Floppy problem with Superboard II

[cyb2600]

Hi all,

I have a Superboard II connected to an external backplane with a D & N Products MEM-CM9 RAM and floppy controller card. Everything was working until one day it suddenly stopped reading disks. The drive light comes on and I hear the head move once, but that's it. I tried running the floppy test and I get the below. I also ran a memory test and everything checks out fine. Any ideas?


Drv=A/5.25 Pattern $18 Passes 1 Normal test R/W > 1
WRITE PROTECT ALL DISKS EXCEPT TEST DISK!

INSERT DISK TO BE TESTED
If errors found the output is DDDD (#### GG BBP)* EEEE
where DDDD is difference between number of bytes written
and read. EEEE is total errors, #### is byte count from
start of track, GG is good byte, BB is bad byte,
P is byte had parity error.
Errors that fit on line are printed.
ESC KEY OR ^X ABORTS...

PRESS ANY KEY WHEN READY >
RTRK 0 -2167
RTRK 1 -2167
RTRK 2 -2167
RTRK 3 -2167
RTRK 4 -2167
RTRK 5 -2167
RTRK 6 -2167
RTRK 7 -2167
RTRK 8 -2167
RTRK 9 -2167
RTRK 10 -2167
RTRK 11 -2167
RTRK 12 -2167
RTRK 13 -2167
RTRK 14 -2167
RTRK 15 -2167
RTRK 16 -2167
RTRK 17 -2167
RTRK 18 -2167
RTRK 19 -2167
RTRK 20 -2167
RTRK 21 -2167
RTRK 22 -2167
RTRK 23 -2167
RTRK 24 -2167
RTRK 25 -2167
RTRK 26 -2167
RTRK 27 -2167
RTRK 28 -2167
RTRK 29 -2167
RTRK 30 -2167
RTRK 31 -2167
RTRK 32 -2167
RTRK 33 -2167
RTRK 34 -2167
RTRK 35 -2167
RTRK 36 -2167
RTRK 37 -2167
RTRK 38 -2167
RTRK 39 -2167

[Mark]

The things that have happened to me:
1-Head is dirty
2-The fiber pressure pad that presses the diskette to the disk head on a single sided drive has fallen off (rebuilt with piece of cassette tape pad & contact cement)
3-The head load solenoid no longer presses hard enough due to foam rubber decay. (replaced foam)
4-logic failure on drive

What drive do you have? You may not have a head load solenoid, or if it's a double sided drive, a pressure pad.
Does RPM test work?

-Mark

[davisgw]

Assuming your floppy controller has the same floppy hardware as the OSI 610 expansion board, it's likely that the data separator is miss-adjusted or the drive is not sending index timing or data clocks for some reason. Can you scope the interface to verify the signals? You are debugging blind without more information to point to what failed.

[cyb2600]

The drive's an MPI 51. This is the result of the speed test

Head unloaded RPM: AVG 300.48 MIN 300.24 MAX 300.60
Head loaded RPM: AVG 300.48 MIN 300.24 MAX 300.72

I have an oscilloscope, I'll look for instructions of what signals I need to be looking for. When I run the disktest in oscilloscope mode I get the following

RTRK 0 No data
RTRK 1 No data
RTRK 2 No data
RTRK 3 No data
RTRK 4 No data
RTRK 5 No data
RTRK 6 No data
RTRK 7 No data
RTRK 8 No data
RTRK 9 No data
RTRK 10 No data
... and so on

[cyb2600]

Hello again,

I finally got around to testing this with an oscilloscope. When I do the read test I see no activity on the Read Data line of the floppy cable. So I think my floppy drive is bad, not the controller. The manual for the MPI 51 says to check if the HDO READ signal goes low when it tries to read data and I confirmed that it does. It looks like it's trying to read data but it doesn't get anything from the disk

[Mark]

Does your drive have the data separator installed? It is the little board that plugs into the main board J5 in the front left corner similar to this:

MPI 51

MPI51-drive_ds.jpg (380.86 KiB) Viewed 4632 times

It looks like there could be two different boards available. One that provides a Drive Ready signal using the disk index signal, and another that has the FM Data Separator circuit, and drives floppy line 34/ Separated Data (was Reserved/Rdy) and line 30 Separated Clock (was raw Read Data).

According to the notes I have, jumper "L" on the schematic must be cut to use the data separator, which is locate near pin 1 of U2G

If the data separator was missing/loose & jumper "L" was cut, no data would be present on the connector pin30(raw read data). Also note the signals are driven with an open collector driver, so you must provide a pull-up to see a change in the signal status. If you're reading the signal while connected to the OSI, the OSI interface board would provide the pull-up resistors. The raw Read Data signal should be available on TP5 or Pin3 of J5. You can see if you are getting anything off a disk before the data separator. Also is the head load solenoid active and the head in contact with the disk?

Other changes to MPI 51 drive for OSI include the side select line is cut, and the jumper for Head Load with Select is set in addition to the correct Drive Select Jumper. Separated data is on floppy Pin34 and Separated clock on floppy pin 30

J5 connector pinout
------------------------
1 +5
2 Drive select output
3 Raw data output
4
5 Separated clock input
6 Separated data input
7
8 Index output
9 Gnd
10 +12v

If possible, could you take a close-up picture of the top & bottom of the data separator? I have found no information about this in the MPI product documentation, and it would be good to document it.

Good Luck!

[cyb2600]

Tuns out it was a problem with the floppy drive itself. This amplifier was dead

mpi.png (95.13 KiB) Viewed 453 times