Correct laser diode current for Onkyo DX-6550?

[Zeljko]

Please,

If anybody has service manual somewhere in sight - which is the correct
laser diode current (or voltage drop at two 33ohm in parallel - R102/R103)?
Now I have 0.92V which is 55mA.

Zeljko

 

[Sam Goldwasser]

Please,

If anybody has service manual somewhere in sight - which is the correct
laser diode current (or voltage drop at two 33ohm in parallel - R102/R103)?
Now I have 0.92V which is 55mA.

I don't have the manual but the laser diodes in CD players are run
in constant optical power mode which means the current is not a
fixed value. There should be either a value for the optical power
out of the objective lens or a sense voltage based on the monitor
photodiode current.

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[LASERandDVDfan]

Please,

If anybody has service manual somewhere in sight - which is the correct
laser diode current (or voltage drop at two 33ohm in parallel - R102/R103)?
Now I have 0.92V which is 55mA.

The best way to measure laser power for optimal performance is through the use
of a laser power meter, which is an instrument that measures the actual laser
light output. You will also need the service literature to determine what the
optimal laser power reading must be.

If you are not sure at all, replace the pickup. Onkyo usually uses Sony
pickups (but there are possible exceptions), so replacements should already be
optimally calibrated from the factory. - Reinhart

 

[Zeljko]

The best way to measure laser power for optimal performance is through the use
of a laser power meter, which is an instrument that measures the actual laser
light output. You will also need the service literature to determine what the
optimal laser power reading must be.

If you are not sure at all, replace the pickup. Onkyo usually uses Sony
pickups (but there are possible exceptions), so replacements should already be
optimally calibrated from the factory. - Reinhart

Thanks...for some CDP I've worked before they stated laser current as
adjustment point (measured through voltage drop on emitter resistors. And on
one model (don't remember which) service manual says - adjust potmeter on
pickup PCB until You get 1Vpp eyepattern on RF point. Of course - power
meter is best, but current is measure of condition of pickup.
And this is beautiful piece of old audiophile player (Integra R1) with
pickup (like KSS110C, but it's not) mounted on linear motor (1 magnet / 1
coil system for rough tracking loop) - no sled motor. It's not possible to
find new pickup anymore. I searched all over the net (and not just me).
Onkyo service in Zagreb doesn't support this anymore. I got it bad - barely
reading only few originals. Many people played with laser power and plastic
cross on potmeter is damaged because of many revolutions. But they didn't
cleaned inside of pick-up. There are upper plastic and lower metal cover
which can be easily removed. Complete upper part with F/T coils can be
unscrewed and carefully put aside. No position adjustment except little play
in holes... Used dry cotton for inside optics. After that it works
perfectly - reading CD-R with no problem. If stressed on last track (...put
my finger on CD in rotation...) it finds position very quick and resumes
playing. It's nice that nobody played with adjustments pots on PCB!
Before all of that I worked-out spindle motor with +- higher voltage,
cleaned and lubricate again motors and shafts, but this didn't bring larger
improvement.
And this player almost gone to scrap. That's why I suspect that current is
maybe too high - reading too good!

 

[Mark D. Zacharias]

Does this correspond to any U.S. model number? Our servicer website doesn't
list this model.

Mark Z.

 

[Zeljko]

Does this correspond to any U.S. model number? Our servicer website doesn't
list this model.

Mark Z.

U.S. model number?
You can find it generally searching via google (search groups!).

According to discussion on this group on 24.9.2001, I found that DX-5700 is
similar to DX-6550.
Search by keywords "Onkyo Integra 5700 CD"

 

[Leonard Caillouet]

U.S. model number?
You can find it generally searching via google (search groups!).

According to discussion on this group on 24.9.2001, I found that DX-5700 is
similar to DX-6550.
Search by keywords "Onkyo Integra 5700 CD"

Yeah, gosh Mark, why can't you just do all of the research for people that
you are trying to help for free.

Leonard

 

[Mark D. Zacharias]

Hey, Len.

I was able to send the guy a service manual. Doesn't show the adjustment he
was asking for though, at least not on a quick look.

mz

 

[Zeljko]

Hey...

Thanks for DX-5700 manual. Optical and servo section looks same...even PCB
layout of servo section and adjustments pots are same.
DX-6550 has different D/A and different main clock oscillator + optical out.

I see now - it has no current specified! There is no adjustments of laser
power either. Pickup is preadjusted.
Just the RF point waveform which amplitude is not visible...but OK. It is
always around 1Vpp.
It helped me a lot in understanding of these circuit. I lowered the current
to 48 mA.

I think I read somewhere "Don't fix if ain't broken..".
And now it's not broken.

Zeljko

 

[Mark D. Zacharias]

Glad that worked out for you.

mz

 

[LASERandDVDfan]

Thanks for DX-5700 manual. Optical and servo section looks same...even PCB
layout of servo section and adjustments pots are same.
DX-6550 has different D/A and different main clock oscillator + optical out.

Of course, this means that what you are working on should directly correlate
with the service literature you are using, despite the difference in models.

I see now - it has no current specified! There is no adjustments of laser
power either.

Ouch! This is kind of unexpected from an Onkyo, especially their Integra line,
and a model that uses a linear tracking motor instead of the traditional kicker
mechanisms according to your observations.

It helped me a lot in understanding of these circuit. I lowered the current
to 48 mA.

I think I read somewhere "Don't fix if ain't broken..".
And now it's not broken.

So this means you got your CD player working again? If so, congratulations!
They certainly don't make CD players like that anymore unless you are willing
to spend big bucks (although an Integra model CD player usually did cost big
bucks). - Reinhart

 

[Zeljko]

Ouch! This is kind of unexpected from an Onkyo, especially their Integra line,
and a model that uses a linear tracking motor instead of the traditional kicker
mechanisms according to your observations.

I searched again - no mention of it under adjustments. In schematic, no
voltage reading on current source for LD. Under replacement, nothing...

So this means you got your CD player working again? If so, congratulations!
They certainly don't make CD players like that anymore unless you are willing
to spend big bucks (although an Integra model CD player usually did cost big
bucks). - Reinhart

I was surprised too. Internal cleaning of pickup is crucial if possible.
I had this experience in two occasions. During my work for Sanyo on
low-low-end Sanyo CD players in musical centres. Ventilation air blows over
the cd. Micro-dust finds it way into the pickup somehow. Raising of laser
power works for some time, but if You clean it internally, customer don't
come back. Of course we blocked ventilation air also. New pickup also gets
dust in short time.
Other occasion is one Sony MDS JA3ES. They also said that pickup needs to be
changed. Precise cleaning of lens from up and down solved the problem.

It's already in the wild. Today customer called me that it works nice.
And he bought it for few tenths of euros...
....plus my humble fee.

Zeljko

 

[LASERandDVDfan]

I was surprised too. Internal cleaning of pickup is crucial if possible.

This is very true.

Dust and smoke are killers of optical pickups.

As you've indicated, cleanings will help to correct dust and smoke related
problems.
However, some pickups are assembled in such a way that disassembly is not
possible unless you want to ruin the pickup. - Reinhart