Denon 2900

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Hi all, I have problem with my denon 2900 DVD that play very well on DVD but it does have problem of reading the CD redbook or copy CD or SACD. Where should I start looking at? Any one in here have the schematic for sale? or where should I buy ? should I do some upgrade? like start to change those opamps? remove the caps ? change those diodes?. Thanks for any help in advance.
 
caoauto said:
Hi all, I have problem with my denon 2900 DVD that play very well on DVD but it does have problem of reading the CD redbook or copy CD or SACD. Where should I start looking at? Any one in here have the schematic for sale? or where should I buy ? should I do some upgrade? like start to change those opamps? remove the caps ? change those diodes?. Thanks for any help in advance.

You are addressing two questions here:

1) A playing problem you have with your Denon. That is not likely to be solved by any upgrades.

2) Upgrading parts to improve the sound.

I have similar problem with my Pioneer DV525, that refuses to play many CDs I have, but plays any DVD I put in. Unusually sometimes plays a CD copy of the same original I have and not the original.


Carlos
 
denon 2900

Thanks for replys so far. Yes I have 2 isues and though upgrade might solve the problem, but if not I better fix it first before talking about upgrading. You are right, play good on DVD but not on CD That is acxactly what I have problem with, so what did you fix ? or how to deal with ?
 
Re: denon 2900

caoauto said:
You are right, play good on DVD but not on CD That is acxactly what I have problem with, so what did you fix ? or how to deal with ?

Well, I don't know how to deal with that CD problem in the Pioneer. But as long as it plays the DVDs fine I will stick with it, and use another player for the CDs.

Right now I started another thread here that didn't get much attention, about a likely candidate: a Marantz LV500. It might be great player, solid and all that, as long as it doesn't threat me with another problem of its own: locking itself up.

But when it played, for CDs it was better than the Pioneer ever was.


Carlos
 
You should contact DENON - try the web site, give them a call and they'll send you a CD with pdf user manual.

The problem is related to a different reflectivity of CD ROM's. Even music CD's you buy in shops vary A LOT when it comes to reflectivity. I have discovered that some bad music CD ROM's have 25% less reflectivity than majority of other music CD's. This could be a problem - especially when the pick-up has to find the beginning of a track! (that is - if it manages to read the TOC at all…)

Regards,

Extreme_Boky
 
denon 2900

Hi every one. Just got the service manual schematic for it. find out bad laser in the CD side and it is kind weak on the DVD side too, I try to see if any magnet that stuck junk in it but it is very clean.
Now the question is how do I get cheaper laser to replace it? because I check the part they want for $100.00 for the whole Assembly, or should I pull the audio board out to build as a DAC for another transport? because it sounds very good, alot music and 8 times up sampling 24 bids 192Khz DAC, and disconect the multi chanel. Thanks again for all the helps.
 
hi all
looking to solve the same problem but can't yet find a parts supplier willing to ship to England - anyone know of one who can supply the schematic on CD and/or the part# 9KC2A063B (updated transport assembly)?
also if anyone has a "spare" copy of the DVD2900 schematic on CD I could offer some $$ in exchange - feel free to email me at lardy_one@(no spam thanks)dsl.pipex.com, minus the (no spam thanks) ...

thank you

ian
 
Back again and really frustrated as still can't fins a US supplier willing to ship to UK.
Found a site with 13 of 14 parts of the .pdf manual posted as .rar archive but one is missing.....grrrr.....
Plus the player is going through the death throes - started to work last night only to fail again "0h00m00s" on the display and fails to spin more than one revolution.
Ho hum back to the Sony/Pioneer/bad SACD/bad video play back.....
Ian
 
I had the same problem with my DENON DVD-2800 and after replacing the laser PU it is playing like new.
It is very easy to do the job, and the head cost around 35EUR. I attach my notes for future replacement.
You can lift the whole chassis by removing the four suspension bolts (51) and the PU's flat cable and 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/
 

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Hi Extreme_Boky,
You probably do not need to replace anything. The laser pick-up has a little trim pot that needs to be adjusted for higher laser diode output. Turn clockwise a tiny bit when facing the trim-pot.
No! Don't do that! The control is factory set for the correct power, and the laser circuit also has automatic power control. Once the level drops the circuit can't correct any more. There is the odd time we do that on the bench just to confirm out suspicions (there are other ways to do this). The intention is therefore that we are about to install a new head. Really bad shops will do this to rip off a customer as this "fix" does not last on average. You'd have better luck cleaning the lens.

I am very afraid that members will take that advice to "fix" a friends unit. Bad advice.

-Chris
 
I do this as a mater of routine when obtaining a replacement unit is difficult - which is exactly the case in this thread - and never charge for a brand new unit + replacement, but I know what you meant about doggy workshops and bad practice....

The factory settings usually work, but what I found with DENON in particular is that the laser output is too low most of the time. I check the eye-pattern level and find that it is okay for most of the ROM's, but not sufficient for those with bad / low reflectivity. The reflectivity variations are quite unbelievable. Things get worse with CD-R's. It is usually just right / on the border for the test CD's which have very high reflectivity.

CD RW have much lower reflectivity compared to ROM’s and CD R’s; however the mechanisms capable of reading CD RW are usually over-scan types which detect the reflectivity first, and adjust the laser output level accordingly. One setting applies to ROM's and CD R's, and different one for CD RW's.

Depending on the CD / DVD player type some will adjust the laser output linearly, but some will not! I found that DENON usually has only two presets: low and high without any linear laser output compensation.

So, the worst thing that can happen is to get the laser going for MANY more years if you are careful about adjusting the eye-pattern level right.

No need to panic! This can be safely done without any harm done to unit.

Extreme_Boky
 
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Hi Extreme_Boky,
You may be fine doing this, but.

I've done Denon warranty service for years. 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.

The other concern I have is that I've seen heads destroyed when the fault lay elsewhere in the circuitry. Even coated optical paths and they only needed cleaning, but the laser was burnt out by another tech.

I check the eye-pattern level and find that it is okay for most of the ROM's, but not sufficient for those with bad / low reflectivity.
Can you say "defective disc"? I can. Why break a device to enable it to play defective media? Why on earth do we expect disc players to play everything? An F1 race car will generally behave poorly driving on a logging road, so will a normal passenger car. Don't blame the equipment for poor performance when the software is to blame.

Sorry to have a strong opinion, but non professionals may read your advice and cause true damage. I guess that's my point.

-Chris
 
The laser power should be adjusted at the factory (DENON). It's not enough to trust the preset level laser power setting from let's say SANYO - one of the laser pick-up assembly manufacturers DENON uses in their High End equipment. RF gain can not be adjusted / changed - the circuit does not give this option.

I have witnessed different laser power settings on two identical units from SANYO - both brand new.

The ROM's I had trouble reading in DENON players play perfectly in other players. I would not call this faulty ROM - rather bad DENON factory setting / adjustment. They do not read all ROM's successfully - those with bad reflectivity can not be played. The laser adjustment is marginal at best and it usually goes off after a year or so. Slightly increasing the laser output does not cause any problems. The eye-pattern pp amplitude varies up to 0.5V between test CD and low reflectivity CD. Enough to cause the low reflectivity CD not to be recognised if the laser power is set too low.

I refer to ROM's as bought-in-the-music-shop audio CD's

I never burnt any laser in my life, but got a lot going and working fine by fine tuning the laser power. I gave the advice to fellow members here on forums who have troubles sourcing the replacement pick-up and who asked for help and should know what they are doing - or should ask for further help if they are willing to do this fine adjustment but are not 100% sure how.

It is possible and quite likely that even the brand new laser pick-up assembly will give troubles if not fine tuned for the given CD/DVD player that is picky when it comes to eye-pattern signal level.


Extreme_Boky
 
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Hi Extreme_Boky,
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).

Laser power is always adjusted with a laser power meter (I have one from Leader) while looking at the laser current. Some early Philips and NEC machines adjust to so many mV (or V) of RF that has to be within a percentage of the Iop reading marked on the head. Some Pioneer as well.

Other factors that really affect tracking would be disc table height and E-F balance. You really must make sure everything else is correct before merrily messing with the laser current. Just because that works does not mean it's even close to the correct procedure. Always look at the mechanical geometry as well. More than one machine has been found with warped mechanisms. Shimming the rail may correct that problem.

Again, cranking the laser power is always the very last thing you do after exhausting all other options. Measure the power and current without fail if you are going to do this. High current = bad head. Aways check with a standard CD.

If you have not got test discs, you have no business messing with the head.

-Chris
 
Thanks very much Fiak !!!
I think the 2800 has a different transport to 2900 as the 2800 has no SACD playback....but I could be wrong - please correct me if so.
I'll try the Irish people again - I know them and tried a search on the part numbers I know are used for the 2900 but I got nothing - their site is a bit messy though ;- )

ian
 
I also got helped by threads in this forum to realize that laser heads loose their intensity by use. Then I took the risk to replace it and I almost lost my legs at the first attempt but it was from the bubbles I had not find, although I looked for one at least, as mentioned at the head's documents. I do not have any records but I do not think there is much deference between the two transports.
It is up to you to decide... :scratch:
Also at those shops they do not know about Denon etc., the head I mentioned is made by HITACHI and - if yours is the same- you have to look for its part number.
 
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