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
Hi all, for a BM6000 non quad version i am searching for the processor IC or for a complete board (pcb 2).
Pls send me a PM if you have any donor parts and we can agree on a price :)
Thanks.
Hi
Are you sure your processor ist dead?
Best Regards Christian
Good question.
What is the problem?
Jacques
When i plug it in it only shows :0 on the display (double dot and a zero).
Measuring the 5V for the processor it shows ok: 5,03 volt and clean.
There is no activity on the busses for the buttons and/or other I/O.
Therefore no reaction whatsoever on any of the local keys or remote.
Maybe this sounds familiar ?
(in the sm there is nothing on this 'code' in the display).
Hi Paul
Seems that you have an Oszilloscope.. elektrostaic protection is recomended.
So check following.
All 5 Volt voltages on the uPC Bord at all IC's
On uPC Board IC 6 PIN 1 schould be 3.975 MHz
On uPC Board IC 6 PIN 6 schould be 15.5 kHz
On uPC Board IC 9 PIN 14 schould be 15,5 kHz
On uPC Board IC 9 PIN 17 schould be 7,75 kHz
On uPC Board IC 7 PIN 7 schould be 7,75 kHz
On uPC Board IC 7 PIN 1 + 12 schould be 3,9 kHz
On uPC Board IC 7 PIN 11 schould be 647 Hz
This schould be measured at the uPC IC 4 PIN 15 (Time Base)
Check on uPC Board IC 4 PIN 16 50/60 Hz belonging to your Countrys mains frequency
Check the reset circurit on uPC Board IC 4 PIN 39 when you pull TP1 to Ground PIN 38 schould go to Ground (Zero) too.
I wish you succsess
Chrischi
Thank you for the tips, most of these i already measured, but...i see a strange reading and that is the 647 Hz on IC7 pin 11, this is present but only abt 2 volt TT and not 5, the others on IC7 are around 5V.
The 50/60 Hz signal is only present hen switched on according to the diagram.
Reset already checked and works ok.
I will look into IC7 because i think that 647 Hz signal should be around 5V....
All power supplies (6,5V and 5V) are ok btw.
correction: 50/60Hz comes from standby transfo but is not present, but maybe because the cpu doesn't run (after all it is only connected to the C of TR4).
Anyway, the low voltage 647Hz is something to look into, maybe a new 74LS93 will do the trick
Hope this is the trick ;-)) Let us know
How does the signal look on IC 7 PIN 1+12 and 14
About 5 V pp?
I believe the 50/60 Hz schould be present even in StBy, I think it's needed for the clock of the timerfunktion.
The 5 V rail for the uPC is present and the StBy transformer is connected to mains.....
I don't know if it's needed for starting the Amp from StBy to On
IC7 pins 1, 12 and 14 look ok indeed, abt 5Vpp.
The 50/60 Hz comes from a transistor with the collector connected to the processor, no pull-up resistor, so somehow it should be pulled up from the processor(?), anyway, that probably will not prevent the processor from running.
Checking datasheets the 74LS93 should have a proper high status on itself (so no open collector), hope that is the bad one, it is easier to find :)
IC7 replaced, same result.
If i disconnect pin 11 (ic7) the level of the pulses rises to abt 4Vpp (like on the other pins).
So it seems the processor causes a load on the out[put of IC7.
Conclusion is still: broken processor IC and requestfor a donor still valid i'm afraid...
So sorry that you had no success with IC7. I've no more idea what you could do now so far, hope another member has the special trick to bring your BM back to life.
Maybe you're owner of a signal generator and try to insert the 647 Hz directly into PIN 15 to see if the uPC comes to life....last chance and more experimental, but there is nothing to loose.
That is the point to make a decision.... I hope for you that someone has a uPC IC lying round in his workshop and that this wil help.
If not now maybe later
Best regards
This week i finally found a donor 6000 and indeed it was the IC.
So no longer searching for it :).
Congrats , as I mentioned sooner or later....The uP are hard to get
Where did you get it?
What did you pay for it?
Are there more spares?
Bet Regards