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Whilst trying to rekindle my old hobby that is Bang & Olufsen I've gone out and purchased a MK1 Century sold as 'not reading CD's' with the intent of having a go to get it working again. I hold my hands up and admit I'm not really tech knowledgeable but do somehow manage to get some things going and enjoy the sense of achievement having done so.
The symptoms are: Load a CD '1' displays in the readout, no movement at all of the CD, <> appears in the display and the CD is rejected - the load arm raises.
The CD mech is the earlier radial without the servo board attached to the back of the CD VAM. I already removed the CD mech to discover this! I believe I have a CDM-4.
I have found a picture of the same servo board and note it's Menahem's picture so I hope he doesn't mind me borrowing it. The two caps I'd like to replace are C2815 and C2823 and by replacing those I'm hoping it will then be repaired. However, I know that the manufacturer and type can make a huge difference in the outcome of success and failure.
Am I correct in replacing these two caps?
If so, where can I get them from?
Thanks
If you think nobody cares, try missing a couple of payments.
I'll think I'll be OK with Vishay 47uf 20% 16v
I'll order them and see if that helps
Edit: Can I use Vishay 47uf 20% 25v instead or does it have to be 16v? I'm thinking that the rating is the max it can handle and it will be OK. Anyone?
Now have the board out and in front of me I note that they are 47uf 10v despite the service manual specifying 16v. Do I replace with 10v or 16v?
Yes, it's the maximum rating. I'm sure either 10V or 16V will be fine.
--mika
Thanks Mika
Argh, whilst I was waiting for the previous mentioned caps to be delivered I thought I'd carefully check the printed side of the board with a digital microscope looking for any dubious bad solder and came across these SMD components (caps?) which looks like it got hot or something. That's way beyond my capabilities. Does anyone think that's definitely the problem?
2
They are resistors. The "472" is a 4.7k (four, seven and two zeroes) and the other one seems to be marked 100 which would, similary, mean 10 ohms.
They don't seem burned, but it looks pretty certain that some not-quite-pro repair guy has been soldering on them for what ever reason.
That's good news, sort of. I did discover they are resistors and investigated. I do hope that it is a previously successful repair but even as a bodger hobbyist I hate it when I find I'm not the first one in there.
I'm losing confidence in getting this going again though. I'll replace the main caps mentioned earlier with fingers crossed and hope.
For no reason other than I investigated to add to this thread before Mika kindly replied, here below are those resistors
Stonk: At least check the resistors onboard, and check connection (tracks) to the next components or points, dont give up.
Collecting Vintage B&O is not a hobby, its a lifestyle.
Søren Mexico: Stonk: At least check the resistors onboard, and check connection (tracks) to the next components or points, dont give up.
You're right Søren. I'll check continuity between points etc as a precaution. Good idea
OK, so the non-readable digit was a four, making that a "104" = 100 k resistor.
Do check them, but looking at the schematic, it seems that C2815 is in the exactly same role as C2103 in many other B&O CD players, and you have probably already read about that elsewhere on the forum. Probably needs replacing.
tournedos: OK, so the non-readable digit was a four, making that a "104" = 100 k resistor. Do check them
Do check them
Will do :)
Yes, the C2815 was my initial place to start though the original is a radial Nichicon so might not be as fussy as the Philips/Vishay axial C2103.
Gee, my memory and attention span are getting dangerously short
It's always a bit suspicious to find marks of poking with a soldering iron in a "non working" unit. With a bit of luck, it is something simple like an open solder, but the entrepreneuring DIY'er might have burnt the laser or something (as with my BC8000 way back).
Check cables and connectors leading to this board as well.
My concern is the laser too. I can't be sure that the pot hasn't been played with. In test mode the motor spins but there appears no life in the laser itself. I know that lasers rarely are at fault but the fact that someone's been stabbing around with a hot iron doesn't instil confidence.
Okay.
Checked tracks, resistors, changed the caps, reinstalled everything and put it all back together. Nothing. It's even worse than before I started
Before in test mode the CD would spin, now it doesn't even do that.
Plan is to lift the CDM4 up and double check all the connections. If that doesn't change anything I'll look at the caps I put in. This unit is a pig to work on though. So many screws (some hidden) to get the back off which is needed to get to the servo board.