Technics M14 tape deck

[darkpeak]

Hello there -

I just got hold of an old Technics M14. It has been working fine, but now, when I switch it on I get a quiet buzzing tone in the right channel. When I press play, I get a very loud buzzing tone in the right channel. What might this be? Any ideas?

Today there was a mild thunderstorm - might this have caused the change?

The only other cause I can think of is that yesterday I tried recording for the first time, but the recording was playing back fine.

I'd be really grateful for any thoughts.


All best, Richard

[Andy5112405]

Is the sound distorted or OK with an overlying BUZZ ?

Good sound with a BUZZ would tend to indicate a faulty capacitor or even one of the PSU diodes, If the sound is distorted then the problem may be more difficult to isolate.

[Phat Daddy Mark]

Good job on your find, these were a pretty good value at the time. I used to repair these things for Panasonic at a factory repair center. If memory serves correct it is just a dirty Record/Play switch.

Take off the cover and look for a very long switch on the main board. They were anywhere from 5mm to 15mm wide and from 50mm to 120 mm long depending on the model. There should be a slot or a small hole at the four corners of the switch. We used to give it a little spritz of tuner degreaser followed by a little tuner cleaner. If it was really dirty, put a few drops of light weight machine oil in a syringe and use sparingly.

If it is really bad you may have to take the switch apart and clean each contact. I used to use a burnishing tool for the sliding contacts and a pencil eraser for the other half. Take your time and be careful. One slip and it is a throwaway.

Post a picture of the insides if you can. If I did have a manual I wouldn't know where to look after 20+ years.

Good Luck,

Mark

[Andy5112405]

A thunderstorm is unlikely to cause dirty contacts on a switch !!!

[zeonrider]

Originally Posted by darkpeak

Hello there -

When I press play, I get a very loud buzzing tone in the right channel. What might this be? Any ideas?

Some ground missing!

Regards zeoN_Rider

[darkpeak]

Thanks for the replies.

Andy5112405: Buzz overlays the undistorted sound.

Phat Daddy Mark: What a good find indeed! 5 euro at the fleamarket. I've cleaned the switch, but with no improvement. However...

After plugging the line-in to my computer's line-out, the buzz went away, even after removing the cable. I suppose this means I have a grounding problem. But why should it only have occurred now, I wonder? There is no earth wire on the unit - how should I set up the earth? Is there an article here I should have read...?

[mrfeedback]

Remove the cover, locate and operate the Rec/Pb switch 100 times to work the contacts.
Noisey Rec/Pb switch contacts can cause several noise type faults.

Eric.

[Phat Daddy Mark]

My money is on mrfeedback. They do run ground returns through the R/P switch. I remember some that were so intermittent that just tapping the case of the unit would cause audible noise. You may need to lift up the end cap of the switch housing or use a foaming cleaner. There is a plastic block that is used to hold the sliding contacts in place. If you just put a drop of cleaner in the hole, the cleaner stays on top of the block and never reaches the contacts.

Andy5112405, the clue was his next sentence, "... yesterday I tried recording for the first time ...". This makes that the R/P switch the most likely cause and not today's thunderstorm.