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Sony TC-377 Playback Problem

Ieatlean

Ieatlean

New Member
Hello there,

(I hope I put this in the right place on this forum)

I got a Sony TC 377 Reel to Reel tape machine recently, it spins fine, and I can FF, reverse and change speeds with no problems, but when monitoring the tape, there is an extremely loud hissing noise which makes the tape unlistenable. As far as I know the tape is an empty tape, but when recording something on it most of the high frequencies get lost. I mean, it can play the things you record in it, but the noise is always louder than the recording no matter at what level you record...which is pretty annoying. The guy that I bought it from told me he replaced the motor capacitor, the quencher and demagnetized the tape path (and some other things which should be irrelevant to the issue). I did clean the tape heads, but it didn’t make any noticeable difference. The Noise only comes when the tape is being played. The tape has a shiny brown side and a matte brown side, but it doesn’t matter which side I’m playing, the noise is still there and remains unchanged.

This video right here shows the noise problem:
https://drive.google.com/file/d/1gu0-MzzYWpZfeWLTqQlU8l471f_7yGRn/view?usp=drivesdk

Is it a problem of the tape itself or is it, like someone on Reddit said, an issue with the bias oscillator? I’d gladly accept some advice.

Thank you for reading, and thank you for your help
 
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This machine has pressure pads that hold the tape against the heads. If you look in the head area you will see 2 or 3 flat plates that move up when you put it in play. There are supposed to be felt pads on them. Are they there?
 
I am not home until the 6th of January but as far as I can remember, there weren’t any felt pads near the heads, but are there supposed to be some on my model?
But still thank you for your answer
 
I looked at the manual and this model does not have pressure pads. (The older ones did.) Therefore, there is a pad that rides against the supply reel table, causing enough friction to provide holdback tension on the tape. If the supply reel turns really freely with no resistance, this may be the problem.
 
So I tried turning the supply reel to see if it moves freely and was able to see that the reel turns freely when turning clockwise and with resistance when turning counter-clockwise. That's how it's supposed to be, right?
 
So when you’re playing that tape and getting the hiss, does the hiss stop when you pull the pause lever down and stop the tape from rolling? If so then you’ve got a tape problem rather than a machine problem. Do you have some other tapes to try out?
 
The noise does in fact stop when pulling the lever and the noise also gets slower or faster if changing the speeds, so a tape problems would make sense. I have ordered new tape to try out, since I don't have any other tape. I will keep you and this thread updated once it arrives.
 
Cool. I should have been more specific though, I should have asked does the noise start and stop with the tape on the entire reel or just on portions of the tape that you have recorded on? I still suspect the tape but I’m just wondering if the noise is occurring when the tape is being recorded on or if it’s just there on the entire tape. FWIW I have had defective tapes before that barely record a signal and produce mainly hiss when recorded on (Realistic Concert Tape was the most recent one).
 
Ieatlean said:
So I tried turning the supply reel to see if it moves freely and was able to see that the reel turns freely when turning clockwise and with resistance when turning counter-clockwise. That's how it's supposed to be, right?
Click to expand...
That's correct, so the holdback tension is working. Could be bad tape, could be an electronic problem. If you could try a prerecorded tape and see if it plays correctly that would tell you if the playback is working properly.
 
audiojones said:
Cool. I should have been more specific though, I should have asked does the noise start and stop with the tape on the entire reel or just on portions of the tape that you have recorded on? I still suspect the tape but I’m just wondering if the noise is occurring when the tape is being recorded on or if it’s just there on the entire tape. FWIW I have had defective tapes before that barely record a signal and produce mainly hiss when recorded on (Realistic Concert Tape was the most recent one).
Click to expand...

The noise occurs on the whole tape and also when it's being recorded on. I bought new blank tape (which arrived today) but sadly it didn't fix the noise issue...the sound quality did improve though (when recording things on it, they sounded better) but still with that annoying white noise.
 
dr*audio said:
That's correct, so the holdback tension is working. Could be bad tape, could be an electronic problem. If you could try a prerecorded tape and see if it plays correctly that would tell you if the playback is working properly.
Click to expand...

So I bought new blank tape, and it didn't fix the issue. That means it's more likely to be some sort of electronic problem, but I'm assuming troubleshooting what electronic part is broken would be pretty difficult, right?
 
Well, now you need some test equipment. An oscilloscope and you would check the erase signal at the erase head. Then the bias signal at the record head.
 
dr*audio said:
Well, now you need some test equipment. An oscilloscope and you would check the erase signal at the erase head. Then the bias signal at the record head.
Click to expand...

Oh well that's very unfortunate to hear...I mean it'll be a challenge getting an oscilloscope but hey, at least there is some solution XD Still thank you for all the help
 
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