ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
There has been some discussions about replacement processors for BM6500 and BM7000 before on the archived forum, but I'm still a bit confused.
I'm on the hunt for a placement for the original Siemens SAB 8032A-P. I've found this SAB 8032B-16-P on ebay and I've looked through the datasheets (SAB 8032A-P - SAB 8032B-16-P) and they look identical to me. But the names must be different for some reason. I can't figure out what the A and B means but I'm pretty sure that the 16 stands for 16 MHz - I just can't figure out if it will make a difference? Can someone tell me if the one on ebay will work in my BM6500?
Thanks in advance.
/Dennis
A with internal rom, B with internal eprom? Intel has had this kind of lettering.
blah-blah and photographs as needed
To me it looks like SAB 8032X is for external ROM whilst SAB 8052X is with factory mask programmable ROM, but thanks for your suggestion, Orava.
(and the same scheme for Intel, and most of the licence manufacturers besides Siemens as well)
-16- is the maximum clock frequency (the 16 MHz part will work just fine at a slower speed). I can't find my Siemens data book so I can't tell what the actual difference between A and B is, but B is the later development and it should be completely backwards compatible.
--mika
Thank you very much for your answer Mika!
You confirmed the theory I had about what A and B stands for, and since I can't find any differences in the datasheets, I think I will order one or two them - they are not that expensive anyway.
I'll return once I've received and tested it and tell if it's a success or not.
The programming inside the BM5500-7000 is pretty dirty.
You can try it with a 8032x2 processor. It is exactly twice the speed of the standard 8032cpu... you will have really a lot of fun. There will be almost no communication in two way. Sometimes it will work for a day, sometimes some minutes and then it will be dead until the fun starts again. The IR range will be less than 1m and you will think....ok, ir transmitter dead or dirty... no, wrong cpu.
Dirty programming: the programmer used to write complete status control words into the cpu registers instead of writing status bits. If the cpu is now more modern, there are more bits used in these registers. So, if only 3 oder 4 bits were used and the newer cpu uses all 8 of them, because it has more registers and capabilities, the other functions are also programmed with complete nonsense.
If you use the x2 cpu, it runs twice the speed because the switch for doubling the speed is activated by such a nonsense bit... the 8032 does not use this bit, the x2 does.
How do you think, will a cpu at wrong speed interpretate an IR signal timing? Nice fun...
I cannot recommend any change of the cpu type. Use the original intel oder philips 8032acpu. Nothing else. It's your fun to repair it.
Hi Die_Bogener
Thanks for your answer.
I'm totally aware of the x2 versions and the complications that follow, if one of these is installed in a BM6500/7000. I've read what you wrote here on the archived forum. But the one I've linked to is the "normal" 8032 version as far as I can see. The maximum clock frequency is 16 MHz whilst the x2 versions have a maximum clock frequency of 33 MHz if I remember correctly.
I've ordered SAB 8032B-16-P, and if it doesn't work out with that one, I will try to find an original SAB 8032A-P.
Do not worry about the basic four-digit parts such as the SAB 8032B-16-P, it is functionally identical and has no hidden tricks over the original Intel 8032 core design.
Most of the extended designs (and 80Cxx parts) are actually CMOS technology (instead of HMOS/NMOS) and they might not be electrically compatible either; the port pins have different specifications.
BTW, how have you determined that the chip needs to be replaced? If it doesn't run (no activity on the ALE pin, 30), double check the components in the reset circuitry. Over the years, B&O designers had a passion to use overly complicated reset designs and problems there can easily prevent the CPU from starting properly.
My father, who is a former electronics technician (Not sure if that's the correct term - he used to repair TVs, radios etc. for a living), has concluded, that the microprocessor has a short.
I bought the BM6500 about two and a half years ago, and I'm pretty certain, that I was able to turn it on back then, but it would go straight back in to standby. My father and I tried to measure different supply voltages, but at some point the fuse on the microprocessor board blew, and even though it was replaced, the standby light had disappeared and it refused to turn on again - at least I think that's how it went, it was two years ago.
My father started to measure around the microprocessor and found the short. I don't know if the microprocessor was cause of the misbehavior or if it was taken out by something else - I will of course make sure, that there isn't some obvious fault before I install the new processor. But what I do know is, that someone else has tried to fix it before I bought it - there has been written on the underside of the power supply/amplifier board, that it is faulty and won't go out of standby. It was written with a ballpoint pen...
I put it aside back then, as I thought a new SAB 8032 was almost impossible to get hold of, but your information has been very helpful.
The short on the cpu board is probably caused by a dead 5.6V zener diode behinde the fuse. If there is an overvoltage, this diode kills itself and the fuse to protect the microprocessor.
Replace the caps on the power supply, especially the smaller 10uf types ;)
I think we changed the zener diode once back then because it shorted together with the fuse, so that will still have to be investigated. The one that is mounted now is perfectly fine and the fuse hasn't blown either, so that was probably what took out the microprocessor.
The 10µF caps in the power supply are the original ones, so I will definitely change them then - thanks for the suggestion. I've changed the trimpots in the output amplifier and the backup battery seems fine, but are there any other known issues in the BM6500 besides them? .
The caps on the cpu board and on the front IR board... they tend to explode or spit acid...
As you have the CPU board out anyway, resolder the cable connectors that are on it as they often have cracked joints. The front panel PCB (with the displays and the IR transceiver) has a couple of electrolytics that might be (and probably are) on the way out as well.
And the caps on the CPU module itself! Unless you have a Metcal or some other top notch soldering iron, some of the through plated joints can be very difficult to melt through without damaging the circuit board. I tend to cut the old (axial) caps off and solder the new one on the wire stubs, much easier that way. While working, remember that some parts of the board are actually powered on as long as the backup battery is in place, so take care to not short anything around the NVRAM chip.
EDIT: Just what Die_Bogener said
Don't forget the reset capacitor on the cpu board.
A little update.
I received two SAB 8032B-16-P a couple of days ago. There is still no sign of life though - I found out today, that IC4 (the eprom) is faulty as well. So if anyone has one lying around, I would be happy to hear from you. The part number is 8341309.
shouldn't the eprom be possible to copy?
//Bo.A long list...
I'm not sure if it is possible to read data from an eprom. If someone is able to do that or has the data and is able to program an eprom I would be happy to hear from him as well.
By the way; did you get anything out of the displays and microprocessors from the BL3000s?
Dennis:By the way; did you get anything out of the displays and microprocessors from the BL3000s?
You can program a 27128 Eprom?
If not, also no problem. I can program the eprom and have all necessary data...
You can also send me the cpu board for repair. Shouldn't be any problem, i still have all parts for this BM6500 or 7000.
Unfortunately I don't have the necessary equipment to program an eprom. I have thought of buying it as I find it interesting and would like to know how to program an eprom, but I don't know where to get the data from - is it available on the internet somewhere?
Regarding sending the cpu board to you, I would rather like to repair it myself - It's part of the fun, and the reason why I bought the BM. Anyway, I've sent you an email.
I think I must have a spare donor board for you. Copying an Eeprom is not that complicated.
Brengen & Ophalen
Hi Leslie
Didn't see your reply until now. So it is possible to copy an eprom? Could you tell me how to do it?
Because besides getting this BM6500 back on track again I have a few BM4500s etc. I would like to upgrade the software in.
Sorry Dennis, have been away for a while. Sure you can copy an Eeprom, did that for a member. Would you like me to show you how to do that?
Yes please, that would be great!