Need help with a Sony TC 510-2 - UK Vintage Radio Repair and Restoration Discussion Forum

sourbiscuits · 9th Dec 2024, 1:05 pm

Hey lads. I got myself the beautiful Sony TC 510-2.

When I plug the unit with power, the right spool starts spinning clockwise without engaging anything on the panel. I tried threading tape but the entire thing seems to work in reverse? Even the pinch wheel spins backwards. If I press the VU meter check, it tries to go down instead of up.

I read for about an hour before powering this on, and I found it to be a center positive 12 v DC, which is what I'm using. I am clueless on what to do. I will admit last night in my effort to try and figure this out, once I found out the pinch wheels spins backwards, I thought I must have switched polarities on the PSU. So for a few seconds I did plug it with a center negative, but nothing happened. It didn't turn on at all. I haven't tried that again, I know how harmful this could be (if it wasn't already).

Anyway, I also plugged my headphones in to look for a hiss at least, but nothing comes out of the headphone out.

I am open to any suggestions.

sourbiscuits · 9th Dec 2024, 2:19 pm

I want to also share that I followed a youtube video that covered how to clean the axes of the fly wheels. One of them was quite stuck. After I put the thing together, I noticed another metal arm that seems to not go back to default position and needs quite the nudge. I suspect the unit must be stuck in reverse?

Mooly · 10th Dec 2024, 5:45 am

You need to do basic checks of all the rails for starters. Although old, this machine uses such things as DCDC conversion... if you reversed the supply anything is possible.

That said the DC input appears to have some form of protection although I can't just see how the diode that looks like it provides reverse polarity protection actually works. It is not obviously across the supply and there is no obvious fuse.

The other diode appears to be in series with the supply to the electronics which would provide protection. The raw 12 volts does go to the motor and also its driver transistor so that may have suffered.

As always though, check ALL rails are correct.

sourbiscuits · 10th Dec 2024, 9:26 am

Ok, so I want to confirm again, that the first time I powerd the unit on, I was using a center positive PSU. It was behaving the exact same way already, so I definitely rule out the reversed polarity causing this. I don't exclude the possibility of potential damage, but I did not see anything affected after I tried reversing the polarity. I still feel very stupid for doing that in all honesty.

Anyway, most of the functionality of the unit is not engaging - lights, arming channels for record, VU measures in reverse, no hiss from the headphone output. I haven't tried the line outs yet, but I dobn't expect a different scenario.

I still have this gut feeling this is something mechanical and not electronical.

I had a look at the schematic, and that diode does look promising. When I plug the PSU, the motor just engages. When I swapped polarities, nothing happened. I engaged play as well, it still didn't do anything. I think I could pick up a very subtle beep coming from the internals, sounding as if the motors is struggling to engage.

Mooly · 10th Dec 2024, 10:12 am

You still have to check the supplies, it is the first rule of faultfinding.

No hiss from the headphone amp... you must check its supply before doing anything else.

The motor is either connected directly across the supply for FF/RW etc or via a transistor for servo control (PB/REC).

Quote:

When I plug the PSU, the motor just engages.

So switch #17 is either in the 'on' position or the transistor is conducting.

sourbiscuits · 19th Dec 2024, 9:13 pm

Thank you for that suggestion. I will be looking at that section when I take this apart again. I will only have time after the holidays but I will make sure to pop an update when I get to it. Enjoy the holidays!

sourbiscuits · 28th Dec 2024, 4:58 pm

I got some time today and did some more work on the unit. Despite cleaning more mechanical parts that seemed stuck in position, the unit would still work in a completely reverse fashion.

Upon plugging it in, the motor itself starts spinning in reverse already. If I engage REW the counter would spin forward instead of backwards. Playback will change the speed of the motor as well, but won't change the direction. I am starting to suspect that it might not be a mechanical issue after all..?

I also looked into the suggested switch 17 and I think the only switch I found to be triggered when engaging FF and REW is the one on this photo. In neutral position, the white part is pushing the button in. REW or FF will swing it left or right and disengage the black button on the bottom (you can't really see it).

Mooly · 28th Dec 2024, 6:17 pm

You need to determine if that white ? (wht on diagram) lead from the motor is grounded or not. If it then the switch is closed and the motor would run all the time.

If not then then you need to look at the transistor and whether it is on or off. If the white lead just happened to read 2.2 ohms to ground then that would point to the transistor being short but I doubt that is the case.

So just do a quick check on that lead. Is it grounded or not?

sourbiscuits · 4th Mar 2025, 9:08 pm

Ok, apologies I was away for so long. I finally have time to try and tinker this again. I am posting a link to a video where I filmed how I test the switch. I also attach a photo to better show the switch. It's basically a 3 pin switch with two positions. I checked for continuity between the white wire and all pins in neutral, ff and rew positions.

https://youtu.be/p-vkLwE3g7I

Here is a link to the video.

sourbiscuits · 4th Mar 2025, 10:43 pm

Also, is it possible that I am wrong about the polarity of the PSU after all? Could it be that it is a center negative instead of positive?

sourbiscuits · 5th Mar 2025, 10:10 am

Ok, after further research, it turned out the psu is center negative after all.. I've been powering it the wrong way the whole time. Right now, when I plug it the right way, ff and rew work, but play wont engage the motor. I only pick up a subtle high pitched noise coming from the chassis and the audio output. I fear for the worst. Is there any hope to troubleshooting this?

Mooly · 5th Mar 2025, 10:40 am

At least there seem to be some protection diodes fitted, one across the supply and one in series. D1001 is across the supply and I would have thought that would at the least have either failed short or else taken your external supply out.

First thing is to check all internal supplies are correct. Also check the output of the DC/DC convertor and the -/+25 volt rails.

If the motor won't spin in play check the supplies to the servo board. Switch 15 looks to be the play switch and that controls pin 8 of the servo chip via Q702 so check the inputs to the chip are good.

sourbiscuits · 14th Mar 2025, 5:15 pm

Quote:

Originally Posted by Mooly

At least there seem to be some protection diodes fitted, one across the supply and one in series. D1001 is across the supply and I would have thought that would at the least have either failed short or else taken your external supply out.

First thing is to check all internal supplies are correct. Also check the output of the DC/DC convertor and the -/+25 volt rails.

If the motor won't spin in play check the supplies to the servo board. Switch 15 looks to be the play switch and that controls pin 8 of the servo chip via Q702 so check the inputs to the chip are good.

Thank you for the response. I was able to locate the servo transistor board (a small pcb with a resistor and what appears to be a transistor with a heat sink on it) if I base that off the illustration on page 8. The servo amp board seems to be right under all the top knobs on the left handside. I have not stripped down the unit to that point yet. I am affraid I might have to.

I can also see the power supply board, it has really chunky caps. Not easy to reach and dismount, but I think I will manage.

Switch 15 does engage the motor on playback. If you look no page 7 of the manual, only when the lower pin is depressed, I will hear a signal in the speaker. The whining sound is only audiable in the outputs. I confirmed that today.

"Check all internal supplies are correct" - I don't know how they look like. Do you mean the power supply board by this? I assume I need a multimeter and check the voltage ratings?, I don't know what are the correct ratings.

I am happy to measure the values if I get a better input on what and how.

Applying a photo of the servo transistor board chip and the label it has. That is Q801 from the schematic.

I think at this point I should take those PCB's out and apply photos to get directions how to proceed with the troubleshooting?

Mooly · 15th Mar 2025, 8:04 pm

Apologies for only just replying.

The first step in fault finding is to check all the supplies and this applies even more so with the reverse polarity that the unit has seen.

You need to measure the voltages at main points such as these.

sourbiscuits · 23rd Jun 2025, 1:12 pm

Hey folks, I wanted to update the thread after a long wait. I gave the unit to a local technician. He replaced an IC on the servo board, but while doing that he must have de-soldered another pin by accident. I saw that today and after soldering that pad I have the unit running as intended, but there is the next issue to solve:

If I engage the unit in the tape monitor position, there is no signal at all neither frop pre-recorded tape nor a signal during recording. I only hear the input signal in the source mode position.

I want to conclude once more that the unit did get fed with a reverse polarity a few times before the repairs.

If anyone has suggestions what to look into, please share them!

Mooly · 24th Jun 2025, 6:46 pm

I would begin by tracing the signal (with a scope) and with reference initially to the block diagram in the manual which makes it easier to initially see the signal path.

You can play a tape and trace the signal and also then apply a line input (I assume in record mode) and do the same.

Do not over look anything. Begin not just with tracing the signal but also checking supplies to each section and block of the audio chain.

sourbiscuits · 9th Oct 2025, 3:25 pm

I had some more time lately and upon further testing, I found out that I get a healthy signal when the player is on and I monitor via source. Tape monitor still has no signal at all. If you can guide me a bit which components to check and how to perform the check, I can send some photos of the PCBs and I'm happy to follow any guides.

Mooly · 9th Oct 2025, 6:59 pm

If you have no signal playing a tape then you need to scope the signal through the head preamp and onward to the switch.

Check the muting transistors Q114 are not turned on. Whether they are on or off, you should see signal on playback level adjust preset R176.

sourbiscuits · 1st Jan 2026, 2:30 pm

I have located Q114 on the main PCB. Could you guide me how to perform the check with the multi-meter tool? If I can get more guidelines on that I would get on it and share the results. The unit is opened and I can get on it as soon as I can get some help on how to check Q114. Happy to also record a video during the tests.

Happy new year to everyone!

JohnBHanson · 1st Jan 2026, 3:59 pm

Simple test to try - Is the fault the same on the left/right channels. If so it is
more likely that the channel specific components are ok and you should think about
components common to both channels. If not then you can compare the left and right
channels as you have a working channel to compare with the faulty channel.

9th Dec 2024, 2:19 pm	#2
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 I want to also share that I followed a youtube video that covered how to clean the axes of the fly wheels. One of them was quite stuck. After I put the thing together, I noticed another metal arm that seems to not go back to default position and needs quite the nudge. I suspect the unit must be stuck in reverse?

10th Dec 2024, 5:45 am	#3
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,569	Re: Need help with a Sony TC 510-2 You need to do basic checks of all the rails for starters. Although old, this machine uses such things as DCDC conversion... if you reversed the supply anything is possible. That said the DC input appears to have some form of protection although I can't just see how the diode that looks like it provides reverse polarity protection actually works. It is not obviously across the supply and there is no obvious fuse. The other diode appears to be in series with the supply to the electronics which would provide protection. The raw 12 volts does go to the motor and also its driver transistor so that may have suffered. As always though, check ALL rails are correct. Attached Thumbnails

10th Dec 2024, 9:26 am	#4
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 Ok, so I want to confirm again, that the first time I powerd the unit on, I was using a center positive PSU. It was behaving the exact same way already, so I definitely rule out the reversed polarity causing this. I don't exclude the possibility of potential damage, but I did not see anything affected after I tried reversing the polarity. I still feel very stupid for doing that in all honesty. Anyway, most of the functionality of the unit is not engaging - lights, arming channels for record, VU measures in reverse, no hiss from the headphone output. I haven't tried the line outs yet, but I dobn't expect a different scenario. I still have this gut feeling this is something mechanical and not electronical. I had a look at the schematic, and that diode does look promising. When I plug the PSU, the motor just engages. When I swapped polarities, nothing happened. I engaged play as well, it still didn't do anything. I think I could pick up a very subtle beep coming from the internals, sounding as if the motors is struggling to engage.

19th Dec 2024, 9:13 pm	#6
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 Thank you for that suggestion. I will be looking at that section when I take this apart again. I will only have time after the holidays but I will make sure to pop an update when I get to it. Enjoy the holidays!

28th Dec 2024, 4:58 pm	#7
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 I got some time today and did some more work on the unit. Despite cleaning more mechanical parts that seemed stuck in position, the unit would still work in a completely reverse fashion. Upon plugging it in, the motor itself starts spinning in reverse already. If I engage REW the counter would spin forward instead of backwards. Playback will change the speed of the motor as well, but won't change the direction. I am starting to suspect that it might not be a mechanical issue after all..? I also looked into the suggested switch 17 and I think the only switch I found to be triggered when engaging FF and REW is the one on this photo. In neutral position, the white part is pushing the button in. REW or FF will swing it left or right and disengage the black button on the bottom (you can't really see it). Attached Thumbnails

9th Dec 2024, 1:05 pm	#1
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Need help with a Sony TC 510-2 Hey lads. I got myself the beautiful Sony TC 510-2. When I plug the unit with power, the right spool starts spinning clockwise without engaging anything on the panel. I tried threading tape but the entire thing seems to work in reverse? Even the pinch wheel spins backwards. If I press the VU meter check, it tries to go down instead of up. I read for about an hour before powering this on, and I found it to be a center positive 12 v DC, which is what I'm using. I am clueless on what to do. I will admit last night in my effort to try and figure this out, once I found out the pinch wheels spins backwards, I thought I must have switched polarities on the PSU. So for a few seconds I did plug it with a center negative, but nothing happened. It didn't turn on at all. I haven't tried that again, I know how harmful this could be (if it wasn't already). Anyway, I also plugged my headphones in to look for a hiss at least, but nothing comes out of the headphone out. I am open to any suggestions.

28th Dec 2024, 6:17 pm	#8
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,569	Re: Need help with a Sony TC 510-2 You need to determine if that white ? (wht on diagram) lead from the motor is grounded or not. If it then the switch is closed and the motor would run all the time. If not then then you need to look at the transistor and whether it is on or off. If the white lead just happened to read 2.2 ohms to ground then that would point to the transistor being short but I doubt that is the case. So just do a quick check on that lead. Is it grounded or not?

4th Mar 2025, 9:08 pm	#9
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 Ok, apologies I was away for so long. I finally have time to try and tinker this again. I am posting a link to a video where I filmed how I test the switch. I also attach a photo to better show the switch. It's basically a 3 pin switch with two positions. I checked for continuity between the white wire and all pins in neutral, ff and rew positions. https://youtu.be/p-vkLwE3g7I Here is a link to the video. Attached Thumbnails

4th Mar 2025, 10:43 pm	#10
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 Also, is it possible that I am wrong about the polarity of the PSU after all? Could it be that it is a center negative instead of positive?

5th Mar 2025, 10:10 am	#11
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 Ok, after further research, it turned out the psu is center negative after all.. I've been powering it the wrong way the whole time. Right now, when I plug it the right way, ff and rew work, but play wont engage the motor. I only pick up a subtle high pitched noise coming from the chassis and the audio output. I fear for the worst. Is there any hope to troubleshooting this?

5th Mar 2025, 10:40 am	#12
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,569	Re: Need help with a Sony TC 510-2 At least there seem to be some protection diodes fitted, one across the supply and one in series. D1001 is across the supply and I would have thought that would at the least have either failed short or else taken your external supply out. First thing is to check all internal supplies are correct. Also check the output of the DC/DC convertor and the -/+25 volt rails. If the motor won't spin in play check the supplies to the servo board. Switch 15 looks to be the play switch and that controls pin 8 of the servo chip via Q702 so check the inputs to the chip are good.

15th Mar 2025, 8:04 pm	#14
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,569	Re: Need help with a Sony TC 510-2 Apologies for only just replying. The first step in fault finding is to check all the supplies and this applies even more so with the reverse polarity that the unit has seen. You need to measure the voltages at main points such as these. Attached Thumbnails

23rd Jun 2025, 1:12 pm	#15
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 Hey folks, I wanted to update the thread after a long wait. I gave the unit to a local technician. He replaced an IC on the servo board, but while doing that he must have de-soldered another pin by accident. I saw that today and after soldering that pad I have the unit running as intended, but there is the next issue to solve: If I engage the unit in the tape monitor position, there is no signal at all neither frop pre-recorded tape nor a signal during recording. I only hear the input signal in the source mode position. I want to conclude once more that the unit did get fed with a reverse polarity a few times before the repairs. If anyone has suggestions what to look into, please share them!

24th Jun 2025, 6:46 pm	#16
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,569	Re: Need help with a Sony TC 510-2 I would begin by tracing the signal (with a scope) and with reference initially to the block diagram in the manual which makes it easier to initially see the signal path. You can play a tape and trace the signal and also then apply a line input (I assume in record mode) and do the same. Do not over look anything. Begin not just with tracing the signal but also checking supplies to each section and block of the audio chain. Attached Thumbnails

9th Oct 2025, 3:25 pm	#17
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 I had some more time lately and upon further testing, I found out that I get a healthy signal when the player is on and I monitor via source. Tape monitor still has no signal at all. If you can guide me a bit which components to check and how to perform the check, I can send some photos of the PCBs and I'm happy to follow any guides.

9th Oct 2025, 6:59 pm	#18
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,569	Re: Need help with a Sony TC 510-2 If you have no signal playing a tape then you need to scope the signal through the head preamp and onward to the switch. Check the muting transistors Q114 are not turned on. Whether they are on or off, you should see signal on playback level adjust preset R176. Attached Thumbnails

1st Jan 2026, 2:30 pm	#19
sourbiscuits Pentode Join Date: Sep 2022 Location: Amsterdam, Netherlands. Posts: 234	Re: Need help with a Sony TC 510-2 I have located Q114 on the main PCB. Could you guide me how to perform the check with the multi-meter tool? If I can get more guidelines on that I would get on it and share the results. The unit is opened and I can get on it as soon as I can get some help on how to check Q114. Happy to also record a video during the tests. Happy new year to everyone!

1st Jan 2026, 3:59 pm	#20
JohnBHanson Heptode Join Date: Aug 2009 Location: Worthing, Sussex, UK. Posts: 704	Re: Need help with a Sony TC 510-2 Simple test to try - Is the fault the same on the left/right channels. If so it is more likely that the channel specific components are ok and you should think about components common to both channels. If not then you can compare the left and right channels as you have a working channel to compare with the faulty channel.