Sony TC-266 bias calibration - UK Vintage Radio Repair and Restoration Discussion Forum

NorfolkDaveUK · 1st Sep 2018, 1:09 pm

I'm having real trouble here working out how to calibrate this.

I have the scope connected to the line out .

I have the player in rec on the left side.
I'm adjusting L201 and nothing is happening .

NorfolkDaveUK · 1st Sep 2018, 2:14 pm

No left output ...lol . So somewhere between playing a tape , and taking it out of the case , something happened to the left output . Don`t you just love these oldies ..lol .

ms660 · 1st Sep 2018, 2:20 pm

T-266 = TC-266?

Lawrence.

NorfolkDaveUK · 1st Sep 2018, 2:57 pm

Yeah sorry typo and I couldn`t correct it . TC-266 .

It was working "ok" the levels were all over the place . Right side record was full of hiss and way way over what the right side was , playback was very low . I re-capped it and it was ok but no change in the symptoms but now the left side has now decided to quit on me I`ve checked all the caps and they are all correct and orientated correctly on all 3 boards . I`ll put a signal in and try and trace it though .

Ted Kendall · 1st Sep 2018, 3:17 pm

That inductor does not set the bias level. The adjustment is for the bias trap to keep bias out of the signal circuits. It shouldn't normally need adjusting unless there have been component changes around it.

ms660 · 1st Sep 2018, 3:18 pm

Do you have a schematic?

Back in the day a long long time ago I used to service a lot of Sony tape recorders, one problem even back then was the small signal transistors breaking down, typical symptoms (permanent or intermittent) included loss of signal, crackling noises and similar, the most common cause of that with the transistors was leakage between the EBC lead outs on the actual base (bottom) of the transistor, tapping around would sometimes give the impression of dry joints on the transistors connection to the PCB, the joints would be re-soldered and all was well....for a bit, then the symptoms would return, this was because the heat from the soldering iron cured the problem with the transistor....but only for so long, to check if they were a problem then giving them a wiggle on top with a finger or whatever would make the symptoms worse or less, upon inspection we used to find an iridescent film on the base of the transistor between the lead outs, scrapping that away could offer a cure but in most cases I replaced the transistor(s) because I worked for Sony and spares/components were not a problem, another indication of those transistors giving those same problems was a black or dark oxide coating on the transistors lead outs.

Not saying your problem is transistors but if you get the above symptoms it's worth a check before doing any mass changes.

Good luck whicheverways

Lawrence.

NorfolkDaveUK · 1st Sep 2018, 3:33 pm

Cheers Lawrence , it was the first cap on the input . Not too sure why it would have failed but it went short . It was a brand new Panasonic so should have been all good . Maybe I shorted it when i put the boards back in or something . The transistors in this thing are hideous ..lol . I`m not going to mess with them for now unless I cant sort out the hiss , but the legs on these things are kinda like foil (little thicker but not much ) .

Sorry Ted just seen your post . Mr "fool" has been in here with his screw driver and turned every thing he could find to turn bud . Its a mess.

ms660 · 1st Sep 2018, 3:48 pm

Quote:

Originally Posted by NorfolkDaveUK

The transistors in this thing are hideous ..lol . I`m not going to mess with them for now unless I cant sort out the hiss , but the legs on these things are kinda like foil (little thicker but not much ) .

Those ones were the worst for the scenario I mentioned in my previous post, they were also fitted to other manufactures equipment including TV's etc, I used to enjoy doing the tape stuff when I worked for Sony....better than TV's

The key to it was that they had all the spares, manuals and test kit/tapes etc that was needed to do a proper service and performance check, most popular were the TC630 and the TC366 machines.

Lawrence.

Ted Kendall · 1st Sep 2018, 3:58 pm

Quote:

Originally Posted by NorfolkDaveUK

Mr "fool" has been in here with his screw driver and turned every thing he could find to turn bud . Its a mess .

Ah - the Phantom strikes again! Happens...

NorfolkDaveUK · 1st Sep 2018, 4:38 pm

Lawrence , I think you could be right about the transistors in this thing . the output on this is just awful at the min , quiet and hissy and crackly . Think I`ll juggle some either 107`s or 550`s into there ,the pinout is different but they should be ok when orientated right. The ones in there are some of the weirdest I`ve seen so far .

ms660 · 1st Sep 2018, 4:45 pm

What are the number types that were fitted as found?

Lawrence.

NorfolkDaveUK · 1st Sep 2018, 4:50 pm

2sc632/4. they are just low power general purpose NPN`s . The 107/550 will be fine as long as they go in the right way round . (one stop anti clockwise turn)

ms660 · 1st Sep 2018, 4:56 pm

Yes, 2SC632 was the original fit, flat lead out wires, a very common transistor in that kind of stuff back in the day. These machines should be easy to set up once any faulty bits have been seen to.

Lawrence

NorfolkDaveUK · 1st Sep 2018, 5:23 pm

transistors changed on the left amp . Signal on the left is now clean crisp and totally clear . Right is still ill . Transistors it was . They even look horrid dont they ..haha

NorfolkDaveUK · 1st Sep 2018, 6:58 pm

Right side done, both channels now sound great on playback. Going to calibrate the record in a second, see how it sounds.

NorfolkDaveUK · 1st Sep 2018, 10:18 pm

All done just need to clean a dirty record switch, clean and tighten the RCA's and we are golden. Thanks for your help as always .

1st Sep 2018, 1:09 pm	#1
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Sony TC-266 bias calibration I'm having real trouble here working out how to calibrate this. I have the scope connected to the line out . I have the player in rec on the left side. I'm adjusting L201 and nothing is happening . Attached Thumbnails Last edited by NorfolkDaveUK; 1st Sep 2018 at 1:22 pm.

1st Sep 2018, 2:14 pm	#2
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Sony T-266 bias calibration No left output ...lol . So somewhere between playing a tape , and taking it out of the case , something happened to the left output . Don`t you just love these oldies ..lol .

1st Sep 2018, 2:20 pm	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Sony T-266 bias calibration T-266 = TC-266? Lawrence. Last edited by ms660; 1st Sep 2018 at 2:28 pm.

1st Sep 2018, 2:57 pm	#4
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Sony T-266 bias calibration Yeah sorry typo and I couldn`t correct it . TC-266 . It was working "ok" the levels were all over the place . Right side record was full of hiss and way way over what the right side was , playback was very low . I re-capped it and it was ok but no change in the symptoms but now the left side has now decided to quit on me I`ve checked all the caps and they are all correct and orientated correctly on all 3 boards . I`ll put a signal in and try and trace it though .

1st Sep 2018, 3:17 pm	#5
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,675	Re: Sony T-266 bias calibration That inductor does not set the bias level. The adjustment is for the bias trap to keep bias out of the signal circuits. It shouldn't normally need adjusting unless there have been component changes around it. Last edited by Ted Kendall; 1st Sep 2018 at 3:35 pm.

1st Sep 2018, 3:18 pm	#6
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Sony T-266 bias calibration Do you have a schematic? Back in the day a long long time ago I used to service a lot of Sony tape recorders, one problem even back then was the small signal transistors breaking down, typical symptoms (permanent or intermittent) included loss of signal, crackling noises and similar, the most common cause of that with the transistors was leakage between the EBC lead outs on the actual base (bottom) of the transistor, tapping around would sometimes give the impression of dry joints on the transistors connection to the PCB, the joints would be re-soldered and all was well....for a bit, then the symptoms would return, this was because the heat from the soldering iron cured the problem with the transistor....but only for so long, to check if they were a problem then giving them a wiggle on top with a finger or whatever would make the symptoms worse or less, upon inspection we used to find an iridescent film on the base of the transistor between the lead outs, scrapping that away could offer a cure but in most cases I replaced the transistor(s) because I worked for Sony and spares/components were not a problem, another indication of those transistors giving those same problems was a black or dark oxide coating on the transistors lead outs. Not saying your problem is transistors but if you get the above symptoms it's worth a check before doing any mass changes. Good luck whicheverways Lawrence.

1st Sep 2018, 3:33 pm	#7
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Sony T-266 bias calibration Cheers Lawrence , it was the first cap on the input . Not too sure why it would have failed but it went short . It was a brand new Panasonic so should have been all good . Maybe I shorted it when i put the boards back in or something . The transistors in this thing are hideous ..lol . I`m not going to mess with them for now unless I cant sort out the hiss , but the legs on these things are kinda like foil (little thicker but not much ) . Sorry Ted just seen your post . Mr "fool" has been in here with his screw driver and turned every thing he could find to turn bud . Its a mess.

1st Sep 2018, 4:38 pm	#10
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Sony TC-266 bias calibration Lawrence , I think you could be right about the transistors in this thing . the output on this is just awful at the min , quiet and hissy and crackly . Think I`ll juggle some either 107`s or 550`s into there ,the pinout is different but they should be ok when orientated right. The ones in there are some of the weirdest I`ve seen so far .

1st Sep 2018, 4:45 pm	#11
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Sony TC-266 bias calibration What are the number types that were fitted as found? Lawrence.

1st Sep 2018, 4:50 pm	#12
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Sony TC-266 bias calibration 2sc632/4. they are just low power general purpose NPN`s . The 107/550 will be fine as long as they go in the right way round . (one stop anti clockwise turn)

1st Sep 2018, 4:56 pm	#13
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Sony TC-266 bias calibration Yes, 2SC632 was the original fit, flat lead out wires, a very common transistor in that kind of stuff back in the day. These machines should be easy to set up once any faulty bits have been seen to. Lawrence

1st Sep 2018, 5:23 pm	#14
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Sony TC-266 bias calibration transistors changed on the left amp . Signal on the left is now clean crisp and totally clear . Right is still ill . Transistors it was . They even look horrid dont they ..haha

1st Sep 2018, 6:58 pm	#15
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Sony TC-266 bias calibration Right side done, both channels now sound great on playback. Going to calibrate the record in a second, see how it sounds.

1st Sep 2018, 10:18 pm	#16
NorfolkDaveUK Banned Join Date: May 2018 Location: Norwich, Norfolk, UK. Posts: 605	Re: Sony TC-266 bias calibration All done just need to clean a dirty record switch, clean and tighten the RCA's and we are golden. Thanks for your help as always .