My Marantz CD32 player made a weird scraping noise then the Sansui AU-11000 amplifier it is connected to went into protection? I had been listening at a low level and the CD player had nearly finished playing the last track. I should mention that the CD transport will open but not close, I have to push it back in manually. The round crumble prone cog for the tray to open & close has been replaced. I would like to know if any DC voltage could get into the CD audio signal making my amplifier go into protection? The amplifier is playing OK now on the tuner?
Most CD players have output coupling capacitors. Yours has a 100uF output cap, before the
output muting transistors. If one of those are damaged (or the capacitor itself), some DC might
be present on the output. Measure the outputs and see.
Marantz CD-32 - Manual - Stereo Compact Disc Player - HiFi Engine
output muting transistors. If one of those are damaged (or the capacitor itself), some DC might
be present on the output. Measure the outputs and see.
Marantz CD-32 - Manual - Stereo Compact Disc Player - HiFi Engine
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While the output is DC-coupled with a 100µ/16V bipolar (whatever shape that might still be in at this point), a sudden jump in output DC voltage could still generate enough of a transient to momentarily trigger protection. After all, the time constant when connected to e.g. a 50 kOhm input would be rather long.
The question now is, which supply voltage did you lose, and why?
I'd start with the unregulated +/-10 V that the motor drivers run on. Should be present on the input of a set of 7805 and 7905 regulators. Make sure none of the 1N4002 rectifier diodes are shorted, and both the 0.8 A fuses are OK.
While failure due to old age is not impossible, there may also be an underlying problem. Dead motor driver, gummed-up motor (has certainly happened with Japanese players), something like that.
There is also a set of 7815 and 7915 regulators. Check those as well. Mind the differences in pinout between 78xx and 79xx.
The odd part is that the motor and audio (+/-15 V) supplies are fed from different turns of the power transformer and have pretty much nothing in common. Well, maybe the DAC on +5V.
HFE has a service manual for these players that you could go study, complete with a faultfinding guide and all. This is from the time when Marantz was a Philips subsidiary, and it's plainly obvious there.
The question now is, which supply voltage did you lose, and why?
I'd start with the unregulated +/-10 V that the motor drivers run on. Should be present on the input of a set of 7805 and 7905 regulators. Make sure none of the 1N4002 rectifier diodes are shorted, and both the 0.8 A fuses are OK.
While failure due to old age is not impossible, there may also be an underlying problem. Dead motor driver, gummed-up motor (has certainly happened with Japanese players), something like that.
There is also a set of 7815 and 7915 regulators. Check those as well. Mind the differences in pinout between 78xx and 79xx.
The odd part is that the motor and audio (+/-15 V) supplies are fed from different turns of the power transformer and have pretty much nothing in common. Well, maybe the DAC on +5V.
HFE has a service manual for these players that you could go study, complete with a faultfinding guide and all. This is from the time when Marantz was a Philips subsidiary, and it's plainly obvious there.
I unplugged the CD player cable to plug it back into the AU-11000 and an RCA connector fell onto the floor? The whole thing! Both the earth and the signal wire broke? lol, I'm not going to bother soldering it back on, this cable looks good but it is a POS, I didn't pull it out by the cable to cause this either! I think this may be the culprit? It must've been a dead short on the inputs on one channel. I haven't done any voltage tests on the CD player yet I've been flat out busy lately, I'm listening to the Marantz now with a new cable and everything is sounding great.
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