[artig]

For me the favourites will always be the ones I had a hand in creating, and of these the Beocord 9000 stands out as one of the best. It was probably one of the most advanced and best cassette decks of all time from any manufacturer in the consumer marketplace.

[artig]

The service manual is an invaluable aid in reverse engineering the requirements, and most of it could be done using that.

Also there may be some information to be found at https://beomicro.wordpress.com which could be helpful. Including contributions from some of the people who worked on the original development.

[artig]

As far as I’m aware there is no such repository, and doubt that even the B&O archive has copies of the software images.

There are a couple of potential problems:

1. The single-chip controllers are mostly mask programmed and it’s not possible to read the ROM memory from them.
2. There are no pin-compatible controllers with eeprom or flash memory available in most cases.

The Beocenter 7700 uses a Mostek 3870 controller (same as Beomaster 6000) which was not available in an EPROM version, but was available as a bond-out with a piggyback board where an EPROM (2716) could be mounted. I have one of these, but without the software image it’s not really of much use for these purposes. I don’t know if any lab samples or pre-production samples were produced with the piggyback chip.

I have heard of someone developing a replacement chip for a Beomaster 8000 using a completely different microchip (PIC, perhaps) on a small circuit board, writing a program from scratch. Someone else was planning the same for a Beomaster 6000 but don’t know if that ever came to fruition. The more usual option is to take a chip from a product which has died of other causes than a SCC failure.

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[artig]

As an aside, the common phone book should be stored on the PSTN as well as on all the Beocoms registered to it and set to common. You should be able to scroll through them even when outside range of the PSTN. Registering a new handset set to common should have the common phone book together with redial and caller ID lists transferred to it as part of the process.

[artig]

There are two aluminium, a black and a grey. All are pre-2010 so matt finish.

[artig]

I have four Beocom 2 handsets that have been in storage for about 20 years that could be plundered for spare parts if necessary, except for the main circuit boards since I don’t know which program version is in their flash memory. Hopefully the batteries haven’t leaked and caused any damage. Everything worked when they were put in storage.

[artig]

Presumably you know that you can get a readout of the values the calibration has found, so you can check if they have changed or if the results are reasonable? The procedure is outlined in the service manual. With Record Open press Stop and Tape Type at the same time. Display blinks 0000. Press digit 1 to 5 to display the values.

[artig]

Guy wrote:

Great video Steve! Regarding your comment at 3m45s that it was the only B&O radial tracker with remote control: Beogram 2400 pre-dated Beogram 2000 this by 5 years, was radial tracking and had remote control (as did BG2402/2404) – the remote was of course the earlier ultrasonic version. I only know because my father had one ? I think BG2000 may be the first datalink-controlled turntable. EDIT: On second thoughts I think BeoGram 6000 (a BG2402 with new electronics) may have been the first datalink beogram.

The datalink was developed and first used for the Beomaster/Beocord/Beogram 8000, so the Beogram 8000 was the first beogram with datalink. The datalink code format and timing was the same as that for the infrared remote control used for the Beomaster 8000.

[artig]

I don’t know if they are legal everywhere, but you can buy small, fairly cheap, BT receivers that transmit a weak FM signal with a range of only a few metres. They need a 12V supply since they are most often sold for use in older vehicles. It’s many years since I’ve tried one, before the time of BT, so it needed a wired signal in. If it works it wouldn’t need any Beolit modification at all.

[artig]

I’ve never owned a BM6000 and apart from the CPUs I don’t have any parts for them.

I meant if anyone who can write 3870 assembler code and wants to re-create the functionality of the original program, as you are doing with a modern processor, then the piggyback CPU would be available.

BTW someone else has already been through the process of making a plug-in replacement for the CPU, using a PIC processor. It would be good to see a pooling or resources for anyone else who might be interested in reviving a BM6000.

[artig]

A posting on this site describes the beginnings of the BM6000 PIC project.
https://archivedforum2.beoworld.org/forums/p/50455/354032.aspx#354032
I’m hoping a full description will be published one day before too long.

It did take months to write the original program. See:

Beomaster 6000

[artig]

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.

 

[artig]

OK, my fault for relying on my poor memory. I don’t have a BM6000 to try it on and I just remembered it as being like other products from that era which did use the 50/60Hz signal for power failure indication. It’s now more than 40 years since I last worked on the BM6000.

[artig]

quattttro wrote:

What about Pin16 on the cpu (the 50/60Hz signal)? This signal comes from TR4 on the power supply board # 16. I’m not getting a square wave from the collector of TR4, but I might not be measuring correctly. Is this signal required for CPU startup?

The signal on pin 16 is definitely required for a normal startup. If the signal is missing it goes into standby mode since this is normally an indication that there is a power failure. If there’s no mains power there’s really no point in going into anything but standby mode.

If you switch off the mains power (or disconnect pin 16 signal) while the unit is operating it will attempt a normal shutdown to standby mode, equivalent to pressing the Standby button.

[artig]

matador wrote:

Martin, what is “Chartol”, please?

I’m not Martin, but Chartol (usually spelled Chatol) could be translated as a writing desk, escritoire or secretaire. Usually with lockable compartments and a fold-down or pull-out  writing surface. Often used as a home office before working from home or computers were a ‘thing’.

[artig]

Before breaking the shell apart I would take a pen or pencil and turn the lower reel slightly clockwise to loosen the tape and try to pull it gently out of the cassette while doing so. It may get the tape back on the reel without any damage. At least with a clear plastic shell you can see what is happening and avoid making it worse. It’s also best done when the dry conditions don’t cause static cling or repulsion.

During development of the drive mechanism it was a problem with tape damage when starting or stopping wind or rewind but whatever the cause it was solved before production started. See:

Beocord 8000

and:

Various reminiscences

 

[artig]

Since there’s really nothing happening on the outputs after /Reset goes high it would seem that the program code is not running at all.

Sorry, I’m out of ideas for things to try.

[artig]

Did you have a crystal oscillator on pins 1 and 2? The /Reset signal shouldn’t really be pulled high until after the 5V and XO are stable. It looks as if Reset goes high just before 5V, but perhaps that is deceptive.

Since the 3870 has no instructions for individually addressing the port pins it’s normal for all pins on the same port to be set at the same time.

I have an unused sample of the CPU but don’t have the means or equipment to set it up and test it. And I don’t have a Beomaster 6000 to compare signals, either.

[artig]

Setting up all the I/O pins would be one of the first things done in the program after the oscillator has started and /RESET has gone high.

Pin 16 input is used only for the clock and for checking whether the mains power has disappeared when it tries to do a properly sequenced close down if it’s active.

The program was definitely written in assembler but I doubt if the source code still exists. For some information about the development of the Beomaster 6000 have a look at:

Beomaster 6000

Also have a look at Appendix 8 and 9 on the same site.

 

 

[artig]

Several products from that time will go into standby or not start up if there is no signal from the 50/60Hz mains frequency. It should be on pin 16 of the microprocessor.

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