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Author Topic: Sony TC-355 Reel to Reel noise in left channel  (Read 15226 times)

Offline ugmold

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Sony TC-355 Reel to Reel noise in left channel
« on: April 06, 2013, 06:02:48 PM »
Hi folks,

I picked up a Sony TC-355 reel to reel, 3 heads. It had been in a garage for years. I plugged it in and the transport was sluggish. Open it up, cleaned everything, lubed everything with sewing machine oil and the transport is pretty good, and seems to get better with use, but this is not the problem.

The left channel is noisy, I would say it was a tube, if it were tubes, but it is solid state, kind of a fuzzy hiss, very faintly hear the music. The other channel is fine. I also de-magged the heads.

Caps maybe? Kind of over my head if so.

Thanks for reading,

-Forrest

Offline ironbut

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #1 on: April 06, 2013, 11:45:41 PM »
Hey Forrest,

Welcome to the forum.

You didn't mention if the noise is heard on playback only or if it's only present when recording.
I'll assume that it's on playback of a tape you're familiar with.
BTW, it could always be something that's happened to the tape (particularly if it's the left channel of a 4 track tape). Ideally, you should try playing that tape on another machine to verify that it's okay.

Be sure that you've cleaned the heads thoroughly and examined them closely with a good light. If any sticky tapes have been played on it, it could take a good bit of work to get the goo off.
A pretty common issue with machines that have been stored for years (decades?) is oxidation and environmental contamination (smoke, dust, smog) on the contacts of switches and pots.
From your description, likely offenders are the switch(s) that toggle between tape/source outputs and the pot for output volume.
Try working those on/off or high/low. If they sound scratchy, they probably need cleaning with an appropriate cleaner/lube. Sometimes just working them will get them working okay.
It could also be a problem with the output jacks. Either bad contacts or maybe a connection barely holding on.

A couple of great resources for these machines are;

http://www.angelfire.com/electronic2/vintagetx/

http://www.vintage-electronics.cc/index.html

Those guys know these machines inside and out,.. literally!



steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades

Offline ugmold

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #2 on: April 07, 2013, 07:26:52 AM »
Thanks for the reply ironbut,

The machine came with a dozen tapes, one was a factory Joe Tex (skinny legs and all) tape, which is what I started with considering it would have been recorded properly. When I turn the knob to play, even before it engages the transport I hear the noise. In the stop position I do not hear anything. I sprayed all the switches and jacks with a contact cleaner made by Peavey called "Funk Out" I've had very good luck with it and the switches sound clean not scratchy.

I tried recording this morning, and got the same results. I'm pretty sure the hiss/fuzzy is from the amp of the unit.

-Forrest



Offline ironbut

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #3 on: April 07, 2013, 01:27:48 PM »
You might go ahead and email those guys at the links I provided.
See if they can give you any hints on the "usual suspects" for that particular machine.
One thing to keep in mind, these machines as well as nicer ones, sell for very little these days. So, before putting any cash into it, look into how much it will cost to replace it.
steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades

Offline ironbut

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #4 on: April 07, 2013, 01:35:05 PM »
Oops,.
Forgot to mention,

Try asking your question over on TapeHeads.
You're likely to find someone with that particular machine there.

http://www.tapeheads.net/
steve koto
 Sony scd 777es(R. Kern mods)> Vpi Aires>Dynavector XX-2mkll>Bent mu>CAT ultimate>CJ premeir 140>Magnepan 1.6qr(Jensen xover)Headphone Eddie Current Zana Deux>AT ad2000,HD800 ,Metric Halo ULN-2 (battery powered),
 HE Audio Jades

Offline ugmold

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #5 on: April 07, 2013, 02:08:08 PM »
Thanks much for the help, I was hoping to use to hear some old primative recordings I made on a Roberts in the 80's at 1 7/8 speed. I know these aren't worth much, kind of why I want to fix it myself. I'll check out the links.

-Forrest

Offline steveidosound

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #6 on: April 07, 2013, 08:08:58 PM »
Going out on a limb here, but without a schematic and more advanced troubleshooting aids, if you have some way of implementing a circuit tracer (test probe with  something like a .1 mfd.  capacitor in series to block DC, and ground wire hooked to the input of another known good amplifier/speaker) and some knowledge of typical board layout and circuit construction, you can put the machine in record pause so it will pass signal, feed a program signal into the line in jacks and "listen through" from input to line output, stage by stage following the signal path, comparing the left and right channels, and determining at what stage you loose the signal to a bad transistor, cap, cold solder connection, or what have you.
 It could even still be one connection / pole of the record / play switch or an internal connector, though there are probably not many of those in that model. You can do the same in play, starting at the head output, but you need a tracer with enough gain to be able to hear something till it goes through the first couple of head preamp stages.
Did you say if you got signal indication on both meters or it passed signal in record, source monitor (being 3 head) input to output on both channels?
 All of the above should get it down to at least one small area, unless there are multiple circuit problems.
Admittedly, this is harder in some machines than others, due to layout and accessibility to the pcb. And, as the machine is under power, please take all precautions to not shock yourself or short something and make the problem worse.

BTW, used ones have sold on eBay recently for anywhere between $15-$125 + shipping.

Sony and many others including Roberts / Akai made many, many other equivalent  2 and 3 head decks. They may have the same sorts of problems, or others, but probably all will have or develop some sort of issues. I guess it is  just a matter of how much time, money and effort you want to put in to restore one of these machines.

BTW, I have a  Panasonic and a Lafayette, both small 2 head self contained  stereo recorders that exhibit almost exactly the same problem as yours - mostly noise and a bit of signal on one channel in record and play. I was able to get it down to 1 transistor and/or an associated capacitor on the Lafayette, using the above technique and comparing the 2 channels. Just have to get a couple of parts now and throw in there to see if that cures it.

Last BTW, this should be moved to the regular reel to reel machines area as the Sony TC-355 is most definitely NOT a Tape Project machine ! :-)
« Last Edit: April 07, 2013, 08:40:27 PM by steveidosound »
Steve Williams

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Offline ugmold

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #7 on: April 08, 2013, 06:46:51 PM »
Thanks for the reply Steve,

When I recorded I did see both meters working as they should, but did not monitor it. When I play it back both meters work, but the right one is far more dynamic than the left.

-Forrest

Offline steveidosound

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #8 on: April 08, 2013, 09:37:51 PM »
Well, if both meters indicate normally on input signal, and presumably it passes signal to the line and or headphone output when in "source", sounds as if you have a problem in the play side with the head preamp stages or some connection in and around those. Somewhere between the head and the tape / source switch in the affected channel. It could still in fact be something to do with the head to tape contact as ironbut Steve suggested. One little hard chunk of oxide holding the tape away from the gap or causing it to wrinkle as it passes can  cause that sound, except I do recall you saying you heard the sound when the transport was engaged before tape moved past the head. So, back to the first few stages past the head.
Something like a small guitar practice amp might have enough gain to function as a signal tracer. Tape obviously needs to be playing, then just go stage by stage comparing the channels. Take a 1/4" cable to nothing on the other end. Connect a .1mfd cap to the center conductor and a ground wire with a clip to the shield. Ground to the chassis of the Sony and go probe around using the capacitor lead. Adjust gain on amp accordingly. Of course it won't be perfect, but you should be able to hear an increase in loudness stage by stage on the good channel. At some point it might be too loud and overload your input and cause some distortion. At the other extreme it might be fairly noisy trying to hear anything right off of the head. This is not necessarily anything wrong with the circuit, just the crude signal tracer. Let the working channel be your reference. If you look for it there is typically some symmetry between the left and right channel board layout to know where you are. You are probably only talking about 2 transistors per channel in this area.
Steve Williams

you don't want to know what equipment I listen to...

Offline ugmold

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #9 on: April 15, 2013, 07:42:01 PM »
Steve I wanted to than you for the post. I've been so busy I haven't gotten back to the deck.I feel intimidated to try to troubleshoot the pc board.

I bet it is a transistor or cap, just not sure how to do it, I read your instructions but not sure on the procedure.

-Forrest

Offline steveidosound

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Re: Sony TC-355 Reel to Reel noise in left channel
« Reply #10 on: April 16, 2013, 12:08:54 AM »
Hi,
Sometimes I am not too specific or clear.
If you are not really sure what I am talking about or don't feel too confident poking around on the PC board listening to various levels than perhaps you might want to enlist some aid.
I was just dreaming up something that you might have that might be able to listen to the levels and find out at which point the signal does not pass as it does in the other channel that works. You have to be able to "read the layout" well enough to somewhat follow the signal path and see that this transistor in the left channel corresponds to that one in the right channel. Then just probe the input and the output of each gain stage and see if the sound comes out a bit louder. If you uncover a difference between the channels, you have found a specific area to check thoroughly for a bad cap or transistor.
It probably is a bad transistor.  Again, if it passes signal all the way through from line in to line out in the source position, the issue is probably somewhere between the play head and the "tape side" of the tape /source switch. That is probably only 2-3 stages per channel. You might not have ideal gain with a guitar level input for those sorts of stages, so you might have to crank the gain to hear anything at all off the head before the first stage. but by the tape source switch the signal should be considerably louder. Of course you must have tape playing to hear anything off the head. You can work your way backwards from the output on the good channel to hear the relative loudness after each stage of amplification. At some point on the affected channel the signal will go from normal (if a bit weak, but the same as the other channel) to the character of what you hear when you play it back through line or headphone outputs. There is your problem stage.
It might not be that easy depending upon the specific circuits used and the board layout, but it is worth a try.
BTW the cap is used as a probe to block the DC from going into your test amp / tracer. The input ground to chassis is to ground the input to your test amp / tracer so you hear the signal level with respect to ground with relatively little hum. I have an actual signal tracer with a  gain control and built in speaker and a probe with a DC blocking cap and a ground wire with an alligator clip to attach to chassis ground of the unit I am checking. A small guitar amp should provide a relatively high input impedance and have enough gain and input level adjustment to listen in to almost everything from the line output level back to the tape head - more or less.
Steve Williams

you don't want to know what equipment I listen to...