Sony CDP-3100 start-up probs

This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hello everyone, I'm new here, very nice forum!
I want to ask of someone now's this strange problem:

After 5 minutes warm-up the Sony works perfectly but at the beginning it has always problems, no disk or it just stop working. Maybe some lubricant is needed on the side bars? this is plastic on metal. The laser works fine and I can see it with the handycam.
The laser type is: KKS-272A
After 5-10 minutes the cd-player works 100% When I pull off the unit and let it cool down the problem starts again when I press on, from a "cold" unit.

Many Thanks!
Forgot the picture from the unit, here it is...


  • sony-cdp-3100.jpg
    31.4 KB · Views: 76
Joined 2007
Paid Member
It maybe a transport problem, or it may not.

For no good reason at all alarm bells ring and I think SMPS (switch mode power supply). I don't even know if this model uses one... however :)

So just some general pointers,
does the disc spin at all from cold ?
Focus is achieved initially with the disc stationery, only when focus is obtained is the disc run up to speed. So there is a clue there in seeing what happens.
Does the servo/system control indicate FOK (focus OK) by the FOK line changing logic state. Just because the laser appears to emit "light" doesn't mean it's good. KSSxxx pickups normally have the exact factory setting of the correct current as part of the pickup serial number. It's the last three digits so 21132512486 would be 48.6 milliamp. Usually checked by observing volt drop across a resistor in the OPC (optical power control) part of the circuit.
Hello Mooly thanks for reply,
Yes indeed it has to do with the power supply, I warmed it up the laser with hearddryer [not to close ofcourse] and the problem after colt start-up was still there. So I headed up the complete laser deck or Mecha-deck in Sony words. Totaly no result, the cd spins 10 times and stops. The displays says "no disk" Just for sure I wait 1 hour again to do a second test. I pull out the complete Mecha-deck so I can hear the power supply only. Okee I headed it up for 1 minute so all alu-coolers and components are warmed up, not overheaded just good on temp.
I start the unit again, surprise the Mega-deck detect the cd directly and after 15 seconds it plays normaly the tracks. Now by accident with measuring I blow 1 fuse N25 special fuse. Anyway that is not the end of the world because I can still order these. Now I'm not sure but I think like you said that possible the cabs/condensers are bad after 20 jears that is possible. I will replace them all I think to get sure the problem is fixed. After I placed them I can see with a scope if the is no hum on the DC Maybe is this the problem and get's the Mega-deck a bad DC on his input.
Unfurtunality the power supply is just a nightmare to get there, you must strip-down the whole unit, nice built but not nice for maintenance;)


  • powersupply.jpg
    29.3 KB · Views: 62
It sounds first & foremost like cold sollder joints, probably on supply regulator transistors/IC's and other hot components, at often at plug-in connectors. It could need caps as well, but this is not likely the cause of the current symptom. You can save yourself time & money by assuming to be just fine any Nichicon or Nippon Chemicon caps in the unit, because they will be perfectly good. If it uses any Elna Duorex(as many Sony players of this vintage did), AUTOMATICALLY replace them, and expect to need to clean chemical corrosion damage above & below the board around them. Also very strongly suspect any Matsushita, Rubycon & other Elna caps in the unit(though the red Cerafines don't usually go bad as yet).
First thing, though, is to simply go through and resolder any connection that looks cracked, crystalised or cooked.
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.