NH900 Read Error - but plays all pre-recorded immediately

[punkrockaddict]

Hi everyone

I just bought a used NH900.It was sold because the display didn´t work.Hoped to repair it and it was easy going.Just a loose connection from the board.

The seller stated it was used only a few times and sat on the desk for years ,

Actually the Unit is in very good condition and looks nearly mint.

But by far it doesn´t act like that.

The Recording head did get pushed inside so it won´t record.I tried to put it back butt it´s broken as the metal shutter is bend up and unrepairable.

The other thing that is causin me to think is the laser. The unit just recognizes and plays pre-recorded discs.

It takes 3-5 sec and the disc is recognized.Plays fine too.

But every other disc causes it to state "read error" Sometimes a himd disc is loaded with no tracks.

I believe i have to calibrate the Laser ?

The failure is 06 as stated in the service menu.That is "Acess loop"

How can i fix this without having the alignment discs?

Ain´t it possible to do so with just an empty disc a recorded and a pre-recorded?

I did read about that but not about how to do it.

Appreciate any help..

greetz

[sfbp]

NH900's are eminently repairable... in fact I just fixed one. But this sounds like a job for Jim. If you have a busted overwrite head, your unit will blank any disk the first time someone presses the track mark button by mistake.

Definitely worth fixing and there's no OLED to die on you.

[punkrockaddict]

Yea i know it will blank..

I got many Minidisc portables and almost every himd unit

In fact i even have 1 Oled for the RH10 in stock You posted something about the Laser setinngs in anothet Thread, didn´t you?

I did take a look at the total recording time for this unit and it was 55.so not very much.And i did calculate the hex

Iam kinda wondering why it does play pre-recorded just as it there never a problem.

Could it be because of the different writing or manufacturing of the dicsc? I did read about manufacturing original Albums and it is different from recording as usual.

I think i will probably contact Jim but at first i will take a look at the overwrite head from a defect RH910 i got.Maybe they´re nearly the same so that i can change them.

I hope somebody who knows can tell me how to do the adjustement values without these alignment discs.I read about that it can be done with a empty disc, a pre-recorded and a recorded one.

thx 4 your reply

[sfbp]

There are numerous people here who would kill for an OLED.

CD reading is completely differently set/specified from MO reading... it's a completely different mechanism and requires special phase of adjustment (which is always done first). That's why you aren't having trouble with it, most likely.

It's easy to make the alignment disks yourself. You basically need 1 empty, and 2 full disks of data (the last is a 1GB), and one pre-recorded. The NH900 is the base model for all the others of that generation, so contains the most detail for you about how to service it yourself anyway.

[AVITWeb]

I don't mean to hyjack, but I have similar issues with my unit. It very speratically reads regular MDs. HIMD it has no problem with...

Is there someone who actually repairs here on the forum? (am I reading this correctly?)

[PhilippeC]

Jim Hoggarth (living in UK) repair MD units : http://forums.sonyinsider.com/user/122646-jimhoggarth/

[punkrockaddict]

unfortunately he doesn´t read my Pm :/

ANybody else got a clue what i can do about it ??

Thx

[Jimma]

I would try contacting him through his website. His contact details are at the bottom of the page.

http://www.angie031056.pwp.blueyonder.co.uk/

[jim.hoggarth]

Don't panic !!! Not been good recently, snowed under with a backlog. I will reply to your PM asap. And that web site is just an experiment - I will be getting my own domain name soon.

Jim

[Azureal]

Jim, your services will be worth a fortune someday! :-)

[jim.hoggarth]

I do hope so, I am barely making any profit at present!

[PhilippeC]

I would try contacting him through his website. His contact details are at the bottom of the page.

http://www.angie031056.pwp.blueyonder.co.uk/

precious link that I keep for reference

[punkrockaddict]

Now to get this pushed again i compared the entries in the test mode for numers 124 and up..

Another NH900 i own does show some other entries.124 , which is Laser, did have 3B in the defect and 38 in a working USA Model.

I tried to change downwards what means more Laser Power, am i right? But i does have no effect.

What i am wondering about is entry 130 which is also different.I guess that could be a change in manufacturing process maybe? so that it could not be important.

That defect Machine does spin the disc the laser moves up and down.. i just can´t get it !

I also read about the difference in reading pre recorded to self made discs. The defect one reads all original Mds without problems and this take a Laser Power of 0,4mW

Reading self made discs needs 0,8mW. Could it be that is the Key?

Iam not that sure about setting the value at adress 124 down is triggring the Laser power up.I did read about this a long time ago.. but i guess its just like that.

Anybody knows about this?

So i thought if the Laser power was bad at adress 124 i could fix it that way. But it don´t work.

Now iam up to assimilate the values from the working to the defect one.All the values from the Laser section.

Bad idea?

Any help appreciated ^^

Thx

ps: Blankdiscs are recognized as Blanks.I mean new Discs.

[sfbp]

There are AT LEAST 4 settings for laser power.

There are two ways to set the laser power

a. using the all in one self-align and a set of disks

b. using a laser power meter.

It's a servo-regulated system, so "just" tweaking it mostly won't help much. You have to get them all right. For example if the laser power output went down, you have to change ALL the thresholds UP.

[punkrockaddict]

Update

I took myself into the shit of changing some magnetic heads.I had a broken RH910 in stock and recently took the head out of it to fit it into the bend one from the NH900.Made some pictures as well from this..

but in the end i slipped off with my hands and bend the new head.. x.x

And if that wasn´t enough suffer the NH900 don´t recognize discs anymore.Iam unsure if its the lasers ribbon cable which is not right in place.

I was so fucked up after bending the head that i had to lay all that stuff beside my desk and let some days pass.

Repairing a broken JE480 was way easier to me .. took just half an hour. Was kinda worth it as it has only 16h playback and 6(x4=24h) total rec.

I don´t like these portables ..in fact these sometimes look as if they should never be repaired.

cheers anyone