PEB disk drive problem question

[+FarmerPotato]

So Howard's PBox came out of my garage. I've lost track of who I got it from or when it was last used. I *think* it came from a TI employee in Plano, with a sticker marked "Works", and that I used it to load some Best of HCM disks. When I tested it recently, I got the drive behavior Howard describes, so I made sure he took another internal drive (I figured just the drive was bad).

 

I tested it with an external 3.5 floppy (from mdude) and the controller was able to initialize and use a disk as DSK3. So I don't think the controller is the problem. Maybe the power to the drive? Maybe the drive motors draw more current when they get old and squeaky? 

 

I have the same problem now, with a formerly good PBox, which can't initialize or read using a TI original full height, or my last known good TEAC 55-BR from 1984. But the controller works ok with the external 3.5.

 

When I use Kryoflux (floppy disk reader with USB interface board) to control the TEAC-55BR, it works. The drive is fine on external power. On my bench supply, it draws more than 500mA on 12V to start the drive. My bench supply maxes out at 500mA, but once the drive gets spun up, it doesn't need 500 mA.

 

So it's possible that an external power supply for the drive will help. An external CDROM enclosure might be just right. A PC power supply would be worth trying.

 

(For a PC supply, you need the button to switch it on, plus a load to start with. I have a "load brick" to put on the 40 pin motherboard connector. I think powering up a spare hard drive does the trick. See https://www.electronics-tutorials.ws/blog/convert-atx-psu-to-bench-supply.html )

 

Ugh, external 5.25" enclosures are not easy to find anymore. I found one for $77 http://www.servercase.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=CK7021&Category_Code=

 

[+hloberg]

 I think I have some old ATX power supplies stored away to test with. I'll check and post the results. honestly I just want to confirm that the disk controller is OK (which I think is) since I plan to replace, eventually, the drive with a HxC drive or just a newer drive anyway.

so far everything else seems to work OK so the disk controller probably does too. Oh, and I got the power button to work just fine too. check out my blog on tearing it apart in part 4 and 5:

 

Edited January 13, 2020 by hloberg

[Ed in SoDak]

Something to do might be to monitor the drive voltages when it's called into duty. If either sags, either the drive will spin slower or logic states might become unstable.

 

Reading you had two full-height drives, I sorta assumed you had an external supply, maybe even an enclosure. I think the PEB's supply is minimal at best with powering drives. I did have one PEB working with dual half-heights in the bay, but now I have a full-height double-sided drive in there and it works fine.

 

I've formatted two disks in SSSD. I can put a few things on one just to see if you can load them or get a directory, save a "Hello World" program to it, etc.

-Ed

[+hloberg]

11 hours ago, Ed in SoDak said:

Something to do might be to monitor the drive voltages when it's called into duty. If either sags, either the drive will spin slower or logic states might become unstable.

 

Reading you had two full-height drives, I sorta assumed you had an external supply, maybe even an enclosure. I think the PEB's supply is minimal at best with powering drives. I did have one PEB working with dual half-heights in the bay, but now I have a full-height double-sided drive in there and it works fine.

 

I've formatted two disks in SSSD. I can put a few things on one just to see if you can load them or get a directory, save a "Hello World" program to it, etc.

-Ed

thanks. after reading @FarmerPotato post i'm thinking that it might be a power issue. then again, maybe not. at least the disk will eliminate the fact I don't have any SSSD disk issues. and later on when I get other newer drives I'll have a proper analog to test with. i have some ideas on test i perform on the power issue.

[Ed in SoDak]

I'm gonna try to get 'em in the mail today.

-Ed

[atrax27407]

The PEB will not usually power two full height drives. It will however, power two 1/2 height drives which usually require less voltage.

[Ed in SoDak]

45 minutes ago, atrax27407 said:

The PEB will not usually power two full height drives. It will however, power two 1/2 height drives which usually require less voltage.

He's only trying one at a time. On my old full-size drives way back before I got some half-height, I often had to adjust the speed trimmer and sure saw some PS sag that would slow down the drive.

 

My own DSK1 and 2 are external. DSK3 is in the PEB so it's not used much.

 

As a test to lighten the PEB's load, could pull the 32k card and anything else other than the controller and interface cards. Metering drive voltages while spinning would tell the tale.

-Ed

[+hloberg]

ugh. now the power switch is giving me an issue again and sticking. I haven't even tried the P-Card or the RS232.

By the way, what would be a good way to test the RS232? I don't have the TI printer cable so printing is out (although I do have a printer with parallel connection).  don't have a terminal emulator cartridge so that's out. is there a way in XB for me to just test the RS232 is detected? 

[+arcadeshopper]

ugh. now the power switch is giving me an issue again and sticking. I haven't even tried the P-Card or the RS232.
By the way, what would be a good way to test the RS232? I don't have the TI printer cable so printing is out (although I do have a printer with parallel connection).  don't have a terminal emulator cartridge so that's out. is there a way in XB for me to just test the RS232 is detected? 

Yes save RS232 or PIO

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[+hloberg]

OK, tested the drives by hooking up a PC power supply to the drives and still got the same errors. so power is not the issue. that leaves the ribbon cable on the drive to the PEB and the disk drive card it self. could still be the disk drives but it would be unusual that both drives come back with the same errors. 

on a positive note the P-Card looks to work as well as the RS232 (thanks @arcadeshopper for the suggestion).

[Ed in SoDak]

Arrgh. At least you've absolved the PEB since other cards seem to work. What's the current plan? Borrow a working controller? Hard to imagine the short cable going bad, but it's possible one of the connectors has been bent so as to no longer make contact or it's simply a bit dirty. I'd think all the swapping has rubbed away any minor contact grundge issues. You're getting some function since the drive is lit up and the motor spins. Is there any side-to-side slop when attaching it, that perhaps it's not aligning well with the connector fingers on the drives? Again, not likely, but easy to check.

 

I wondered about the pic you posted on the bottom of the first page of this thread showing the WD1171 chip having an exposed window, but I see that in at least one other pic on Mainbyte's pages. Thierry's site seems to show it covered by tape, but the pic is very low-res. I've never opened my own controller to compare.

 

I own a non-working sidecar disk controller that also uses the WD1771, but don't recall if the chip is socketed or soldered in or if the window is exposed or not. Chip-level troubleshooting takes some sleuthing with a logic probe and/or an oscilloscope and good knowledge of what to look for. Card replacement is probably the easiest way to go. Stephen Shaw had some good info on tracing out and repairing wonky controllers.

-Ed

[+hloberg]

some plans, 1st I'm getting a NanoPEB so i can use the computer. 2nd, in March at our retro club meeting I'm going to borrow another disk drive card, ribbon cable and a 1/2 hi 5.25 drive and test each part that way. should be able to narrow down the issue then. I never had any intention of using the old full hi drives anyway. I just want to verify everything worked before I started investing in 1/2 hi drives and HxC drives. my plan all along was to make drive 1 a 1/2 hi drive and drive 2 a HxC drive and put them both in the case. if for whatever reason I can't do that for any realistic amount of work or cost, then, i'll have to evaluate my next steps with the PEB.

[Omega-TI]

17 minutes ago, hloberg said:

...before I started investing in 1/2 hi drives and HxC drives. my plan all along was to make drive 1 a 1/2 hi drive and drive 2 a HxC drive and put them both in the case. if for whatever reason I can't do that for any realistic amount of work or cost, then, i'll have to evaluate my next steps with the PEB.

Once you confirm your TI-FDC is operating, or once it's repaired/replaced, I highly recommend the 80 track modification for your TI, especially if you plan on getting an HxC.  Why?  Because that little baby can emulate two drive at once (DSK1 & DSK2) leaving that 1/2 height drive as DSK3, giving you access to 1M of storage space at the same time (assuming all are setup as DSSD 80 track.

 

Another path you could take, assuming things and cost do not work out with the FDC issue is to nix the drives altogether and slip a TIPI & RPi in the box.  

[+hloberg]

27 minutes ago, --- Ω --- said:

Once you confirm your TI-FDC is operating, or once it's repaired/replaced, I highly recommend the 80 track modification for your TI, especially if you plan on getting an HxC.  Why?  Because that little baby can emulate two drive at once (DSK1 & DSK2) leaving that 1/2 height drive as DSK3, giving you access to 1M of storage space at the same time (assuming all are setup as DSSD 80 track.

 

Another path you could take, assuming things and cost do not work out with the FDC issue is to nix the drives altogether and slip a TIPI & RPi in the box.  

thanks, i'll look into the 80 track mode if all works out.

[Omega-TI]

Has the topic of termination resistors come up yet?

[+hloberg]

18 hours ago, --- Ω --- said:

Has the topic of termination resistors come up yet?

i think they are set right. i got this with the drive already in the peb and at one time was working.

[+arcadeshopper]

Most of the time these issues are the cable

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