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 Everyone,
I'm a newbie to Beoworld but have been very into Bang and Olufsen since first seeing it in the local showroom window in the early 80s. I've accumulated quite a mix of equipment over the years, but a recent purchase has me stumped and I thought I'd ask the people who know for advice :)
I just took a chance of buying a Beogram CD5500 to upgrade from my CD50. When I bought it I was told it hadn't been used for 15 or so years, and it certainly looked like it! It has a few issues, and whilst I'm going to swap out the caps etc which should hopefully resurrect it I wanted to make sure it was worth doing as there are more faults than the usual CD read issue (which it also has).
Firstly the CD tray will not eject. The belt, mechanism etc seems OK - but the motor only seems to get 0.4v which is not enough to get it moving. Could this be a cap issue or something more serious?
Secondly - the laser almost seems loose! The laser assembly moves very very freely and - I could almost blow on it to get it to move to its maximum extent. If you move it gently with the unit powered down it will move to and fro and take a few seconds to come to rest. When I manually insert a CD and try to play it it does move to the centre of the disc - but I'm still not convinced this is correct. I didn't want to start recapping if it has a dead laser mechanism. Does this sound right?
I'm hoping I can fix the above issues and add another fantastic CD player to my collection.
Thanks for your help :)
Mark
The "loose" movement of the laser unit is quite normal. This is OK.
0,4V for the motor means a defect, there is something wrong.
check cabling and bad solderpoints from main board
blah-blah and photographs as needed
If it is anything built like the 6500 there is a switch in the middle of the unit which controls opening and closing of the cd deck.
This can be faulty or just have to be bend slightly back in shape.
Hi,
Thanks you all for your advice. I've spent some time this evening looking at the CD player. I cannot see any broken joints, or loose components. I've also checked the tray switch and that seems OK too.
I've tested the circuit - and curiously it actually seems to work - but does not provide enough volts. When you hit the open button with the drawer closed one side of the motor goes to +0.4v and the other to -0.8v but the combined potential difference is not enough to turn the motor. If you extend the tray to its maximum extent then the polarity is reversed but the tray still does not move.
That being the case the logic seems to work ok - but there is some kind of power issue. Could it be faulty capacitors? There do not seem to be many related to the tray IC4 circuit.
NB - the IC4 pin 1 supply is +5v as you would expect.
Thanks
Try no load, maybe with a resistor to emulate motor
I've done further testing tonight and have found what looks like a power issue. There is not 12v at D5 or pin 4 of IC5. Tracing this back further there is not 15v at the emitter of TR1. Testing the caps with the system powered down it looks like C3 has shorted - which would presumably cause the drop of power.
Looks like I need to replace this cap - but an initial search seems to indicate that 470uf 40v caps are not easy to come by...
Just use a 470uF, 50V capacitor instead. You can always go up in voltage value. You just don't want to ever go lower on the voltage rating.
-sonavor
Beware, on my CD5500 the 12 V zener diode was blown. Do make sure it is okay before anything else.
Jacques
Hi All,
Thanks for the advice. I did check the Zener diode and fortunately that was ok. I've now ordered the parts from Dillen who also advised replacing the four diodes in the rectifier. Hopefully this will get everything working. I'll keep you posted on the fix :)
Just thought I would post back and say that the parts from Dillen arrived today and the CD player is all fixed.
I replaced the capacitor and rectifier on the main board first, and that fixed the CD drawer not opening issue - that now works perfectly.
I rebuilt the main board and tested each of the old caps as I removed them. Some were a bit out, but none seem drastically faulty. When I put it back together the unit still wouldn't read discs and seemed exactly the same. Grabbing at straws I cleaned the laser lens - it didn't look dirty but some dirt certainly came off. After this the CD player worked perfectly!
I should have checked this first of course - but as the main board needed recapping I just assumed the read fault was because the servo board needed it too. Mind you - everything should now be back in tolerance.
I'm dead chuffed to have repaired my first item - thank you all for your help :)
AAAH - it was all working fine, and whilst I was testing it playing CDs earlier it suddenly cut out and has lost all power. Not even the standby light illuminates!
I've tested the power supply and everything is ok - although I seem to have lost the 5v supply that feeds most of the ICs. I only have 0.3v at pin3 of IC1 instead of the 5v it should have. The 13v supplies seem ok.
I haven't found any dodgy caps - and the Zener diode reads 12MOhms when the negative lead is on the cathode, and open circuit when the leads are swapped.
Has anyone got any suggestions as to what I could check for this? I'm beginning to think this item has spent too many years suffering in the heat and cold of a loft and may now be very unreliable.
Cheers
--Duplicate post--
The 5V are supplied by 2x 7805 Regulators... pretty easy to check.
Thank you - I've taken a look at this - and unsoldered pin 3 of IC1. When I test that there only seems to be 0.3v. Presumably there should be 5v? There is 13v going in, but almost nothing coming back out.
Should I replace this regulator? Would it have failed because of some other fault on the board?
7805 Regulators can fail because of overload. Use a regulated power supply with 5V 1A and insert the 5V by the power supply. Then you see wether there is a short or something else.
Then replace the 7805.
Or just replace it and test the heat consumption. You will see pretty soon wether there is overload.
Thanks for that - I have replaced IC1 with a new 7805 and now power has been restored! Great! The temperature of the regulator seems good too - it is certainly lower than the other two regulators bolted onto the same heat sink.
All the logic seems to work - tray loading, disc scan, track skip etc. If you leave it to play it will cycle through the various tracks. I thought I had cracked it - but when I connect it to the Beomaster there is no sound! I've double checked all of the connections - but there is definitely no audio! The SPDIF connector does not work either! There is no humming - nothing at all!
I'm not even sure what fault this suggests - all of the ICs seem to have power.
I'm starting to take a strong dislike to this CD player :) It does not want to be repaired I think :D
I've done a few more checks on the CD5500 this evening to try and work out what its latest issue is. My thinking is that the muting circuit has somehow got activated - which would be the simplest explanation.
When a CD is playing I have a small voltage (just under 2v) at pin 7 of IC11 and IC12. When I stop the CD this drops to 0v. Looking at the wiring I'm wondering if this voltage would be the 'audio' signal. Unfortunately I don't have a scope so can't determine anything more. If I then test on the other side of C111 and C211 there are 0v again which suggests the circuit has been grounded - effectively muting the audio.
I also have -15v at the base for TR103 and 203 - which presumably would switch on the transistor and ground the audio.
Am I understanding this circuit correctly? If so is there any simple cause that could lead to it getting activated?