Denon 2900

[Extreme_Boky]

I disagree with your findings. For one, you are talking about RF level, not laser power. Laser power is set at the head factory, not at Denon. You would then need to increase the RF gain to correct that situation.

Most CD players do not have an RF level adjustment as it affects the slice level. It's a very simple circuit in the RF amp. Just change a resistor. This has been a modification with some machines from the factory (can't remember each exactly).

I don't understand why you are constantly talking about RF gain? I have never mentioned anything in regards to changing the gain of RF stage…

Start considering laser diode output, CD ROM in use and given RF gain (with sensitivity of focus tracking / sled + spindle servo circuitry) as one block that needs to work as one to be able to read all CD ROM's - difficult ones as well.

Again, cranking the laser power is always the very last thing you do after exhausting all other options.

???????? who's cranking the laser diode output?????????

Please read carefully what I wrote!!!

I am not going to continue with this any more. If you think changing the laser assembly is solution to a problem - fine.

The eye-pattern level should always be checked whenever there’s a problem with reading the disk. From this point onwards, decision is made on tweaking the laser power, or full laser pick-up replacement.

I can not believe that authorised (?) Denon service DOES NOT check the factory pre-set laser output on newly installed laser pick-ups. Using only laser power meter is not enough!

Anyway, my suggestion is to increase the laser diode output while observing the eye-pattern amplitude. If it’s possible to get it up to around 1.6V pp – it’s okay to continue using it + you learned something and saved some dough. And this is what DIY is all about…..

After laser pick-up assembly replacement it’s mandatory to check the eye-pattern amplitude making sure that it’s within 1.6Vpp (+ - 0.3V). These levels vary for model to model, but are corect for +5V Vcc. If this is not done, you are relying on mass – production factory pre-set levels which could be (and are, in my experience) wrong!

Extreme_Boky

 

[lardyl]

I had the same problem with my DENON DVD-2800 and after replacing the laser PU it is playing like new.
...check the part number of the head. It is probably HOP-1000 which is replaced by HOP-1120. On the new head look very carefully (by comparison to the old one) to locate and remove the two babbles which disable the CD and DVD function. Use half a drop of gun oil on the right side rod and a pin head of very light grease on the head at the points it comes in contact with the left rod.
I got mine from:http://www.donberg.ie/

mine says: 3K04 0522 H6VD 1200 RN on the other side of the head...... damn those ribbon cables are hard to get back into the sockets....grrr.
ah but doing a search for the HOP pickup gave this site:
http://www.pltv.org.uk/laser.htm
looks hopeful.

thanks again
ian

also anyone know where these pots that determine the power of the laser are located.....thought a stab with that could not do too much harm....???

 

[anatech]

Hi Extreme_Boky,
What I am talking about is simply that you are adjusting the RF level by increasing the laser output power. I am suggesting the gain of the RF amplifier can be modified and achieve the same result that you are after. After all, you are attempting to play software that is well out of "red book" standards. My gas powered car will not run on diesel. I'm sure the design of the motor can be modified to run on diesel instead.

Looking at the eye pattern is like taking a blood sample from a human. That's always one of the first things we do. You can tell an awful lot from the eye pattern display. It is one of the main things we would monitor before and after a repair. Looking at the focus and tracking servos can tell you a little more in addition.

Laser power is adjusted at the factory by measuring the optical power and the head. They have better equipment than we do. I'll trust that adjustment.

I'm just trying to keep people out of trouble.

Like Ian here,

also anyone know where these pots that determine the power of the laser are located.....thought a stab with that could not do too much harm....???

A small slip "to you" can permanently damage your laser diode. I wouldn't mess with those adjustments unless you have the experience working on many machines, and have the proper equipment. It's totally up to you.

-Chris

 

[fiak]

Hi Ian,
Those numbers are not helpful to locate the head in the free market.
Did you get any photos? Here are some from the time I opened mine.

 

[fiak]

Next step.

 

[fiak]

And here is the part number.
Also I find this:
http://www.soundevolution.nl/home.html

 

[lardyl]

thanks fiak
mine's similar but not quite the same (I think)
have some photos to post but need to wait until my internet connection is stable - having problems with the rain !!

 

[lardyl]

Hi all
now back on the broadband (ADSL) trail....
here are some shots of the transport - looks similar but maybe not quite the same?

 

[lardyl]

and here:

 

[fiak]

I think your laser head is the Hitachi HOP 1200 RN, take a look here:
http://www.n-tronics.com/ntronicslaserpickups.htm
It is easier to lift the traverse assy by removing the four suspension bolts, the head's flat cable and the power supply socket. -Then if you disconnect the remain flat cable you can totally remove the traverse assy-. This is not necessary if you just want to replace the head.
Here are some shops in the States where you can find the traverse assy in case you will need it, but you must find a way because they do not sell abroad: (at the first shop just click on SUBMIT then select DENON and write DVD2900)
http://www.pacparts.com/electronics...action=list_part&CFID=465787&CFTOKEN=35684920
http://www.partstore.com/ModelDetail.aspx?MfgId=86&ModelID=376520&close=0&exact=1
I made a long search for all these as our DVD players are very expensive, highend items for both the sound and the picture.

 

[fiak]

Here is a better destination for the second shop:
http://www.partstore.com/partnumbersearchresults.aspx?PartNumber=9KC2A063A

 

[caoauto]

Here is the part number in my service manual: 9kc2a063b
It is an assy'. $94.00 in the US.

 

[lardyl]

thanks guys - the 9kc2a063b can't be got for love nor money in the UK and the various US vendors won't send it to me....grrrr....will try the local specialist store when I get more time (just moved office so not had chance to check this forum for a while!!!).
Ian

 

[q1]

Just have replaced my laser in my denon 2900. Had trouble reading red book cd's and some SACD's. (wont start)

It works fine now!!

It is different from the original. More metal and heavier. number is 2F05 0408 12LE 12LE HOP-1000 .


Obtained it here for 49 euro's by Gerner Electronics, Ralf Gerner
http://www.lasertrader.de lasertrade.de
Best.Nr.: 0140

Denon repair service would have cost about 170 euro.

 

[anatech]

Hi q1,
That's one of the newer active servo machines, isn't it? There is no alignment anymore, except for disc table height maybe.

-Chris

 

[fiak]

Check also this thread.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1271160#post1271160

 

[yurikov]

Hello all,

My beloved 2900 is getting ever more problems with redbook CD's. SACD's and DVD's no problem though.

I've read your post on the forum and consider installing a new laser head a/o assembly.

I've some questions:

- Which part# of the head is the right one? HOP-1000 or HOP-1120 (the last one I've found much cheaper, 21 euro on internet).

- Do you recommend replacing the head only or inclusive the assembly?

Hope you can help me!

Regards

 

[coloradosound]

I have a DVD-2910, no problems yet, but was wondering if
anybody else has ever had similar problems with this model?

 

[joe]

No Adjustments?

Is this a drop in replacement or are there any adjustments to be made with a new laser head?

Thx
Joe

 

[yurikov]

In the meantime, I've had the laser head replaced by a (very knowledgeable) repair-shop. My 2900 is fine since then.