Panasonic ju455 FDD

[Mike_Z]

Yesterday a neighbor was getting rid of an old Win98 machine, HP8650C. He asked me if I wanted it, since I'm a collector of odd stuff (according to the neighbors at least). I thought that I'd make a DOS machine out of it, since I needed a 5.25 floppy drive. This machine has a 20 gb HD and a 3.5 FDD. I pulled it appart and cleaned it out. Wiped the HD and used FDISK and Format to get a working DOS 6.22 in it. Gee, I hadn't done that in a while, kind of forgetten some stuff, but it came back. I checked the BIOS and it supports 2 floppy's and 360K and 1.2M 5.25" are options. The 3.5" works so I was going to leave it in and make the 5.25" A:\. Well first I had to find a multi FDD cable in all my old stuff. I connected up the drives and set the BIOS and neither of the drives would work. Pulled the 5.25 and the 3.5 was fine. Figured that the Panasonic JU455 was not too good. I then cleaned the rails and the heads and everything seemed clean and smooth operating. Tried it again, same thing. So I pulled my XT apart and installed the Panasonic in it and the FDD works like a charm. I could read/write/ format everything. Then I thought that maybe the new machine didn't need the terminating resistors, the Panasonic has a 150 ohm chip, so out it came. Now on boot the Panasonic motor starts but the LED never comes on and the stepper doesn't move the head at all. When I ask for A:\, the motor starts but nothing else and I get a "seek error reading A:", yet I know that the stepper works and the rails are free. So I tried changing the BIOS settings and no dice. I'm kind of out of bullets trying to get this thimg to work. It just occured to me, I'll try adding "DRIVPARM" to the config.sys and see it that works any better. Anyone have any ideas, short of getting another floppy drive?

By the way, I'm new with this forum, how do you get spell check to work on this? Kan't seam ta foind ait.
Thanks Mike

 

[Chuck(G)]

I have a couple of suggestions.

1. Are you certain that your cable is a FDD cable (with the correct "twist") and not a ST412/506 HDD cable with a different twist?

2. I suppose it's possible that your FDC can't support the higher current demand of the 150 ohm pullup. Consider replacing the terminator with a 1K or 2.2K one.

 

[Stone]

It's *possible* that this machine only supports one floppy drive at a time so give it a try without 3½" floppy attached or configured although if it lets you configure both simultaneously I would expect that it would work that way.

Test the dual FDD cable in another machine to verify that the end (A) connector is working on the cable itself.

Also, Chuck(G)'s suggestions look good so be sure to check them out.

FWIW, there is no spell check here. If you want one you'll need to use one locally, on your machine. Additionally, the search feature here sucks big time and is extremely limited in its usefullness. You'll need to experiment with it to see what it can/can't handle. But a Google search will reveal nearly everything you could hope for here so try that.

 

[Mike_Z]

Thanks for responding. I know that the FDD cable is OK, because I had to borrow it from another working computer. Seems all I have left are singles or one that only has one type on it (5.25 0r 3.5), but I'll try another one just to be sure.

I tried not using any terminating resistors and all that happens is the motor runs. I'll try some higher values.

I have tried many configurations of drives (one or two; 3.5 as A or B; 5.25 as A or B), and different BIOS FDD settings.

The dual cable works with the 3.5, but maybe there is an open in the 5.25, could be.

The DISKPARM didn't help. I'm going to try the Panasonic FDD in Win2000 machine I have. I wonder if the Chuck is on to something, maybe the new computer just can not provide the necessary current to get the FDD going.

Thanks Mike

 

[Mike_Z]

Well...... I tried a couple of other FDD cables, no soap. I tried the Panasonic FDD in my Win 2000 machine and it does n't work in there either. So I tried a Teac FDD in the HP 8650C and it works fine. So I think that the Panasonic FDD is the problem. The old XT just led me stray. Apparently it has enough horse power to drive the marginal Panasonic. I tried it again just to prove it to myself. Apparently this old stuff does fail or just get tired. Well, I re learned a bunch of stuff and I want to thank you for the help.

Mike

 

[vwestlife]

Note that by the time 5.25" floppy drives became obsolete in the late '90s, some PCs came with a straight, non-twisted floppy cable with only one connector on it, for the factory-supplied 3.5" drive. So if you want to add a second floppy drive to these machines, you not only need to replace the floppy cable with a regular one that supports two drives, you also need to set up the drives in the opposite of the normal convention: the A: drive goes before the twist in the cable, and the B: drive goes after the twist. This caused me many headaches in trying to add a 5.25" B: drive to my PIII Compaq DeskPro until I figured it out!

 

[modem7]

If the JU-455 has its RY jumper on, try removing that jumper.

 

[MikeS]

For the moment forget about connecting both drives; if the 3.5" drive works with whatever cable you're using, but the 5.25 (plugged into the same location on the same cable and with the BIOS correctly set to 360K 5.25) does not, then yes, there's an issue with the drive. What are the jumper settings?

 

[Mike_Z]

Yes, I agree about the cable, but what vwestlife mentioned is good to remember. I tried removing the RY jumper (it was made up), but it didn't help. There are bunch of jumpers.

DR Closed
RR Open
SW Open
RD Closed
RY Closed

WP Closed

DS Closed
MX OPen
MS Open
MM Closed

J7 Open

DS1 Open
DS2 Closed
DS3 Open
DS4 Open

I've been looking around for a listing for the jumpers, but so far hav not found anything that would help. If you know what these mean (other than DS) I'd like to know.

Mike

 

[MikeS]

Yes, I agree about the cable, but what vwestlife mentioned is good to remember. I tried removing the RY jumper (it was made up), but it didn't help. There are bunch of jumpers.

Those jumpers don't match any JU-455 that I'm familiar with but there were quite a few variations; is there a suffix after the JU-455 and if so, what is it?

In any case, the important jumpers seem to be set correctly; is there no TM jumper?

If the drive works in an XT then it would seem to be a simple cabling or BIOS issue.

- Does your cable (single or double) have both 3.5" and 5.25" drive A connectors after the twist (i.e. at the end)?
- Does your BIOS have all four options (3.5&5.25 DD/HD) for both drives A and B?
- With the 3.5" drive (and only the 3.5 drive) plugged into the A connector and the BIOS set for drive A=3.5" HD, does it work correctly?
- With the 5.25" drive (and only the 5.25 drive) plugged into the equivalent A connector and the BIOS set for drive A=5.25" DD 360K, what happens, exactly?
- If you remove the RY jumper, is anything at all different?

All this assumes that you have a good diskette in the drives (48TPI DS/DD for the 5.25" drive).

 

[Stone]

All this assumes that you have a good diskette in the drives (48TPI DS/DD for the 5.25" drive).

Not necessarily. A properly configured drive can return an error message like ... 'Drive Not Ready' with no disk in the drive or 'This disk is not bootable' or 'Non System Disk or Disk Error' with a bad disk in the drive.

 

[MikeS]

Not necessarily. A properly configured drive can return an error message like ... 'Drive Not Ready' with no disk in the drive or 'This disk is not bootable' or 'Non System Disk or Disk Error' with a bad disk in the drive.

Umm, yes...

"Not necessarily"? You don't think it's a good idea when testing whether a drive is working to make sure there's actually a diskette in it, preferably a good one of the correct type for that drive?

 

[Stone]

Umm, yes...

"Not necessarily"? You don't think it's a good idea when testing whether a drive is working to make sure there's actually a diskette in it, preferably a good one of the correct type for that drive?

Why, yes, Mike, I do. But just because you and I may think something is a good idea doesn't even begin to speak as to what some others of a different persuasion might have in mind. And I know that you know all-too-well that this *is* the case.

 

[MikeS]

Why, yes, Mike, I do. But just because you and I may think something is a good idea doesn't even begin to speak as to what some others of a different persuasion might have in mind. And I know that you know all-too-well that this *is* the case.

Maybe I shouldn't have said "this is assuming"; one can't assume anything when remotely troubleshooting, so I just wanted to make it clear that the testing should be done with a diskette of the correct type in the drives. If it works correctly in the XT then it does sound like something simple and obvious is being overlooked.

 

[Mike_Z]

I'm sorry, for being brief. The entire number is 'JU-455-5 AAG'.

There is a spot for a TM jumper on the circuit board, but there is no hardware for one. There is also not wire solder across the spot, as there is in other places.

I have tried a number of cables (8 actually), both single and double and have tried 3.5 and 5.25 in each place. The Panasonic is very stuborn.

The BIOS I have has 5 options, the ones you mentioned and a 3.5 2.88M.

The original computer only had the one 3.5" FDD and the cable was for a single FDD. With that setup the 3.5 FDD works fine in all modes.

When only the 5.25 is connected to the computer, as the computer boots, the FDD drive motor will start, but the LED never lights and the head motor never moves the head. The computer will boot from C:\. After the machine is running on C:\, if I ask for DIR A:\ the FDD drive motor will start but nothing else occurs. After a long time out, I get the message "Seek error reading drive A". Which makes sense because the head stepper never moves.

The RY jumper (what ever it does) has no effect on the above opertaions.

I have also tried many different DS/DD floppies and I know that they work, I've tried them all in a few other machines.

It's not that I need this Panasonic Drive, It's just that I'd like to figure it out.

Thanks for the help, Mike

 

[MikeS]

I'm sorry, for being brief. The entire number is 'JU-455-5 AAG'.

Thanks.

There is a spot for a TM jumper on the circuit board, but there is no hardware for one. There is also not wire solder across the spot, as there is in other places.

Odd; but probably not an issue with only one drive connected.

When only the 5.25 is connected to the computer, as the computer boots, the FDD drive motor will start, but the LED never lights and the head motor never moves the head.

Sure sounds like the drive's not being selected, but then how could it work in the XT...
You didn't say; are you changing cables when you change drives or does your cable have both types of connector at the end (after the twist)?
Can you try grounding the DS2 jumper to see if the light comes on?
If you move the MM jumper to MS does the motor still start?

The RY jumper (what ever it does) has no effect on the above opertaions.

Connects the Ready signal to pin 34 AFAIK.

It's not that I need this Panasonic Drive, It's just that I'd like to figure it out.

So would I ;-)

 

[modem7]

The RY jumper (what ever it does) has no effect on the above opertaions.

Connects the Ready signal to pin 34 AFAIK.

Yes. Worth a shot. See top of http://www.minuszerodegrees.net/5170/problems/5170_known_problems_issues.htm

 

[Chuck(G)]

I'm assuming that you can boot the system from hard disk, no matter what the floppy drive does.

So hook the floppy drive up as drive A:, boot the system, get into DEBUG and use the following command:

O 3F2 1C

The motor should turn on, and if the drive select is configured to DS2, the select light should go on, assuming that there's a disk in the drive. To check for other drive select errors, also try:

O 3F2 1D
O 3F2 1E
O 3F2 1F

You're testing nothing but the drive-select and motor control circuitry on the disk. Basically, the 3F2 register is laid out like this:

m n o p i d s t

Where m corresponds to the motor control line for the 4th drive, n for the 3rd drive, o for the 2nd drive and p for the first drive. i = 1 for interrupt enable, d = 1 for DMA enable and s t correspond to a 2 bit binary code for drive select.

 

[Mike_Z]

Well.... you guys are amazing! I really appreciate the time and effort you have given this.

You didn't say; are you changing cables when you change drives or does your cable have both types of connector at the end (after the twist)?

The cable that I have been using has four device plugs on it. Two (5.25 & 3.5) prior to the flip and two after.

Can you try grounding the DS2 jumper to see if the light comes on?

Yes the LED does come on.

If you move the MM jumper to MS does the motor still start?

Didn't try yet.

I tried the DEBUG commands and the Panasonic motor will start but the LED does not light. I find this a little frustrating so I bolted the FDD back into the XT and it does work. I tried the DEBUG command on it and that works too. So I decided to put a real test onto it. With the FDD in the XT, I formated a disk, transferred files, deleted stuff, install the OS, over and over and over, after a bunch of transfers I started to get some of the same errors, seek error. I noticed that the LED would flicker a little while formating and the heads would bounce, resulting in bad sectors. There must be a problem on the FDD. I pulled the circuit boards and look closely for cracks, cold solder joints or any other visual problem, but no soap. There must be a bad part somewhere. I think it is time to write this thing off. Again, thanks for all the help. Mike

 

[Chuck(G)]

Here's a simple test--connect the drive up to a power supply, but don't connect the signal cable. Using a test probe, jumper pin 12 to ground. Does the LED go on?

If not, try the following. With no power or drive cable connected, use an ohmmeter to measure the resistance between pin 12 and the +5 power supply rail on the drive. If it's 150 ohms or less, you have your answer--your FDC on your newer machine doesn't have the drive capability to pull the DS2 line down to activate the drive. You need to modify the on-drive terminator pullup to a higher value.

Modern 3.5" drives tend to use about 2Kohm for these, while the old Shugart standard was 150 ohms--and SN7438 drivers for the signal lines, which can sink 48 mA per output.