A problem with a cd player

[Arfa Daily]

FEOF should be the one, but a 1 meg scope won't really get it. You can
adjust for maximum envelope size, which probably is good enough, but you
can't look at the diamond shaped center area of the expanded "eye" pattern
as viewed on a 30mHz or higher scope. Sometimes a x10 probe is required,
but in my experience it is rare for a direct probe to load down this
measurement.

You can "Google CD eye pattern" and see what I'm talking about.

Mark Z.

All that Mark says, but before you start, CAREFULLY mark the EXACT positions
of the pots before attempting adjustment. If you do adjust more than one of
them (the temptation *will* be there - trust me !!) and you do not have the
proper bandwidth 'scope, and the experience to know exactly what you are
adjusting and why, it is staggeringly easy to get those pots to a point
where nothing will be read at all, often with just a few degrees
mispositioning of a couple of them. Re-finding the correct places to get it
going again, can then be a most frustrating excercise ...

Arfa

 

[krw]

Big time for sure. Thirty years ago, I thought I was immortal, and could
keep going for two or more days at a time without sleep. I just couldn't
figure how people could degenerate into the old farts that they did. Now I
am one, and I look at my daughter looking at me thinking "I just can't
figure ... "

You're still young. Don't worry, as your daughter gets older,
you'll get wiser. ;-)

 

[Gaetan Mailloux]

FEOF should be the one, but a 1 meg scope won't really get it. You can
adjust for maximum envelope size, which probably is good enough, but you
can't look at the diamond shaped center area of the expanded "eye" pattern
as viewed on a 30mHz or higher scope. Sometimes a x10 probe is required, but
in my experience it is rare for a direct probe to load down this
measurement.

You can "Google CD eye pattern" and see what I'm talking about.

Mark Z.

Hello

I will borrow a Sencore SC61 scope to a friend who do not use it, maby I
will buy it anyway since it is doing nothing in his basement.

Btw, what would be T.BAL , F.BAL, TEOF ?


Thank for your help

Bye

Gaetan

 

[Arfa Daily]

Hello

I will borrow a Sencore SC61 scope to a friend who do not use it, maby I
will buy it anyway since it is doing nothing in his basement.

Btw, what would be T.BAL , F.BAL, TEOF ?


Thank for your help

Bye

Gaetan

T.B(AL) is tracking balance. Sometimes also known as E-F BAL (named for the
designations of the two photodiodes, "E" and "F" in the pickup, which are
responsible for generating the tracking control signal). It is required in
order to remove unwanted positional offsets of the lens which would
otherwise be caused by imbalances in the tracking servo photodiodes in the
pickup, and the following opamp in the tracking servo processor.

F.B(AL) is focus balance. Does the same for the focus servo circuitry as
TBAL does for the tracking.

TE(OF) is tracking error offset. Allows the electrical zero point of the
tracking servo to be set to match the lens suspension mechanical zero. It is
needed to offset mechanical errors in the construction of the laser, and
electrical servo errors which may creep in as a result of imperfect opamps
etc in the servo amplifier.

FE(OF) would be the same thing for the focus servo, and is needed to correct
for such things as an error in the turntable height, and similar servo
electrical errors.

You may find a pot called PLL on some players. The setting of this is
*extremely* critical to data recovery from the disc, and requires an
accurate frequency counter to set it up. NEVER adjust this pot randomly,
even if you think that you have marked its original position perfectly.

It is rare to find any of these adjustments present, in modern players. The
servo processor ICs are these days capable of performing an analysis of the
signal, and introducing and storing appropriate correctional offsets.

Other pots which may also be encountered are T.G(AIN) and F.G(AIN). These
set the operational gains of the tracking and focus servo loops. They are
often to still be found in modern players. Adjusting these up slightly, can
often improve a player with marginal performance, but if set too high,
particularly in the case of the focus servo, will result in the lens making
a mechanical 'hissing' noise, particularly on a marked or scuffed disc.

Finally, there is always a pot on the laser which sets its output power.
With a few notable exceptions such as Pioneer, this pot is sealed and MUST
NOT be adjusted. Even a small overdrive of the laser diode, can result in
its partial, or even complete destruction.

Arfa

 

[Arfa Daily]

You're still young. Don't worry, as your daughter gets older,
you'll get wiser. ;-)

Depends how you define "young", I guess. I've not yet reached decrepit, but
certainly old enough to be waking up in the night for a bathroom stop, and
waking up in the morning feeling worse than I did when I went to bed ...
d;~}

Arfa

 

[Arfa Daily]

Even a grunt would be nice.

Go to Waitrose, Dave. The staff in there are everything that you would ever
want them to be, and then some ... I actually don't mind being called
"sir". It shows that if nothing else, my age has won me at least a modicum
of respect from the next generation down !

Arfa

 

[Arfa Daily]

Sir Arfa Daily.

Has a good ring to it ;-)

If you're familiar with the TV series from the eighties which spawned it,
even more so !! Interestingly, a 'brought up to date' remake of it starts
on British TV this Wednesday evening. Big boots to fill for all concerned,
but in the write-ups, the cast say that they are very clear about that, so
we'll givit a go ...

Arfa

 

[krw]

Depends how you define "young", I guess.

If your daughter still thinks you're dumb, you're not old. As you
(she) ages, amazingly, you'll get a lot smarter.

I've not yet reached decrepit, but
certainly old enough to be waking up in the night for a bathroom stop, and

As long as you're still waking up...

waking up in the morning feeling worse than I did when I went to bed ...
d;~}

I grew out of that a while back, except when the RA is doing its
thing. Then mornings are a pain everywhere (but my butt).

 

[krw]

If no one picked nits, we'd be buried in the lousy things!

And there is nothing lousier than nits.