Forum Replies Created
-
It took some time, but I now think I have found out how the circiut is constructed in the MKII. I used both multimeter and microscope to spot all the connections. Microscope picture here:
And from the the other side of the PCB:
Most of the VIA’s just end up in testpoints with a solder blob on them. This is a little confusing when trying to figure out where the traces go.
This is how I have analysed it to look like in diagram form. I have tried to make it in the same form as the diagram in the MKI service manual to make comparison easier.
I have used the names from the connectors in the MKII servicemanual. It might be a little confusing as there is both use of PL and MCL in that.
One thing to notice is that the circitry is now divided in two. One with the PL sp.on from PL pin 4 which is connected to MCLTX, and one with the PL data from PL pin 6 which is connected to MCLRX.
Event though the BL3500 MKII is faulty I can still do some detective work on the PCB’s about the PL connection.
Pin 4 – Not really sure. I measure 100 Ohms resistance between the numbered soldering point and the pin 3 on the flat cable to the crossfield PCB. It is called SP ON on the block diagrams in the servicemanual. Unfortnuatly I can’t trace it further from the connecter on the crossfiled PCB which looks very much the same as in a MK1 BL3500
I have to admit that I was wrong in my quick assumption that the Crossfield PCB’s was that same in the MKI and the MKII
Having a harder look and probing with my multimeter I found the place where the connection from PIN 4 on the powerlink connecter goes. I have marked the route with red arrows on the above pictures. It ends up in a area with 3 transistors and some other components in the right bottom corner. The PL data signal is also comming to this area.
This area is clearly rearranged compared to the MKI.
Looking at the diagrams for the MKI I can see that this is where the MCL data signal come in on that and pass to the microcomputer
I have yet to analyze how the PL pin 4 signal is comming in to this circitry, and if there are changes in it.
One thing is for sure though. The PL pin 4 signal is not present in the MKI.
I have done a test with the MKI earlier https://forum.beoworld.org/forums/topic/bl3500-and-the-mcl-pl-connector/page/2/#post-17635 where I was able to activate the speaker with powerlink data conncted instead of MCL data, so the use of the PL Pin 4 signal might have to be in combination with powerlink data.
I just did a quick test on the MKII with powerlink from my MCL2AV just to see if it would activate anything, but no luck. However that could be due to the other faults I have on it.
Had some time look further into it today.
Try the amp without speakers to activate from 0 to 64 to check all these segments. Usually there will be a “8” problem… and a problem with the source led.
The 7 segment display can show 88 i both display units.
It can be the chip or the power supply itself.
Power measured at pin 2 and 5 in connector p11 on the front panel PCB is 5,18V steady even with the flickering and relay clicking
About the relay clicking, now that I have the BM5500 open I can see that it is the relay behind the plug PCB that is clicking rapidly
But I noticed that the relay on the PSU board (betwen the transformer and the large caps) is also clicking once in awhile if that is an indicator for something.
Usually some caps in the power supply are the cause…
Which caps would that be if I should try to test some of them?
Thanks in advance
Was a little curious about the BLC 1610 so I had to open one up to see what is ticking inside:
All pins in use on the two ML connectors are wired in parallel, so just kind of an internal junction box.
What is unusual with the ML connectors is that pin 3, 4, 5, 6 and 12 is all connected where pin 12 is supply voltage +, and most of the others are normally no used. This however explains where this box is getting power as the same pins are supplying +12V on the diagram for the AV9000
One other curiosity is that next to the external 1-2-3 switch is an internal switch with 2 positions:
These are named:
- Central 1610
- Local 1611
Not really sure if that means it will function like a 1611 if it is in that position.
Might do some more testing around that at a later point.
