Jump to content
Rybags

Both 1050 drives gone bad

Recommended Posts

have you tried a different SIO cable or can you test that cable with another device?

Share this post


Link to post
Share on other sites

The thought was to bypass the internal PS board and supply the 5 & 12 VDC direct.

Share this post


Link to post
Share on other sites

LDW and California Access drives used a 5v & 12v DC combined power supply but ive never heard of a 1050 converted to this.

you can buy generic power supplies with the above output voltages - they are intended to power IDE hard drives but i suppose they can be used as they have decent amp output

anyone fancy a try?

Share this post


Link to post
Share on other sites

Your power sounds good - don't mess with it.

 

The drive belt tends to stretch and skip a little. Crud builds up in the disk jacket, putting more load on the spindle. Watch the disk spin while you very slowly close the latch. The disk should just come up to speed evenly as  the latch closes.

 

Do you need some new disks?

 

 

Bob

Share this post


Link to post
Share on other sites

If it's not disks, I'm tipping it's going to be something actually affected by age - Like rubber idlers/belts or capacitors.

Share this post


Link to post
Share on other sites

I have had to replace the belts on two different 1050s years ago after they sat for a while.

Share this post


Link to post
Share on other sites
On 03/02/2021 at 6:25 PM, xrbrevin said:

LDW and California Access drives used a 5v & 12v DC combined power supply but ive never heard of a 1050 converted to this.

Behold: https://atariage.com/forums/topic/197540-1050-reset-mod/ (too bad the pictures are gone @Fox-1 / mnx )

 

 

Also the 7805 and 7812 regulators can be replaced with modern switching versions from tracopower or cheaper similar ones from various (china) sources: 

http://www.mathyvannisselroy.nl/Atari 1050 goes green.htm

 

 

Share this post


Link to post
Share on other sites

What's the accepted drift of speed?

I've done a high speed video and a strobe measurement by phone on one drive, looks like it's about 287 from the strobe, 288 on the dot from the video.   So looks like it's OK there, though I will remeasure it with a floppy present.

Edited by Rybags

Share this post


Link to post
Share on other sites

Well I'm fresh out of ideas.  Both drives seem fine re RPM with or without a floppy inserted (got RPM by doing a 240 FPS recording of rotation which conveniently gives 50 frames for 288 RPM)

 

Could it be something within the logic portion?  Like bad cap or an IC with dirty contact (though aren't these guys soldered in) ?

Share this post


Link to post
Share on other sites
On 2/4/2021 at 2:24 AM, TGB1718 said:

1050 is 9VAC, you can't use a PC PSU as all outputs are DC

9VAC is such a PITA regarding retro hardware as quite often newer switch mode power supplies aren't really suitable either.

Share this post


Link to post
Share on other sites
18 minutes ago, Mazzspeed said:

as quite often newer switch mode power supplies aren't really suitable either.

Have to agree there, when I build something new, I tend to use older 'analogue' power supplies as I've gathered quite

a few over the years and can cover a wide range of DC voltages which obviously don't introduce high frequency noise

into sensitive circuits.

  • Like 2

Share this post


Link to post
Share on other sites
11 minutes ago, TGB1718 said:

Have to agree there, when I build something new, I tend to use older 'analogue' power supplies as I've gathered quite

a few over the years and can cover a wide range of DC voltages which obviously don't introduce high frequency noise

into sensitive circuits.

And this is the problem, you have to use old linear power supplies. I have used a DC PSU before and tapped in before the bridge rectifier.

Share this post


Link to post
Share on other sites
On 03/02/2021 at 5:52 AM, Rybags said:

I was using an ED disk that has games on it (and doesn't matter if it gets wiped).

Do you have any SD disks you can try reading? If you have a spare disk it may also be useful to observe these drive's behaviour when trying to format a disk in SD vs ED if there are calibration differences between FM/MFM.

 

Did you ever by chance swap or replace the 2793/2797 controller chips in these two drives? It's important those remain with ther original 1050 motherboard as they are individually factory calibrated to each chip.

 

Check out this prior post from @tf_hh where he describes how to check the "125 KHz rectangled frequency for single density base clock, a 230 microsecond long impulse for precompensation (when using double density, MFM mode) and others" supplied to the 2793/2797 controllers:

 

 

Share this post


Link to post
Share on other sites

Neither drive has had any modification or been opened up for anything beyond head cleaning.  Format attempts get the same result whether SD or ED.

I've tried what I think are some SD disks but same result (generally the only disks I formatted to SD were full disk games)

 

I checked that linked thread - could it be possible some of my adjustable pots/caps have gone bad?

Share this post


Link to post
Share on other sites

Hi Rybags,

 

I take it you have tried a different computer to see if this eliminates this part of the set up?

 

Regards

Share this post


Link to post
Share on other sites

@Rybags

It seem beyond strange are both dead. The only time I've seen such a thing was when a guy had blown out the sio isolation chips and also had drive select slide switch problems...

try deoxit and working the slide switches first... Have the drives hooked up all by themselves one at a time and try with a know good Single density boot disk. Make sure to plug the drive power supply into the wall last!

If the switches weren't the issue- move on to the chips u1 LM3086 is rattling around in my head, and u7 pia (6532)

T D

Edited by _The Doctor__

Share this post


Link to post
Share on other sites

I haven't tried a different computer - SIO2SD has been on the chain after the drive and it's fine.

The drives respond to commands as would be expected also (just that the result is obviously not what's wanted).

The ID switches are OK as I had different settings along the way which all worked.

 

But I might try another computer just to be sure though I'm not expecting any difference.

Share this post


Link to post
Share on other sites

Did you try without the sio2sd? I think was one of the questions

heads clean and alone on the sio with known good single density bootable disk.

 

also what rev sio2sd are you using?

Edited by _The Doctor__

Share this post


Link to post
Share on other sites

Just a guess.. sounds like the read circuit is shot.  Makes me wonder if write works.  If you take a disk you know has data on it (by using some other floppy drive) and then format it on the busted 1050s, is the data then looking erased on a working drive?

 

Very odd problem indeed.

Share this post


Link to post
Share on other sites

Tried it without SIO2SD, yes.  "Working drive" - that's the problem to begin with, 2 now dud 1050s and an 810 that when powered up 10 years ago did nothing at all.

Like I said, the format fails.  I guess I could try a write operation but not holding high hopes.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites
14 minutes 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.

Have you tried another A8 yet? The odds of both drives failing identically are so remote, and basically I consider all the measurements you've taken thus far to be basically within spec.

Share this post


Link to post
Share on other sites

Tried my 800XL for the exact same result.

 

It's got me beat.  The only common elements - I've only got one 1050 PS though I just tried a 400 PS and got the same result, both drives not used for probably 4 or more years and stashed in my bedroom so not the worst environment with low to medium humidity most of the time and temps from about 8 to 30 C at worst.

 

I also pulled up and reseated the 6810, 6832 and WDC controller chips a little while ago.

Share this post


Link to post
Share on other sites
10 minutes ago, Rybags said:

Tried my 800XL for the exact same result.

 

It's got me beat.  The only common elements - I've only got one 1050 PS though I just tried a 400 PS and got the same result, both drives not used for probably 4 or more years and stashed in my bedroom so not the worst environment with low to medium humidity most of the time and temps from about 8 to 30 C at worst.

 

I also pulled up and reseated the 6810, 6832 and WDC controller chips a little while ago.

Replace any caps in one of the drives and see what happens. There shouldn't be many, I think it's best you work on one drive at a time to reduce diagnosis complexity just in case both problems are the result of different causes with identical symptoms. Which I think you're doing anyway.

 

Caps are cheap and easy to replace, at such an age they should be replaced as a matter of course anyway.

Edited by Mazzspeed

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...