Denon - old universal players failing to read redbook CD

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RHCD

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Joined 2010
#1
I've recently acquired a Denon DVD-2900 as an SACD source. I was hoping to tweak it following ideas on this forum, and thinking it might then take over redbook CD duties as well (from a Rega Saturn).

However, although it plays DVDs and SACDs it cannot read redbook CDs, and I have found enough discussion of this issue on the internet to know it's a not uncommon problem, and occurs in other relatively high-end Denon players as well. It has a brief look at a normal CD and then displays 00h00m00s and stops.

Though I found several people posting about this, I saw no authoritative answer about what might be wrong with the CD laser assembly. I assume this is at fault.

This seems the most likely forum to find someone who can advise me, if there is any way at all I can fix it short of replacing the laser assembly. I imagine that is now impossible, 10 years after manufacture.

Can anyone offer any hope?

Robert
 
#2
I have DVD3910 schematics. DVD2900 might be similar or even have identical transport / RF IC section...

There are two laser V-outs out of the CXD1881AR IC on 3910, the DVDLD and the CDLD. There's also RF AC test point where you can adjust the laser outputs to be within the appropriate range to take into account laser output capability deterioration.

Start by adjusting the CD laser trim pot clockwise just a bit and see if it works. Later on you can adjust the correct laser output by monitoring the RF AC test point for the correct amplitude.

Also, search the forums by my user name; I have posted before on numerous occasions everything one needs to know to adjust the laser output properly, in particular on Denon CD / DVD players.

Boky
 
#3
It's going to be either a bad HOP1200 laser or a bad entire drive unit. The most expedient way to diagnose, and potentially repair, is to order a HOP1200R or HOP1200S(but not HOP1200W), available as cheap as 13usd from at least USA retail parts places I use, throw it in & try it. It's a "drop in" replacement. Just remember to unsolder the two(as I recall) static protection shorting "jumper" blobs before install. The HOP1200 & the rest of that Hitachi drive, is the MOST UNRELIABLE piece of junk hardware yet used in any dvd/universal player, sadly used by Denon over several years and by Rotel & numerous others. It is garbage and will keep failing every 1-3 years, or more, for as long as you keep the player. But I've ranted about it before on here, so no point keeping on.
 
#4
Thanks both of you - searching for your old posts has led me to very informative old threads. I find the HOP-1200 available in the UK at about £10, so that's fine, I can pop one in easily enough.

It seems worth having a go at your trim pot adjustment first, though, Boky - I see from the old threads it has worked for others. The only thing I haven't been able to find is a photograph with the correct pot pinpointed on it - is there one online you could point me to?

I am now very optimistic I can have everything working properly before I begin the modifications!

Cheers
 
#6
OK, for an outlay of £10 have bought and received a new HOP 1200 laser to install. Or is it new? When I was looking into this, I found a post somewhere saying that when the laser assembly is new the lens should be white, and it turns blue with age - a blue lens, he insisted, is a sign of a worn out used part that has been recycled. Is there any basis for this or is it nonsense?

Needless to say the lens of the HOP 1200 assembly I have received is bright blue....
 
#7
A bit of searching has turned up the source of all these HOP replacement lasers, for sale by the tens of thousands from Shenzhen, and the manufacturer's photographs almost all show the lens blue, so I guess the website I was looking at was talking through its hat...

Will report on success of replacement!
 
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