Sony TPS-L2 noise when rewind,forward and play

Yes, a faulty electronic component can cause increased current (although unlikely) but:
1. It would not cause hum if it's not from the motor;
2. You will likely see another issue in regard to audio, tape speed, very high wow&flutter;

On PLAY the current draw it's kind of acceptable, although shouldn't be nearly as high, but the real issue is on FF/REW where it's almost double.
Here, simple logic tells me this: the same electronic circuits are powered in both PLAY and FF/REW,
so the increased current in REW has to come from increased load. There's just no other possible cause.
If the increased current was to be from a faulty IC or a shorted capacitor, you would have that high current in all operating modes.

The flywheel thrust play should be around 0.1mm (from factory it's always higher than that, so no issue), meaning you should have just a tiny bit of up-down play
and the flywheel should spin completely free (it should have inertia) when belts are not installed.

Distorsion at higher volume is normal (as it is on many SONY walkmans) because the amplifiers start to clip. It's inherent to the design of these amps.
The distorsion-free (or almost let's say) range is to about volume 6 or so on the linear potentiometers. Higher than that would have very audible distorsion.
It also depends on the headphones used, the amps not being able to drive low impedance headphones as good as higher impedance ones.

In regard to cleaning and oiling, I think it's best to upload a picture with the mechanism (can be one found online) and mark on it exactly what parts you have oiled.
This way I can tell exactly if there is anything you have missed or not.

 

Oiled parts i showed in blue.

 

Distortion isn't the right word. I misused it. Intermittent sound, come in and out rapidly and it happens irregularly. Plays two seconds, than it starts, than ends, again starts 3 seconds. You know what i mean? And it begins after 4/10. And it increase in each step when i increase the volume and near max it reaches to a phase where the sound very rapidly come in and out. When i turn the volume down, it becomes less and less and disappear around 4/10 of volume.

 

So I decided to upload a video, I thought it's better to show. Here is the link:

 

This walkman has more than one problem that was mentioned initially.
@flyman has started a private conversation with me and once we reach some conclusions we will update the thread as it's already too long.

The title may also be changed as the current one is not suggestive at all in regard to the actual problems.

 

Hello, I have the exact same problem here. I'm also looking into it and will share something if I find it. Thanks for the new information.
The problem does not exist when powered by the bench source at exactly 2.2v.

 

@Romulo Lubachesky Which problem do you have exactly ? Cause here there is more than one problem:
1. There's the motor hum;
2. There's excessive wow&flutter, which is audible and has been confirmed to be an issue with measurement (0.6-0.8% WRMS);
3. There are those loud pops in the audio at higher volumes, which was determined are dependent on voltage;

And second question is does the problem go away only at exactly 2.2V and not below ?

 

I actually do suspect about power delivery, as well. I also observed a similar thing. With same volume level, with two different sets of batteries( one set reads 1.3-1.4v, other set is new and reads full 1.5v) the device acts different. I mentioned this point to Valentin in our private chat. Can bad connections and/or cables cause this?

 

@Valentin
there is no abnormal engine hum. I also have expected W&F measurements. The only problem is the distortion of the audio when the volume of the two channels exceeds the mark of 5. Following Flyman's logic, I tested it with a 2.2v power supply to simulate weak batteries and the distortion disappears, even at maximum volume. However, reducing close to 2v makes the motor run slower, so this is the gold number for the test.
I also tested the ESR of the 220uf capacitors, they are all good.

 

found out!
in the amplification pcb there are 5 electrolytic capacitors of 47uf. All had high ESR. I replaced all 4 and everything seems to work fine now.

 

Thanks for sharing with us, I suspected capacitor issues from the beginning in regard to the loud pops, but @flyman didn't measure them yet as we focused on the wow&flutter and hum problems for the time being.
I recommend to replace all electrolytic capacitors for good measure even if they measure good in such a situation.

The 220uF output coupling ones are likely a bit down on capacitance and new ones (especially polymer ones) can improve the bass response a bit, especially since this device has a significant rolloff in bass to begin with.
Additionally, for those that want to improve the bass a bit more can replace the output coupling caps with 330uF or 470uF.

 

Thanks for the tip on bass.
I will replace them all, preferably with tantalum. For now, I put Chinese generics that I had here. I'll make a list and buy new ones. I share the results here.