Sony TC-K611S - No VU Meter output - UK Vintage Radio Repair and Restoration Discussion Forum

mightyi · 15th Jan 2022, 1:53 pm

First post so please be kind

I recently moved house which has allowed me to finally have a "Man Cave" - so all my old HiFi has finally been taken out of the double binbags in the attic, cleaned and put on a new rack. Everything is working...except the TC-K611s!

First problem was disintegrated belts - managed to find replacements and fit them. Then the audio wow and flutter was awful - upon investigation found the pinch roller was blistering and completely shot. Only new ones i could source where from Poland - so finally had them delivered.

Installed and put everything back together, and it plays, but sound was not good, plus had gone much slower. I've stripped the mech and re-greased, cleaned etc and then reset the motor speed and adjusted the head to get a bit better result - I've sourced a test tape and will connect a scope to try and tweak it properly soon. But I also had some really bad mains hum from the deck - so stripped down and took board out to check it over.

I found quite a few solder joints looking rather suspect, so I went round and re-flowed any i could see with new solder and re-assembled.

Now, the hum is better - but the VU meters are not registering anything at all - everything else seems to be working.

I've looked at the service manual but the one i have seems to only have the first corner of the diagrams, so can't easily trace the VU meter control circuitry - the fact everything else is ok and both L&R are completely dead would kind of imply a supply voltage issue maybe (I'm by no means an expert on this sort of thing!)

Can anyone offer me any good advice of where to start? I've also seen a lot of mention of replacing the caps because of the age. as the deck has been sat in a cold attic for about 8-10 years I'm suspecting they are on their way out (and maybe contributing to the noise) - they all look ok, but has anyone done one of these and recommend the primary ones to attack? there is not sign of leaking or bulging caps anywhere.

Thank you in advance for any help!

Kentode · 15th Jan 2022, 4:55 pm

First of all, congratulations on getting a man cave! Hi-fi Engine have a service manual and other information so it might be worth looking there.

I don't know the model you have, but might you have disturbed a plug-in connection when you opened it up?

Hope this helps.

Welcome to the forum!

mightyi · 15th Jan 2022, 5:05 pm

Thank you for the welcome Ken, appreciated!

Yes i think i've been quite lucky - its my Music/DJ/Vintage computer cave really - CDJ-1000's, Technics 1210's and a few BBC Micro and Masters to add to the vintage hifi!

I've managed to find a service manual with the full diagrams now - thanks! upon looking i was checking around the headphone amp and discovered the reason why you should NEVER do soldering at 2am....i'd managed to bridge some wire links....

Been over the board in daylight and cleaned up the other suspect joints properly now! That has thankfully fixed the VU meter and slight distortion issue on the headphone amp without leaving any damage which is a bonus!

I'm now trying to calibrate the deck properly - I've bought a (non genuine) test tape from one of the more reputable sellers on eBay to try with a range of test tones on; but when connected to the scope and using the laptop with Techmind frequency counter software, I am seeing way too much speed variation - around 1.5-2%. The mech has been completely stripped down, re-greased with superlube synthetic grease, new belts fitted and the pulleys completely cleaned - and a new pinch roller which has also been fully cleaned.

bearing in mind the steps already done - am i to assume the worst and start looking for a new motor? I'm struggling to find a source of a tension test tape for less than the cost of another deck!

paulsherwin · 15th Jan 2022, 5:13 pm

The speed variation is unlikely to be a bad motor. There will be some sort of mechanical problem. My guess would be that there's excessive tension on the takeup reel - if so, the variation will be much worse at the start of the tape than the end.

mightyi · 15th Jan 2022, 5:51 pm

I did look at the pinch roller tension - it seems quite light tbh, but i've no tape to test tension - and looking at prices they are excessive!

15th Jan 2022, 1:53 pm	#1
mightyi Diode Join Date: Jan 2022 Location: Widnes, Cheshire, UK. Posts: 3	Sony TC-K611S - No VU Meter output First post so please be kind I recently moved house which has allowed me to finally have a "Man Cave" - so all my old HiFi has finally been taken out of the double binbags in the attic, cleaned and put on a new rack. Everything is working...except the TC-K611s! First problem was disintegrated belts - managed to find replacements and fit them. Then the audio wow and flutter was awful - upon investigation found the pinch roller was blistering and completely shot. Only new ones i could source where from Poland - so finally had them delivered. Installed and put everything back together, and it plays, but sound was not good, plus had gone much slower. I've stripped the mech and re-greased, cleaned etc and then reset the motor speed and adjusted the head to get a bit better result - I've sourced a test tape and will connect a scope to try and tweak it properly soon. But I also had some really bad mains hum from the deck - so stripped down and took board out to check it over. I found quite a few solder joints looking rather suspect, so I went round and re-flowed any i could see with new solder and re-assembled. Now, the hum is better - but the VU meters are not registering anything at all - everything else seems to be working. I've looked at the service manual but the one i have seems to only have the first corner of the diagrams, so can't easily trace the VU meter control circuitry - the fact everything else is ok and both L&R are completely dead would kind of imply a supply voltage issue maybe (I'm by no means an expert on this sort of thing!) Can anyone offer me any good advice of where to start? I've also seen a lot of mention of replacing the caps because of the age. as the deck has been sat in a cold attic for about 8-10 years I'm suspecting they are on their way out (and maybe contributing to the noise) - they all look ok, but has anyone done one of these and recommend the primary ones to attack? there is not sign of leaking or bulging caps anywhere. Thank you in advance for any help!

15th Jan 2022, 4:55 pm	#2
Kentode Octode Join Date: Mar 2015 Location: Yorkshire, England. Posts: 1,301	Re: Sony TC-K611S - No VU Meter output First of all, congratulations on getting a man cave! Hi-fi Engine have a service manual and other information so it might be worth looking there. I don't know the model you have, but might you have disturbed a plug-in connection when you opened it up? Hope this helps. Welcome to the forum! __________________ Regards, Ken. BVWS member

15th Jan 2022, 5:05 pm	#3
mightyi Diode Join Date: Jan 2022 Location: Widnes, Cheshire, UK. Posts: 3	Re: Sony TC-K611S - No VU Meter output Thank you for the welcome Ken, appreciated! Yes i think i've been quite lucky - its my Music/DJ/Vintage computer cave really - CDJ-1000's, Technics 1210's and a few BBC Micro and Masters to add to the vintage hifi! I've managed to find a service manual with the full diagrams now - thanks! upon looking i was checking around the headphone amp and discovered the reason why you should NEVER do soldering at 2am....i'd managed to bridge some wire links.... Been over the board in daylight and cleaned up the other suspect joints properly now! That has thankfully fixed the VU meter and slight distortion issue on the headphone amp without leaving any damage which is a bonus! I'm now trying to calibrate the deck properly - I've bought a (non genuine) test tape from one of the more reputable sellers on eBay to try with a range of test tones on; but when connected to the scope and using the laptop with Techmind frequency counter software, I am seeing way too much speed variation - around 1.5-2%. The mech has been completely stripped down, re-greased with superlube synthetic grease, new belts fitted and the pulleys completely cleaned - and a new pinch roller which has also been fully cleaned. bearing in mind the steps already done - am i to assume the worst and start looking for a new motor? I'm struggling to find a source of a tension test tape for less than the cost of another deck!

15th Jan 2022, 5:13 pm	#4
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,931	Re: Sony TC-K611S - No VU Meter output The speed variation is unlikely to be a bad motor. There will be some sort of mechanical problem. My guess would be that there's excessive tension on the takeup reel - if so, the variation will be much worse at the start of the tape than the end.

15th Jan 2022, 5:51 pm	#5
mightyi Diode Join Date: Jan 2022 Location: Widnes, Cheshire, UK. Posts: 3	Re: Sony TC-K611S - No VU Meter output I did look at the pinch roller tension - it seems quite light tbh, but i've no tape to test tension - and looking at prices they are excessive!