Need help with a Sony TC 510-2

[sourbiscuits]

Thank you for the response John! Unfortunately, I get no audio output through any of the channels in Tape mode - just the hum noise I described. Source audio feeds equally fine through both L & R when I flick the monitor switch.

[Red to black]

Sony usually provide decent system block diagrams, I often look at this simplified view first to see what is or is not happening to narrow the fault down to one block or area rather than look at the circuit diagram as a whole.

Once you identify which block is in trouble only then use the schematic to 'zoom in' on the problem area to those specific components only associated with that area, makes it far easier to fault find.

[Mooly]

Originally Posted by sourbiscuits

I have located Q114 on the main PCB. Could you guide me how to perform the check with the multi-meter tool?

Measure the voltage on the lower end of the resistor that goes to the base of Q114

If you simply remove the transistor and the audio is then present on that channel then you know it was in a mute state.

A simple oscilloscope is your best friend for tracing faults like these.

[sourbiscuits]

I have an update on my issue and it got solved by a local technician. I believe the core problem came down to the dc-dc converter. He also replaced the majority of the caps. He also fixed the record cam which was broken and missing.

The unit is running quite fine but I have another question regarding the PSU.

Basically, I've been using my Tascam Porta Two PSU which matches polarity and voltage to the one the Sony needs. I happen to have two of those porta two bricks and both of them are a 12v center negative power supplies so I thought I can just use the second one for the sony. I've had it before where I would measure the voltage on a PSU and despite it being labeled 12v, it will output more than that.

To my big surprise, this seems to be the case for both bricks I have for the porta two. Just to be on the safe side, I measured the second one and it seems to output 15.8 V so I thought, this could be due to the label on the porta two which says 11-15V. I then went to measure the one I used on the sony all along and that one has a shocking 18.8V output.

I am quite paranoid about damaging these units so I really wanted to ask about this before we can close this thread. How did none of the two get damaged by the extra voltage output and what should I do with this situation?

I am currently using the 15v output PSU on the porta two to be on the safe side, but I don't dare power the Sony with more than 12V even though the technician was using the 18v psu all along and the unit was running very well and was tested throughout.

I will be grateful if someone can help me clear this out.

I've attached photos.

[AD360 Rob]

I would say, based on appearance that the 2 power supplies are of the unregulated type. These will give a higher output when measured "off load" (i.e. not connected to the equipment) than when connected and powering the equipment.

[Mooly]

I'm pleased to hear you have got it fixed, I know there was a lot of history to it all.

That little Tascam PSU looks very small and lightweight which if so suggests it might be an SMPS (switching type supply). Only you will know by seeing how much it weighs, if its very light it is an SMPS, if heavy it suggests a standard transformer.

That said an SMPS would normally be spot on voltage wise. So an unknown at a distance so that ties in with Rob's mention of unregulated supplies.

The 500ma output also sounds a bit low to run your recorder, at least during some operations.

18 volts is to much, at least for any length of time. 15 volts and no more is probably OK (I'm thinking 16v caps etc). An unregulated supply voltage will fall under loading so you could see if that happens.

[DMcMahon]

I see that the original (optional) Sony power adaptor for the TC 510-2 was a Sony AC-26, this was rated at 12V/400mA

The circuitry for the AC-26 shows it to be unregulated.

David

[DMcMahon]

The schematic of the AC-26 shows the unloaded output to be 16V

David

[sourbiscuits]

I just got off the phone with the technician and we discussed the situation. He also advised that I should just keep an eye on the brick in case it gets really warm, but voltage-wise, the voltage does indeed drop when loaded so it should be fine.

Both PSU bricks weigh about the same and I would definitely say they are on the heavy side compared to let's say a standard 9v guitar pedal PSU (I have quite a few).

To stay safe, I will keep the 18v one for the Tascam as it was, and the 15v one I will use for the Sony. I am going to look for a 12v 1000 mA or more to replace it with pretty soon. They are very easy to find in the thrift stores around. Just today I saw two that can fit. I always check the voltage output on those and now I know why they don't match 12v on the dot sometimes.

I am very happy with the machine, it sounds spectacular and it's definitely a keeper and the best sounding one from all the units I have and had so far. I really appreciate everyone being here with me. Hopefully this thread can serve useful as I could not find much online about the Sony TC 510-2.

PS: Thank you so much for confirming that David. That's another confirmation I should be safe to go for the Tascam 15.8v PSU I have at least for now. But I will keep that value in mind when I look for a higher power replacement soon!

[Uncle Bulgaria]

If you meter the inside of the DC socket when the machine is on, you'll see what the loaded voltage really is. Machines, almost ubiquitously, include the regulator circuitry inside, especially before small switch-mode wall-wart supplies became commonplace. Some Uher tape decks for instance have an input voltage of 12-24VDC. I see from earlier posts in the thread that there's a separate DC-DC converter board, and also a zener diode helping to regulate the input voltage. I wouldn't worry about your PSU. If it's working and the brick isn't getting hot then it's fine. There's no need for a 1A rated supply if the original AC-26 was 0.4A. The electricity is all the same. A higher rated amp supply won't affect the current draw of the machine, there would just be wasted headroom. A transformer supply (heavy PSU) can be beneficial too, as it won't inject high-frequency switching noise into the mains or machine, as is often the case with modern switch-mode supplies (light PSU).

[sourbiscuits]

Thank you for the confirmation fellow Bulgarian!

I have another technical question here. I have gone ahead and did some recordings with the unit and I am a little baffled.

Basically, I recorded a drum loop of 8 bars from a digital source. That sample is a perfect loop on a 60 BPM grid.

After I recorded the sample on the tape reel, when I play it back from the unit and record it to digital again, I can see that the loop is not perfectly on the grid anymore. In other words, when the loop finishes playing before the 8 bars are done counting in the digital software. That should mean that the playback is faster. If I take 1 bar and pitch it down with -16 semitones(digitally), that piece of the loop will line up perfectly with my grid again.

Is this due to the belts being old? Belts have not been replaced but also did not look like they are deformed or worn out.

[Uncle Bulgaria]

If the technician has performed a service as described in the service manual, part of that would be adjusting the speed. All tape recorders by their very existence will have speed variation: the belt has slippage; the bearings have friction; there is variation in the motor supply. All these can be very small variations indeed, but will make a measurable difference with sensitive enough equipment. This manifests as slow changes ('wow') or fast changes ('flutter'). You can imagine what they sound like from the words used - guitarists even have wow pedals. Do you have another known-good machine you can play-back recordings on to check the speed, or perhaps a test-tape? These are fundamental to aligning tape recorders as otherwise there's no way to tell from the unit itself (without careful mathematics combined with measuring and monitoring the rate of rotation of the capstan, I guess) whether the tape speed is correct before we get into questions of speed variation over the course of playback. Test tapes have recordings of set frequencies made to a high standard of accuracy which can be monitored during calibration in order to ensure the tape is playing at the correct speed.

I have an interest in music production, but very little experience. I would have thought combining tape and digital in the manner you want to is difficult, as the variations in the tape speed, very small as they are with a good quality machine, will be very difficult to align with the absolute exactitude of a digital timekeeper. Synchronising tape sound recordings with analogue film for example is done with various magnetic or optical methods whereby (as I understand it) a constant frequency outside the audio domain is monitored by the receiver and variations in this from changes in tape speed are thus able to be accounted for. There are some great experts and professionals around this forum who would no doubt be able to tell you exactly how these systems work. Perhaps you need something like that if you are trying to synchronise these different methods of working. I was imagining something like Brian Eno's early work where big loops of tape were being played as they draped around a room; physically cut up and reassembled...

If you mean that by lowering the recording's pitch (increasing the wavelength) it lines up with your grid as expected, then you have differing speeds between recording and playback. Unless there is something specific to this model, I can't understand the mechanism for this since in every tape deck I've come across the same mechanical systems are engaged for both recording and playback, with the same pinch-roller . You're not trying to play back a recording on a slow-running machine on a fast-running machine, for example, so the speeds (minus any wow and flutter) should be the same. It's certainly possible that the belts could be slipping unpredictably and each recording and playback will be slightly different in speed, but I would expect this to manifest as wow and flutter rather than steady but different speeds, as it doesn't make sense. The belts can be worn out without looking any different. Perhaps under a microscope they'll be cracked and perished, simply through age. It's good practice to replace belts if it is suspected they are original, as it is very rare indeed to find a rubbery material that hasn't suffered after several decades.

[Mooly]

It is unrealistic to expect a tape recorder of this or any era really to hold its speed over even a few minutes. I would guess that -/+0.5% would be not far off the mark. Absolute speed will be better when the machine has run for an hour or so.

I ran a 'listening test' on another forum some years ago with a pristine Sony TCK5 cassette deck where users had to say which recorded music sample they preferred. Many resort to file analysis and couldn't put their finger on what was 'wrong' with this one sample but no one guessed it was analogue. As you find, things didn't line up quite as they should.

In the absence of a test tape you should record a low level test tone from a stable generator (say 1kHz) from cold for say ten minutes and then play the centre portion back from absolute cold and then from very warm and see what the absolute speed variance is.

[sourbiscuits]

Thank you both for the extensive responses! This very much lines up with what I suspected - wow and flutter, and of course the simple fact that the machine is mechanical in it's core.

This imperfection is quite what I am after as well and one of the reasons as to why I would process some of my digitally produced audio stems through tape and then back to digital.

After I left my reply, I tested again and noticed that the speed offset was now down from -16 semitones, to -6 that day. Today I ran two full spools of tape and I conducted the same test. The speed offset is not -5 semitones. Also, I can actually set that -5 semitones pitch to the entire 8 bars instead of just 1 bar and the loop will align quite acceptably well still. I can also visually see how across the 8 bars, the loop will catch up in some spots and then run a ms late, then go back up to speed compared to the grid.

This is most certainly something I can live with and having the rest of the information helps me understand tape as a medium more and more.

[sourbiscuits]

As for the servicing, I am pretty sure the guy did his very bets to cover everything he could regarding fine tuning the machine.

When I arrived he was trying to figure out a difference between the left and right channel levels. To my understanding, he concluded the tape/source switch is not conducting the signal at it's best so, right now, when I record a signal or play back a tape, there is a few db of difference so I need to compensate for that via the input level adjustment (either gain one, or lower the other), but the right channel is a bit lower than the left. That does line up with what I discovered in my video - I had to play with the switches to get them to conduct.

It was a bit of a last moment adjustment he was doing, as I arrived without realizing the machine was still not done as his email ended up in my spam that day and I did not see it. I wonder if this could also be a trim pot on the main board, but he did measure the signal flow using a 1kHz signal as mentioned to adjust left and right.

[sourbiscuits]

I decided to run a flat digital signal to the stereo line in and when I started flipping between Line/Mic and Source/Tape I could see how the VU meters will not snap back to the original position they were at the start of the test. Flipping each switch a few times would eventually align them correctly, so I can confirm it's definitely the switches and not the trim pots, as suggested by the tech who adjusted the unit.

[Uncle Bulgaria]

Cleaning switch contacts is usually the first thing to do with a machine that has sat for a while. If you can access them, a cotton bud with contact cleaner liquid is good, if not then simply 'exercising' them is highly recommended. An amplifier with a missing channel that I dealt with last week was simply tarnished contacts on a switch. Switch cleaner and operating the switch a hundred times solved the problem.

Trimmers are only to be used with a signal generator and according to the manual. They will relate to specific signal levels which are to be injected and adjusted with reference to sensitive test equipment. It is far more common for problems in tape decks to be gummed up lubricant, perished belts and tarnished switch contacts. Play/Record switches are particularly notorious, as they often have a large bank of contacts and will have been left in one position possibly for decades. A clean, lubricate, new belts and good switch exercise will usually sort problems. Unless the 'phantom twiddler' has 'got at' a machine, the internal trimmers will have been set correctly so there would be no need for adjustment unless recalibrating for a different type of tape, or to account for wildly drifted out of tolerance old components, which it would be better to replace anyway.

[sourbiscuits]

Just wanted to update that I cleaned the switches but I still had a significant difference between tape and source. I looked into the record trim pots and I actually had to adjust my L input to match R. No the signal is matching spot on for both sides.

[TIMTAPE]

Originally Posted by Mooly

It is unrealistic to expect a tape recorder of this or any era really to hold its speed over even a few minutes. I would guess that -/+0.5% would be not far off the mark. Absolute speed will be better when the machine has run for an hour or so.

I ran a 'listening test' on another forum some years ago with a pristine Sony TCK5 cassette deck where users had to say which recorded music sample they preferred. Many resort to file analysis and couldn't put their finger on what was 'wrong' with this one sample but no one guessed it was analogue. As you find, things didn't line up quite as they should.

In the absence of a test tape you should record a low level test tone from a stable generator (say 1kHz) from cold for say ten minutes and then play the centre portion back from absolute cold and then from very warm and see what the absolute speed variance is.

Yes even two separate playbacks will not synchronize in time with each other. But this is only noticeable when we are directly comparing one with the other where when started at the exact same moment they start to drift.

If you want to use tape distortion as a production effect better to avoid this slight speed variation by using the "3 head" system built into this Sony machine. Record your digital file into the Sony and at the same time record the Sony's playback back into digital as a new recording on a new digital track. This requires a soundcard which can both play and record at the same time, like the Sony. This is called a "duplex" card.

[sourbiscuits]

When it comes to distortion, I want to confirm that this thing does magic to drums, bass and even some keyboard instruments if I crank up the gain gently. Moreover, the built in limiter feature is also surprisingly good on this thing. I am almost tempted to try and master a song for the experiment. With the limiter on, it's doing a really good job on the signal.


As for the real time recording, I can do that without any issues with my digital sound interface I use. I also have an external mixer which I can route to the sony to create an analog tape delay patching setup. I haven't tried it yet. Too bad the vari speed is bypassed in record, it could give a very good range of tape delay speeds. I wonder if that can be modified? I wouldn't know how to do it myself though.