Hoping someone can identify a problem with my Sony CF-570L - UK Vintage Radio Repair and Restoration Discussion Forum

LunarJetman · 21st Jul 2018, 4:14 pm

Hi All,

Long time lurker, first time poster - hoping someone can help me solve a problem I've just caused myself

I wanted to use my beloved 1974 Sony CF-570L Radio Cassette as an external speaker for my PC. The Sony has a 'DIN' output switch as well as Cassette & Radio. I presumed this was utlised with the DIN port on the back marked REC/PB so I purchased a 5 pin DIN>RCA adaptor from Amazon. When I plugged it in there was a bit of hum and feedback for a few seconds, and the left channel was working. Turns out the DIN plug is for line in AND out and therefore i I think I have blown something - now, when I switch to Cassette or DIN on the function switch, the tuning strength meter goes up to 7 (normally it would not be displaying anything in these modes) and I get hiss through the speakers, with a bit of output displayed on the VU meters. I seem to have damaged something by sending an audio signal into a port that was designed for output.

Would anyone know what I might have damaged on the board please? I love this deck, it's immaculate, and was, before my stupidity, functioning perfectly.

Any help or advice would be GREATLY appreciated!

Best Wishes.

LunarJetman · 21st Jul 2018, 5:13 pm

Forgot to say in my post above - the cassette still outputs sound from tapes, it's just there is hiss in the background all of the time now - and I have a tuning strength meter indicating something when playing cassettes - it should be on zero. The radio still plays fine and the tuning meter functions as it should when this mode is selected.

Very odd.

Thanks in advance for any advice.

camtechman · 21st Jul 2018, 10:04 pm

Is the 5 pin DIN>RCA adaptor still in place? And does the problem stop when it's removed?

LunarJetman · 21st Jul 2018, 10:33 pm

Thanks for replying.

The problem remains even upon removal of the cable.

However, I think I may have identified the cause. I have liberally added DeOxIt to the selector switch, tuner band switch and to the REC/PB port itself and things seem better. Embarrassingly, it seems the Tuning meter may have always had that behaviour - it doubles up as a battery gauge, and looking at YouTube videos, it also operates when on mains power - guess I stupidly never noticed.

So... maybe I haven't blown anything up - it could just be that the internals are so gummed up (it's not often been switched from FM radio, and has been stored for many years), that all it needed was a clean. I will try it again tomorrow and see how things look.

Thanks for your help!

Best, LJ

Restoration73 · 22nd Jul 2018, 2:49 am

This is an alternative method of feeding in an external audio signal;
https://www.halfords.com/technology/...ssette-adapter

21st Jul 2018, 4:14 pm	#1
LunarJetman Retired Dormant Member Join Date: Jul 2018 Location: Coventry, West Midlands, UK. Posts: 5	Hoping someone can identify a problem with my Sony CF-570L Hi All, Long time lurker, first time poster - hoping someone can help me solve a problem I've just caused myself I wanted to use my beloved 1974 Sony CF-570L Radio Cassette as an external speaker for my PC. The Sony has a 'DIN' output switch as well as Cassette & Radio. I presumed this was utlised with the DIN port on the back marked REC/PB so I purchased a 5 pin DIN>RCA adaptor from Amazon. When I plugged it in there was a bit of hum and feedback for a few seconds, and the left channel was working. Turns out the DIN plug is for line in AND out and therefore i I think I have blown something - now, when I switch to Cassette or DIN on the function switch, the tuning strength meter goes up to 7 (normally it would not be displaying anything in these modes) and I get hiss through the speakers, with a bit of output displayed on the VU meters. I seem to have damaged something by sending an audio signal into a port that was designed for output. Would anyone know what I might have damaged on the board please? I love this deck, it's immaculate, and was, before my stupidity, functioning perfectly. Any help or advice would be GREATLY appreciated! Best Wishes.

21st Jul 2018, 5:13 pm	#2
LunarJetman Retired Dormant Member Join Date: Jul 2018 Location: Coventry, West Midlands, UK. Posts: 5	Re: Hoping someone can identify a problem with my Sony CF-570L Forgot to say in my post above - the cassette still outputs sound from tapes, it's just there is hiss in the background all of the time now - and I have a tuning strength meter indicating something when playing cassettes - it should be on zero. The radio still plays fine and the tuning meter functions as it should when this mode is selected. Very odd. Thanks in advance for any advice.

21st Jul 2018, 10:04 pm	#3
camtechman Nonode Join Date: Jan 2008 Location: Milton Keynes, Bucks. UK. Posts: 2,552	Re: Hoping someone can identify a problem with my Sony CF-570L Is the 5 pin DIN>RCA adaptor still in place? And does the problem stop when it's removed? __________________ When I die, please don't let my Wife sell my collection for the amount I told her I paid for it!

21st Jul 2018, 10:33 pm	#4
LunarJetman Retired Dormant Member Join Date: Jul 2018 Location: Coventry, West Midlands, UK. Posts: 5	Re: Hoping someone can identify a problem with my Sony CF-570L Thanks for replying. The problem remains even upon removal of the cable. However, I think I may have identified the cause. I have liberally added DeOxIt to the selector switch, tuner band switch and to the REC/PB port itself and things seem better. Embarrassingly, it seems the Tuning meter may have always had that behaviour - it doubles up as a battery gauge, and looking at YouTube videos, it also operates when on mains power - guess I stupidly never noticed. So... maybe I haven't blown anything up - it could just be that the internals are so gummed up (it's not often been switched from FM radio, and has been stored for many years), that all it needed was a clean. I will try it again tomorrow and see how things look. Thanks for your help! Best, LJ

22nd Jul 2018, 2:49 am	#5
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: Hoping someone can identify a problem with my Sony CF-570L This is an alternative method of feeding in an external audio signal; https://www.halfords.com/technology/...ssette-adapter