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Beolover SyncDrive: DC Platter Motor Replacement for Beogram 4002 and 4004 (Type 551x and 552x)

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

Showing posts with label wires. Show all posts
Showing posts with label wires. Show all posts

Sunday, February 11, 2018

Beomaster 8000: Reassembly...Where do all the wires go?

I think it is best to remove all of the Beomaster boards and parts to work on them. It is easier to work on the components individually and not worry about accidentally damaging a nearby component. It also allows the empty cabinet to be inspected and cleaned.

Reassembly of all the removed parts can be a daunting task. Fortunately I have done this enough times and have plenty of photos of where everything goes.

The next sequence of photos show the reassembly of the Beomaster starting with the (almost) empty cabinet.






















First I add in the left and right output amplifier board assemblies. These are the assemblies I have already bench tested. To reassemble them in the cabinet I had to remove the transistors (and PTC) from the heatsink and then connect them back up. I am so glad I am using the sil-pads.




















The power supply board and regulators are next.






















Then the FM and FM Interface boards.






















Followed by the preamplifier board.






















Before continuing with the microcomputer board I added some of the interconnect cables.
Now the microcomputer board.




Time for the display board.























The Filter and Tone Control board.























Here is everything installed in the Beomaster cabinet again.
Tomorrow this receiver should move from the work bench to the test bench.

Tuesday, September 9, 2014

Beomaster 8000: Wire Bridges on Microcomputer Board (#9) and Broken Phono Jack

Before I put the Beomaster 8000 back together for a test-drive in the living room together with his play-pals, the Beocord 9000 and the Beogram 8000, I cleaned and de-oxidized all the contacts on the microcomputer board (PCB #9), and had a look at the inner sanctum, the EMI shielded processor cans. Usually one needs to re-solder the few vias that are on this board, since they tend to be poorly soldered...clearly in the 80's the PCB technology was not that advanced, yet. Anyway, what I found in this particular Beomaster was remarkable. Someone already had put in the B&O recommended wire bridges (and then some...), and they were directly soldered to the processor pins. Unbelievable! Here is a pic:






























While the soldering appears to have been carried out with some capability, I would never do it this way...the only parts of the Beomaster 8000 that are truly non-replaceable are the microcontrollers that contain proprietary coding, i.e. one would have to extract the code from a working one, if one would want to attempt replacing it with a NOS chip...

Anyway, clearly, this needs to be left as is. I could not risk to expose those rarefied microcontroller pins to another heat-cool cycle. In a way, since the chips survived this assault, this solution is probably the most reliable...several fewer spring based contacts in between the controllers and their slaves...so I decided to just replace the two electrolytic capacitors on this board and move on.

Here is a pic after putting in the caps:



The last thing that needs to get fixed in this Beomaster is a broken phono jack in the 'socket panel' that lost its tabs that prevent it from popping into the panel when trying to plug in the Beogram:



I am working on a creative solution, since not even Dillen of Beoworld.org has this part available.  He said it is rare, since it often breaks...Another day, another 3D print...;-)