The Workbench

Re: Beosound 4000 Philips CDM 12 not working

auric — Wed, 23 Jul 2008 11:33:56 GMT

Well... it was an adventure but I have the Beosound 4000 working finally. I found a used servo board and swapped it over and it works fine now.

I ended up not upgrading to the CDPRO2 transport. I spoke to some technicians in the jukebox business. They told me that the CDM-12 is a more reliable and ultimately more repairable mechanism simply based their repair statistics. They run these things over 12 hours a day. The CDPRO2 is also finicky when it comes to swapping components from donor transports. So keep those CDM-12 running.

So here's what I've found:

1) CDM -12 IND (the cast aluminum version used by B&O) can be repaired by changing the optical pickup supplied from a CDM-12. There are still inventories of these all over the place and are available at very reasonable costs. Around $30.

2) The servo boards on regular CDM-12s are not interchangeable with the ones used by B&O.

Derek

Re: Beosound 4000 Philips CDM 12 not working

joeyboygolf — Sat, 05 Jul 2008 17:42:56 GMT

I'm sure that the Ouverture kit came with all the necessary parts. At least, I don't remember ordering extra parts and it was a quick repair. Possibly some mods to the power supply but parts were supplied. I have found the fitting instructions for the 9300 kit but the Ouverture fitting instuctions have been misplaced.

I am pretty sure that the replacement will cure your problems.

Re: Beosound 4000 Philips CDM 12 not working

auric — Sat, 05 Jul 2008 13:36:50 GMT

Thanks Graham.

A couple of quesions.

1) Given that my in test mode all functions respond except for the laser powering on, do you believe if I did upgrade the mechanism, the unit will function properly again?

2) Are the mechanisms supplied completely with all parts? Is it simply a swap and replace? I.e. Would I need to transplant things like the spindle or the plastic sledge cover over the optical pick up?

Thanks,

Derek

Re: Beosound 4000 Philips CDM 12 not working

joeyboygolf — Sat, 05 Jul 2008 02:43:00 GMT

I looked into this a few years ago and concluded that the servo boards were indeed different to the standard Philips offering.

The B&O replacement mech is very reasonably priced and includes the CDM Pro mech and servo board together with new cd interface. Around £100 as I recall and installation was trouble free with comprehensive instructions.

I have done the job on BC9300 and Ouverture.

Re: Beosound 4000 Philips CDM 12 not working

auric — Fri, 04 Jul 2008 16:22:09 GMT

I tested/replaced all of the electrolytics on the CDM 12 servo board. They are fine. The diode is still not lasing.

I swapped out the board from another known working CDM 12 and it is still not working. Oddly in the test mode I can't even get the motor to spin up or the optical carriage to move. The boards are identical except the numbers on the sticker label vary. I suspect that B&O has special firmware coded onto the servo board making them incompatible.

Does anyone know for sure?

Thanks,

Derek

Re: Beosound 4000 Philips CDM 12 not working

auric — Fri, 04 Jul 2008 00:48:45 GMT

Hi Martin:

Checked the laser with my camera. Its not lasing..... everything else seems just fine.

Does anybody have a CDM-12 schematic?

Derek

Re: Beosound 4000 Philips CDM 12 not working

Dillen — Thu, 03 Jul 2008 16:07:11 GMT

Desoldering braid is also what I use with good results.

Martin

Re: Beosound 4000 Philips CDM 12 not working

auric — Thu, 03 Jul 2008 15:50:41 GMT

Hi Mika:

Thanks for the tip! I'll see what I can do haha. I suppose worse some to worse, I can always put regular caps in by bending the leads.

Re. getting the old solder off the tabs, I've found using a good desoldering braid is excellent. It sucks/soaks up all of the solder.

Derek

Re: Beosound 4000 Philips CDM 12 not working

Dillen — Thu, 03 Jul 2008 15:47:36 GMT

Yes, but if there's enough room you can solder in standard leaded caps.

Martin

Re: Beosound 4000 Philips CDM 12 not working

tournedos — Thu, 03 Jul 2008 14:56:23 GMT

Yes, but you will need a sharp pin-like tip for your soldering iron, don't bother trying with those that look like a 5mm flat screwdriver.

I usually apply a little (very little) solder on both of the PCB pads, then just lightly press the cap on and apply the soldering iron on both tabs in turn. Once it melts, the cap will sink in place and the plastic won't melt, at least not enough to cause damage to the cap.

The twist off strategy really works. The hard part is usually cleaning the PCB pads from the old solder. When I repaired my VX5000, the solderings on the servo board had turned into something that did not want to melt at standard soldering temperature! I believe the chemicals from leaking caps do this.

Re: Beosound 4000 Philips CDM 12 not working

auric — Thu, 03 Jul 2008 13:59:00 GMT

Great!

Now.. how to solder the new caps back in place? Can I do it with a standard iron? The tabs are folded "in" up tight against the molded plastic.

Derek

Re: Beosound 4000 Philips CDM 12 not working

Dillen — Thu, 03 Jul 2008 13:51:17 GMT

If the SMD caps are of the round electrolytic alu-can type, they can simply be rotated off using pliers.

I believe Die_Bogener (the other Martin) described it in another thread, I think it was regarding repairs to the capstan motor in the VX5000.

A bit drastic sounding, I know, but in the vast majority of cases, the board will not be damaged and it's the only way if you don't have hot-air soldering tools.
Even if I have hot-air soldering tools, I still twist these caps off, it's the fastest way and the hot-air will easily do more harm to the board if things go wrong.

If you have no laser light output, you have a current problem = caps first.

Martin

Re: Beosound 4000 Philips CDM 12 not working

auric — Thu, 03 Jul 2008 11:39:48 GMT

Hi Martin:

I'll check again tonight with my digital camera, but I say no, the laser does not come on.

Usually you can look obliquely at the laser lens and see the glow off the refraction. I also placed a piece of paper in front of the lens and say nothing.

The CDM 12 laser board is complicated. It is all surface mount components including the capacitors which makes repair difficult since I don't have the proper tools. I can replace transistors but the capacitors much harder since it is often difficult to get the iron under the solder base of the device.

B&O does have CDM PRO upgrade (mech + decoder board) however I'm reluctant to buy it unless I can confirm that fault doesn't lie in the rest of the unit.

I don't suppose anyone has an extra CDM 12 servo board / and decoder?

Derek

Re: Beosound 4000 Philips CDM 12 not working

Dillen — Thu, 03 Jul 2008 11:11:25 GMT

I never stumbled on one of these decks but basically you will have to at least measure the voltage across the laser diode or even better a series resistor if that's possible and then calculate the current.

Is the laser producing any light at all ?
Use a digital camera or cell phone camera to check (NEVER look directly into the laser !), the check should be made while it searches for the focus point. Most cameras will show the light as a light-blue spot.

I've seen many strange faults caused by bad capacitors on the associated board(s), it could be something like that. The laser diodes are generally very robust devices.

Martin

Re: Beosound 4000 Philips CDM 12 not working

auric — Thu, 03 Jul 2008 09:15:05 GMT

Martin:

I did not because I'm not sure how to. The manual on the site here is for a
CDM 4. The CDM 4 laser current is easier to measure. On the CDM 12 the laser current adjustment components is on the pickup itself, not on the servo board.

At any rate, the optical pickup is new. This leaves 2 areas of fault. The servo board or decoder board.

Do you know how to check which is at fault?

Derek