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Dead NeXTstation floppy drive
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 57
Location: St Gallen, Switzerland

PostPosted: Sun May 08, 2016 2:02 pm    Post subject: Dead NeXTstation floppy drive Reply with quote

Dear All,

I couldn't find much help on this topic, so I'm opening a new thread, hope is not duplicating anything already existing.

I have a NeXTstation mono, everything worked fine until last time I've tested it.
Today, however, I've found out by chance that the floppy is apparently totally dead, to the point is not even recognised by the system.
Any test I've tried is just suggesting that the drive is not installed. Of course it is and the ribbon cable is OK (already checked). The diagnostic at start up is giving no error, so I assume the mother board (recently re-capped) is also OK.
I can only speculate the issue is in the drive, model is "MP-F40W-1X".
No matter what I do, there's no sign of life at all.
Neither the pick up motor, nor the main motor and not even the eject motor seems to be alive, despite there some current flowing through the board.
I've measured some voltages and they seem to be consistent, reading 5V wherever it should.

By lifting the board, to the eye everything looks OK, however there's one electrolytic capacitor (47 muF / 6.3 V) and 2 other through hole components I can't identify (one looks like a transistor, but the designator reads "PS", the other one I have no clue at all and is designated "X1").

Unfortunately, I don't have any other NeXT hardware around I can use for swapping components, I only have a Cube 030 which has no floppy.
I have many Apples, though.

Hence my questions:

1) is there any way to tell whether the motherboard is OK, is there any connector pinout reading one can check the board against?

2) is there any document about the floppy (recently I've brought back to life a 400 k floppy from a Mac 512k and I could use some schematics available on line as reference)

3) is there any best practice for checking the floppy functionality by attaching it to some other hardware (Apple? With another ad hoc made cable, of course).

4) same for the motherboard?

5) any idea about the pass through components on the floppy board (beside the capacitor)?

Any suggestion on how to test and, in case, repair the floppy drive is more than welcome.

Thanks in advance for your feedback!
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bobo68



Joined: 03 Jun 2015
Posts: 194
Location: Germany

PostPosted: Sun May 08, 2016 2:36 pm    Post subject: Reply with quote

The NeXT diagnostics "dvt040" can also check the floppy. Have a look at http://www.nextcomputers.org/NeXTfiles/Software/Diagnostic_Utilities/68040_manual.pdf. dvt040 must be in the root directory of a boot drive (not neccesarily a floppy).

You can find schematics of the turbo slabs here: http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/Schematics/Turbo_slab/ - maybe you can draw conclusions from that.

It might be that the floppy itself has defective caps...
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Rob Blessin Black Hole
Site Admin


Joined: 05 Sep 2006
Posts: 597
Location: Ft. Collins, Colorado

PostPosted: Sun May 08, 2016 5:10 pm    Post subject: Re: Dead NeXTstation floppy drive Reply with quote

paolo.bertolo wrote:
Dear All,

I couldn't find much help on this topic, so I'm opening a new thread, hope is not duplicating anything already existing.

I have a NeXTstation mono, everything worked fine until last time I've tested it.
Today, however, I've found out by chance that the floppy is apparently totally dead, to the point is not even recognised by the system.
Any test I've tried is just suggesting that the drive is not installed. Of course it is and the ribbon cable is OK (already checked). The diagnostic at start up is giving no error, so I assume the mother board (recently re-capped) is also OK.
I can only speculate the issue is in the drive, model is "MP-F40W-1X".
No matter what I do, there's no sign of life at all.
Neither the pick up motor, nor the main motor and not even the eject motor seems to be alive, despite there some current flowing through the board.
I've measured some voltages and they seem to be consistent, reading 5V wherever it should.

By lifting the board, to the eye everything looks OK, however there's one electrolytic capacitor (47 muF / 6.3 V) and 2 other through hole components I can't identify (one looks like a transistor, but the designator reads "PS", the other one I have no clue at all and is designated "X1").

Unfortunately, I don't have any other NeXT hardware around I can use for swapping components, I only have a Cube 030 which has no floppy.
I have many Apples, though.

Hence my questions:

1) is there any way to tell whether the motherboard is OK, is there any connector pinout reading one can check the board against?

2) is there any document about the floppy (recently I've brought back to life a 400 k floppy from a Mac 512k and I could use some schematics available on line as reference)

3) is there any best practice for checking the floppy functionality by attaching it to some other hardware (Apple? With another ad hoc made cable, of course).

4) same for the motherboard?

5) any idea about the pass through components on the floppy board (beside the capacitor)?

Any suggestion on how to test and, in case, repair the floppy drive is more than welcome.

Thanks in advance for your feedback!


Hello Paolo and Forum members: I have new old stock NeXT Mono 68040 25Mhz Motherboards for $30 or used working Motherboards for $20 and New Old Stock NeXT Floppy Drives for $15 or used working $10, it may be the easiest route if you can't repair! I would test both to make sure they work but they are in original packaging . Shipping for floppy USPS Priority mail is $34.95 or First Class is $20 ... Shipping for Motherboard and floppy $65.50 to Europe. best Regards Rob

best regards Rob Blessin
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Rob Blessin President computerpowwow ebay sales@blackholeinc.com http://www.blackholeinc.com
303-741-9998 Serving the NeXT Community since 2/9/93
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 57
Location: St Gallen, Switzerland

PostPosted: Mon May 09, 2016 12:23 pm    Post subject: Reply with quote

Dear Rob, dear Bobo,

thanks for the prompt feedback.
Before ordering a spare drive, first of all I want to understand what is wrong with my disk drive or mainboard for what it matters.

I won't have time to go through the documents for some days to come, I will then investigate and decide accordingly. I will surely share my findings for other people in this great Community to benefit from this minor, yet unfortunate situation.

Paolo
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 57
Location: St Gallen, Switzerland

PostPosted: Mon May 09, 2016 2:13 pm    Post subject: Reply with quote

Gents,

does anyone have high res pictures / schematics of the NeXTstation mono (original one) logic board, showing the specs of all surface mounted capacitors?
First of all, I want to rule out that I've made gross mistakes while recapping it. Should not be, since I normally pay a lot of attention in such an activity and all hardware checks are passed, but you can never known...

Thanks in advance,

Paolo
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bobo68



Joined: 03 Jun 2015
Posts: 194
Location: Germany

PostPosted: Tue May 10, 2016 12:41 pm    Post subject: Reply with quote

I can take some pictures next weekend. Most probably the caps are:
    47uF, 16V, SMD type
    220uF, 25V, 105 C, HFQ, radial type
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barcher174



Joined: 07 Dec 2012
Posts: 558

PostPosted: Tue May 10, 2016 2:10 pm    Post subject: Reply with quote

bobo68 wrote:
I can take some pictures next weekend. Most probably the caps are:
    47uF, 16V, SMD type
    220uF, 25V, 105 C, HFQ, radial type


Those are the only 2 types of electrolytics. The number of 47uF is dependent on the board revision of which there are at least 3 for the mono slab. The floppy controller chip should be right under the drive. If there is a problem with the board I would start there. I suspect it's the drive itself causing the issue.
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 57
Location: St Gallen, Switzerland

PostPosted: Fri May 13, 2016 1:37 pm    Post subject: Reply with quote

Dear All,

thanks for your feedback.

This week end I will check the board, but I'm pretty sure it has been properly re-capped, I've only replaced the SMD capacitors with tantalum ones, all of them 47uF 16 V. The radial ones still look like new.
I also suspect it's the floppy. Will investigate and let you know.
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 57
Location: St Gallen, Switzerland

PostPosted: Sun May 15, 2016 10:53 am    Post subject: Reply with quote

Hello Gents,

So I took some time for investigating the floppy issue.

Honestly, I could not collect sufficient evidence for identifying the root cause, but I suspect it's something with the power management board section of the floppy drive, I guess something has blown off.

Running the diagnostics, all test are successfully passed, except the one about the floppy, so I'd speculate the logic board is OK.

https://db.tt/yafaQ5Ti

Only thing I don't like, the fact that the solder looks "altered" for one of the pins in the connector on the motherboard side.
I got the same clue one an Apple 400k floppy I've recently fixed and in that case it was clear sign that the transistor connected to that very pin was gone.
But here it's just a junction pretty far away to any power component, so I could not link it to any visibly damaged component.
Surely, not a good sign, but for me it's hard to tell more.

https://db.tt/ztJW4bsY

So, I've focussed my attention on the floppy drive.
Honestly, everything looks OK, no sign of damage whatsoever, at least at a superficial visual inspection.
There are just three through hole components, one capacitor and two I was not able to identify (see pictures).
One look like a transistor (and could be suspect number one), but the designator is reading something different and, unfortunately, very generic.

https://db.tt/vBSn7EXd
https://db.tt/BqjOzYea

Just for the sake of it, I replaced the capacitor on the floppy board, but, as expected, brought no results, the floppy is still completely dead.

On the B side of the board, there's a clear designator of a fuse / circuit breaker, but that's all I could understand.

https://db.tt/peeYk176

I could measure 3.0 V where 5.0 V should be, so I suspect something has blown off, but I'm not able to tell what.

If someone is able to identify a replacement part for the other two components, I will replace them too, just to say I've done all I could possibly do with a soldering iron and a tester.

Otherwise, I guess I will give up and get a spare drive from our friend Rob.
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bobo68



Joined: 03 Jun 2015
Posts: 194
Location: Germany

PostPosted: Sun May 15, 2016 12:17 pm    Post subject: Reply with quote

The melted solder on the pin of the mainboard floppy connector looks fishy to me. Which pin is it? The floppy connector is the usual 34-pin floppy connector. Have a look at http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/Schematics/Turbo_slab/CSlab33-12.pdf to identify what the pin is for.

My guess on the X 1 part is that it is indeed a fuse. X usually denotes a fuse or lamp holder on a pcb. I've seen this kind of part but cannot remember what it is. Can you lift the white cap?

Of course just changing the fuse (if it is one) will normally not help because there must be a reason why it blew. Maybe the pin with the melted solder is an indication.
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barcher174



Joined: 07 Dec 2012
Posts: 558

PostPosted: Sun May 15, 2016 1:56 pm    Post subject: Reply with quote

Did you verify 5v at the system logic board? Also I wouldn't be too worried about the solder pad having extra solder. You see this type of variation all the time with these machines.
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wa2flq



Joined: 18 Dec 2008
Posts: 30
Location: Chicagoland

PostPosted: Sun May 15, 2016 3:01 pm    Post subject: Reply with quote

bobo68 wrote:
....

My guess on the X 1 part is that it is indeed a fuse. X usually denotes a fuse or lamp holder on a pcb. I've seen this kind of part but cannot remember what it is. Can you lift the white cap?


Its a Crystal Oscillator. It will show open when tested for resistance. It can be hard to test even high impedance oscilloscope or RF counter, as the extra capacitance or resistance could inhibit the oscillation.
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paolo.bertolo



Joined: 24 Sep 2015
Posts: 57
Location: St Gallen, Switzerland

PostPosted: Mon May 16, 2016 2:17 am    Post subject: Reply with quote

Quote:
Did you verify 5v at the system logic board?

Yes, on the logic board side I can read 5 V on the powered pins. It seems as though the current is being cut off at some stage on the floppy board. I guess it's the circuit breaker / fuse that blew off.
Quote:
My guess on the X 1 part is that it is indeed a fuse.

Quote:
Its a Crystal Oscillator.

I also think it's an oscillator: however, all I could figure out is that it's 3 pin component. Not much. Googling the name led to no match.

Same for the other component that looks like a transistor (designator on the board is PS01, "PS" power supply, in theory). However, the B side of the board is actually indicating the symbol for a fuse, but everything is so dense that telling what is what is really hard.
My (null) skills end here, even thought I have the feeling that it's just one or two components that has to be replaced, I'm not planning to spend more time on this, higher level of knowledge is required in order to track down the issue in a professional way.
All I can do is replace pass through components that look damaged and only in case a spare is identified, which doesn't seem to be the case. Or at least I can't make any progress on my own.

However, if you have suggestions or ideas, I'm more than open to test them in order to create a first record for future cases.

Thanks
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bobo68



Joined: 03 Jun 2015
Posts: 194
Location: Germany

PostPosted: Mon May 16, 2016 2:31 am    Post subject: Reply with quote

paolo.bertolo wrote:

Quote:
Its a Crystal Oscillator.

I also think it's an oscillator: however, all I could figure out is that it's 3 pin component. Not much. Googling the name led to no match.


wa2flq is right, it is most probably a crystal oscillator. Found a similar piece described as part of another Sony floppy drive: http://matthieu.benoit.free.fr/101.htm. Also the symbol underneath the component seems to designate an oscillator.
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bobo68



Joined: 03 Jun 2015
Posts: 194
Location: Germany

PostPosted: Mon May 16, 2016 2:38 am    Post subject: Reply with quote

There is a drive select switch (S101). Is it properly set (seems to be between 0 and 1)?
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