Good morning! This forum seems to be the home for those who would be able to help me, and I have already benefitted from much reading here. I need some expert assistance on my failed CD player. Help here from Martin, Mike, or Richard was particularly recommended to me on another forum.
My Naim CD5 is the victim of stupidity, at least I think that's what has caused the issue. The stupidity is all mine, of course.
When listening to a CD a couple of months ago for the first time in several weeks, I heard severe crackling in the right earcup of my AKG headphones. After a range of hurried and careless diagnostics, I concluded, I believe wrongly, that the CD player was the source of the difficulty. (The headphones still display the fault and I believe they were the cause all along, though I suppose it is possible they were also an effect. The system without the CD5 and those headphones works correctly.)
Obviously, a CD5 is long out of production and even though I have only owned it a year I know that finding someone to repair it for any reasonable price will be difficult. I live in Virginia in a rural area and there are no repair shops within easy striking distance. Naim's U.S. service provider, to which they directed me, wasn't initially responsive and they do have a reputation for being very expensive. In the UK, I suspect finding service would have been much easier.
But I have some hobbyist experience finding and repairing faults in audio equipment, and have a modest set of test equipment bought mostly for my amateur radio hobby. So, I removed the lid so that I could see if I could trace the audio path with a scope probe find the source of the crackling.
When I powered it up sans lid, however, I noticed immediately that two of the diodes in the bridge rectifier were releasing their magic smoke even as I watched. I immediately switched it off, of course, and thought about it. I'm not a fan of coincidence, so I thought I must have done something in my disassembly to cause the power supply to short out and burn up those two 1N4007 rectifier diodes. The only reasonable guess is Stupid Thing No. 1--that I was tilting the case back to get the parts that interested me into bifocal range, and with the backpanel loose, managed to short the two wires--okay--I have to digress to explain Stupid Thing No. 2. When I bought the unit, I did not buy an external power supply. The seller, a high-end equipment reseller out of New York, had installed (or accepted from who they bought it from) an alternative to the shorting plug that Naim provides for using the internal power supply. They used short lengths of #14 solid-core copper wire bent into a U shape to short the pairs of pins needed to imitate the shorting plug. Of course, that exposes the power being carried by that plug to the outside world without protection. So, back to the story--my best theory is that I managed to short those wires against the chassis when I powered it up without the lid, and that's what burned up the diodes.
I replaced the diodes, and I am able to measure steady DC voltages at places where DC voltages should be, such as the legs of voltage regulators. I have no schematic, so I'm trying to follow traces and look for DC power points. I do not see evidence of having blown a power-supply filter capacitor--without that I would be seeing ripple in that DC. (I'm using an oscilloscope to measure voltages.)
Now, the unit powers up just fine--the display powers up, the buttons work, and so on. But now, the laser unit seems unwilling to confirm focus. The unit gives a CD an initial short spin, almost immediately stops, and does not read the table of contents on the CD. Pressing Play at that point attempts the spin again, stops, and returns an error.
Everything I read about this suggests the laser is unable to focus on the CD. Again, I don't believe in coincidences, and for this to happen at the same instant as blowing two rectifier diodes does not suggest to me a weak laser. Nevertheless, I replaced the laser unit with a typical cheapie Chinese VAM1205 clone, in full recognition that it might not work, but just to see if the behavior changed. It did not--no change to the symptoms.
Without a schematic or service manual, I am at a loss as to where to look or conduct tests. I have confirmed that all the ribbon cables are attached and making contact, and the scope readings of the legs of all the voltage regulators I can find look like smooth DC. But I don't know what the values are supposed to be.
Here's my hope: Someone on this forum will have the expertise and patience to give me a few things to test, will wait for a day or two (depending on work) for me to test it, and then give me the next thing to test based on the results. I'm in no hurry, but I don't want to seem like I am being unresponsive if I have to leave it for a few days--I travel for work and suddenly travel is happening again for me. I will follow through. The resulting thread might be interesting for others and a future resource.
The system in which this unit was operating at the time: downstream--Adcom GFP-565 preamp, B&K Reference 125.2 amplifier, Revel F12 tower speakers. Other sources: Cambridge CXC feeding a Topping E30 DAC, a Yamaha YDP2006 parametric equalizer in the processor loop, a Musical Fidelity DAC for playing from a computer, a Benchmark ADC-1 for recording to the computer, a Thorens TD-166II turntable into the phono section of the preamp, a Nakamichi BX300 cassette deck, and a Teac A4300 open-reel deck. I have in the last month replace the Adcom preamp with a B&K MC-101 Sonata, which has a passive mode I wanted, and also the potential for balanced outputs. And I am always trading out amplifiers for fun, but none of them are any higher-end than the B&K.
For test equipment, I have a Hantek DSO5102P scope (newish, to replace the ancient portable Tektronix scope I was previously fighting), a Tektronix audio signal generator, Tek frequency counter, a Trio solid-state microvoltmeter, and a Fluke DVM.
Thank you for reading this far.
Rick "waiting in hope" Denney
My Naim CD5 is the victim of stupidity, at least I think that's what has caused the issue. The stupidity is all mine, of course.
When listening to a CD a couple of months ago for the first time in several weeks, I heard severe crackling in the right earcup of my AKG headphones. After a range of hurried and careless diagnostics, I concluded, I believe wrongly, that the CD player was the source of the difficulty. (The headphones still display the fault and I believe they were the cause all along, though I suppose it is possible they were also an effect. The system without the CD5 and those headphones works correctly.)
Obviously, a CD5 is long out of production and even though I have only owned it a year I know that finding someone to repair it for any reasonable price will be difficult. I live in Virginia in a rural area and there are no repair shops within easy striking distance. Naim's U.S. service provider, to which they directed me, wasn't initially responsive and they do have a reputation for being very expensive. In the UK, I suspect finding service would have been much easier.
But I have some hobbyist experience finding and repairing faults in audio equipment, and have a modest set of test equipment bought mostly for my amateur radio hobby. So, I removed the lid so that I could see if I could trace the audio path with a scope probe find the source of the crackling.
When I powered it up sans lid, however, I noticed immediately that two of the diodes in the bridge rectifier were releasing their magic smoke even as I watched. I immediately switched it off, of course, and thought about it. I'm not a fan of coincidence, so I thought I must have done something in my disassembly to cause the power supply to short out and burn up those two 1N4007 rectifier diodes. The only reasonable guess is Stupid Thing No. 1--that I was tilting the case back to get the parts that interested me into bifocal range, and with the backpanel loose, managed to short the two wires--okay--I have to digress to explain Stupid Thing No. 2. When I bought the unit, I did not buy an external power supply. The seller, a high-end equipment reseller out of New York, had installed (or accepted from who they bought it from) an alternative to the shorting plug that Naim provides for using the internal power supply. They used short lengths of #14 solid-core copper wire bent into a U shape to short the pairs of pins needed to imitate the shorting plug. Of course, that exposes the power being carried by that plug to the outside world without protection. So, back to the story--my best theory is that I managed to short those wires against the chassis when I powered it up without the lid, and that's what burned up the diodes.
I replaced the diodes, and I am able to measure steady DC voltages at places where DC voltages should be, such as the legs of voltage regulators. I have no schematic, so I'm trying to follow traces and look for DC power points. I do not see evidence of having blown a power-supply filter capacitor--without that I would be seeing ripple in that DC. (I'm using an oscilloscope to measure voltages.)
Now, the unit powers up just fine--the display powers up, the buttons work, and so on. But now, the laser unit seems unwilling to confirm focus. The unit gives a CD an initial short spin, almost immediately stops, and does not read the table of contents on the CD. Pressing Play at that point attempts the spin again, stops, and returns an error.
Everything I read about this suggests the laser is unable to focus on the CD. Again, I don't believe in coincidences, and for this to happen at the same instant as blowing two rectifier diodes does not suggest to me a weak laser. Nevertheless, I replaced the laser unit with a typical cheapie Chinese VAM1205 clone, in full recognition that it might not work, but just to see if the behavior changed. It did not--no change to the symptoms.
Without a schematic or service manual, I am at a loss as to where to look or conduct tests. I have confirmed that all the ribbon cables are attached and making contact, and the scope readings of the legs of all the voltage regulators I can find look like smooth DC. But I don't know what the values are supposed to be.
Here's my hope: Someone on this forum will have the expertise and patience to give me a few things to test, will wait for a day or two (depending on work) for me to test it, and then give me the next thing to test based on the results. I'm in no hurry, but I don't want to seem like I am being unresponsive if I have to leave it for a few days--I travel for work and suddenly travel is happening again for me. I will follow through. The resulting thread might be interesting for others and a future resource.
The system in which this unit was operating at the time: downstream--Adcom GFP-565 preamp, B&K Reference 125.2 amplifier, Revel F12 tower speakers. Other sources: Cambridge CXC feeding a Topping E30 DAC, a Yamaha YDP2006 parametric equalizer in the processor loop, a Musical Fidelity DAC for playing from a computer, a Benchmark ADC-1 for recording to the computer, a Thorens TD-166II turntable into the phono section of the preamp, a Nakamichi BX300 cassette deck, and a Teac A4300 open-reel deck. I have in the last month replace the Adcom preamp with a B&K MC-101 Sonata, which has a passive mode I wanted, and also the potential for balanced outputs. And I am always trading out amplifiers for fun, but none of them are any higher-end than the B&K.
For test equipment, I have a Hantek DSO5102P scope (newish, to replace the ancient portable Tektronix scope I was previously fighting), a Tektronix audio signal generator, Tek frequency counter, a Trio solid-state microvoltmeter, and a Fluke DVM.
Thank you for reading this far.
Rick "waiting in hope" Denney
