Hello everyone,
Found a beautiful Technics SL-1300 MK2 in an abandoned storage unit a while back, finally cleaned it and got it running. Cue arm lift is broken, no biggie, manual operation is fine by me until I get around to wire/epoxy fixing the mechanism. I've been using it and loving it otherwise for about 200 listening hours until the pitch started sounding off, a little warbly sometimes. Then I found the pitch control buttons no longer changed anything (I know they did work as expected for a while). The buttons themselves are fine (I did fully remove them and clean/lube them anyway), and in fact when I press them, the LCD dims a little and the tracking dots clearly waver, this stops once I've release the button. I tested each button with a voltmeter as well, the contacts open and close promptly. Same goes for the start/stop buttons and 33/45 buttons. Anyway, I would simply power cycle it and the problem would go away.
About 40 hours of play time later the pitch has dropped to -10% (the readout still says 0.0% change), I timed the platter rotations to find this out. That, and it obviously just sounds slow.
I've since then gone through the manual, and using my oscilloscope calibrated all the variable resistors to an exact degree. No change. Then I went through the more advanced troubleshooting procedure listed in the service manual, and I think the IC201 (Frequency divider circuit, labeled DN860) might be acting up. One of the first pin the troubleshooting flow chart has you check seems to have a square wave slow by about 10%. I haven't gone past that so far. The chart says if this diagnostic step fails the tests, its either the IC or 6 specific transistors, which I will be checking tonight (there is a handy list of expected voltages at each pin for each transistor). I still need to fully check the actual pitch control IC301, because I feel like the behavior of the buttons and lcd tells me that's whats failed.
Anyone had experience with this problem in this model?
Found a beautiful Technics SL-1300 MK2 in an abandoned storage unit a while back, finally cleaned it and got it running. Cue arm lift is broken, no biggie, manual operation is fine by me until I get around to wire/epoxy fixing the mechanism. I've been using it and loving it otherwise for about 200 listening hours until the pitch started sounding off, a little warbly sometimes. Then I found the pitch control buttons no longer changed anything (I know they did work as expected for a while). The buttons themselves are fine (I did fully remove them and clean/lube them anyway), and in fact when I press them, the LCD dims a little and the tracking dots clearly waver, this stops once I've release the button. I tested each button with a voltmeter as well, the contacts open and close promptly. Same goes for the start/stop buttons and 33/45 buttons. Anyway, I would simply power cycle it and the problem would go away.
About 40 hours of play time later the pitch has dropped to -10% (the readout still says 0.0% change), I timed the platter rotations to find this out. That, and it obviously just sounds slow.
I've since then gone through the manual, and using my oscilloscope calibrated all the variable resistors to an exact degree. No change. Then I went through the more advanced troubleshooting procedure listed in the service manual, and I think the IC201 (Frequency divider circuit, labeled DN860) might be acting up. One of the first pin the troubleshooting flow chart has you check seems to have a square wave slow by about 10%. I haven't gone past that so far. The chart says if this diagnostic step fails the tests, its either the IC or 6 specific transistors, which I will be checking tonight (there is a handy list of expected voltages at each pin for each transistor). I still need to fully check the actual pitch control IC301, because I feel like the behavior of the buttons and lcd tells me that's whats failed.
Anyone had experience with this problem in this model?