Both 1050 drives gone bad

[Mclaneinc]

As someone said, its so unlikely 2 separate drives would suffer the exact same fault at the exact same time, I'd be searching commonalities in the situation, is there anything both drives share, are they on the same mains supply spur, have they been linked in any way..Stuff like that..

 

Sorry its not real help but its such a weird situation...

[Rybags]

Power supply really is the only common thing aside from storage location (and at that they were apart).

 

I might give the DC power supply idea a try tomorrow.

[Wilheim]

13 hours ago, Rybags said:

Update - I bought a multimeter that has frequency/duty cycle measurement.  Pulled one drive apart and tested for 125 KHz and got 124.9 reported (the actual test point is TP 9 for that).

Adjusting all 3 trimmers made no difference.

 

Wasn't able to get a reading on the other 2 points.

 

But now the big revelation - neither drive seems to write anything to the disk.  Both will commence and fail a format command doing the full 40 in/out steps but I've just determined that the disk itself isn't written to.  I was using a C64 formatted floppy to test and just got out that machine and 1541 and it's still a Commodore floppy.

I have 2 hypotheses:

 

1. The 12v voltage regulator could be malfunctioning.

2. The power supply is not enough to make the disk drive work. You need at least 30VA. The 400 power supply will not work.

 

IIRC, the floppy head needed 12V.

 

Edited February 9, 2021 by Wilheim

[+Nezgar]

23 hours ago, Rybags said:

But now the big revelation - neither drive seems to write anything to the disk.  Both will commence and fail a format command doing the full 40 in/out steps but I've just determined that the disk itself isn't written to.  I was using a C64 formatted floppy to test and just got out that machine and 1541 and it's still a Commodore floppy.

If erase function is not working there was an earlier thread with where a similar issue was resolved by replacing U21 (3086; TBA331 in my drive at hand). U17, U21 and CR10 are also mentioned in the post:

 

[Rybags]

Changed the 3 power conversion section caps on my Tandon type drive.  Initially no action which was fixed with a quick reflow of one joint.

 

But now just back to the same responses - normal powerup, makes the right noises when commencing a read or format operation but both fail.

My next thought is maybe replace the electrolytic caps in the logic section ?

[+Peter Rabitt]

Hay,@Rybags Did you ever fix the 1050. I was following it and learning some info about 1050 trouble shooting the drive...

Just wondering if you ever fix it or gave up..Not a problem giving up as sometimes it is just to deep to fix.

 

Peter

 

 

[+Peter Rabitt]

On the subject of 1050 disk drives has any body come across and information on substituting a DS (double sided,two heads one on each side of the disk. ) 5.25 drive for the SS (single side) in the 1050??.

I think I saw a thread talking about troubleshooting a 1050 and said that signal was for double sided drive...???

Could the electronics be there but no one has looked at it... I do have some DS 5.26 but not to sure how to interface them to the Atari interface..

Need to remove some of the sasi or what ever PC world and add the Atari interface...

O WELL just thinking!!!

 

Peter

 

 

 

[Rybags]

I've bought caps to replace the remainder but haven't tried that or anything else yet.

[Faicuai]

2 hours ago, Rybags said:

I've bought caps to replace

You are in a really tight corner... replacing passives means going down a deep rabbit hole, with no clear end in-sight.

 

I would first test the very obvious: externally check aggregate power-consumption (at the a/c plug of 9V a/c power-block) while executing a read-attempt and FORMAT-attempt (regardless if it fails). Should be drawing 25w to 30+watts... Compare your results with this reference:

 

 

if power-reading are there  I would go straight to Controller, RAM or ROM a swap, leaving CPU last... Now, if power consumption clearly drops below 25w during these operations, I would check the ENTIRE front-end power section of the drive (internally). and discard that first.

[Rybags]

I've already deemed the external PSU and voltages coming off the regulators to be good.

 

Additonal to that, it's 2 drives with the exact same behaviour - accepting commands and doing seek and even going through the motions of the first half of formatting.

But no writes or reads are succeeding.  A C= formatted floppy with attempt to 1050 format gives an error and remains a C= floppy.

 

My theory given both drives were used probably 4-5 years ago and stored in the same room - environmental/normal deterioration.  So liklely passive components gone bad.

I tried frequency measurements of the relevant test points and they seemed to be OK.

[Faicuai]

9 hours ago, Rybags said:

voltages coming off the regulators to be good.

I am afraid that will not be enough.

 

The entire chain of power-derivative passives will have to be checked. All of them. That is the problem when attempting to (thoroughly) test-and-discard passives.

 

As an example, I have here one (of several) 800 power-boards that is crooking all video outputs (RF, composite, Y/C) and, yet, when scope-reading the board's regulators, everything looks fine-and-dandy... but it is not. That means much deeper forensics needed.

 

Having said that, if you feel totally confident that front-end power-stage is fine, then proceed to immediately replace RAM, ROM and Controller, in that order... I would not be surprised if any of them already failed (and several of them can fail, under similar environmental conditions). 

 

Another possibility is that the heads have failed... but I suspect that would skew global power-consumption levels, hence the importance of getting those readings, too.

[BillC]

16 hours ago, Peter Rabitt said:

On the subject of 1050 disk drives has any body come across and information on substituting a DS (double sided,two heads one on each side of the disk. ) 5.25 drive for the SS (single side) in the 1050??.

I think I saw a thread talking about troubleshooting a 1050 and said that signal was for double sided drive...???

Could the electronics be there but no one has looked at it... I do have some DS 5.26 but not to sure how to interface them to the Atari interface..

Need to remove some of the sasi or what ever PC world and add the Atari interface...

O WELL just thinking!!!

 

Peter

 

While one of the FDCs compatible with the 1050 supports DS operation there is no additional circuitry supporting a second head.

I have a Percom AT88-S1 which does appear to have the additional circuitry required, the adapter board mounted on the mechanism has a header for connecting the second head, this adapter board converts the mechanism from a minimal version like the 810/1050 to a 34-pin floppy interface.

[+bob1200xl]

Are the disks spinning inside the jacket? Hard to believe that formatting a C= disk, even if it's bad data would leave any C= senses to it. Belts may take a set if they sit around for years. If the disk is stalled in the jacket, open the lever half-way - enough to engage the spindle, but not so much to stall the diskette.

 

DC voltages on the power nets should be +12 and +5. AC should be zero.

 

Bob

 

[Rybags]

Drive spins normally.  I did an RPM measurement by both filming at 240 FPS and by using a strobe app.  Both came up normal.

 

Like I said before, it goes through the actions of spin up, seek, attempt to read, write or format but the operation fails every time.

First thought of course was dirty heads but they're nice and clean.

[_The Doctor__]

alignment and track zero location.... are you able to read your old disks? or are you trying new disks or disks from someone else?

 

also some packs of disks require bulk erasing to work, I've had a few packs that refused to work... degaussing bulk erasure worked on almost all of them

[Rybags]

Existing disks, some from someone else - same result.

And the chance of 2 drives becoming misaligned & showing same symptoms at once I think are very remote.

Track 0 I think is fine too, no ridiculous clicks or noises.

[massiverobot]

Bad caps would explain it- same env for all those years would affect the caps the exact same way. May have dried out. Same thing is happening to all the ADAM drives as well- they seem ok, just stop 'working' all of a sudden. I have one in that state- reading the ADAM section in AA someone said replacing caps on drive fixed the issue. Something to consider (you did some already).

 

[+bob1200xl]

Are you measuring the spindle RPM or the disk media RPM?

 

When you write to the disk, you erase the old data and write new data, so either head will splash the old data. Only way not to scramble the disk is for both head circuits to go FUBAR or for the disk to stall in the drive. It seems like your drive writes a full format, just fails the read-back. In reality, it is not writing at all?

 

Bob

 

[_The Doctor__]

okay hopefully you've done the basics and the heads are clean and the belts don't slip.

check head load pressure spring too much or too little pressure (make sure pressure pad isn't dirty or fallen out (rabbits fur)

check u13, u18-20, and u22-24

check j6 for orientation and connection

u15-18

transistor q1

u11

this covers the bulk of read write erase...

ram (6810) can be at fault for random I/O errors.

 

make sure after loading any software that the only thing connected to SIO is the disk drive in question.

 

be easier to have this I bet http://www.atarimania.com/documents/atari-1050-field-service-manual.pdf

Edited August 10, 2021 by _The Doctor__
add fsm link

[+kheller2]

Or this cleaner complete version: https://archive.org/details/1050FSMRebuiltAKH

 

[Rybags]

The format operation - does the 40 steps out then fails on the verify.

As I said before there is no writing taking place.  A Commodore floppy attempted to format on these drives remains that way and reads on a 1541 normally.

[+DrVenkman]

29 minutes ago, Rybags said:

The format operation - does the 40 steps out then fails on the verify.

As I said before there is no writing taking place.  A Commodore floppy attempted to format on these drives remains that way and reads on a 1541 normally.

Makes me think no current is getting to the R/W heads on the drive. Start from first principles - dig out the schematics and start checking continuity back from the heads all the way to the SIO jacks if necessary.

 

It’s just heckin’ weird that it hit both your drives at the same time. I’d obviously suggest something about your Atari or the SIO cabling if not for the fact that the drive responds to command at all.

[+bob1200xl]

Does the C= write to the same side of a SS disk as the Atari? Can you punch out the back side notch on the diskette and try a format on the back of the disk on one of your 'bad' 1050s? That may wipe out the old C= data.

 

It sounds like you are formatting in the wrong density. 

 

Bob

 

[Rybags]

Yes, 1541 is the same config of SS mechanism.