Hi All,
Looking for help troubleshooting the following issue that occurred after I replaced the electrolytic capacitors. Another reminder of the adage if it aint broken, don't fix it🙂
I am afraid I may have damaged IC201 or IC202. The only tool I have is a DMM.
After replacing the electrolytic capacitors on the driver board:
33.3RPM is working fine. If I spin the platter little bit faster than 33.3RPM the speed control becomes unstable and seems to oscillate a steady frequency. The issue clears after stopping the platter.
Switching to 45 RPM causes the same issue of course, and switching back to 33.3RPM will not clear the issue. I verified 3.4V/4.0V on the speed switch 33/45rpm per service manual which is attached. I figure there's something wrong with the rotation sensor circuit. Thanks for reading and any help is appreciated.
Looking for help troubleshooting the following issue that occurred after I replaced the electrolytic capacitors. Another reminder of the adage if it aint broken, don't fix it🙂
I am afraid I may have damaged IC201 or IC202. The only tool I have is a DMM.
After replacing the electrolytic capacitors on the driver board:
33.3RPM is working fine. If I spin the platter little bit faster than 33.3RPM the speed control becomes unstable and seems to oscillate a steady frequency. The issue clears after stopping the platter.
Switching to 45 RPM causes the same issue of course, and switching back to 33.3RPM will not clear the issue. I verified 3.4V/4.0V on the speed switch 33/45rpm per service manual which is attached. I figure there's something wrong with the rotation sensor circuit. Thanks for reading and any help is appreciated.
If you just replaced the capacitors why do you think you have damaged the IC-s?
... and also for replacement lytics soldered in with reversed polarity.
Thanks for the responses.
I’ll double checked polarity, values and my work.
33RPM locks and the electric brake works as expected.
Some possible causes:
One of the capacitors I removed was glued to Q203. I heated up that capacitor via the leads to loosen the glue. Perhaps that damaged Q203? Q203 OFF voltages are within 10% of the service manual. I’ll post those values, as well as IC pin values later.
I powered the turntable with 33/45 connector partially connected.
I’ll double checked polarity, values and my work.
33RPM locks and the electric brake works as expected.
Some possible causes:
One of the capacitors I removed was glued to Q203. I heated up that capacitor via the leads to loosen the glue. Perhaps that damaged Q203? Q203 OFF voltages are within 10% of the service manual. I’ll post those values, as well as IC pin values later.
I powered the turntable with 33/45 connector partially connected.
DC Voltages on “Stop” were verified.
IC101(11) and IC201(17) are off by a few Volts: 1.4Volts. The value should be 5.1V.
I checked and IC201(16) and IC201(17) are not shorted. I haven’t been able to verify the other pins that require an oscilloscope.
Q203(E) = 0.36V
Q203(C)= 3.5V, it should be 2.5V this seems high.
Q203(B) = 1.0V
IC101(11) and IC201(17) are off by a few Volts: 1.4Volts. The value should be 5.1V.
I checked and IC201(16) and IC201(17) are not shorted. I haven’t been able to verify the other pins that require an oscilloscope.
Q203(E) = 0.36V
Q203(C)= 3.5V, it should be 2.5V this seems high.
Q203(B) = 1.0V
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