[chilibt]

I did a test of the keyboard buttons and the contacts work, giving a response to the end of the connectors. Summary, the unit has full functionality using the remote, only the keyboard has no response when any key is pressed, and the keys apear to work.

Any suggestions what to look at next?

[chilibt]

Thanks for the excellent help! Here are the results:

First checked main 10000 uF caps, there was a slight vent of crust, so replaced with newer ones that tested good. (new were on order)

put fuse in

[PLUG OUT]
Remove P41 & P42 from Board 16 and P34 from Board 9. Leave P40 connected on Board 16.
[PLUG IN]

the dim bulb lit up then the fuse blew. I investigated further and found the 2200 uF cap was now shorted. I replaced it with one on hand sand the unit worked! (except the keyboard).

The Cap set arrived and I thought the board 2 recap would be the best start. It did not bring the keyboard up and working. The ribbon cable is fine (c0ntinuity) the solder joints are ok.

Any thoughts on the keyboard fix?

The next issue is on board 8, It has a 10uF cap in place of the spec 22nF. attached picture. Should I put a 22nf back or replace the same 10uF? (pictures on this site shows others have the 22nF) I have another unit with the 10uF. Was this a factory improvement?

 

[chilibt]

hi,

back at the beginning of this post

spassmaker wrote:
Hi The Strobe issue on the BM 8000 was just a misaligned Pot R15 which has to be adjusted to minimum ~3.6 Volt, the Pot was turned the whole way down and the CPU did not recorgnized the too small signal below 3,6 Volt. This Pot is not present in the BM 6000.

On my BM6000, I had the :. also. (same symptoms)

Did you try VR 2R89 and adjust it? When I did yesterday on mine it worked as before the :. was gone and the . was there, It was not shut down and frozen now.

The VR was set wrong when I replaced it, and once adjusted the display and whole unit was in standby and able to work with the remote in all functions.

[chilibt]

Hello Gentlemen, I fixed mine with the :. display! (Just now)

Story:

I was starting “my new to me” BM6000 (update to follow to Glitches help in my other post), and had no display but a . (stby dot)

I had a dead keyboard but the remote worked. When on, there was no frequency display, and the tuning indicator arrow>< showed and worked.

I decided to start a rebuild with the beoparts cap kit, and board 2 was a perfect start. It was 3 caps and a VR (R89) lower right on front of board 2.

I kept the board in place. Took a reading on the old VR and put the new one in with the same resistance setting.

Result: only got the :. and no remote or keyboard input brought it out of this state.

I rechecked all the connections and polarities – no change.

Then I read your post and although it is way over my head, there was the suggestion that a VR could be set wrong. Two tries on R89 – 30 degrees each move and it worked! It lit up in Standby (one dot) and the remote perfectly works.

I still have no keyboard working so here we go! any suggestions for the dead keyboard?

Regards

Terry

[chilibt]

Great info, thanks,

I discovered the bulb issue before it was too late in the past (thanks for reminding me).

I like this info as a reminder, as I have not worked on these in a year and now -it is fresh in mind!

[chilibt]

Thanks again, you are very generous with your knowledge.

I am cautious at the schematic interpretation (in case I miss something) and I thought they may be connected on the trace but it would need to be confirmed with removing the board from the heat sink… thus pushing the wires into another bending which can lead to trouble (I do not trust all disassembly to be trouble free).

I found on my current 6000 that the antenna connections have the smallest fragile wire in a solid nylon shield, breaking the wire easily and giving me the dreaded 78.8(or similar) display. It now makes me aware not to tear at the unit for reviews/repairs without a full understanding of the manual and visible information on the board.

Thanks for the bench test suggestion!

[chilibt]

Thanks Glitch,

(I responded twice so far and get “errors” and lose the text. I am trying again.)

This is an amazing list of steps that will help me and others start up an “unknown” unit. Thank you very much!

I have some questions about grounding and test points, my questions are in bold:

Test Main Amp with Bench Power Supply

1. Connect to power supply

B9-P34-1 -50v* * Start at about +-10v and work your way up
B9-P34-2 GND What ground do I use, the chassis, the removed conector, of the Mains ground?
B9-P34-3 GND (I can’t remember if pins 2 & 3 are connected on the board) As above?
B9-P34-4 +50v*
B9-P31-3 GND** As above
B9-P32-3 GND**
** The ground signals on P31 & P32 are not connected to the grounds on P34 on Board 9. I think B&O wired things this way to avoid a ground loop within the chassis.

2. Set power supply voltage to +-10v and the current to about 0.10A

3. Connect voltmeters to measure the Idle Current and Offset Voltage per the Service manual

4. [POWER ON] Adjust R110/R210 for an idle current “voltage” of around 5mV and R134/R234 for an offset voltage near 0.0v. The actual voltages are not critical now as long as they are below the 22mV and near the 0.0V that you are trying for at full voltage.

 

The Test points (TP) in the testing diagrams and schematics, list the TP on R244/243 and R144/143. The actual PCB has a different point indicated as printed on the Board. The printing shows the adjacent small Resister as the test point. I believe it is printed on the PCB wrong. I am attaching photos of the different boards and spots. Am I correct, the error is on the PCB?

Thanks again for the list. I will be working on and posting the results after Christmas.

Regards

Terry

 

 

[chilibt]

Thank you for an easy to follow checklist, it is greatly appreciated.

As a hobbyist (Not Tech) of course this leads to more questions that you can hopefully answer:

Test the capacitors OK (main power caps are to be tested)
Test the main power supply (Board 16): By regular mains power after checking caps and disconnecting other boards?
Test the CPU power supply (Board 6): Using power from the main power supply board 16(above) once tested?
Test the main amp (Board 9) with a bench power supply. This is a part that could go bad for me, can you confirm (P34-1 [50v -] and P34-4 [50v+] to be the power pins, I brought the voltage up slowly with current limits in place. What current limits did you use? This is a good time to adjust the no-load current and offset voltage.
Reassemble everything except the power connector to the main amp and test with the light bulb rig (what bulb wattage? 60, 75 or higher? The specs say the amp has 50-300 watts consumption). It is hit or miss that the receiver will start in this configuration since the RESET circuit will likely trip.
Test with the main amp power connected and the light bulb rig.
Try power-up connected directly to the mains (only if step 5 & 6 looks good)

Thanks again for your help in this start up process.

[chilibt]

I also read that starting with a Variac should be done at 70 or 90 volts and not lower. If a variac were to be recommended, then which initial voltage would be recommended?

[chilibt]

Thanks for the advice,

This is a 120V unit. Preservation of This receiver is the goal. I currently have a dc power supply, multimeters, and could buy a variac if it is the best way to start the test of the unit. This has one fuse out of its holder on one end of the holder-not touching, and was sold as “not working” …making me think that the fuse out of place may be why it was “not working”. There is no smell or visual damage inside so it gives more evidence that it could be a out of place fuse as the culprit. Restoration to operational is the goal.

The Variac was the unknown to use for me as the damage of the main IC was my concern. I read conflicting accounts on the use of a variac with modern (non tube) receivers and most information on variacs are tube focused.

I have another unit which has a problem with the amp board shutting down the receiver, both these units have some scuffs on the aluminum. Ideally I will make one unit the best exterior and a fully restored interior by using all best parts, and the second will have the worst exterior panels but be restored and have a functioning receiver (the exterior aluminum may not look as nice).

I like the idea of testing the main Power supply (PS) capacitors and unplugging the boards to test the PS first. Would a variac be good here or just give it a try once the caps were determined as OK.

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