Mark Ormond | 1 Nov 2010 04:58

Floppy controller - 7416 failure symptoms?

Still trouble shooting floppy problems and was wondering if anyone can tell me type symptoms that failing
7416 chips would have in a controller?
It's a fd500.

Also on the fd500 note, does anyone know of a way to add the missing cart connectors? (Pin 37 actually, I need a13.)

I was thinking maybe a rear defroster repair kit to make a contact with 30g kanar wire painted in and super
glued running to the rom?

Later,
dabone

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Gene Heskett | 1 Nov 2010 05:53
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Re: Floppy controller - 7416 failure symptoms?

On Monday, November 01, 2010 12:23:25 am Mark Ormond did opine:

> Still trouble shooting floppy problems and was wondering if anyone can
> tell me type symptoms that failing 7416 chips would have in a
> controller? It's a fd500.
> 
> Also on the fd500 note, does anyone know of a way to add the missing
> cart connectors? (Pin 37 actually, I need a13.)
> 
> I was thinking maybe a rear defroster repair kit to make a contact with
> 30g kanar wire painted in and super glued running to the rom?
> 
> Later,
> dabone

I have used several different methods over the years, with the longest 
lasting being a strip of copper foil from a tape it up and solder it PCB 
kit from 25 years ago.  A 3/8" long piece of that, laid where the trace was 
missing, and pressed in place by rolling it heavily, stuck it tightly 
enough that it never came loose.  I did form the end of it so it rolled 
over the edge by about 5 thousandths so the socket connectors couldn't 
catch it and get under it at insertion time.  That board was in and out of 
an old grey ghost many times as I did not have an MPI back in those days.

I think today, that I would see if I could get under a finger pattern that 
was gold flashed with an exacto knife or similar, and roll it back flat & 
super glue it with a very small drop of glue so it only glued the piece.

The most extreme bit of tom foolery along these lines is still in service.  
I sawed the whole gold plated finger pattern off an expired ISA bus pc card 
(Continue reading)

Darren A | 1 Nov 2010 06:37
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Re: Floppy controller - 7416 failure symptoms?

On 10/31/10, Mark Ormond  wrote:
> Still trouble shooting floppy problems and was wondering if anyone can tell
> me type symptoms that failing 7416 chips would have in a controller?
> It's a fd500.
>

The two 7416 chips are primarily responsible for inversion of the
drive control lines.  Symtoms could include failure to produce proper
Motor On / Drive Select signals and stepper motor pulses.

A couple of the gates are also used for the NMI* and HALT* lines.  The
computer would likely freeze up or crash during disk I/O if one of
these signals were compromised.

Darren

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jdaggett | 2 Nov 2010 00:22
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Re: Floppy controller - 7416 failure symptoms?

On 31 Oct 2010 at 23:58, Mark Ormond wrote:

> Still trouble shooting floppy problems and was wondering if anyone can tell me type symptoms that failing
7416 chips would have in a controller?
> It's a fd500.

The 7416 is Open Collector Hex inverter. It has the capability of sinking 40 mA of current 
when the output voltage is low. 

Failure would be recognized by no switching of the output of a gate(s) when the input 
changes level.  Failure can be the output transistor of the gate failed internally to the device 
or a failure of the pullup resistor. Also check the pullup resistors for open or poor 0solder 
joint. Since the device is an Open Collector to source current it must have an external pullup 
resistor. That value along with voltage will determine source current. 

james

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Mark Ormond | 2 Nov 2010 03:35

Re: Floppy controller - 7416 failure symptoms?

I'm having faulty read/writes I still don't have a second floppy drive to test with so I'm also checking to
see if it could be the controller.
The drive will also only format a few older disks and none of my newer ones (dsdd). These disk work fine in a
commodore 1541 drive.
(and yes they have the single sector hole). The disks it does format are not reliable.

I have a lead on a couple of drives from a Compaq portable one I guess when they come in we will see what is
actually the problem

Later,
dabone

-----Original Message-----
From: coco-bounces@...
[mailto:coco-bounces@...] On Behalf Of jdaggett@...
Sent: Monday, November 01, 2010 7:22 PM
To: CoCoList for Color Computer Enthusiasts
Subject: Re: [Coco] Floppy controller - 7416 failure symptoms?

On 31 Oct 2010 at 23:58, Mark Ormond wrote:

> Still trouble shooting floppy problems and was wondering if anyone can tell me type symptoms that failing
7416 chips would have in a controller?
> It's a fd500.

The 7416 is Open Collector Hex inverter. It has the capability of sinking 40 mA of current 
when the output voltage is low. 

Failure would be recognized by no switching of the output of a gate(s) when the input 
changes level.  Failure can be the output transistor of the gate failed internally to the device 
(Continue reading)

Gene Heskett | 2 Nov 2010 03:57
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Re: Floppy controller - 7416 failure symptoms?

On Monday, November 01, 2010 10:40:07 pm Mark Ormond did opine:

> I'm having faulty read/writes I still don't have a second floppy drive
> to test with so I'm also checking to see if it could be the controller.
> The drive will also only format a few older disks and none of my newer
> ones (dsdd). These disk work fine in a commodore 1541 drive. (and yes
> they have the single sector hole). The disks it does format are not
> reliable.
> 
> 
> I have a lead on a couple of drives from a Compaq portable one I guess
> when they come in we will see what is actually the problem
> 
> Later,
> dabone

A couple things come to mind here.  The plastic 'rosette' that clamps the 
disk to the drive spindle may not be doing its job as the plastic tends to 
relax if left in a closed position for a couple decades. :)  This also 
allows the disk to not be well centered, and can make itself known at times 
by the slightly damaged edges of the spindle hole, because the rosette also 
shrinks as it relaxes.  The phenomenon is called cold flow.

And, if the spindle is belt driven, same deal, the belts stretch and start 
slipping after a couple decades.

One of the hazards of trying to care for 25 year old stuff.  There are some 
belt treatments about but I've not had any great luck with them myself.

Just recently, I was re-installing the latest ubuntu on my milling machines 
(Continue reading)

Mark Ormond | 2 Nov 2010 05:28

Driect Connect Modem pack to Drive pak conversion.

I scored a Direct Connect Modem Pak off ebay with a joystick and Orchestra 90-cc pak for cheap.

I really don't need a modem, so I decided to try to make it into a drive pak.

To do the basic conversion you will need.

1 28 Pin socket.
1 udrive
1 microsd card.
1 27128 thru 27512 (your choice) eprom with coconet. If using a larger rom, just repeat the image till the rom
is filled.

Cut the rom from the modem pack and install the 28 pin socket.
Run a jumper wire from pin  2 of ic3 (74ls133) to pin 26 of the rom socket.
(This enables A13 on the socket, thus giving us 16k eprom capability)

Go ahead and install your eprom and make sure coconet comes up.

Now turn over the board and solder a jumper wire between pins 16 and 17 of the 6551 uart (IC2)

Next up, cut out the modem chip located at IC5 (74HC943n) (Yes this chip is a 300 baud modem)

Now from the empty socket The pins you will need are as follows.

Pin 5 RXD
Pin 6 VCC (+5)
Pin 11 TXD
Pin 14 GND

Socket	Udrive
(Continue reading)

Little John | 2 Nov 2010 05:44

Re: Driect Connect Modem pack to Drive pak conversion.

Replacing the Crystal may require that the 6551 be replaced with a 6551A, 
which is a good idea anyway since the 6551A is rated at the 2Mhz bus speed. 
Of course if it works without replacing it, then I guess the "if it ain't 
broke don't fix it" applies :)
Or did the DCM Pak have a 6551A? My deluxe RS-232 has the 6551...
JohnT
====

----- Original Message ----- 
From: "Mark Ormond" <markormond@...>
To: "CoCoList for Color Computer Enthusiasts" <coco@...>
Sent: Monday, November 01, 2010 11:28 PM
Subject: [Coco] Driect Connect Modem pack to Drive pak conversion.

>I scored a Direct Connect Modem Pak off ebay with a joystick and Orchestra 
>90-cc pak for cheap.
>
> I really don't need a modem, so I decided to try to make it into a drive 
> pak.
>
> To do the basic conversion you will need.
>
> 1 28 Pin socket.
> 1 udrive
> 1 microsd card.
> 1 27128 thru 27512 (your choice) eprom with coconet. If using a larger 
> rom, just repeat the image till the rom is filled.
>
> Cut the rom from the modem pack and install the 28 pin socket.
> Run a jumper wire from pin  2 of ic3 (74ls133) to pin 26 of the rom 
(Continue reading)

Mark Ormond | 2 Nov 2010 12:43

Re: Driect Connect Modem pack to Drive pak conversion.

It has a 6551. I just replaced the crystal (I remembered my extra swiftlink clone board had one) and it's
currently doing read tests.
Seems to be working fine, but I'll wait for more testing before I declare it working.

Now I just need to mod the udrive leds over to the cd and on leds on the outside of the case. (And maybe dim them some.)

Gotta quit playing and get to work now.

Later,
dabone

-----Original Message-----
From: coco-bounces@...
[mailto:coco-bounces@...] On Behalf Of Little John
Sent: Tuesday, November 02, 2010 12:44 AM
To: CoCoList for Color Computer Enthusiasts
Subject: Re: [Coco] Driect Connect Modem pack to Drive pak conversion.

Replacing the Crystal may require that the 6551 be replaced with a 6551A, 
which is a good idea anyway since the 6551A is rated at the 2Mhz bus speed. 
Of course if it works without replacing it, then I guess the "if it ain't 
broke don't fix it" applies :)
Or did the DCM Pak have a 6551A? My deluxe RS-232 has the 6551...
JohnT
====

----- Original Message ----- 
From: "Mark Ormond" <markormond@...>
To: "CoCoList for Color Computer Enthusiasts" <coco@...>
Sent: Monday, November 01, 2010 11:28 PM
(Continue reading)

Darren A | 2 Nov 2010 13:55
Picon

Re: Driect Connect Modem pack to Drive pak conversion.

On 11/2/10, Mark Ormond  wrote:
> It has a 6551. I just replaced the crystal (I remembered my extra swiftlink
> clone board had one) and it's currently doing read tests.
> Seems to be working fine, but I'll wait for more testing before I declare it
> working.
>

---

If the 6551 proves unreliable with the 3.6864 Mhz crystal, you don't
necessarily need to revert all the way back to 1.8432 Mhz.  The uDrive
will support bit rates from 300 to 256K bps, including non-standard
rates.

A 4.096 Mhz crystal would deliver the maximum rate. I have no idea if
the 6551 (or 6551A) could handle that.  There is also the question of
how fast the CoCoNet software can service the ACIA.

Darren

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