pmbs@nvuxh.UUCP (P.BILODEAU) (01/10/86)
I have a Pioneer CTF900 Cassette Player that has developed an annoying click in the output to my amplifier. It doesn't matter whether the tape has anything recorded on it or not, so I am tending to shy away from the record portion of the circuitry. The beast is so complex that before I go too far and wished I hadn't, I thought that I would poll the net to see if anyone has had a static click appear on their machine, and if they found or knew the fix. (The click seems to be at random intervals and affects both channels). Thanks for your help and if I stumble across the solution I will query the net to see if anyone else needs it. Paul Bilodeau Bell Communications Research NVC-2X229 331 Newman Springs Road Red Bank, NJ 07701 201-758-5397
IAIPS-ACIPS@USC-ISI.ARPA (01/15/86)
Paul --
It's kinda hard to diagnose something without an opportunity
to deal with it "hands-on" - but, in addition, more information
on symptoms would be needed before even trying to suggest something.
Perhaps the several clarification questions may help point you to
a smaller area. Knowing the answers to the questions may not provide
any additonal help to distant-diagnosers, but here goes:
a. You say the click is random, and on both channels;
but is it simultaneously heard on both channels when
occuring? This may help determine whether it is an
externally radiated source or a common internal problem,
like a power supply which would affect both audio channels
at the same time - or some other problem (mechanical or
whatever) which may affect each channel in a different
random way.
b. I assume, from the wording of your message, that it only
occurs on playback - but, does it happen only when the
tape is in motion - or does the clicking occur when the
amplifier is in a quiescent state with no input signal
from the playback head? This may differentiate between
a mechanical/electronic tape mechanism problem, and a pure
amplifier problem. Try grounding the playback head/input
to the playback amp to see if the problem is definitely
being induced/caused in the playback amp itself.
c. Is the clicking at the tape amp output terminals a function
of playback volume; indicating a problem before or after
the gain pot.
d. Does the recorder use a common amplifier for both record
and playback. Have you definitely ruled out the record
amplifier; i.e., does it click on cassettes recorded on
other machines.
e. Is the noise a definite sharp click which may indicate
mechanical sources; or is it a softer "pop" with a
rise/decay which may imply an electronic problem (faulty
capacitor), or have a scratchy noise which may imply
friction or static discharges?
f. Are you sure it's coming from the tape output, and
not being introduced at the amplifier's input?. Have
you tried disconnecting any inputs to the recorder
so as to break any potential noise loop conditions?
g. Does the noise also appear at the headphone output (if
there is one?
h. On an outside chance, have you cleaned the heads and
demagnetized lately. Cassette heads are notorious
"oxide scrapers". I have a TASCAM 122 which is supposed "oxide scrapers". I have a TASCAM 122 which is supposed
to be a good semi-pro machine, and the manual recommends
cleaning after every day's use or every few hours.
And I can attest to that after losing the high end during
mastering session three hours into the day.
i. Did you try moving the set to another part of the house;
or a different location (i.e. different ac power source).
Does your unit need to be grounded? Is it part of a
more extensively wired system. Assuming it was OK before,
what changes were made to the system recently, or other
areas of the house (furnace? new refrigerator etc?)
Now, I'm starting to grab at straws. But I'd isolate the unit from
whatever system it's connected to; determine whether the source
is before or after the gain control; whether its a function of
tape motion - and go from there.
Please keep us advised on what you found out.
73,
George, W1TQS/4jhs@mitre-bedford.ARPA (01/16/86)
I seem to recall periodic zaps due to static buildup on the tape on one of my tape decks. Cleaning the heads and guides might help. Increasing the humidity in the room is another possibility. Dunno what else it might be unless a nearby radar is sweeping past you very rapidly! Good luck! -John S., W3IKG