Thanks a lot for your help, Glitch. Hopefully I'm missing something obvious, will continue to work on it.

One final question, how does the "St.by" circuit work on board #2? Specifically around TR27. I know it gets 15V from board #6. I've got 15V at the DD (TR27 emitter) and 14.3V at the base, but then nothing on the collector (if I did, the relay would switch on). I'm guessing this tells me the CPU is not providing the necessary signal and TR28 is not pulling to ground? Thanks again!

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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

I removed my response since I really didn't answer the question. Hemenex's reply below makes more sense.

Glitch

Sorry but if you have 15V at emitter TR27 and 14.3V at Base then TR27 as a PNP type should turn on. (0,7V on its BE-diode)

I would check TR27…

hx

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.

quattttro:  Have you made any more progress?

I revisited my BM6000 that doesn't power-up properly. I was able get it to work with a known working good CPU from another BM6000. Now I'm very confident that the original CPU is bad. With the bad CPU, I observe two different (pseudo-random) behaviors when I plug-in the receiver.  The first is a ":." display, the second is a "." display with the main amp rail relay kicking in.

Glitch

link

quattttro: Have you made any more progress? I revisited my BM6000 that doesn’t power-up properly. I was able get it to work with a known working good CPU from another BM6000. Now I’m very confident that the original CPU is bad. With the bad CPU, I observe two different (pseudo-random) behaviours when I plug-in the receiver. The first is a “:.” display, the second is a “.” display with the main amp rail relay kicking in. Glitch

No progress. Sits on my workbench, haunting me. I'm pretty sure mine has the same problem though, a faulty CPU. It is consistently unresponsive .:", & the main amp relay never kicks on unless I mess with the startup timing.  Shame to turn it into a parts unit, but not much choice.

If anyone with a faulty Beomaster 6000 CPU is interested I have two unused CPUs, with no way of checking whether they are working or not. They have never been installed, but are original production samples. They have the same B&O item number, 8340285, but different dates, 8107 and 8138. I don't know if any changes were made between those two dates, but presumably there were.

For anyone with the means, ability, and interest in rewriting the original program I also have a piggyback version of the 3870 processor with a socket for a 2716 EPROM on its back. There's also a 2716 EPROM, but I don't know if that contains a version of the BM6000 program or not, and no longer have the capability to read it.

 

A posting on this site describes the beginnings of the BM6000 PIC project.
/forum/beogram/how-does-the-beogram-tx-compare#post-1681837
I'm hoping a full description will be published one day before too long.

It did take months to write the original program. See:
https://beomicro.wordpress.com/beomaster-6000/