Teac cassette > Distorted audio?

[Tedd Doda]

Hi People:

I just got in a Teac model W-450R cassette deck with a
distorted output problem. The right channel is almost
non-exsistant (and distorted), and the left channel is
about the right level and very distorted. There is a
4066 swwitching chip just before the Sony dolby chip
(cx20187), and the input and output are fine. On the 'scope,
the signal seems to be missing the bottom part (like a
half-wave rectified ac signal).

One wierd thing about this chassis, is that it has 2 (two)
7812 regulators? I would expect a 7812 and a 7912 (+/-).

Does anyone have the pinouts of the cx20187? I checked the
Sony site, but the chip is discontinued :(

Thanks for any and all help....(and I thought audio
problems were easy!).

Tedd Doda, CET

packet va3sed@va3sed ******* Running FBB under Warp Ver4
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[Raymond Carlsen]

> I just got in a Teac model W-450R cassette deck with a distorted output
> problem. The right channel is almost non-exsistant (and distorted), and
> the left channel is about the right level and very distorted. There is a
> 4066 swwitching chip just before the Sony dolby chip (cx20187), and the
> input and output are fine. On the 'scope, the signal seems to be missing

> the bottom part (like a half-wave rectified ac signal). Does anyone have

> the pinouts of the cx20187? I checked the Sony site, but the chip is
> discontinued :(

Tedd,
I went 'round and 'round on that model. I ordered (from Teac... nice
folks) and installed the Sony Dolby chip... didn't fix it (still have it
here somewhere). Changed the 4066. Nope. Look for leaky or shorted bypass
caps (more than one), about 100uF at 25 volts, if I remember correctly,
close to and on both sides of that chip. Bet that's your problem. Kind of
an unusual failure... caps open up, but leaky or shorted is actually rather
rare in my experience.. The failing caps load down the lines of the chip and
produce the wierd symptoms.

Ray Carlsen
CARLSEN ELECTRONICS... a leader in trailing-edge technology.

[SargW1]

> I just got in a Teac model W-450R cassette deck with a distorted output
>> problem. The right channe

Does this model have a multi terminal slide switch, for the record play
function, or is it all switched electronically. I once had a similiar problem,
thought it was the dolby chip etc, and turned out to be a very dirty record
play switch. pete
Pete Sargent

[Bill Samuel]

SargW1 <sar...@aol.com> wrote in article
<19981208235019...@ng156.aol.com>...

Common problem on a lot of older tape decks. <G>

Those switches helped pay for my pickup. <G>

Bill