I'm playing with a nice Philips cd210 that I've found (TDA1543 based). Made basic mods: nonoversampling and replaced opamps with LM4562. I really like the sound. So I wanted to add a dedicated 5v supply for the dac: cut the existing trace and connected the little pcb (input from main filter capacitor+capacitor+7805+capacitor) but when I switched on the player the motor started to run neverending! 
I really don't understand what happened, I think isn't a big problem but I'm not able to fix it.
Please really need help...
Thanks
I really don't understand what happened, I think isn't a big problem but I'm not able to fix it.Please really need help...
Thanks
I've replaced everything but when I switch on the player the motors still start to run. Maybe something in the SAA7310 chip?
Try removing the mod that caused this problem and see if the issue remains, if it does perhaps there is a bad chip or some other damage done as a result of the mod.
Quite often, a ridiculously spinny motor is due to a lack of clock signal.
Maybe you've upset the power to the clock? or the decoder?
Maybe you've upset the power to the clock? or the decoder?
Phil is right; you always need the clock to start before the decoder chip (the SAA7310 in this case) tries to take control of the disc servos.
Either undo the new-psu mod to the dac, or at least ensure this new PSU starts-up before the rest of the player. That might be as simple as juggling time-constants with the raw smoothing caps - smaller values for the DAC's supply, so it (and the attached clock) start first.
Incidentally, what dac does this player use..?
Either undo the new-psu mod to the dac, or at least ensure this new PSU starts-up before the rest of the player. That might be as simple as juggling time-constants with the raw smoothing caps - smaller values for the DAC's supply, so it (and the attached clock) start first.
Incidentally, what dac does this player use..?
Thank you for your replies. Actually I didn't connect the new PS. This is the algorithm 😉 :
-cut the trace before the resistor that precedes the dac;
-connected a twisted pair wires to first filter capacitor pins;
-connected the other end of the twisted pair with new PS (capacitor+7805+capacitor)
-switched on the player (I wanted to check the voltage after regulator with a multimeter)
-SMOKE from the new PS
-ok, just an inverted capacitor (a little tantalum with invisible writing)
-replaced capacitor
-switched on the player: I don't remember if the motors started suddenly to run or if this happened a little later (anyway the player was reverted as I was working under the pcb: I don't know if this means something)
-PANIC
-tried to replace the cut trace with a little wire
-ok but the motors don't stop
-I really didn't understand
-I still don't understand 😕
ps: Martin, the dac is a TDA1543 one.
-cut the trace before the resistor that precedes the dac;
-connected a twisted pair wires to first filter capacitor pins;
-connected the other end of the twisted pair with new PS (capacitor+7805+capacitor)
-switched on the player (I wanted to check the voltage after regulator with a multimeter)
-SMOKE from the new PS
-ok, just an inverted capacitor (a little tantalum with invisible writing)
-replaced capacitor
-switched on the player: I don't remember if the motors started suddenly to run or if this happened a little later (anyway the player was reverted as I was working under the pcb: I don't know if this means something)
-PANIC
-tried to replace the cut trace with a little wire
-ok but the motors don't stop
-I really didn't understand
-I still don't understand 😕
ps: Martin, the dac is a TDA1543 one.
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