Mitsubishi HS-HD2000U audio interference on L track only?

[hahpiQ]

I've been working through a lot of tapes with this Mitsu but apparently I was doing a lot of mono recordings as it took a while for this issue to crop up. On tapes with stereo tracks, there is a very loud almost staticky noise that gets loud and quiets out repeatedly. Its seemingly every tape with stereo (both L and R lit up on the display). If in the video menu I select mono, its gone, R track its gone, its there on L and on the stereo mix

Example video clip
https://imgur.com/a/i3YqvMI

Changing cables makes no difference, and its present on both sets of audio output jacks. I haven't taken a look inside yet, and if there's nothing that can be done mechanically I will have to live with forcing output in mono, but figured I'd ask if anyone else has ran into something like this before and there's any components I should look closer at

[aramkolt]

Could be an alignment problem, though usually if it's stereo, that would mean HiFi audio which would basically have the same tracking as the picture. Those HD2000's also do have some SMT caps inside, though I'm not sure if them being bad would cause this problem.

Ideal first step would be looking at the audio RF waveform using an analog oscilloscope to verify that the heads are getting a good audio signal. If it is, then the problem is more likely to be electrical rather than a mechanical alignment thing.

[latreche34]

It sounds like head switch noise, not entirely sure though since I don't know anything about how this tape is being recorded, If this is an off air recording it could be baked in as noise related to poor stereo separation during reception, But if the linear track don't have the noise this rules out this scenario, which could mean a head switch noise. I would not recommend it but sometimes twisting the drum motor stator very slightly in one direction gets rid of the buzzing but you will have to put it back to the original location so it won't mess the head switch point for other tapes, I've demonstrated it in my YT channel.

[hahpiQ]

This particular example was recorded off television but this seems to be the same sort of noise in every tape I have with stereo tracks, including commercially produced ones

[hahpiQ]

And I don't know if this helps but I set up my other cheap VCR plugged into the inputs on the Mitsubishi to pass the signal thru, no sound issues at all that way on the output. So definitely coming from the head or related tape circuitry

[aramkolt]

Agree with latreche34, having a video or even just audio sample will give some better insight, though I still think looking at the audio RF waveform is the way to start. If it truly is variable, then I don't think a bad head or tracking issue would cause that.

This machine does similar to what you describe, except the noise is constant. Looking at the RF audio waveform shows every other head sweep is giving just noise which either suggests a bad audio head or something in that path that only affects one of the heads. Even with one head knocked out, you'll still get stereo sound as can be seen on the VU meter:
https://www.dropbox.com/scl/fi/2hs6y...xmwbz6p5y&dl=0

[hahpiQ]

Quote:

Originally Posted by aramkolt

Agree with latreche34, having a video or even just audio sample will give some better insight, though I still think looking at the audio RF waveform is the way to start. If it truly is variable, then I don't think a bad head or tracking issue would cause that.

I linked to a recorded clip above, it has audio you may have to unmute it- https://imgur.com/a/i3YqvMI

Here's another one, this from a commercially produced tape - https://imgur.com/rqOLdXE

[latreche34]

Look at the service manual for your deck and check to see if there is a potentiometer for adjusting the head switch point instead of physically adjusting it by using the drum motor stator, Note the original position of the pot.