MD transport in JB980 & JE470

[zokuchou]

Does anyone know if the transport mechanism in these two machines are the same or not? If so, are they inter-changeable?

Thanks.

[sfbp]

I'd guess the answer is "yes and no".

I haven't looked carefully at the specs but both are NetMD capable. JB980 is definitely higher grade machine, though Jim claims it's the same as the 780. Check the connectors in the service manuals very carefully.

The model of the drive in 470 and 770 is MDM-7A, in the 480, 780, 980 is MDM-7S1A

What are you trying to fix?

[PhilippeC]

more information (in french) here : http://jonathan.dupre.free.fr/articles/articles.php?id=50&cat=17

Thanks to jonathanpotato

[zokuchou]

I recently had to remove the transport in the 980 (my unit) after a disc wouldn't eject and the unit was making a loud ratcheting sound (my son had lovingly fed no less than two 5c pieces into my machine!). The 470 (that I've been trying for months to fix for Danny) has a C13 error. If the transports were compatible then I wanted to see if I swapped them would I get the same error. However I don't want to do anything untoward with my transport if not.

Thanks.

[PhilippeC]

How to unstuck a MD from your deck (video : JB980 , JE470)

[sfbp]

C13 probably means a laser adjust. Want me to take a shot at it?

If there are the same number of strands (ie the connector fits), I say go for it. I think the settings are stored in the drive, not the deck.

[jonathanpotato]

As I have understood, you can swap complete transport block safely only if it's the same reference. Think twice about.

At the beginning of MD, we had to distinguish two things :

• MDM-Xyyy (X = 1 to 7) refer only to a MD THREADING/LOADING MECHANISM
• MBU-Xzzz refer to a BASE UNIT (reading unit) = combination of three elements : base chassis (metal plate / sled & spindle motors) + OPU model/revision + BD BOARD model and version since MDM-2 to 7 labeled like (example) "1-234-567-AB" or like "A-1234-567-B")

Of course MBU-X units can be mounted only on same MDM-X mechanism.

Just an example with MDS-B3 et MDS-B4P (service manual) :

Here we have 2 MDM models and 2 MBU models for each device according to if record function possible or not = overwrite head installed or not.

[jonathanpotato]

But since MDM-3, MBU does not exist (individually) anymore. So just labeled MDM-Xyyy for the WHOLE MECHANISM BLOCK (BASE UNIT INCLUDED).

Example :

See MDS-JE510 and MDS-JE320 service manuals (on the net) :

MDS-JE510 US, CND, E, SP, HK = MDM-3A = MDM-3 + KMS-260A + BD BOARD A-4699-092-A (with CXD2650R)

MDS-JE510 AEP, UK, G = MDM-3B = MDM-3 + KMS-260A + BD BOARD A-4699-770-A (with CXD2652AR)

MDS-JE320 = MDM-3GC = MDM-3 (revised PIN OUTSERT) + KMS-260A + BD BOARD A-4699-770-A (with CXD2652AR)

So, mechanical parts are interchangeable but pay attention with board's revisions.

[jonathanpotato]

To answer zokuchou, JE470 and JB980 BD boards seems to be pin compatibles. But without warranty due to possible software errors or bad behaviour.

[zokuchou]

Thanks all for the information & help. One small oversight...Danny's machine is a JE780, not a JE470. Does that make any difference? Thanks.

[sfbp]

See post #2

[zokuchou]

LOL! Sorry Stephen, please excuse my sleep deprived brain!!

OK so in light of this news I swapped over the transports and the 780 worked fine. So as expected the 780 transport is causing the C13 error.

In response to your post about adusting the laser, then yes - I'd like a shot at doing this.

One question - when the display reads "Reading TOC" the disc isn't spinning. Tell me - does the laser read the disc first before it spins up the disc?

Thanks

[sfbp]

It's a servo system. Read something, adjust based on what comes back, try again, until it's right.

The laser is turning on in the anticipation that shortly something will be spinning beneath it.

But if the disk won't even turn then there's no chance anything will work. Now you have to figure out why. Most often it will spin a couple of times and then stop because coherent signal doesn't come back from the head.

[zokuchou]

So do I need to look at adjusting the laser?

[sfbp]

Does the disk turn at all when you insert? You won't be able to see this unless you take the lid off the actual drive unit.

Probably it needs to be sent to someone with a laser power meter (me or jim?) although some problems are mechanical or basic electronic in nature and can be fixed without. Mind you for those, Jim may be a better bet. I tried so called repair shops here and they hadn't a clue.

It's up to you if you think you can learn to fix then good on you, I'll try to pass on what I know.

I'm still unclear how the damage happened in the first place,,, whether it was the KidInsertsCoin thing or just years of use.

The problem I think is that being a servo system that as things begin to drift then heating occurs, and ultimately the laser gets fried. Most times I don't think it actually dies, it's just that adjusting it (or installing a new one) is a bit tricky.

The procedures are all in the service manual, although sometimes the later manuals assume you already knew the previous procedures and only bother to explain the parts that are new. All very confusing.

[zokuchou]

The disc doesn't spin at all. The cogs for the head "twitch' after a disc is inserted. They do this a further two times and then the disc is automatically ejected. Thanks.

[sfbp]

Sounds like (I am not really an expert) the root cause is the motor is not turning. So you need to put on your deerstalker and take your magnifying glass in hand (well, not literally on either count) and figure out why.

Sounds like the coin insertion could have caused some capacitor to blow, would be my guess. You have to start measuring voltages. The good news is that you have two of these things, so this enables you to eliminate a lot of possibilities by comparing the same point on the other drive.

The right voltages must be reaching the drive since a "foreign" drive works when plugged in to the same base. I'd try to look on the circuit board itself and figure out anything which is different a. from the other unit b. from the printed values in red near every pin of most IC's.

For instance, on p.44 of the JE480 service manual there is a chip IC440 "Loading motor drive" on the top left. I don't think that's what you want (because your fault will be on the BD board), but go ahead and look anyway. As soon as you find something that looks wrong, try to track back the source to figure out which component is dead. Not that hard, I think. Most likely it won't be one of the major chips, but a (single) capacitor or inductor or transistor.

Along the way you may spot something stupid and mechanical, such as a broken piece of plastic

Jim, how am I doing??? (I know he's not currently reading this)

[zokuchou]

Thanks for the detailed response. I'll take a look when I get a chance.

For the record it was my 980 that had a coin stuck in it and that still works fine.

Cheers!

[sfbp]

There I go mis-associating cause and effect again. I thought it died BECAUSE of the coins.