BETA HiFi - missing chroma

[Douglas Reedy]

So thanks to some of you here I recently got my Toshiba V-S443 BETA Hi-Fi
deck working again after replacing the capstan belt and getting the drum
servo spinning after a decade of sitting in one position. At that time I had
it connected to a TV and was getting decent color video. However I was more
interested in getting some old BETA HiFi recordings captured from tape to my
computer, so I disconnected from the TV and moved over to a computer to work
with the audio.

While working with the HiFi audio I experienced frequent audio problems with
playback of these old tapes (Sony, BASF and Kodak). The audio starts out
clean and clear, then after upwards of a minute I get a few seconds of
horrible clicks and distorted audio, like something is losing synch. After a
few seconds of this normal playback resumes for a while before the next
audio anomaly. The anomalies don't appear to be at regular intervals and
some tapes (ie Kodak) are better than others (ie BASF). Also they don't
always seems to happen in the exact same place upon replay, sometimes they
are and sometimes they aren't.

To try and rule out the old (possibly worn) tape factor, I recorded some
test patterns on a newer Kodak tape. The patterns were 220, 440, and 880Hz
tones, and sine-wave sweeps from 20Hz to 22Khz over 40 seconds. Upon
playback the tones were clean and clear, and the sweep was alright under
5KHz. From ~5 to ~15KHz there are severe clicks, but nothing that sounds
like loss of synch. I tried cleaning the heads with a chamois and isoproyl
alcohol (turning the servo - no up or down motion) but that did not seem to
help at all. These clicks are also triggered when playing back HiFi with
certain transients (like "S" or "T" vocals, cymbal crashes, etc).

So I did the best I could do with the audio, but not really happy with the
resulting CD. Now I've reconnected the BETA to a TV and there is no chroma,
just luma. I had good color when I first got the drum servo spinning but
somewhere along the way I've lost it. Is this a head problem or is it more
likely an electronics issue? Are the bad HiFi and the chroma loss related?
Should I just give up on this unit and have it professionally serviced, or
just throw it away? I really don't think I can justify repair costs since I
don't have much beyond the HiFi worth salvaging.

Douglas

 

[JURB6006]

Were these old tapes recorded in audio only mode ? If so and you are playing
them on a different machine, it might not be able to handle the lack of
vertical sync. I know that my Sony SL-HFR 60 / HFP 100 supresses all modulation
of the video carrier in this mode. With no video, of course the unit switches
to monochrome mode, which ups the vertical frequency from 59.97 Hz to near 60
Hz.

However, if the deck servo locks on a color recorded tape, the only way for
your tweaking of the servo circuit to affect color is if the time base errors
are so great (likely on old tapes) that there is simply not enough burst to
turn on the chroma decoder. Burst is <u>not</u> detected through the Y signal,
but sync for the BGP is, so timing is the issue when the color scrambles or
drops when the video is poor.

While the horizontal AFC in the set you are viewing the tape on might follow
the distorted sync, the chroma decoder in the Beta might not. Beta uses a more
complex scheme for coding the chroma.

Applying only to older sets, there is an off chance that the reference
frequency is off on the VCR, in the opposite direction of the set to which it
is connected. Newer sets usually use a sweeper circuit which adjusts the
APC/AFC for the color oscillator every time you change sources.

One question, will the color video signal which you see in monochrome record in
color on another VCR ? Could be an important piece of information.

JURB

 

[the terminator]

In article &lt;GL5zb.1727$tu1.329@fe3.columbus.rr.com&gt;,
"Douglas Reedy" &lt;plook@despammed.com&gt; wrote:

So thanks to some of you here I recently got my Toshiba V-S443 BETA Hi-Fi
deck working again after replacing the capstan belt and getting the drum
servo spinning after a decade of sitting in one position. At that time I had
it connected to a TV and was getting decent color video. However I was more
interested in getting some old BETA HiFi recordings captured from tape to my
computer, so I disconnected from the TV and moved over to a computer to work
with the audio.

While working with the HiFi audio I experienced frequent audio problems with
playback of these old tapes (Sony, BASF and Kodak). The audio starts out
clean and clear, then after upwards of a minute I get a few seconds of
horrible clicks and distorted audio, like something is losing synch. After a
few seconds of this normal playback resumes for a while before the next
audio anomaly. The anomalies don't appear to be at regular intervals and
some tapes (ie Kodak) are better than others (ie BASF). Also they don't
always seems to happen in the exact same place upon replay, sometimes they
are and sometimes they aren't.

To try and rule out the old (possibly worn) tape factor, I recorded some
test patterns on a newer Kodak tape. The patterns were 220, 440, and 880Hz
tones, and sine-wave sweeps from 20Hz to 22Khz over 40 seconds. Upon
playback the tones were clean and clear, and the sweep was alright under
5KHz. From ~5 to ~15KHz there are severe clicks, but nothing that sounds
like loss of synch. I tried cleaning the heads with a chamois and isoproyl
alcohol (turning the servo - no up or down motion) but that did not seem to
help at all. These clicks are also triggered when playing back HiFi with
certain transients (like "S" or "T" vocals, cymbal crashes, etc).

So I did the best I could do with the audio, but not really happy with the
resulting CD. Now I've reconnected the BETA to a TV and there is no chroma,
just luma. I had good color when I first got the drum servo spinning but
somewhere along the way I've lost it. Is this a head problem or is it more
likely an electronics issue? Are the bad HiFi and the chroma loss related?
Should I just give up on this unit and have it professionally serviced, or
just throw it away? I really don't think I can justify repair costs since I
don't have much beyond the HiFi worth salvaging.

I did see something like this on an old Sanyo. Suddenly the colour
signal would disappear. Moving the upper PCB or pressing on it brought
it back.

My theory was that since the unit sat on a cheap TV stand, and the shelf
had sagged, gravity had distorted the chassis due to a lack of support
in the middle of the unit. In turn this had caused a stress problem on
the pcbs.

For your HIFI problem, it could be overloading caused by worn heads.
There is a slight buzz in the audio caused by carrier switching, and
this may be amplified now. Or the noise reduction cct that handles that
isn't working as well anymore.