hello, i found a Technics RS-616 cassette deck but it has a problem. On the right channel there is a high pitched tone. It is present at the output of the RCA plugs and i can see it on the vu meter. Even when there is no tape in there its still present. Does anyone have a idea at what may cause this? Mb someone has a schematic of this unit? Thanks in advance.

-Andrei

 

Hi Andrei;

I spend around 10 years collecting, buying, selling and repairing vintage audio hi-fi equipment. Mostly from the 70s as this was a peak of it's consumer interest (pre PC and other digital consumer products). There was lots of competition between manufactures in all price ranges and some great quality products were designed and made in that era.

Anyway the most common problem with symptoms you describe is dirty switch contacts. On a cassette deck there is usually a large multi-pole switch usually mounted on the main circuit board. It's used to switch signals from playback to record mode and can cause oscillation and noise if some of the switch contacts are dirty. The solution is usually a good cleaning with a good contact cleaner and working the switch contacts. I've saved several cassette decks with just a good cleaning of all the switch and variable pots, nothing else required. Not sure it will solve your problem but it's something pretty easy to do yourself without a large expense. True troubleshooting generally requires a O-scope, schematic and experiance in signal tracing for problem isolation, but give it a good cleaning first and see if that helps or not.

Good luck
Lefty

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Measurement changes behavior

 

hello Lefty, thank you for ur info i will clean all switches and pots. also another thing i just noticed. this deck has a eq switch for Chrome, Ferro-Chrome and Normal tapes. On the Normal tap position its just simple high frequency tone but on the other two position the tone becomes like pulsed. like its gated.

-Andrei

 

I cleaned the switch and the tone is gone. Thank you so much Lefty!!! I can enjoy this good deck again. I really like this unit. Its not as good sounding as a nakamichi but still. Thanks again and mb we can talk more about vintage audio. Im a collector too and also repaired and reconditioned some. Just didnt met this behaviour again.

-Andrei

 

Good deal, glad I could help. The best vintage audio forum I've come across is audiokarma at:

http://www.audiokarma.org/forums/index.php

You can find a ton of help and information and it's a pretty friendly place. It started with a few dozens of us and now numbers in the tens of thousand members. Vintage hi-fi can be a very great hobby.

Lefty

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Measurement changes behavior

 

Just got to say, this is (or was) an EXTREMELY common problem - it's because the bottom of the head is switched between record and play - dirty contacts mean the output of the amplifier is connected back to the input, causing it to oscillate.

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PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Glad you told me; I was dreading going through my player with a scope for my oscillation problem.
Plus, I lost the schematic!