That means your player differs from the diagram then.
If you look at the location reference number on the diagram it also says U14A and U14B meaning U14 is the component reference number on the board and the A and B refer to the two opamps in the one package.
The diagram shows a total of four actual devices for both channels. One dual and one single per channel.
If yours are all NE5534's then you must be seeing six IC's in total. Does that look right?
Manufacturers do sometimes have different versions of equipment so that could be a possibility.
If you look at the location reference number on the diagram it also says U14A and U14B meaning U14 is the component reference number on the board and the A and B refer to the two opamps in the one package.
The diagram shows a total of four actual devices for both channels. One dual and one single per channel.
If yours are all NE5534's then you must be seeing six IC's in total. Does that look right?
Manufacturers do sometimes have different versions of equipment so that could be a possibility.
Later Cambridge audio cd players have a known design fault undersupplying power to the relay design fault, the relays are on the outputs/ mute circuit.
(https://www.diyaudio.com/community/...s-minimum-value-required.352201/#post-7942602)
I dont know if it goes back as far as that machine, but the fact that the design flaw/s affect three separate models ( 2004 -) suggests it might.
The sonic problems you describe are similar to the ones experienced, although I dont seen any relays in the insides of the players i just looked at.
It's usually on the servo board. upload pics
(https://www.diyaudio.com/community/...s-minimum-value-required.352201/#post-7942602)
I dont know if it goes back as far as that machine, but the fact that the design flaw/s affect three separate models ( 2004 -) suggests it might.
The sonic problems you describe are similar to the ones experienced, although I dont seen any relays in the insides of the players i just looked at.
It's usually on the servo board. upload pics
What I saw in the screen shot in post 35 was a 5534 opamp which I assumed was the opamp to test and if no joy to test at the points indicated by the arrows. The board has 2 AD712 dual opamps which I will of course test as suggested.
🙂 Post 35
It is the AD712 to test first at its outputs. If that shows a problem then see what is at those two arrowed locations. The 5534 is the DC reference generator, nothing to check here with the scope at this point.
It is the AD712 to test first at its outputs. If that shows a problem then see what is at those two arrowed locations. The 5534 is the DC reference generator, nothing to check here with the scope at this point.
Yes.
There are two relays on the output pcb on the CD6, yellowish in color on the images i'm looking at. Is this what you have?
Similar design faults of relays not having enough power to close the contacts properly are know on the successors; 540C; 640C; 740C; 840C.
They manifest audio faults as you describe, when they get really bad they can make intermittent noises and ultimately drop out all together loosing the signal, on both bal and unbal outputs.
The first sign is loss of bass. Another is imbalance between L + R balance.
Hunt down a legible schematic of the CD6 and post it here.
Find out what the relays are.
Find the data sheet for the relays, post it here.
Trigger the relays out of circuit, measuring the resistance between the on/off contacts, (two switches on each relay / double pole)
they should be close to 0Ω if they're not, replace the relays and adjust the circuit if necessary to the correct current and voltage supply.
Update related capacitors to polymers.
Unless you've nailed it, this would be No.1 on the list of 'process of elimination' fault finding checks, everything else is speculation
#44
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There is a confirmed lineage of design flaws do do with the muting/ relay circuitry, (if i am correct) the CD6 happens to be the first of that line , perhaps those faults are also attendant. by the time it got to the 840c there was an internal memo by Cambridge audio that those players should have the adjustments made whilst in for repair, not exactly a recall, but an acknowledgement.
Cant see the relay types on the images posted, however in the players mentioned, they also suffered from cheap relays that fail, along with the design flaws of insufficient powering of relays/ insufficient watt rating of resistors to the relays, all of them manifesting oddities on the both analogue outputs.
I think an unusual design decision to have a virtual earth/ muting arrangement convoluted matters to unreliability.
If the problem is 'further up the chain', it would be present on both digital and analogue outputs,
this would be one of the 'process of elimination' checks to do,
again I cant see if there are digital outs on that machine, a BNC perhaps?
Cant see the relay types on the images posted, however in the players mentioned, they also suffered from cheap relays that fail, along with the design flaws of insufficient powering of relays/ insufficient watt rating of resistors to the relays, all of them manifesting oddities on the both analogue outputs.
I think an unusual design decision to have a virtual earth/ muting arrangement convoluted matters to unreliability.
If the problem is 'further up the chain', it would be present on both digital and analogue outputs,
this would be one of the 'process of elimination' checks to do,
again I cant see if there are digital outs on that machine, a BNC perhaps?
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I got a chance to scope the AD 712s. Both readings at Pins 1 & 7 were the same and I attach pics of the readings at start and finish. At the start of the 10hz to 10khz sweep was a simply a flat line which changed very little until approx 20s in. In relation to the said relays. I thought by their shape that they were caps, but clearly not. They get quite warm when the player has not been on very long. I assumed they were caps as there is no tell tale click from them on turn on.
Ultimately the relay shorts the RCA socket output to mute so I think in one sense its fairly conventional.... and I see Puffin has posted.... and if the signals are the same in amplitude (and this is important, if they are the same) then I would think the relay has to be opening OK.
The opamp should drive the 100 ohm series feed resistor OK even if the output is grounded because the signal levels are low. If the signal is the same at each end of the 100 ohm then there is no current flow into the muting relay.
The fault though doesn't make sense in affecting just the bass.
If there is doubt then the 100ohm can be lifted (isolate one end) and the levels checked again on the opamp outputs.
That result confirms the lack of bass. No output at low frequency. That is bizarre to me. And both channels are the same... odd.
Given that @Earths has mentioned the relay as a known fault perhaps you could just isolate one of the 100 ohm resistors and then measure directly on the opamp pin that resistor comes from. That would eliminate the relay. If you are neat soldering and don't want to remove the board and so on then perhaps just snip the resistor to check and then resolder it back when done.
I lifted the 100ohm resistor at Pin 1 of the R channel 712. The scope showed no output and on pin 7 it showed the same straight line and squashed signal as already posted. I heard the relays clicking today, now it could be that it is because I now know they are relays although I first heard them on power down. When I powered on again I was not sure that I could hear the R channel one but that is where the 100r was lifted.
Its all very very bizarre is this fault. It really is 🙂
With the 100 ohm lifted at pin 1 and no signal at pin 1 we can say the relay is not affecting things... but lets cover all possible bases so we don't need to backtrack. Because of the cross connection of R16 in that stage to the other opamp lets also now isolate the second 100R. So both 100R's are lifted.
If there is still the lack of bass shown on the scope at pins 1 and 7 we have to look at these points now. I'm going to ask someone else on here as well whether any of this makes sense. It sure is an interesting issue:
With the 100 ohm lifted at pin 1 and no signal at pin 1 we can say the relay is not affecting things... but lets cover all possible bases so we don't need to backtrack. Because of the cross connection of R16 in that stage to the other opamp lets also now isolate the second 100R. So both 100R's are lifted.
If there is still the lack of bass shown on the scope at pins 1 and 7 we have to look at these points now. I'm going to ask someone else on here as well whether any of this makes sense. It sure is an interesting issue:
If you are working on the left channel (and it doesn't matter which channel you pick as both channels are the same) then according to the circuit the opamp is U14. The 100R's are a bit blurry on the diagram to read both the numbers but it is these. You then measure on pins 1 and 2 as before and if that is no good then move to the points I circled above.
Isolating these two resistors together 100% isolates them from the mute circuit and the sockets.
Isolating these two resistors together 100% isolates them from the mute circuit and the sockets.
More thoughts after discussing it with others.
Do a quick check with your meter of the DC voltage on pin 6 of the NE5534 opamp. It should be 2.5 volts DC. Also check the 5 volt rail on pin 7
If both those are OK then set your scope to AC coupling and make sure there is no noise or ripple on 6 and pin 7 of the IC.
Do a quick check with your meter of the DC voltage on pin 6 of the NE5534 opamp. It should be 2.5 volts DC. Also check the 5 volt rail on pin 7
If both those are OK then set your scope to AC coupling and make sure there is no noise or ripple on 6 and pin 7 of the IC.
Do the digital outs bypass the relays?
Are you getting the same fault out of the digital outs?
Mooly;
The sonic disturbances on the 840 lacked bass, simply not enough signal getting through the relays as they were not fully closed due to under supplied power to activate the relays fully, restricting the output.
Are you getting the same fault out of the digital outs?
Mooly;
I should have made it clear that that arrangement exists on the 540, 640 + 640Mk2.
The sonic disturbances on the 840 lacked bass, simply not enough signal getting through the relays as they were not fully closed due to under supplied power to activate the relays fully, restricting the output.
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The audio does not pass through the relays in this player. They are configured to short the signal to ground for a mute condition, not to open to break the audio path.