Sony TC-560 Tape Heads | Stereo/Mono Problem

[Chris-Something]

Hi, everyone.

Last night I replaced the playback/record heads on my Sony TC-560. The old ones (PP102-4202) are worn and one of them is physically damaged. The replacements (PP77-4202) came from an identical deck.

The issue I'm having? Well, when I listen to a tape that I know is in stereo, through the headphone jack it only plays in mono, selecting the left and right channels separately borderline mutes it apart from the tiniest mumble.
Now, when I listen back (with the same headphones) through the line output, I do get stereo, but the separation is very minimal.

All this happens in both play directions.
The heads are very clean and the wires have been soldered in all the correct locations.
I know there isn't an issue with the headphone jack itself, because when I attach the two microphones and arm the deck for recording, it sounds perfect, with great stereo separation.

I hope someone here can shed some light on this issue.
Thanks in advance.

[saxmaniac]

For a quick check of whether the fault is in the amp rather than the head, why not desolder the head and touch screwdriver on left and right wires alternately and see if you have 2 separate channels. Keep the volume turned fairlyry low while doing this

[Chris-Something]

I like this idea. The heads on mine have four wires each though, should I try all of them?

[DMcMahon]

They should be screened cables so it is the inner core (live) that should be touched.

David

[Chris-Something]

I have attached an image of the cables. This is exactly how they were on the previous heads.

[DMcMahon]

Difficult to be sure but these look like they could be twin core screened cables.

I see this deck does reverse play and record as well as the normal forward, so this makes it more complex and there is a separate combined Play/Record head for Forward and Reverse.

I would disconnect all 4 wires and touch each one and note any effect, with the direction switch set to match the head, in Playback mode and volume not at minimum you should get noticeable hum on the live playback wire.

David

[Chris-Something]

I'll have to strip back the wires to see what the cores are like.
In playback, both the forward and reverse heads have the same issue, which to me, would suggest something's up with the amp, but then I'm still wondering how the headphone out and line out sound different. I mean, why would the headphone out be mono while line out is stereo?

[John_BS]

The two rec/pb heads appear to have different type numbers. Are you sure you haven't got two identical heads fitted?

John

[Chris-Something]

The heads are different visually, yes, but they came from an identical deck. But even if they may be slightly different, how would that explain the headphone jack being in mono while line out seems normal?

[TIMTAPE]

There is always a little crosstalk between the channels due to mutual inductance of the coils within the head, but nothing like enough to make the outputs identical. I've never come across a stereo head outputting a mono signal, ie: left and right summed to mono.

If the headphone output is in mono while the line out is in stereo, the problem cant be the heads but somewhere downstream of them.

[Chris-Something]

That's what I reckon. I'm not going to rule out what the others have said yet, but downstream makes the most sense to me. Even though the problem only started after the head replacement. Could the headphone jack's related circuitry have gone faulty just before or during the head swap? It's strange considering I hadn't touched any of that.
I'm assuming the line out and headphone jack use different circuitry and are reacting differently to these new heads.

[TIMTAPE]

Have you considered the headphones you are using? If the shield or common wire breaks at the jack plug (headphone leads can get a beating) you will get a kind of "mono" signal.

[Chris-Something]

The headphones are perfectly fine. I used them to listen to line out as well. I've also tried multiple adaptors to see if that would make a difference, but it did not.
There is a third output option, 'speaker out', which I've yet to try out.
I'll try that now and see what I get.

[Chris-Something]

OK, I cannot explain this, I am very confused, but very happy.
I have not yet tried any of your suggestions and while I was about to, I no longer need to.
It just decided to work.
I repeat - I did nothing to it. I'm listening to it in exactly the same way I did last night when it wasn't working.
Maybe the deck is self-aware and felt bad for me, who knows..?

[sortedradio]

Dirty contacts in the headphone socket maybe?

[Chris-Something]

Perhaps.
But now I think my pinch rollers are pinching too tight. The tape in forward-play gets pulled down and folds over itself. In reverse-play the playback is ever-so-slightly slower than normal but if I physically pull the roller away very slightly it plays normally.
This is probably because the rollers have gone hard, but I don't have other rollers to compare them to. This TC-560 is the only deck I have and have seen in person.
How soft should they feel? If I squeeze my rollers, they barely flex.

[paulsherwin]

I suspect you just hadn't pushed the headphone plug fully into the socket. Maybe there was a bit of crud in there stopping it going in. In those circumstances the earth contact will connect with the ring, and the ring contact will connect with the tip. You'll hear the right channel in both ears.

I can't comment on the capstan roller, but if it's original then it may be going hard by now.

[Chris-Something]

The headphone plug was definitely firmly in place, it was the first thing I checked, but I won't rule out the chance that there may have been a dodgy connection going on. I should get some contact cleaner.