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
Hello,
I'm working with BC9500 to fix the CD player. The symptoms were (and still are ;-D) as in classic case of faulty C2103, when CD is loaded it spins two times but is not recognized. Looking at the CD PCB it looks like some one has already changed some of capacitors:
- C2103 Philips 33uF 40V
- C2104/C2107 SME 47uF 63V
- C2138/2140 220uF 25V
- C2159 Wima 1.5uF 63-x7
Now I'm wondering if one of previous owners has already tried to fix CD with capacitor kit from Martin/Dillen, anyone knows what capacitors Martin has used in his kits?
I should also mention that C2104/C2107 were connected wrongly (plus and minus inverted).
I have verified the BC by testing with other CD unit and no problem there, also tried to replace the C2103 with similar capacitor I have used earlier successfully fixing CD unit's in BC9000 and BC9500. I have also checked the laser current and focus current. Laser seems to emitting as faint red light can be seen in lens of laser unit.
Any suggestions how to proceed with repairing the CDM 4?
Cheers, Jyrki
Here is few pictures of capacitors on PCB30
Not a very recent kit but definitely one of mine.
Martin
This type of board is very sensitive to heat, check the solder joints of those caps and check forbroken copper traces.A person, who fits capacitors the wrong way around could maybe also have the temperature ofhis soldering iron set too high.
Is the focus assembly free to move?When you press down on the lens,it should spring back up when released.N.B. DON'T look into the lens when the unit is powered up.Laser current should be checked with a meter
If it's not free to move,you may have debris/dust lodged inside the assembly that you may be able to remove with say an air duster aerosol.
I had a focus assembly siezed solid in one case,rendering the whole unit scrap.I was able to transplant a working assembly from a donor unit happily.
Also,is the laser assy ribbon fitted correctly to the pcb socket?
You may need to check the wiring loom security between the servo and decoder pcb's.It's quite common for these wires to fracture but still look ok.If data is'nt reaching the decoder,the disc will stop.
Nick
Thanks Martin for verifying the source of capacitors, good to know they are from reputable source. I have re soldered the capacitors and checked the PCB. One capacitor leg has copper trace bit loose, but it's still making OK contact. Is it possible that capacitors connected wrong way could have caused some other component to fail?
Nick - The lens is moving up and down when laser is trying to get focus on CD. I'll check the cabling between servo and decoder PCB when I get back to home, will also check the ribbon cable more closely. Thanks.
Jyrki
Did some more testing / checking today. Cable between servo and decoder PCB is working OK (tested connectivity with resistance meter). The ribbon cable looks OK, I could not see any cracks or sharp bends.
Noticed following thing when testing today: when CD is started without disk the motor spins twice and lens assembly is moving, but when testing with disk the motor starts only once and disk seems be spinning "faster than it should" and after that CD door opens. Dunno if this really means anything...
Oh well, "search" continues...
jlehtinen: Noticed following thing when testing today: when CD is started without disk the motor spins twice and lens assembly is moving, but when testing with disk the motor starts only once and disk seems be spinning "faster than it should" and after that CD door opens. Dunno if this really means anything...
I have never got to the bottom of this problem as I am not sufficiently qualified however, on the several occasions that I have seen the problem, a change of Interface board has always cured it!
Regards Graham
joeyboygolf: The symptoms you describe here indicate a fault on the CD Interface board rather than the servo board. I have never got to the bottom of this problem as I am not sufficiently qualified however, on the several occasions that I have seen the problem, a change of Interface board has always cured it!
The symptoms you describe here indicate a fault on the CD Interface board rather than the servo board.
That sounds interesting, I happen to have a working CD unit from BC9000 laying around... Do you think that interface board can be swapped between CDM 4/33 and CD unit from BC9000?
The CD Interface board, sometimes called the decoder board is Board 31 in the base of the BC9500/9000 situated behind the tin can containing the microprocessor.
If you had a 16 bit BC9000, and most were except the very early ones, then the CD Interface board is identical and the BC9000 board will fit straight in to the BC9500 and all the connectors are identical.
NB I am not talking about the CD servo board, I am talking about the CD Interface board, Board 31
If you are not sure, download part 1 of the service manual on the site and check the location of the correct board on the diagram.
Thanks for clarification, in my mind I was thinking about disk motor control board. I have a BC9000 that is doomed for parts donation, so I can source working decoder board from that one and test again.
Did quick test today and connected the CD unit (the one I'm trying to fix) from BC9500 to my spare part BC9000 (working electronics, but mechanically and cosmetically disaster). CD unit spins up as it did in BC9500, but it still can't read cd... I'm not sure, if it should even work though. Next step I guess is to move the decoder board from BC9000 to BC9500 and test again, as suggested by Graham.