Circuit diagram/information for Naim Audio CD5 CD Player

[Lightstream]

Very much required is any circuit information for a Naim CD5 player (not the later models, except for maybe the CD5i). Some years ago the player got infested with ants and they created a mess that was cleaned up and then later the unit was switched on, blowing two power supply diodes, damaging the board underneath and burning four resistors throughout the board. The rest of it looks fine, the main PS caps are fine and I'm hoping for the very best that the op-amps are fine too. 

 However, four resistors are burnt enough that I can only just make out the markings, though if I've got the values correct they all read quite low, so must be replaced. The rest of the unit looks good to and the Flatcap 2 is perfect. 

 So, I either need circuit information (there's nothing on line from Naim or anywhere else that I can find) or another board, which may be far more than I can afford.

I know this player is 20 years old now, but I'd love to have the pair up and running perfectly. Any info would be fantastic. 

[stereo coffee]

2 hours ago, Lightstream said:

Very much required is any circuit information for a Naim CD5 player (not the later models, except for maybe the CD5i). Some years ago the player got infested with ants and they created a mess that was cleaned up and then later the unit was switched on, blowing two power supply diodes, damaging the board underneath and burning four resistors throughout the board. The rest of it looks fine, the main PS caps are fine and I'm hoping for the very best that the op-amps are fine too. 

 However, four resistors are burnt enough that I can only just make out the markings, though if I've got the values correct they all read quite low, so must be replaced. The rest of the unit looks good to and the Flatcap 2 is perfect. 

 So, I either need circuit information (there's nothing on line from Naim or anywhere else that I can find) or another board, which may be far more than I can afford.

I know this player is 20 years old now, but I'd love to have the pair up and running perfectly. Any info would be fantastic. 

You could try contacting Naim directly , their contact info is here:   https://www.naimaudio.com/contact-information

 

If attempting this on your own you need  power off and AC cord disconnected,  Generally lots of excess current draw is a short, so the reason should begin to explain itself, either with visual checks or using a multimeter.  The power supply should have some form of current limiting, and a resistor generally is way too slow, and presents a fire hazard when it burns rather there should be fuses fitted.

 

A popular method sometimes used though, was a quad of  1 ohm resistors in parallel, these having fuse like characteristics, seemingly disconnecting a load without fire risk, but always used with a fuse as well.   I would check or replace psu capacitors as these are usually directly across the power supply rails with each polarity.

 

Check resistance across the four resistors,  if open circuit, Hooray ! then the resistors have saved the day, and need to be replaced, BUT you need to discover why EXACTLY they expired first, so check from before and after those resistors with your multimeter, as the ants might have eaten through a track or tracks on the circuit board. Check for shorts particularly after the resistors, by measuring from the resistors to ground with your meter  - or the circuits lower potential - usually ground marked GND.  Post up an image or two, and I , and others on the forum might be able to help.    

 

Will be good to see it running again.  a good way of stopping ants is to use ginger ( better )  or cinnamon powder - they get all confused and usually turn back defeated.

[Lightstream]

Thank you for all that, stereo coffee, I don't know the full "Ant" situation, as it was done a few years ago in the previous owner's possession. Last night I found at least one more resistor that looked fine on the surface and was completely open circuit. Heaven knows how much more damage might have been done to regulators and op-amps and if there is, the board may just need to be replaced altogether and be much better for it. 

 I will write to Naim and see what they can suggest for me. I will also post a pic or two here. 

 

[Lightstream]

A few photos of the damaged CD5 board. first pic is the power supply for the analogue stage - I'm assuming, as I have no circuit info other than the fact that this is where the external power supply comes in from the Flatcap 2 - the 4k7 resistor on the LHS that feeds one of the transistors bottom left is open circuit even while looking fine. A couple of the other above it have damaged ends yet measure perfectly. 

 Burned resistors are obvious in the next pics, and the power supply diodes, or what's left of them. With pic four, the overheated 4.7 ohm resistor below the RH side of the chip is obviously done for, there are actually two of them around there.  Flatcap 2 (last pic) is fine ... EMPTY but fine. No doubt a lot of money was paid for a mostly empty box, but then again, this one was given to me, so no hard feelings there! 

[bob_m_54]

2 hours ago, Lightstream said:

the 4k7 resistor on the LHS that feeds one of the transistors bottom left is open circuit even while looking fine.

 

If the resistor you're talking about is the the 3rd one up from the bottom, (yellow, purple, orange, gold) it's 47K 5%, not 4K7.

[Lightstream]

2 hours ago, bob_m_54 said:

 

If the resistor you're talking about is the the 3rd one up from the bottom, (yellow, purple, orange, gold) it's 47K 5%, not 4K7.

I've just double checked it against some other resistors nearby, it's definitely a red band, not orange. So 4k7 it was, dead as a Dodo now. Thanks for spotting it though, the photo makes look more orange than it actually it. 

 Awaiting a reply from Naim ...... it could be a while. 

[bob_m_54]

10 hours ago, Lightstream said:

I've just double checked it against some other resistors nearby, it's definitely a red band, not orange. So 4k7 it was, dead as a Dodo now. Thanks for spotting it though, the photo makes look more orange than it actually it. 

 Awaiting a reply from Naim ...... it could be a while. 

Yes, photos can be deceiving eh? Lots of luck with the repair..

[lenticularis]

The Naim user community forum might be another useful source of advice if you draw a blank with Naim themselves.