Author Topic: help with floppy adapter PCB  (Read 3215 times)

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Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #25 on: 04:55, 30 April 17 »
Audronic,

I live on the other side of the country so the offer would be expensive for me to collect...LOL

Yes I am using 720 K discs. The continuous light seems to both me much as i would have thought that it come on when drive is selected and motor is enabled.

Ray

Offline Audronic

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Re: help with floppy adapter PCB
« Reply #26 on: 06:05, 30 April 17 »
@rpalmer


Hi Ray P


do you have Parados fitted to your machine ?
I often use that in the Verify mode to look at Problem disks etc.


Ray W
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Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #27 on: 01:11, 01 May 17 »
audronic,

I do have the ability to create a ParaDOS rom and can replace the internal ROM, but chose not to do so as I want to be able to get the replacement drive to work on the basic unmodified CPC.

I may plan to change to ParaDOS later, but for now I am happy with plain AMSDOS.

rpalmer

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #28 on: 02:14, 03 May 17 »
Some sad news about the my cpc.

I had just fried the Z80 CPU (accidentally touched GND and 5V using multimeter)... bugger  :'(

I have order some DUIP40 8MHz Z80 and expect to get up and going again soon.

rpalmer

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #29 on: 15:41, 04 May 17 »
While I wait for the delivery of my replacement Z80's.

I have re-visited the web site (http://www.cpcwiki.eu/index.php/DIY:Floppy_Drives#Multi-Adaptor_Cable_for_External_Floppies_.2F_HxC_emulator) detailing how to replace the internal floppy drive with the HxC/PC Floppy and find there appears to be an inconsistency with the cable shown.

The inconsistency is with the cable adapter mentions that the 6 rows of the 26-Way cable from the red line are shift by 1 pair of pins in the PC interface floppy cable.

I checked what the shift in the cable means for a PC floppy interface and find the following occurs:

 CPC Pin 2 (/DRV1)   connects to Pin 10 /MED0 on the PC floppy interface
 CPC Pin 4 (NC)        connects to Pin 12 /DRV1 on the PC floppy interface
 CPC Pin 6 (/MED1)  connects to Pin 16 /MED0 on the PC floppy interface

Pin 14 (/DRV0) is left unconnected on the PC Floppy interface as shown.

What this means is that both /DRV0 and /DRV1 on the PC floppy interface are effectively not driven (in fact they are 'floating'), so how can this interface adapter work if both drive selects are not used? I can only assume that Pin 14 on the PC interface is tied "low", but this is not specified anywhere on the site. Robcfg highlights in yellow what appears to indicate that it is, but the connection would be very hard to join even for those game to try.

Meanwhile I read further down and find that only Pins 1 to 2 of the CPC cable should be moved 1 pair of pins to align with the /IND signal and ground lines with the PC floppy interface while the other signals lines are mapped 1 to 1 with the PC interface. This means that pin 26 of the CPC floppy cable matches with Pin 34 of the interface and so on going backwards up to cable. This mapping of the cable matches more closely how the connection should be done for a 3.5 inch floppy and leaves only the Ready/Side select signal to be modified as required for a standard PC floppy drive.

Have I missed something from the web-site?

rpalmer
« Last Edit: 15:43, 04 May 17 by rpalmer »

Offline Bryce

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Re: help with floppy adapter PCB
« Reply #30 on: 16:43, 04 May 17 »
While I wait for the delivery of my replacement Z80's.

I have re-visited the web site (http://www.cpcwiki.eu/index.php/DIY:Floppy_Drives#Multi-Adaptor_Cable_for_External_Floppies_.2F_HxC_emulator) detailing how to replace the internal floppy drive with the HxC/PC Floppy and find there appears to be an inconsistency with the cable shown.

The inconsistency is with the cable adapter mentions that the 6 rows of the 26-Way cable from the red line are shift by 1 pair of pins in the PC interface floppy cable.

I checked what the shift in the cable means for a PC floppy interface and find the following occurs:

 CPC Pin 2 (/DRV1)   connects to Pin 10 /MED0 on the PC floppy interface
 CPC Pin 4 (NC)        connects to Pin 12 /DRV1 on the PC floppy interface
 CPC Pin 6 (/MED1)  connects to Pin 16 /MED0 on the PC floppy interface

Pin 14 (/DRV0) is left unconnected on the PC Floppy interface as shown.

How do you come to this conclusion? If I skip the first 6 cavities, then pin 2 of the CPC (Index) goes to pin 8 (Index) of the PC floppy connector. Pin 4 (DSEL0) goes to PC Pin 10 (DS0) and CPC Pin 6 (NC) goes to PC Pin 12 (DS1). Pin 14 of a PC floppy drive (the one that gets skipped in the middle of the flat cable) is DS2.

Just a wild guess here, but as well as mixing the pin numbers, are you possibly looking at the pinout of a shuggart controller instead of a PC floppy drive pinout?

Bryce.

Edit: For reference, here is the pinout of a PC floppy drive vs. Shuggart controller pinout:
http://marcosim.homepc.it:8080/sites/Marco/FloppyArduino/index.php/downloads/Floppy_Pinout.pdf

Edit 2: If anyone is wondering why I connect CPC Pin4 although it's not connected in the CPC, this was to allow certain ABBA switch methods to work with the cable.
« Last Edit: 16:48, 04 May 17 by Bryce »

Offline Bryce

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Re: help with floppy adapter PCB
« Reply #31 on: 16:55, 04 May 17 »
Ok, I've just spotted that someone (not me) added a section with "Signal assignment on connectors" and has wrongly listed the Shuggart CONTROLLER pinout instead of the Floppy disk shuggart pinout. That could be the reason for some of the confusion.

Virtual slapping to whoever did that, I'll change it now....

Bryce.

Edit: Pinout corrected on Wiki page. Maybe now it makes more sense?
« Last Edit: 17:06, 04 May 17 by Bryce »

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #32 on: 23:59, 04 May 17 »
Bryce,

At the web side the connections in "Internal floppy connector CD201 to standard floppy connector 34pin" section showed that only 2 lines are moved and it is this which is inconsistent with moving 6 lines in the cable layout in the section "Adaptor Cable for Internal Floppies / HxC emulator".

The section "Standard floppy connector 34pin" is now currently incorrect as it previously it was correct.

rpalmer

Offline Audronic

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Re: help with floppy adapter PCB
« Reply #33 on: 05:15, 05 May 17 »
The one i use is the "Current" for all the old machines i work on.


Good luck


Ray W
Procrastinators Unite,
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Offline Bryce

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Re: help with floppy adapter PCB
« Reply #34 on: 10:27, 05 May 17 »
Bryce,

At the web side the connections in "Internal floppy connector CD201 to standard floppy connector 34pin" section showed that only 2 lines are moved and it is this which is inconsistent with moving 6 lines in the cable layout in the section "Adaptor Cable for Internal Floppies / HxC emulator".

The section "Standard floppy connector 34pin" is now currently incorrect as it previously it was correct.

rpalmer

Sorry, but you are wrong. The google image you have linked to is NOT the pinout of a floppy drive, it's the pinout of a floppy drive controller which is different. Unfortunately this mistake is repeated all over the internet which is extrememly annoying. I deliberately included this link earlier: http://marcosim.homepc.it:8080/sites/Marco/FloppyArduino/index.php/downloads/Floppy_Pinout.pdf  because it shows both the controller and floppy pinouts so that the differences can be seen.

Equally, whoever made these tables in the CPCWiki (someone called Petermeier according to the Wiki records), didn't even manage to copy the CD201 pinout correctly from the schematics. If you look at the attachment below you will see that DSEL1 (marked in green) definitely doesn't go to CD201, it only goes to the 34way connector (as it should be). Only DSEL0 (red) goes to the CD201. And pin 8 is not MED1 because the 765 doesn't have MED signals. The CPC MotorON (which is what pin 8 really is) is derived externally from IC212 and enables the motor of all drives at the same time.

The easiest way to resolve the inconsistencies would be to remove all those tables from Peter completely as they are full of errors. Or someone needs to take the time to go through them all and correct them.

Eitherway, the two cables diagrams that I made, both the external multicable and the internal 26 to 34way cable have been built many many times and are working fine for anyone who has one, so they are definitely correct.

Bryce.

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #35 on: 11:24, 05 May 17 »
ah the waters part and the path is made clear...thanks bryce

Offline Bryce

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Re: help with floppy adapter PCB
« Reply #36 on: 11:29, 05 May 17 »
ah the waters part and the path is made clear...thanks bryce

Call me Moses :D

Bryce.

Edit: For those who are interested. The pinout difference between the controller and the floppy drive is what makes the famous cable twist seen in PC floppy cables possible. By twisting the cable you are swapping the positions of /DRV1 + /MED1 with /DRV0 + /MED0, hence making the drive with the twist to A: and without twist B:.
« Last Edit: 11:34, 05 May 17 by Bryce »

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #37 on: 13:11, 10 May 17 »
no for good news...

I just installed my new Z80 cpu and my beloved CPC is alive and kicking goals....yeah... ;D

The new cpu are the 8MHz variety...oh do i wish i could push it to their specified 8Mhz speed.... that would make the CPC run like usain bolt LOL.

rpalmer
« Last Edit: 13:14, 10 May 17 by rpalmer »

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #38 on: 09:51, 14 May 17 »
I have just etched and tried an interface with the same pins moved as detailed by bryce, yet I still cannot get the drive to work as expected.

The youtube video
https://youtu.be/XochiSlCAtU shows that the drive spins to get the disc moving after the command "CAT" is issued, but then there is only a "whinny" sound. The command does not return.
If i remove the disc  after the whinny sound starts I get "disc missing" error.

The floppy drive is a TEAC FD-235F and has pin header to set the drive as DS0/DS1 (I chose DS0). It also has a DC/RY select ... guess what I chose RY for disc ready.
I also tried  an Alps DF-354H modified to be DS0 and not DS1... it too failed to work.. although i cant tell if the motor was spinning as the cover blocks seing in motion.

Before anyone says oh you must have a short somewhere to get the drive to make that whinny sound.....

I check the interface for shorts and found none.
I checked the cables and found none there as well.
I checked if the cables to see if they were not aligned when inserted ... they were both properly inserted.
I checked if the pins from the CPC interface went to the correct pins on the floppy drive...guess what they were correctly linked (pin 26 to pin 34, pin 24 to pin 32, etc)

Attached is the PCB photos and eagle layout in PDF.

WHAT HAVE I DONE WRONG?????

I would like to note one of my previous attempts seemed to work, but resulted in the drive making a similar whinny noise and on that occasion the cat command did return. The sound did not stop though.

rpalmer

Offline robcfg

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Re: help with floppy adapter PCB
« Reply #39 on: 10:22, 14 May 17 »
Are you sure the power part is correctly wired?

I mean, it seems that on your pcb you removed the 12v, but if I remember right the power pins are really swapped so you are feeding 5v to the wrong pin.


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Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #40 on: 11:11, 14 May 17 »
robcfg,

If the 12V were fed to the floppy drive then it would not have worked at all as I had disconnected the 12V supply with the monitor (it was not needed anymore) and the drive would have no power at all.

rpalmer

Offline Bryce

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Re: help with floppy adapter PCB
« Reply #41 on: 12:50, 14 May 17 »
What OS are you using? AMSDOS or ParaDOS? If the disk is starting to spin but nothing else happens, then your problem seems to be with the ready signal.

Bryce.

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #42 on: 14:03, 14 May 17 »
bryce,

I am using AMSDOS. I can program an EPROM with paraDOS, but I understand that should not be a problem.

Can't be the ready signal as the TEAC drive provides it. The Alps drive does not but the jumper was tied to ground and so the CPC was seing the drive as 'always' ready.

Rpalmer

Offline Bryce

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Re: help with floppy adapter PCB
« Reply #43 on: 23:26, 14 May 17 »
Are you sure the FDC circuitry is ok? Have you any 3in drive that works on this CPC?

Bryce.

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #44 on: 00:35, 15 May 17 »
Bryce,

Sadly I don't have a spare one, which makes this effort so much more harder to get working.

One of the previous PCBs seemed to work when I was able to get disk catalogs, but I was unable to run anything cleanly. It maybe the discs have corrupted sectors, but again I cant tell easily if the media is kaput or the copy I had the corrupted sectors when copied back. My copy was from original discs of CP/M+ which was used for testing. I was also testing a copy of Disc Master which started up but gave disc errors.

rpalmer

Offline Bryce

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Re: help with floppy adapter PCB
« Reply #45 on: 11:53, 15 May 17 »
The reason I ask is because it is very easy to damage the two output buffers on the FDC if you wrongly connect a drive. I suspect that you have damaged the FDC circuitry and your adapter / disk drives are actually fine.

Bryce.

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #46 on: 13:46, 15 May 17 »
I have a spare FDC chip I could try.

Offline tjohnson

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Re: help with floppy adapter PCB
« Reply #47 on: 02:09, 16 May 17 »
I don't think there is an issue with your FDC, my external drive is playing up and has symptoms like yours but the internal drive is just fine.   Before you start desoldering chips can you get an external cable and connect it to the back of the machine, jumper the ready signal and it should work as drive B.  I would try that before desoldering anything, if that doesn't work then maybe there is another issue somewhere.

Offline rpalmer

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Re: help with floppy adapter PCB
« Reply #48 on: 15:06, 16 May 17 »
tjohnson,

My FDC was socketed and I can replace it when i need to... thank heavens for forward thinking almost 15 years ago.. ;D

rpalmer

Offline tjohnson

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Re: help with floppy adapter PCB
« Reply #49 on: 21:51, 16 May 17 »
tjohnson,

My FDC was socketed and I can replace it when i need to... thank heavens for forward thinking almost 15 years ago.. ;D

rpalmer
That's good.  Do you have an old school floppy cable with the edge connector?  Definitely think it's worth trying that, i have a feeling it might have something to do with the adapter.

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