Mains noise stops Technics CD player!

Whilst playing a CD, My Technics SL-PS7 CD player either mutes the output completley or produces a nasty hash sound when a light or power socket switch is thrown downstairs in the house. I did'nt think CD players were particularly sensitive to noisy mains/spikes. I have a couple of other players that I use are untroubled by the electrical activity in the house.?
Does anybody have any ideas as to what the problem is please?
Thanks in advance.
 
That is pretty unusual & pretty sad for a cd player.
I don't know how old that model is, but, being made by Panasonic, it is quite likely full of Panasonic/Matsushita electrolytic capacitors. These are extremely likely to start chemically leaking & dying after 5-10 years, but often a lot sooner. The symptom suggests that caps in the power supply are drying up, i.e., losing capacity, or were simply of inadequate size to start with.
 

wwenze

Member
2008-03-07 12:46 pm
It's sad that it happens, but why not? I used to have a USB ADSL modem that gets knocked out every time the fluorescent lamp is switched on.

I also have a DAC that gets knocked out by such surge, but a more powerful one from switching on an SMPS. One AC line filter later, I rarely see it hang again.
 
That is pretty unusual & pretty sad for a cd player.
I don't know how old that model is, but, being made by Panasonic, it is quite likely full of Panasonic/Matsushita electrolytic capacitors. These are extremely likely to start chemically leaking & dying after 5-10 years, but often a lot sooner. The symptom suggests that caps in the power supply are drying up, i.e., losing capacity, or were simply of inadequate size to start with.

Thanks for the suggestion, its most appreciated.
The player is a late nineties model, so over ten years old. Is there a way I can identify the suspect caps and should I be looking at just the electrolytics? I do have a circuit diagram, a multimeter and some limited knowledge, but no scope.
Cheers, Steve
 
First step to find any VERY dying caps is to look at all of the dc voltage test points in the power supply, before & after regulator circuits & check ac level on each of those dc points. Pre-regulator ac readings should be no more than about half a volt of ac. Post-regulator, the ac component should be damn near zero. If you get more than 50mV ac after any regulator, and there's not excessive ac before that reg, then look for bad caps along that post-reg supply line.
Panasonic/Matsushita caps are marked with simply a capital M in sort of brackets, as [M]. Other very suspect brands are Elna, Rubycon, Sanyo and pretty much any lytic cap that is not a Nichicon or Nippon Chemicon(small ones have just a blank sort of flattened chevron logo). Matsushita caps usually 'die quietly' and won't show badness until you remove it & find white chem residue around the leads. Elna caps usually leak more overtly & corrosively, and Rubycons usually start bulging at the top first. Any 'NC' or 'NIC' brand will be bad by now, no doubt, and should be replaced. If you do replace caps on the supply lines, higher value caps are always a good thing to do, of equal or higher voltage, and use Nichicons if you want the player to last forever.
It is also somewhat possible the fault is cold solder joints. So, carefully inspect for cracked joints while you're in there, especially on regulators & other hot components. Oh, and tighten up any board-holding screws that you see, in case they are grounding screws that are not making good contact.