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My poor Technics RS-TR474 cassette deck needs a new IC


hardnrg
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I got hold of the updated service manual for my Technics RS-TR474 cassette deck, and with the aid of my DMM and 10MHz digital scope, followed the troubleshooting guide and narrowed the problem down to a single IC.

 

The mechanism works fine, as does the display, except the level meters are fixed at 0dB on playback, regardless of an audio signal being present on the tape or its amplitude.

 

There is no audio output from the line output, nor from the headphone output at the front. The IC in question, Panasonic AN7356SC-E2, is the playback/recording amp, so it makes sense that if it failed, there would be no sound, and the levels would be reported wrong.

 

Arg, anyway, I search for ages for this IC, and most of the places that I found it had a minimum order from anywhere around $75 up to like $500 or something crazy. I'm not even sure if this chip is available still (the cassette deck is almost 10 years old now), but I emailed a few places that seemed to offer it for ~$21.

 

I'd like to repair it because it isn't completely dead, and I'm fairly certain it is just this one IC that is stopping it from working. It's a shame as I paid

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Can you check your part number again? I can't seem to find any existance of a chip by that number at all. Even google chokes on that number.

 

I've got a few sources that generally let you order just one of something, but none of them have what you've got listed right now.

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Sorry, I can't help ya...too old for my sources...

 

About all I can suggest is contacting Panasonic, buying another dead deck for parts, or trying one of those shady-looking obsolete parts suppliers a google search turns up.

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Relunctantly, I disassembled one of the circuit boards from the right-hand deck mechanism (dual deck machine) and found an open-circuit on one of the resistors! :) it looks kinda toasted, and the capacitor near it looks like it might have blew (the plastic is kinda raised on one side at the top, even though the metal body seems intact)

 

I can get resistors and caps at work for pennies, so with some luck, this'll solve it! :D

 

I'm at work later today, so hopefully my $300 tape deck can be fixed for about $0.40 hehe

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managed to fix it... the faulty resistor was all that was stopping the whole audio output section from working lol

 

still analogue, still lovin it :D

 

*seriously* enjoying the sound of some tapes from circa 1994...

 

OOOH! analogue overdrive saturation!!! *has an eargasm*

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OOOH! analogue overdrive saturation!!! *has an eargasm*
Word... Old school ftw!

 

:lol: Speaking of nostalgia, I found a 5 1/4 inch floppy today :lol:
:D I've still got a bunch of old 5'1/4's somewhere along with a couple drives I think... :ph34r:

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