Sony TC-6251 - Japan only model - problem - UK Vintage Radio Repair and Restoration Discussion Forum

Phantomrose1999 · 26th Jan 2019, 5:10 pm

Hi All,

I got hold of an immaculate Sony TC-6251, which is in a beautiful wooden case that is cover in something, and has metal corner covers and great clips to hold it closed. Got it rather cheap..

Tried it out, and the inside is immaculate, the rubbers are perfect and the belt is PERFECT ! its quite amazing that its mechanically perfect..

That was the good, i tried to play a tape and when play is engaged, both the VU meters just hit the max end of the scale very hard and stay there.

Looks like something is perhaps osciallating, but both channels do this. I did clean the main speed selector switch and the play switch which was black with corrosion.

I cant find a schematic or any info on it, seem to be a japan only model.

Any transistor experts here, to suggest where i could start to look ?

paulsherwin · 26th Jan 2019, 5:54 pm

Clean the switchgear very thoroughly. This sort of instability is usually caused by oxidised record/play switch contacts.

ms660 · 26th Jan 2019, 6:33 pm

The front looks very similar to the Sony TC-252d, the schematic for that one can be found on the vintageshifi site.

Lawrence.

Phantomrose1999 · 27th Jan 2019, 1:29 pm

Quote:

Originally Posted by paulsherwin

Clean the switchgear very thoroughly. This sort of instability is usually caused by oxidised record/play switch contacts.

Thanks for the response. I noted the rotary switches i cleaned were black and i only had sandpaper to clean it with. You could be right, and i will have to buy some contact cleaning spray to get inside the Rec/play switch, not easy to get to.

Quote:

Originally Posted by ms660

The front looks very similar to the Sony TC-252d, the schematic for that one can be found on the vintageshifi site.

Thanks Lawrence, will chase up a schematic for this model. Never seen one in a rugged case like this before, quite interesting.

Maarten · 27th Jan 2019, 11:13 pm

Both sandpaper and a random kind of contact cleaner will, respectively could, work out very badly!

Sandpaper will leave a large surface area for oxidising quickly and toroughly. Contact cleaner comes in acidic and non-acidic kinds. Acidic is only to be used for heavy layers of oxide and should be cleaned off afterwards. Using products from Kontakt, they recommend using 60 (acidic, only for heavy pollution), then WL (cleaner, you could also use isopropanol) and finally 61 (lubricant). There's also other types and brands of non-acidic contact sprays.

Also, those sprays should be applied using a piece of paper or something, not by spraying into the switch.

26th Jan 2019, 5:10 pm	#1
Phantomrose1999 Hexode Join Date: Mar 2008 Location: Melbourne, Victoria, Australia Posts: 289	Sony TC-6251 - Japan only model - problem Hi All, I got hold of an immaculate Sony TC-6251, which is in a beautiful wooden case that is cover in something, and has metal corner covers and great clips to hold it closed. Got it rather cheap.. Tried it out, and the inside is immaculate, the rubbers are perfect and the belt is PERFECT ! its quite amazing that its mechanically perfect.. That was the good, i tried to play a tape and when play is engaged, both the VU meters just hit the max end of the scale very hard and stay there. Looks like something is perhaps osciallating, but both channels do this. I did clean the main speed selector switch and the play switch which was black with corrosion. I cant find a schematic or any info on it, seem to be a japan only model. Any transistor experts here, to suggest where i could start to look ? Attached Thumbnails

26th Jan 2019, 5:54 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,943	Re: Sony TC-6251 - Japan only model - problem Clean the switchgear very thoroughly. This sort of instability is usually caused by oxidised record/play switch contacts.

26th Jan 2019, 6:33 pm	#3
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Sony TC-6251 - Japan only model - problem The front looks very similar to the Sony TC-252d, the schematic for that one can be found on the vintageshifi site. Lawrence.

27th Jan 2019, 11:13 pm	#5
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,199	Re: Sony TC-6251 - Japan only model - problem Both sandpaper and a random kind of contact cleaner will, respectively could, work out very badly! Sandpaper will leave a large surface area for oxidising quickly and toroughly. Contact cleaner comes in acidic and non-acidic kinds. Acidic is only to be used for heavy layers of oxide and should be cleaned off afterwards. Using products from Kontakt, they recommend using 60 (acidic, only for heavy pollution), then WL (cleaner, you could also use isopropanol) and finally 61 (lubricant). There's also other types and brands of non-acidic contact sprays. Also, those sprays should be applied using a piece of paper or something, not by spraying into the switch. Last edited by Maarten; 27th Jan 2019 at 11:23 pm.