V, 0.5mA fuse inside. I opened up both transformers and sure enough, the fuses had blown.


































This resolved the Beocord 9000 power supply questions. Now it is on to figure out why the unit will not come on.

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