• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Turntable Problem

geode

geode

F4 Phantom Seat Jockey
Subscriber
I have an old Pioneer PL-25 TT. It didn't work when I got it. I've been working through some issues trying to bring it back to life. The motor shaft was frozen and wouldn't turn. I soaked it in WD-40 for a couple of days and it finally freed up. I took it apart and wiped it down with alcohol and then relubed the bearings with 3 in 1 oil. It spins fairly easily now. However, when I plug it in the motor shaft doesn't turn. THe power supply get a little warm but not hot at all. This is a very clean unit and the motor doesn't have any signs that it burned up. IN fact, it hadn't been used in over 25 years. This old table doesn't have a circuit board, it only has one capacitor in it. I'm thinking it needs to be changed since it is 40 years old. I'm not much of an electronics wizard, in fact, I know very little. This old capacitor has these markings on it

CP-C
0.047 uF (M)
1000 WV

I know the capacitor is .047 microfarads and the 1000 is working voltage. I'm just having a difficult time finding a match on these specs. It is also a axial capacitor. Any feedback that will allay my confusion will be greatly appreciated. Additionally, is it a good probability that this capacitor could be the problem with the motor not engaging. Thanks.
 
Register to hide this ad
geode said:
I have an old Pioneer PL-25 TT. It didn't work when I got it. I've been working through some issues trying to bring it back to life. The motor shaft was frozen and wouldn't turn. I soaked it in WD-40 for a couple of days and it finally freed up. I took it apart and wiped it down with alcohol and then relubed the bearings with 3 in 1 oil. It spins fairly easily now. However, when I plug it in the motor shaft doesn't turn. THe power supply get a little warm but not hot at all. This is a very clean unit and the motor doesn't have any signs that it burned up. IN fact, it hadn't been used in over 25 years. This old table doesn't have a circuit board, it only has one capacitor in it. I'm thinking it needs to be changed since it is 40 years old. I'm not much of an electronics wizard, in fact, I know very little. This old capacitor has these markings on it

CP-C
0.047 uF (M)
1000 WV

I know the capacitor is .047 microfarads and the 1000 is working voltage. I'm just having a difficult time finding a match on these specs. It is also a axial capacitor. Any feedback that will allay my confusion will be greatly appreciated. Additionally, is it a good probability that this capacitor could be the problem with the motor not engaging. Thanks.
Click to expand...

Did you switch the motor's magnets by chance? You may wish to ask this question in the turntable forum, as there are some real experts in there.
 
NYListens said:
Did you switch the motor's magnets by chance? You may wish to ask this question in the turntable forum, as there are some real experts in there.
Click to expand...

I don't think so. I only removed the top and pulled the shaft out from the top. it could really only be reinstalled the way it came out. I have a thread open in the TT forum and have gotten a lot of help on other issues I was having. That thread seems to be dying though. I am determined to get this TT working again. Next up is the capacitor, which I am having some difficulty deciphering its markings and finding the correct replacement. Thanks for the feedback.
 
Have you tested the motor windings for continuity with an ohmeter? That would be the next step.

The capacitor is not inline with the motor, it's across the motor leads, or across the two incoming lines of the AC power supply, correct? If so it's not relevant to the motor running.

Also confirm you have power to the motor. If you have power to the motor and the motor windings are good, it should run.
 
nashvillebil said:
Have you tested the motor windings for continuity with an ohmeter? That would be the next step.

The capacitor is not inline with the motor, it's across the motor leads, or across the two incoming lines of the AC power supply, correct? If so it's not relevant to the motor running.

Also confirm you have power to the motor. If you have power to the motor and the motor windings are good, it should run.
Click to expand...

Thanks a lot for that information. I do have an ohm meter. When you say test the windings, I m guessing I would probe the positive and negative wires connecting into the motor. It has four wires going into the motor. Sorry if this is really elementary stuff, I don't know a whole lot about electronics.
 
4 wires going into the motor? I'm guessing this model is capable of running either 220 volts or 110, so a schematic would be useful....so it's a split coil motor, running the 2 coils in series would be for 220 volts, run the 2 coils in parallel for 110 volts. Each coil should see continuity, a reading of some sorts.
 
or it could be a multi-speed motor.

or when you reinstalled the armature, you could have caused the brushes to stop making connection.

the first thing you'll have to do is check to see if you have juice to the motor. if yes, the motor is the culprit. if not, trace the wires upstream. the switch that controls the power could be bad, or the transformer, or the power cord.

the capacitor is most likely used for hum resistance purposes. .047 mF is a common rating. if you can't find one the same voltage, substitute one of higher voltage.
 
nashvillebil said:
4 wires going into the motor? I'm guessing this model is capable of running either 220 volts or 110, so a schematic would be useful....so it's a split coil motor, running the 2 coils in series would be for 220 volts, run the 2 coils in parallel for 110 volts. Each coil should see continuity, a reading of some sorts.
Click to expand...

This table can be set to run 220 or 110 volts. It is properly set to 120 V. I've been looking for documentation on this table, but there is very little out there on this model. I ran the continuity test by probing each coils + and - wires. I got a tone on each. So I'm guessing the motor windings are okay.
 
lguise said:
or it could be a multi-speed motor.

or when you reinstalled the armature, you could have caused the brushes to stop making connection.

the first thing you'll have to do is check to see if you have juice to the motor. if yes, the motor is the culprit. if not, trace the wires upstream. the switch that controls the power could be bad, or the transformer, or the power cord.

the capacitor is most likely used for hum resistance purposes. .047 mF is a common rating. if you can't find one the same voltage, substitute one of higher voltage.
Click to expand...

I guess that is possible about the brushes. I can take it apart again. I checked the plug and am getting 120 volts through it. The motor/transformer does get a little warm when plugged in and the arm moved over the platter which activates the motor to turn. . I can upload a picture of it.
 
nashvillebil said:
Brushes? I'd be surprised if this motor had brushes.
Click to expand...

I don't see any brushes. This thing is really basic. I'm wondering if the switch that controls the operating voltage just needs a shot of deoxit and worked a bit.
 
How easily does the motor turn? If its stiff, you may have twisted the bearings slightly, either by not lining up the outer parts quite properly, or if the bearings are adjustible, by getting them a little out of line when you removed the rotor. If the latter, use a plastic scredriver handle to give the motor shaft a sharp rap -- not a smash, but a rap strong enough to jostle be bearings into alignment. If its the former, perhaps loosening up the screws slightly and then doing the rap would shift the whole top plate into location. And change the cap -- sometimes it matters. You might be able to find a suitable one on another junker table.
 
Nat said:
How easily does the motor turn? If its stiff, you may have twisted the bearings slightly, either by not lining up the outer parts quite properly, or if the bearings are adjustible, by getting them a little out of line when you removed the rotor. If the latter, use a plastic scredriver handle to give the motor shaft a sharp rap -- not a smash, but a rap strong enough to jostle be bearings into alignment. If its the former, perhaps loosening up the screws slightly and then doing the rap would shift the whole top plate into location. And change the cap -- sometimes it matters. You might be able to find a suitable one on another junker table.
Click to expand...

Thanks Nat. It spins fairly easy. I have located an exact spec poly film cap that is .047uF and 1000V with axial leads. I have to buy 10 to get the 1 I need, but it is only $10 plus shipping.
 
DexotIT should not be used for AC power switches.

* * * * *

The first thing I would do here is to go to the wires feeding the motor and -- using my AC voltmeter -- see if I had 120 volts AC.

* * * * *

If the capacitor is open, the motor will still turn, though not well. If the capacitor is shorted, it, or something in series with it, will get HOT.

* * * * *

Check the switch that applies power to the motor with an ohmmeter.

* * * * *

Fred
 
Fred Longworth said:
DexotIT should not be used for AC power switches.

* * * * *

The first thing I would do here is to go to the wires feeding the motor and -- using my AC voltmeter -- see if I had 120 volts AC.

* * * * *

If the capacitor is open, the motor will still turn, though not well. If the capacitor is shorted, it, or something in series with it, will get HOT.

* * * * *

Check the switch that applies power to the motor with an ohmmeter.

* * * * *

Fred
Click to expand...

Thanks Fred. OOPs, already put a little squirt of Deoxit on the switch. It is the switch that controls the operating voltage. I measured the voltage and got 119 Volts. When I move the Arm over the platter and feel the capstan on the motor, I can feel it trying to turn. I don't detect anything heating up. I will need to measure the voltage at the switch that controls the voltage. I have a new Cap on the way. Again, thanks a lot for offering your infinite wisdom on these things. I'm sure whatever ails it is something minor. This table is very basic except for all that mechanical linkage.
 
Have you tried running the motor loose? it might be something else in the drive train gunked up and keeping it from spinning.

If the cap is not open or shorted, its probably fine as is, Electrolytics are the usual age killed caps. (The ones marked with polarity)
 
hmm. If there's power to the motor and it doesn't spin...I'd say you need a new motor, unless you can fix the old one. Motors are pretty simple, they either work or they don't. Most turntable motors arent the kind that you can take apart.

I'd start looking for one. Pioneer doesn't have one, I checked.
 
outlawmws said:
Have you tried running the motor loose? it might be something else in the drive train gunked up and keeping it from spinning.

If the cap is not open or shorted, its probably fine as is, Electrolytics are the usual age killed caps. (The ones marked with polarity)
Click to expand...

I'm trying it with the platter removed and just watching the capstan. I'm pretty sure it is an electrolytic but I don't have a schematic. I can turn it with my fingers and it doesn't take much force to turn it. . But I can't spin it even once. I'm not sure how easy this thing is supposed to turn.
 
Sansui Louie said:
hmm. If there's power to the motor and it doesn't spin...I'd say you need a new motor, unless you can fix the old one. Motors are pretty simple, they either work or they don't. Most turntable motors arent the kind that you can take apart.

I'd start looking for one. Pioneer doesn't have one, I checked.
Click to expand...

I think it's getting power. I just don't see what could go wrong with this motor. The windings check out with a meter and it doesn't have brushes. Thanks.
 
geode said:
I'm trying it with the platter removed and just watching the capstan. I'm pretty sure it is an electrolytic but I don't have a schematic. I can turn it with my fingers and it doesn't take much force to turn it. . But I can't spin it even once. I'm not sure how easy this thing is supposed to turn.
Click to expand...

It still has some drag somewhere, the (brushless) motor should spin freely, with nothing more that it's mass keeping it from attaining speed, and rotating freely after you stop the "finger spin"
 
You must log in or register to reply here.
Back
Top Bottom